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Author SHA1 Message Date
Niels LohmannandClaude Sonnet 5 55ff4c9eff test: drop a trailing NUL byte from the nativejson-benchmark 1e308 fixture
The "doubles" compliance test built its 1e308 literal as a std::string
sized to 312 bytes with an explicit trailing '\0' at index 311, relying
on the old NUL-as-EOF lexer behavior removed earlier in this branch: with
that removed, the NUL is ordinary (invalid) trailing data instead of
being silently swallowed, so json::parse() correctly rejected it with
parse_error.101 - breaking CI across every compiler/platform, since this
one nativejson-benchmark TEST_CASE is exercised by every test job.

No padding is needed at all: json::parse(const std::string&) already
uses the string's own size(), not a NUL terminator. Drop the trailing
byte and shrink the string by one to match (index 310 - the new last
index - is where ']' now goes), fixing this the same way the other
pre-existing tests in this branch that depended on the same bug were
already fixed.

Signed-off-by: Niels Lohmann <niels.lohmann@gmail.com>
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4RQ1Ahan5YAGbnAQGjZTY
2026-09-15 10:22:47 +00:00
Niels LohmannandClaude Sonnet 5 633eef8494 fix: treat a NUL byte in the input as an ordinary byte, not EOF
The lexer's token dispatch had `case '\0':` fall through to the same
`end_of_input` handling as the real end-of-file sentinel, with a comment
claiming the NUL case was "needed when parsing from string literals".
That rationale no longer holds: input_adapter(const char*) already uses
strlen() to compute its range, so it never hands the lexer a trailing
NUL, and the const-char* overload is the only "string literal" path the
comment could be referring to. In practice, `case '\0':` only ever fired
on a genuine embedded or trailing NUL byte in real input data (e.g. a
std::string with '\0' appended), which was then silently swallowed as if
it were EOF instead of producing the parse_error.101 any other
unexpected byte gets. Two more spots in the comment-skipping logic had
the same NUL-as-EOF idiom, stopping a `//` or `/* */` comment scan early
at an embedded NUL instead of continuing to the real terminator.

Removing all three still left one real regression: input_adapter's
T(&array)[N] overload (used for a string literal like
json::parse("123"), as opposed to a decayed const char* pointer) passes
the array's full extent through unchanged, trailing '\0' included. That
path was relying on the lexer's old NUL-as-EOF behavior to make ordinary
literal parsing work at all. It now gets its own strlen()-like handling
for char arrays specifically: a single trailing NUL terminator is
excluded, mirroring the pointer overload, while non-char arrays (e.g.
uint8_t buffers for binary formats) are left untouched since a trailing
zero byte there may be data.

Also updates a few existing tests that (mostly incidentally) depended on
a trailing NUL being swallowed - std::array<uint8_t, 5>{"true"} left the
5th element zero-initialized - and adds an FAQ entry.

Signed-off-by: Niels Lohmann <niels.lohmann@gmail.com>
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4RQ1Ahan5YAGbnAQGjZTY
2026-09-15 07:12:35 +00:00
Niels Lohmann e5f84e1ebf refactor: split the strict and non-strict paths in parser
Folding the release_lookahead() call into the existing strict check left
the "in strict mode" comment on an else-if branch, and made the strict
condition in sax_parse() redundant with the branch it followed.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-19 22:50:21 +02:00
Niels Lohmann 7fc3a7d87e docs: drop the whitespace-separator caveat from the parsing pages
The caveat added in #5343 describes the behavior this branch fixes: a
number no longer consumes the character that terminates it, so
concatenated values need no separator.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-19 22:46:12 +02:00
Niels Lohmann 43b689b9b6 Merge remote-tracking branch 'origin/develop' into claude/issue-5340-restore-unget
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-19 22:41:46 +02:00
Niels Lohmann a13902a33f docs: match the version history wording to the peek-based fix
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-04 14:44:23 +02:00
Niels Lohmann c021a09b08 fix: leave the character that terminates a number in the input
Read the character following a number without consuming it, instead of
consuming it and putting it back. input_stream_adapter now peeks with
sgetc() and only steps over the character when the next one is requested
or when the adapter is destroyed, so releasing it cannot fail - no
putback position is required from the streambuf.

Suggested by gregmarr in #5344.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-04 14:39:05 +02:00
Niels Lohmann e4aaf46d38 Merge branch 'develop' into claude/issue-5340-restore-unget
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-04 14:25:17 +02:00
Niels Lohmann 5bc24e876b tests: fix CI failures in the #5340 test helpers
Four CI failures, all in the new test code:

- GCC (-Werror=useless-cast): drop the `json(...)` wrapper around
  `json::parse(...)`, which already returns a `json`.
- GCC (-Werror=unused-result): assign the discarded `json::parse()`
  result to a dummy, the idiom used elsewhere in the test suite, and
  catch `json::parse_error&` for consistency.
- clang-tidy (google-default-arguments): remove the default argument
  from the `pbackfail()` override; `sungetc()` supplies the base
  declaration's default.
- MSVC (bad allocation): `no_putback_streambuf::underflow()` set a
  one-character get area without advancing `m_pos`, so an implementation
  whose `istream::get` peeks before it bumps re-read the same character
  forever. Keep no get area at all: `underflow()` peeks, `uflow()`
  consumes, and `sungetc()` still always lands in `pbackfail()`, which
  is what the test needs.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-03 19:42:06 +02:00
Niels Lohmann da7b9bdb3d fix: restore the character that terminates a number (#5340)
operator>> is documented to leave the stream positioned right after the
parsed value, so that concatenated JSON values can be read back to back.
That did not hold for numbers: a number is only terminated by the
character following it, and lexer::scan_number() reads that character
and calls unget() -- which is simulated and rewinds only the lexer's own
bookkeeping. input_stream_adapter consumes via sbumpc() with no matching
sungetc(), so the terminating character stayed consumed and the next
extraction started one byte too late ('1true' left the stream at 'rue').

Propagating unget() to the adapter directly does not work: next_unget
makes the following get() replay the cached character, so the terminator
would be delivered twice. Instead, restore the still-pending character
once at the end of a non-strict parse, where the input is handed back to
the caller:

- input_stream_adapter gains unget_character() (sungetc()) and advertises
  it via supports_unget, detected the same way as supports_seek.
- lexer::restore_pending_unget() turns a pending simulated unget of a
  real (non-EOF) character into a real one and clears next_unget so the
  character is not also replayed. It is a no-op for adapters that cannot
  unget, and reports failure when sungetc() fails, in which case the
  input is left as it was before.
- parser calls it on the three non-strict paths, i.e. for operator>> and
  sax_parse(strict = false).

Strict parse()/accept() are unaffected: they require the input to end
after the value, so the character is consumed by the end-of-input check
anyway. Parse error messages and reported positions are unchanged.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-01 07:33:11 +02:00
Niels Lohmann 634f49bc5b docs: qualify the operator>> stream positioning guarantee
operator>>'s notes state that it leaves the stream positioned right
after the parsed value, so that concatenated JSON values can be read
back to back. That does not hold when the value is a number: a number
is only terminated by the character that follows it, and the lexer's
unget() is simulated (it rewinds only the lexer's own bookkeeping),
so that character stays consumed from the stream.

Document the actual behaviour: the guarantee holds for all value types
except numbers, which must be followed by whitespace. Also qualify the
cross-reference on the JSON Lines page, which repeated the unqualified
claim.

Documentation only; the behaviour itself is tracked in #5340.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-01 07:27:53 +02:00
195 changed files with 5420 additions and 24445 deletions
+1 -12
View File
@@ -108,9 +108,7 @@ The tests are located in [`tests/src/unit-*.cpp`](https://github.com/nlohmann/js
are structured along the features of the library or the nature of the tests. Usually, it should be clear from the
context which existing file needs to be extended, and only very few cases require creating new test files.
When fixing a bug, edit `unit-regression3.cpp` and add a section referencing the fixed issue.
`unit-regression2.cpp` holds the older tests; the two files exist because a single one grew large enough for the
MinGW linker to fail relocating it, so please keep adding to the smaller file rather than growing the larger one.
When fixing a bug, edit `unit-regression2.cpp` and add a section referencing the fixed issue.
#### Exceptions
@@ -158,15 +156,6 @@ make amalgamate
Running `make amalgamate` will also apply automatic formatting to the source files using
[`Artistic Style`](https://astyle.sourceforge.net/). This formatting may modify your source files in-place. Be certain to review and commit any changes to avoid unintended formatting diffs in commits.
If you add, rename, or remove a header in `include/nlohmann`, also regenerate the header list in
[`BUILD.bazel`](https://github.com/nlohmann/json/blob/develop/BUILD.bazel) (requires CMake) by executing:
```shell
make BUILD.bazel
```
The amalgamation check in CI fails if any of these generated files is out of date.
## Recommended documentation
- The library’s [README file](https://github.com/nlohmann/json/blob/master/README.md) is an excellent starting point to
-1
View File
@@ -2,7 +2,6 @@
- [ ] The changes are described in detail, both the what and why.
- [ ] If applicable, an [existing issue](https://github.com/nlohmann/json/issues) is referenced.
- [ ] If applicable, a fixed [OSS-Fuzz](https://issues.oss-fuzz.com) issue is referenced as `OSS-Fuzz: <id>` (see [fuzz testing](https://github.com/nlohmann/json/blob/develop/tests/fuzzing.md#handling-oss-fuzz-reports)).
- [ ] The [Code coverage](https://coveralls.io/github/nlohmann/json) remained at 100%. A test case for every new line of code.
- [ ] If applicable, the [documentation](https://json.nlohmann.me) is updated.
- [ ] The source code is amalgamated by running `make amalgamate`.
-21
View File
@@ -29,27 +29,6 @@ labels:
files:
- ".github/external_ci/.*"
- label: "CI"
files:
- ".github/(dependabot|labeler)\\.yml"
- label: "aspect: binary formats"
files:
- "include/nlohmann/detail/input/binary_reader\\.hpp"
- "include/nlohmann/detail/output/binary_writer\\.hpp"
- "tests/src/unit-(bson|cbor|msgpack|ubjson|bjdata|binary_formats)"
- "tests/src/fuzzer-parse_(bson|cbor|msgpack|ubjson|bjdata)"
- "docs/mkdocs/docs/features/binary_formats/"
- "docs/mkdocs/docs/(api/basic_json|examples)/(to|from)_(bson|cbor|msgpack|ubjson|bjdata)"
- label: "aspect: binary formats"
title: "(?i)(bson|cbor|msgpack|messagepack|ubjson|bjdata|binary format)"
- label: "python"
files:
- "\\.py$"
- "requirements[^/]*\\.txt$"
- label: "S"
size-below: 10
- label: "M"
+5 -18
View File
@@ -11,7 +11,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -34,7 +34,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -57,31 +57,18 @@ jobs:
python3 -mvenv venv
venv/bin/pip3 install -r $MAIN_DIR/tools/astyle/requirements.txt
- name: Regenerate amalgamation, formatting, and BUILD.bazel
- name: Regenerate amalgamation and formatting
run: |
cd $MAIN_DIR
python3 $TOOL_DIR/amalgamate.py -c $TOOL_DIR/config_json.json -s .
python3 $TOOL_DIR/amalgamate.py -c $TOOL_DIR/config_json_fwd.json -s .
# the header list of the Bazel "json" target must match the files in include/
cmake -P cmake/scripts/gen_bazel_build_file.cmake
${{ github.workspace }}/venv/bin/astyle --project=tools/astyle/.astylerc --suffix=none --quiet \
$INCLUDE_DIR/json.hpp $INCLUDE_DIR/json_fwd.hpp
# fail loudly if a directory is renamed or removed: find would only warn
# about the missing path and silently drop its files from the check
SOURCE_DIRS="docs/mkdocs/docs/examples include tests"
for DIR in $SOURCE_DIRS; do
if [ ! -d "$DIR" ]; then
echo "::error::source directory '$DIR' does not exist"
exit 1
fi
done
${{ github.workspace }}/venv/bin/astyle --project=tools/astyle/.astylerc --suffix=none --quiet \
$(find $SOURCE_DIRS -type f \( -name '*.hpp' -o -name '*.cpp' -o -name '*.cu' \) -not -path 'tests/thirdparty/*' -not -path 'tests/abi/include/nlohmann/*' | sort)
$(find docs/examples include tests -type f \( -name '*.hpp' -o -name '*.cpp' -o -name '*.cu' \) -not -path 'tests/thirdparty/*' -not -path 'tests/abi/include/nlohmann/*' | sort)
- name: Build patch and check for differences
id: diff
@@ -90,7 +77,7 @@ jobs:
mkdir -p ${{ github.workspace }}/patch
git diff --patch --no-color > ${{ github.workspace }}/patch/amalgamation.patch
if [ -s ${{ github.workspace }}/patch/amalgamation.patch ]; then
echo "The source code has not been amalgamated/formatted correctly or BUILD.bazel is out of date. Diff:"
echo "The source code has not been amalgamated/formatted correctly. Diff:"
cat ${{ github.workspace }}/patch/amalgamation.patch
echo "has_diff=true" >> "$GITHUB_OUTPUT"
else
+1 -1
View File
@@ -9,7 +9,7 @@ jobs:
runs-on: ubuntu-22.04
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
+4 -4
View File
@@ -27,7 +27,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -38,14 +38,14 @@ jobs:
# Initializes the CodeQL tools for scanning.
- name: Initialize CodeQL
uses: github/codeql-action/init@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
uses: github/codeql-action/init@5595ccaf912efad79be6eef63a5619ff05969be3 # v4.37.6
with:
languages: c-cpp
# Autobuild attempts to build any compiled languages (C/C++, C#, or Java).
# If this step fails, then you should remove it and run the build manually (see below)
- name: Autobuild
uses: github/codeql-action/autobuild@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
uses: github/codeql-action/autobuild@5595ccaf912efad79be6eef63a5619ff05969be3 # v4.37.6
- name: Perform CodeQL Analysis
uses: github/codeql-action/analyze@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
uses: github/codeql-action/analyze@5595ccaf912efad79be6eef63a5619ff05969be3 # v4.37.6
@@ -19,7 +19,7 @@ jobs:
pull-requests: write
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -95,13 +95,13 @@ jobs:
issue_number: issue_number,
owner: context.repo.owner,
repo: context.repo.repo,
body: '## 🔴 Amalgamation check failed! 🔴\nThe source code has not been amalgamated and/or formatted correctly, or `BUILD.bazel` is out of date.'
body: '## 🔴 Amalgamation check failed! 🔴\nThe source code has not been amalgamated and/or formatted correctly.'
+ (hasPatch ? '\n\n📎 A ready-to-apply patch is attached to the [failed workflow run](' + runUrl + ') as the `amalgamation-patch` artifact.'
+ ' Download it, then apply it locally from the repository root with:'
+ '\n\n```shell\ngit apply amalgamation.patch\n```\n\n'
+ 'This does not require installing astyle yourself.'
: '')
+ (first ? '\n\n@' + author + ' Please read and follow the [Contribution Guidelines]'
+ '(https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md#amalgamate-the-source-code).'
+ '(https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md#files-to-change).'
: '')
})
+1 -1
View File
@@ -17,7 +17,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
+2 -2
View File
@@ -27,7 +27,7 @@ jobs:
security-events: write
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -43,6 +43,6 @@ jobs:
output: 'flawfinder_results.sarif'
- name: Upload analysis results to GitHub Security tab
uses: github/codeql-action/upload-sarif@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
uses: github/codeql-action/upload-sarif@5595ccaf912efad79be6eef63a5619ff05969be3 # v4.37.6
with:
sarif_file: ${{github.workspace}}/flawfinder_results.sarif
+1 -1
View File
@@ -17,7 +17,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
+2 -1
View File
@@ -7,6 +7,7 @@ on:
- develop
paths:
- docs/mkdocs/**
- docs/examples/**
workflow_dispatch:
# we don't want to have concurrent jobs, and we don't want to cancel running jobs to avoid broken publications
@@ -26,7 +27,7 @@ jobs:
runs-on: ubuntu-22.04
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
+2 -2
View File
@@ -36,7 +36,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -76,6 +76,6 @@ jobs:
# Upload the results to GitHub's code scanning dashboard.
- name: "Upload to code-scanning"
uses: github/codeql-action/upload-sarif@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
uses: github/codeql-action/upload-sarif@5595ccaf912efad79be6eef63a5619ff05969be3 # v4.37.6
with:
sarif_file: results.sarif
+2 -2
View File
@@ -32,7 +32,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -61,7 +61,7 @@ jobs:
# Upload SARIF file generated in previous step
- name: Upload SARIF file
uses: github/codeql-action/upload-sarif@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
uses: github/codeql-action/upload-sarif@5595ccaf912efad79be6eef63a5619ff05969be3 # v4.37.6
with:
sarif_file: semgrep.sarif
if: always()
+1 -1
View File
@@ -16,7 +16,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
+6 -6
View File
@@ -35,7 +35,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -60,7 +60,7 @@ jobs:
target: [ci_test_amalgamation, ci_test_single_header, ci_cppcheck, ci_cpplint, ci_reproducible_tests, ci_non_git_tests, ci_offline_testdata, ci_reuse_compliance, ci_test_valgrind]
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -100,7 +100,7 @@ jobs:
container: ubuntu:focal
strategy:
matrix:
target: [ci_cmake_flags, ci_test_diagnostics, ci_test_diagnostic_positions, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls, ci_test_disableenumserialization, ci_test_skiplibraryversioncheck, ci_test_simdutf, ci_test_strict_nul_handling, ci_test_no_thread_local]
target: [ci_cmake_flags, ci_test_diagnostics, ci_test_diagnostic_positions, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls]
steps:
- name: Install build-essential
run: apt-get update ; apt-get install -y build-essential unzip wget git libssl-dev
@@ -118,7 +118,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -369,7 +369,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
@@ -392,7 +392,7 @@ jobs:
target: [ci_test_examples, ci_test_build_documentation]
steps:
- name: Harden Runner
uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
with:
egress-policy: audit
+2 -6
View File
@@ -124,11 +124,11 @@ jobs:
steps:
- uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
- name: Run CMake (Release)
run: cmake -S . -B build -G "Visual Studio 18 2026" -A ARM64 -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/W4 /WX"
run: cmake -S . -B build -G "Visual Studio 17 2022" -A ARM64 -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/W4 /WX"
if: matrix.build_type == 'Release'
shell: pwsh
- name: Run CMake (Debug)
run: cmake -S . -B build -G "Visual Studio 18 2026" -A ARM64 -DJSON_BuildTests=On -DJSON_FastTests=ON -DCMAKE_CXX_FLAGS="/W4 /WX"
run: cmake -S . -B build -G "Visual Studio 17 2022" -A ARM64 -DJSON_BuildTests=On -DJSON_FastTests=ON -DCMAKE_CXX_FLAGS="/W4 /WX"
if: matrix.build_type == 'Debug'
shell: pwsh
- name: Build
@@ -158,10 +158,6 @@ jobs:
# to fit: IMAGE_REL_AMD64_SECREL against `.debug_line'" because the
# MinGW linker cannot relocate the debug sections this test produces.
# The tests are only built and run here, so the debug info is not used.
# Do not add -O1 here to shrink the objects further: it does make them
# link, but the binaries clang 11.0.1 and clang 18.1.8 then produce crash
# before doctest prints its first line - 39 of 102 tests on clang 18.
# Keep the objects small by splitting the test files instead.
- name: Run CMake
run: cmake -S . -B build ^
-DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" ^
+1 -4
View File
@@ -30,10 +30,8 @@ cc_library(
"include/nlohmann/detail/input/input_adapters.hpp",
"include/nlohmann/detail/input/json_sax.hpp",
"include/nlohmann/detail/input/lexer.hpp",
"include/nlohmann/detail/input/number_parse.hpp",
"include/nlohmann/detail/input/parser.hpp",
"include/nlohmann/detail/input/position_t.hpp",
"include/nlohmann/detail/input/string_scan.hpp",
"include/nlohmann/detail/iterators/internal_iterator.hpp",
"include/nlohmann/detail/iterators/iter_impl.hpp",
"include/nlohmann/detail/iterators/iteration_proxy.hpp",
@@ -51,14 +49,12 @@ cc_library(
"include/nlohmann/detail/meta/detected.hpp",
"include/nlohmann/detail/meta/identity_tag.hpp",
"include/nlohmann/detail/meta/is_sax.hpp",
"include/nlohmann/detail/meta/logic.hpp",
"include/nlohmann/detail/meta/std_fs.hpp",
"include/nlohmann/detail/meta/type_traits.hpp",
"include/nlohmann/detail/meta/void_t.hpp",
"include/nlohmann/detail/output/binary_writer.hpp",
"include/nlohmann/detail/output/output_adapters.hpp",
"include/nlohmann/detail/output/serializer.hpp",
"include/nlohmann/detail/recursion_depth_limit.hpp",
"include/nlohmann/detail/string_concat.hpp",
"include/nlohmann/detail/string_escape.hpp",
"include/nlohmann/detail/string_utils.hpp",
@@ -71,6 +67,7 @@ cc_library(
],
includes = ["include"],
visibility = ["//visibility:public"],
alwayslink = True,
)
cc_library(
-6
View File
@@ -59,7 +59,6 @@ option(JSON_LegacyDiscardedValueComparison "Enable legacy discarded value compar
option(JSON_Install "Install CMake targets during install step." ${MAIN_PROJECT})
option(JSON_MultipleHeaders "Use non-amalgamated version of the library." ON)
option(JSON_SystemInclude "Include as system headers (skip for clang-tidy)." OFF)
option(JSON_StrictNulHandling "Build with strict NUL-byte handling enabled." OFF)
if (JSON_CI)
include(ci)
@@ -109,10 +108,6 @@ if (JSON_Diagnostics)
message(STATUS "Diagnostics enabled (JSON_DIAGNOSTICS=1)")
endif()
if (JSON_StrictNulHandling)
message(STATUS "Strict NUL-byte handling enabled (JSON_STRICT_NUL_HANDLING=1)")
endif()
if (JSON_Diagnostic_Positions)
message(STATUS "Diagnostic positions enabled (JSON_DIAGNOSTIC_POSITIONS=1)")
endif()
@@ -146,7 +141,6 @@ target_compile_definitions(
$<$<BOOL:${JSON_Diagnostics}>:JSON_DIAGNOSTICS=1>
$<$<BOOL:${JSON_Diagnostic_Positions}>:JSON_DIAGNOSTIC_POSITIONS=1>
$<$<BOOL:${JSON_LegacyDiscardedValueComparison}>:JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1>
$<$<BOOL:${JSON_StrictNulHandling}>:JSON_STRICT_NUL_HANDLING=1>
)
target_include_directories(
+1 -5
View File
@@ -250,16 +250,12 @@ Further documentation:
### `BUILD.bazel`
The build definition for [Bazel](https://bazel.build). The file is generated by
`cmake/scripts/gen_bazel_build_file.cmake`, which derives the header list from the files in `include`; change the
script rather than editing the file by hand. The file can be updated by calling
The file can be updated by calling
```shell
make BUILD.bazel
```
The "Check amalgamation" workflow fails if the file is out of date.
### `meson.build`
The build definition for the [Meson](https://mesonbuild.com) build system.
+5 -26
View File
@@ -1,4 +1,4 @@
.PHONY: pretty clean ChangeLog.md release update_hedley update_hedley_undef BUILD.bazel
.PHONY: pretty clean ChangeLog.md release
##########################################################################
# configuration
@@ -30,9 +30,8 @@ AMALGAMATED_FWD_FILE=single_include/nlohmann/json_fwd.hpp
# main target
all:
@echo "amalgamate - amalgamate files single_include/nlohmann/json{,_fwd}.hpp from the include/nlohmann sources"
@echo "BUILD.bazel - regenerate the Bazel BUILD file from the include/nlohmann sources"
@echo "ChangeLog.md - generate ChangeLog file"
@echo "check-amalgamation - check whether sources have been amalgamated and BUILD.bazel is up to date"
@echo "check-amalgamation - check whether sources have been amalgamated"
@echo "clean - remove built files"
@echo "doctest - compile example files and check their output"
@echo "fuzz_testing - prepare fuzz testing of the JSON parser"
@@ -42,8 +41,6 @@ all:
@echo "fuzz_testing_ubjson - prepare fuzz testing of the UBJSON parser"
@echo "pretty - beautify code with Artistic Style"
@echo "run_benchmarks - build and run benchmarks"
@echo "update_hedley - download Hedley and regenerate hedley.hpp / hedley_undef.hpp"
@echo "update_hedley_undef - rebuild hedley_undef.hpp from the JSON_HEDLEY_* #define names in hedley.hpp"
##########################################################################
@@ -173,13 +170,8 @@ check-amalgamation:
@diff $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_FWD_FILE)~ || (echo "===================================================================\n Amalgamation required! Please read the contribution guidelines\n in file .github/CONTRIBUTING.md.\n===================================================================" ; mv $(AMALGAMATED_FWD_FILE)~ $(AMALGAMATED_FWD_FILE) ; false)
@mv $(AMALGAMATED_FILE)~ $(AMALGAMATED_FILE)
@mv $(AMALGAMATED_FWD_FILE)~ $(AMALGAMATED_FWD_FILE)
@mv BUILD.bazel BUILD.bazel~
@$(MAKE) BUILD.bazel
@diff BUILD.bazel BUILD.bazel~ || (echo "===================================================================\n BUILD.bazel is out of date! Please run 'make BUILD.bazel'.\n===================================================================" ; mv BUILD.bazel~ BUILD.bazel ; false)
@mv BUILD.bazel~ BUILD.bazel
# generate the Bazel BUILD file; phony, because a removed header would not trigger a rebuild
BUILD.bazel:
BUILD.bazel: $(SRCS)
cmake -P cmake/scripts/gen_bazel_build_file.cmake
##########################################################################
@@ -249,24 +241,11 @@ update_hedley:
rm -f include/nlohmann/thirdparty/hedley/hedley.hpp include/nlohmann/thirdparty/hedley/hedley_undef.hpp
curl https://raw.githubusercontent.com/nemequ/hedley/master/hedley.h -o include/nlohmann/thirdparty/hedley/hedley.hpp
$(SED) -i 's/HEDLEY_/JSON_HEDLEY_/g' include/nlohmann/thirdparty/hedley/hedley.hpp
grep "[[:blank:]]*#[[:blank:]]*undef" include/nlohmann/thirdparty/hedley/hedley.hpp | grep -v "__" | sort | uniq | $(SED) 's/ //g' | $(SED) 's/undef/undef /g' > include/nlohmann/thirdparty/hedley/hedley_undef.hpp
$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley.hpp
$(MAKE) update_hedley_undef
$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley_undef.hpp
$(MAKE) amalgamate
# Rebuild hedley_undef.hpp from every JSON_HEDLEY_* name that hedley.hpp
# #defines. Hedley does not #undef all of its public macros internally (see
# #5408), so grepping those #undef lines misses names such as
# JSON_HEDLEY_PRAGMA. cmake/scripts/gen_hedley_undef_check.cmake is the
# single source of truth for this extraction (tests/CMakeLists.txt uses the
# same script, in MODE=checks, to generate the matching leak-check test), so
# the vendored header, the generated #undef list, and the regression test
# cannot drift apart.
update_hedley_undef:
cmake -DHEDLEY_HPP=include/nlohmann/thirdparty/hedley/hedley.hpp \
-DOUTPUT=include/nlohmann/thirdparty/hedley/hedley_undef.hpp \
-DMODE=undef \
-P cmake/scripts/gen_hedley_undef_check.cmake
##########################################################################
# serve_header.py
##########################################################################
+7 -67
View File
@@ -1421,7 +1421,7 @@ I deeply appreciate the help of the following people.
6. [Joshua C. Randall](https://github.com/jrandall) fixed a bug in the floating-point serialization.
7. [Aaron Burghardt](https://github.com/aburgh) implemented code to parse streams incrementally. Furthermore, he greatly improved the parser class by allowing the definition of a filter function to discard undesired elements while parsing.
8. [Daniel Kopeček](https://github.com/dkopecek) fixed a bug in the compilation with GCC 5.0.
9. [Fiona Johanna Weber](https://github.com/Fiona-J-W) fixed a bug in and improved the performance of the comparison operators.
9. [Florian Weber](https://github.com/Florianjw) fixed a bug in and improved the performance of the comparison operators.
10. [Eric Cornelius](https://github.com/EricMCornelius) pointed out a bug in the handling with NaN and infinity values. He also improved the performance of the string escaping.
11. [易思龙](https://github.com/likebeta) implemented a conversion from anonymous enums.
12. [kepkin](https://github.com/kepkin) patiently pushed forward the support for Microsoft Visual Studio.
@@ -1523,14 +1523,14 @@ I deeply appreciate the help of the following people.
108. [Kevin Tonon](https://github.com/ktonon) overworked the C++11 compiler checks in CMake.
109. [Axel Huebl](https://github.com/ax3l) simplified a CMake check and added support for the [Spack package manager](https://spack.io).
110. [Carlos O'Ryan](https://github.com/coryan) fixed a typo.
111. [James Upjohn](https://github.com/jupjohn) fixed a version number in the compilers section.
111. [James Upjohn](https://github.com/jammehcow) fixed a version number in the compilers section.
112. [Chuck Atkins](https://github.com/chuckatkins) adjusted the CMake files to the CMake packaging guidelines and provided documentation for the CMake integration.
113. [Jan Schöppach](https://github.com/dns13) fixed a typo.
114. [martin-mfg](https://github.com/martin-mfg) fixed a typo.
115. [Matthias Möller](https://github.com/TinyTinni) removed the dependency from `std::stringstream`.
116. [agrianius](https://github.com/agrianius) added code to use alternative string implementations.
117. [Daniel599](https://github.com/Daniel599) allowed to use more algorithms with the `items()` function.
118. [Julius Rakow](https://github.com/juliusrakow) fixed the Meson include directory and fixed the links to [cppreference.com](https://cppreference.com).
118. [Julius Rakow](https://github.com/jrakow) fixed the Meson include directory and fixed the links to [cppreference.com](https://cppreference.com).
119. [Sonu Lohani](https://github.com/sonulohani) fixed the compilation with MSVC 2015 in debug mode.
120. [grembo](https://github.com/grembo) fixed the test suite and re-enabled several test cases.
121. [Hyeon Kim](https://github.com/simnalamburt) introduced the macro `JSON_INTERNAL_CATCH` to control the exception handling inside the library.
@@ -1581,7 +1581,7 @@ I deeply appreciate the help of the following people.
166. [Mark Beckwith](https://github.com/wythe) fixed a typo.
167. [yann-morin-1998](https://github.com/yann-morin-1998) helped to reduce the CMake requirement to version 3.1.
168. [Konstantin Podsvirov](https://github.com/podsvirov) maintains a package for the MSYS2 software distro.
169. [remyabel](https://github.com/remyabel2) added GNUInstallDirs to the CMake files.
169. [remyabel](https://github.com/remyabel) added GNUInstallDirs to the CMake files.
170. [Taylor Howard](https://github.com/taylorhoward92) fixed a unit test.
171. [Gabe Ron](https://github.com/Macr0Nerd) implemented the `to_string` method.
172. [Watal M. Iwasaki](https://github.com/heavywatal) fixed a Clang warning.
@@ -1608,7 +1608,7 @@ I deeply appreciate the help of the following people.
193. [Hubert Chathi](https://github.com/uhoreg) made CMake's version config file architecture-independent.
194. [OmnipotentEntity](https://github.com/OmnipotentEntity) implemented the binary values for CBOR, MessagePack, BSON, and UBJSON.
195. [ArtemSarmini](https://github.com/ArtemSarmini) fixed a compilation issue with GCC 10 and fixed a leak.
196. [Evgenii Sopov](https://github.com/sea5kg) integrated the library to the wsjcpp package manager.
196. [Evgenii Sopov](https://github.com/sea-kg) integrated the library to the wsjcpp package manager.
197. [Sergey Linev](https://github.com/linev) fixed a compiler warning.
198. [Miguel Magalhães](https://github.com/magamig) fixed the year in the copyright.
199. [Gareth Sylvester-Bradley](https://github.com/garethsb-sony) fixed a compilation issue with MSVC.
@@ -1702,7 +1702,7 @@ I deeply appreciate the help of the following people.
287. [NN](https://github.com/NN---) added the Visual Studio output directory to `.gitignore`.
288. [Romain Reignier](https://github.com/romainreignier) improved the performance of the vector output adapter.
289. [Mike](https://github.com/Mike-Leo-Smith) fixed the `std::iterator_traits`.
290. [Richard Hozák](https://github.com/richardhozak) added macro `JSON_NO_ENUM` to disable default enum conversions.
290. [Richard Hozák](https://github.com/zxey) added macro `JSON_NO_ENUM` to disable default enum conversions.
291. [vakokako](https://github.com/vakokako) fixed tests when compiling with C++20.
292. [Alexander “weej” Jones](https://github.com/alexweej) fixed an example in the README.
293. [Eli Schwartz](https://github.com/eli-schwartz) added more files to the `include.zip` archive.
@@ -1727,7 +1727,7 @@ I deeply appreciate the help of the following people.
312. [Gareth Sylvester-Bradley](https://github.com/garethsb) added `operator/=` and `operator/` to construct JSON pointers.
313. [Michael Macnair](https://github.com/mykter) added support for afl-fuzz testing.
314. [Berkus Decker](https://github.com/berkus) fixed a typo in the README.
315. [Illia Polishchuk](https://github.com/ilqvya) improved the CMake testing.
315. [Illia Polishchuk](https://github.com/effolkronium) improved the CMake testing.
316. [Ikko Ashimine](https://github.com/eltociear) fixed a typo.
317. [Raphael Grimm](https://github.com/barcode) added the possibility to define a custom base class.
318. [tocic](https://github.com/tocic) fixed typos in the documentation.
@@ -1797,66 +1797,6 @@ I deeply appreciate the help of the following people.
382. [bitFiedler](https://github.com/bitFiedler) made GDB pretty printer work with Python 3.8.
383. [Gianfranco Costamagna](https://github.com/LocutusOfBorg) fixed a compiler warning.
384. [risa2000](https://github.com/risa2000) made `std::filesystem::path` conversion to/from UTF-8 encoded string explicit.
385. [AM](https://github.com/maqnouch) fixed typos in the README.
386. [dmenendez-gruposantander](https://github.com/dmenendez-gruposantander) fixed typos in the comments of the examples.
387. [Mihai Stan](https://github.com/mstan-xx) fixed comparisons against the literal `0`.
388. [Matt Gumbel](https://github.com/intelmatt) fixed some `-Weffc++` warnings.
389. [vimpunk](https://github.com/vimpunk) moved a lambda out of an unevaluated context to support older compilers.
390. [Chris Harris](https://github.com/cjh1) fixed the compilation with GCC 4.8.
391. [Palmer Dabbelt](https://github.com/palmer-dabbelt) generated and installed a pkg-config file.
392. [Gus Pozuelo](https://github.com/ap-viavi) made `ordered_map` compatible with GCC 5.5, Clang 3.6, and Xcode 9.
393. [AK](https://github.com/Lioncky) fixed an MSVC build error caused by the `min`/`max` macros from `windows.h`.
394. [Sergiu Deitsch](https://github.com/sergiud) provided a fallback for missing `char8_t` support.
395. [Xiaochuan Ye](https://github.com/XueSongTap) fixed `from_msgpack` for `std::byte` input by specializing `std::char_traits`.
396. [Ville Vesilehto](https://github.com/thevilledev) fixed an overflow in the BJData size calculation and rejected overflowing negative integers in CBOR.
397. [NmPassTHFan](https://github.com/nmpassthf) replaced the deprecated `std::is_trivial` for C++26.
398. [Chris Ever](https://github.com/chirsz-ever) added the `ignore_trailing_commas` parser option.
399. [Kuan-Fu Wu](https://github.com/kfwu1999) fixed the example code for `json_pointer` initialization.
400. [David Kilzer](https://github.com/ddkilzer) added a missing header to the input adapters.
401. [Miko](https://github.com/mikomikotaishi) added proper C++20 module support, simplified the module API, and fixed missing exports.
402. [hitgirl](https://github.com/hitgil) fixed the CMake configuration when cross-compiling.
403. [Devon Thomas](https://github.com/ThomaDevOSU) mentioned the Artistic Style formatting in the contribution guidelines.
404. [Erik Hu](https://github.com/Erikhu1) made Coveralls upload errors non-fatal in the CI.
405. [co63oc](https://github.com/co63oc) fixed typos.
406. [DmitriBogdanov](https://github.com/DmitriBogdanov) fixed broken package manager links in the documentation.
407. [Bander](https://github.com/banderzhm) improved the MSVC compatibility of the C++ modules.
408. [Andy Choi](https://github.com/ccpong) removed an unnecessary `template` keyword before `get` in the README and the documentation.
409. [SamareshSingh](https://github.com/ssam18) fixed single-element brace initialization to copy/move instead of wrapping in an array, fixed the `WITH_DEFAULT` macros for `ordered_map`, and handled moved events in `serve_header.py`.
410. [Aditya](https://github.com/Lumowhisp) improved the documentation of the documentation generation.
411. [cheese1](https://github.com/cheese1) clarified the README.
412. [KhloodElhossiny](https://github.com/khloodelhossiny) enabled `std::string_view` keys in `operator[]`.
413. [Charles Cabergs](https://github.com/cacharle) fixed a `-Wtautological-constant-out-of-range-compare` warning.
414. [EALePain](https://github.com/EALePain) made the `std::tuple` conversion work with reference types such as `std::tie`.
415. [koala_oishi](https://github.com/chibi-dogs) fixed grammatical wording in the README.
416. [riccardoori11](https://github.com/riccardoori11) fixed a typo in the documentation.
417. [Swastik Bose](https://github.com/VasuBhakt) fixed the parent pointers after `update()` with `JSON_DIAGNOSTICS` and fixed the Doxygen autolinking of requirements.
418. [trdesilva](https://github.com/trdesilva) added `front`, `pop_front`, and `push_front` to `json_pointer`.
419. [Akhilesh Arora](https://github.com/akhilesharora) fixed an incomplete-type error with `ordered_json`.
420. [Hariom Phulre](https://github.com/hariomphulre) fixed the C++20 modules compilation with GCC.
421. [Kirill Lokotkov](https://github.com/RUSLoker) fixed printing `long double` values.
422. [George Sedov](https://github.com/radistmorse) added the `NLOHMANN_DEFINE_TYPE_*_WITH_NAMES` macros.
423. [Caillin Nugent](https://github.com/nugentcaillin) added the `NLOHMANN_JSON_SERIALIZE_ENUM_STRICT` macro.
424. [Cosmin D.](https://github.com/drcosmin) fixed `std::filesystem::path` conversions and added an MSVC workaround for `std::unique_ptr`.
425. [Paul Dreik](https://github.com/pauldreik) fixed a test relying on implementation-specific behavior.
426. [Daniel Falk](https://github.com/daniel-falk) added missing copyright notices to the SBOM.
427. [Federico Sfriso](https://github.com/federicosfriso05-dotcom) added support for constructing JSON values from C++20 range views.
428. [Luke Banicevic](https://github.com/banaboi) fixed corrupt BSON output for lengths exceeding `INT32_MAX`, cleaned up the BSON writer, and improved the documentation.
429. [Patrick Armstrong](https://github.com/Patrick10199) updated the CBOR references and the half-precision float assertions.
430. [Yash Bavadiya](https://github.com/xevrion) added checks to all BSON reads.
431. [hum4nBeing](https://github.com/hum4nBeing) fixed the overflow handling of high-precision numbers in UBJSON.
432. [tomatotomata](https://github.com/tomatotomata) added checks for reading CBOR tagged subtypes.
433. [YingqiDuan](https://github.com/YingqiDuan) documented the BSON interoperability.
434. [KBS](https://github.com/youdie006) documented the standards compliance and the strictness of `parse()` and `operator>>`.
435. [Petr Bělohlávek](https://github.com/petrbel) added Clang 21 and 22 to the CI.
436. [Dmitry Rantovov](https://github.com/darkdi) fixed the placement of a CBOR documentation block.
437. [ljcjclljc](https://github.com/ljcjclljc) fixed the comparison of large unsigned integers with signed integers.
438. [Sahil Kamate](https://github.com/sahilkamate03) fixed the handling of CBOR tags 0-5 and 21-23.
439. [Krishnanand G](https://github.com/Krishnanand-G) made the UBJSON writer reject `use_type` without `use_size`.
440. [whn](https://github.com/Whning0513) documented the lenient BSON input handling and corrected the complexity of `to_bson`.
441. [elix3r](https://github.com/22elix3r) fixed `update()` with `merge_objects` when merging a primitive into an object.
442. [Avionic Harshit](https://github.com/avionicharshit-byte) made `diff()` linear when an array shrinks.
443. [Qatadaha Bin Matloob](https://github.com/qatcod) fixed comparisons between integers and floats and fixed unparsable BJData output.
444. [Wu Shuwen](https://github.com/dajiaohuang) removed an unused include.
Thanks a lot for helping out! Please [let me know](mailto:mail@nlohmann.me) if I forgot someone.
+9 -82
View File
@@ -213,38 +213,18 @@ add_custom_target(ci_test_legacycomparison
)
###############################################################################
# Validate UTF-8 with simdutf.
# Enable brace-init copy semantics.
###############################################################################
add_custom_target(ci_test_simdutf
add_custom_target(ci_test_brace_init_copy_semantics
COMMAND ${CMAKE_COMMAND}
-DCMAKE_BUILD_TYPE=Debug -GNinja
-DJSON_BuildTests=ON -DJSON_TestSimdutf=ON
# simdutf needs C++17, so the library falls back to its scalar validator
# below that: build the suite at C++11 to cover the fallback with the macro
# defined, and at C++17 to run every test against simdutf itself
"-DJSON_TestStandards=11\;17"
-S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_simdutf
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_simdutf
COMMAND cd ${PROJECT_BINARY_DIR}/build_simdutf && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
COMMENT "Compile and test with simdutf UTF-8 validation enabled"
)
###############################################################################
# Enable strict NUL-byte handling.
###############################################################################
add_custom_target(ci_test_strict_nul_handling
COMMAND ${CMAKE_COMMAND}
-DCMAKE_BUILD_TYPE=Debug -GNinja
-DJSON_BuildTests=ON -DJSON_FastTests=ON -DJSON_StrictNulHandling=ON
-S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_strict_nul_handling
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_strict_nul_handling
# unit-testsuites contains a fixture (a "1e308" test value) that relies on the
# legacy NUL-as-end-of-input behavior this macro disables; exclude it here, as
# it is expected to fail under strict NUL handling and is out of scope for it
COMMAND cd ${PROJECT_BINARY_DIR}/build_strict_nul_handling && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure -E "test-testsuites"
COMMENT "Compile and test with strict NUL-byte handling enabled"
-DJSON_BuildTests=ON -DJSON_FastTests=ON
-DCMAKE_CXX_FLAGS=-DJSON_BRACE_INIT_COPY_SEMANTICS=1
-S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_brace_init_copy_semantics
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_brace_init_copy_semantics
COMMAND cd ${PROJECT_BINARY_DIR}/build_brace_init_copy_semantics && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
COMMENT "Compile and test with brace-init copy semantics enabled"
)
###############################################################################
@@ -262,59 +242,6 @@ add_custom_target(ci_test_noglobaludls
COMMENT "Compile and test with global UDLs disabled"
)
###############################################################################
# Disable enum serialization.
###############################################################################
add_custom_target(ci_test_disableenumserialization
COMMAND ${CMAKE_COMMAND}
-DCMAKE_BUILD_TYPE=Debug -GNinja
-DJSON_BuildTests=ON -DJSON_FastTests=ON -DJSON_DisableEnumSerialization=ON
-S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_disableenumserialization
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_disableenumserialization
COMMAND cd ${PROJECT_BINARY_DIR}/build_disableenumserialization && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
COMMENT "Compile and test with enum serialization disabled"
)
###############################################################################
# Skip the multiple-inclusion library version check.
###############################################################################
# tests/src/skip_library_version_check.cpp deliberately simulates a scenario
# (mixing two differently-versioned inclusions of the library in one
# translation unit) that unavoidably triggers the compiler's own "macro
# redefined" warning, so -- unlike the ci_test_* targets above -- it is
# compiled directly here, with a modest warning set, instead of being folded
# into the library's own -Weverything/-Werror unit test matrix.
add_custom_target(ci_test_skiplibraryversioncheck
COMMAND ${CMAKE_COMMAND} -E make_directory ${PROJECT_BINARY_DIR}/skip_library_version_check
COMMAND ${CMAKE_CXX_COMPILER} -std=c++11 -Wall -Wextra
-I${PROJECT_SOURCE_DIR}/include
${PROJECT_SOURCE_DIR}/tests/src/skip_library_version_check.cpp
-o ${PROJECT_BINARY_DIR}/skip_library_version_check/skip_library_version_check
COMMAND ${PROJECT_BINARY_DIR}/skip_library_version_check/skip_library_version_check
COMMENT "Compile and run a translation unit simulating a mismatched library version, with JSON_SKIP_LIBRARY_VERSION_CHECK defined"
)
###############################################################################
# Disable thread-local storage.
###############################################################################
# Without thread-local storage, copying and comparing cannot bound their
# descent and handle every object and array without the call stack. Those paths
# are otherwise only reached by values nested deeper than the bound, so this
# target is what runs the whole test suite through them.
add_custom_target(ci_test_no_thread_local
COMMAND ${CMAKE_COMMAND}
-DCMAKE_BUILD_TYPE=Debug -GNinja
-DJSON_BuildTests=ON
-DCMAKE_CXX_FLAGS=-DJSON_NO_THREAD_LOCAL
-S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_no_thread_local
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_no_thread_local
COMMAND cd ${PROJECT_BINARY_DIR}/build_no_thread_local && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
COMMENT "Compile and test without thread-local storage"
)
###############################################################################
# Coverage.
###############################################################################
@@ -367,7 +294,7 @@ file(GLOB_RECURSE INDENT_FILES
${PROJECT_SOURCE_DIR}/tests/src/*.cpp
${PROJECT_SOURCE_DIR}/tests/src/*.hpp
${PROJECT_SOURCE_DIR}/tests/benchmarks/src/benchmarks.cpp
${PROJECT_SOURCE_DIR}/docs/mkdocs/docs/examples/*.cpp
${PROJECT_SOURCE_DIR}/docs/examples/*.cpp
)
set(include_dir ${PROJECT_SOURCE_DIR}/single_include/nlohmann)
+6 -39
View File
@@ -1,57 +1,24 @@
# generate Bazel BUILD file
#
# usage: cmake -P cmake/scripts/gen_bazel_build_file.cmake (or: make BUILD.bazel)
#
# The header list of the "json" target is derived from the files in include/. Everything else is fixed text below,
# so edit this script rather than BUILD.bazel.
get_filename_component(PROJECT_ROOT "${CMAKE_CURRENT_LIST_DIR}/../.." ABSOLUTE)
set(PROJECT_ROOT "${CMAKE_CURRENT_LIST_DIR}/../..")
set(BUILD_FILE "${PROJECT_ROOT}/BUILD.bazel")
file(GLOB_RECURSE HEADERS LIST_DIRECTORIES false RELATIVE "${PROJECT_ROOT}" "${PROJECT_ROOT}/include/*.hpp")
list(SORT HEADERS)
set(CONTENT [=[
load("@rules_cc//cc:cc_library.bzl", "cc_library")
load("@rules_license//rules:license.bzl", "license")
package(
default_applicable_licenses = [":license"],
)
exports_files([
"LICENSE.MIT",
])
license(
name = "license",
license_kinds = ["@rules_license//licenses/spdx:MIT"],
license_text = "LICENSE.MIT",
)
file(GLOB_RECURSE HEADERS LIST_DIRECTORIES false RELATIVE "${PROJECT_ROOT}" "include/*.hpp")
file(WRITE "${BUILD_FILE}" [=[
cc_library(
name = "json",
hdrs = [
]=])
foreach(header ${HEADERS})
string(APPEND CONTENT " \"${header}\",\n")
file(APPEND "${BUILD_FILE}" " \"${header}\",\n")
endforeach()
string(APPEND CONTENT [=[
file(APPEND "${BUILD_FILE}" [=[
],
includes = ["include"],
visibility = ["//visibility:public"],
)
cc_library(
name = "singleheader-json",
hdrs = [
"single_include/nlohmann/json.hpp",
],
includes = ["single_include"],
visibility = ["//visibility:public"],
alwayslink = True,
)
]=])
file(WRITE "${BUILD_FILE}" "${CONTENT}")
-112
View File
@@ -1,112 +0,0 @@
# Shared extractor for the JSON_HEDLEY_* macro names defined in hedley.hpp.
#
# Every macro that hedley.hpp #defines must be #undef-ed again once json.hpp
# has been fully processed (see include/nlohmann/detail/macro_unscope.hpp
# and https://github.com/nlohmann/json/issues/5408). Deriving the macro list
# straight from hedley.hpp here -- instead of hand-maintaining it in two
# places -- means hedley_undef.hpp and the regression test that checks for
# leaked macros can never drift apart, even after a future `make
# update_hedley` pulls in new macros from upstream Hedley.
#
# MODE=undef (default): write hedley_undef.hpp (SPDX header, #pragma once,
# one #undef per macro name) -- used by `make update_hedley_undef`
# MODE=checks: write one #ifdef/FAIL_CHECK/#endif per macro name,
# meant to be #include-d inside a TEST_CASE -- used by
# tests/CMakeLists.txt to (re)generate the include for
# tests/src/unit-no-macro-leak.cpp
#
# Required variables:
# HEDLEY_HPP path to include/nlohmann/thirdparty/hedley/hedley.hpp
# OUTPUT path of the file to (over)write
# Optional:
# MODE "undef" (default) or "checks"
if(NOT DEFINED HEDLEY_HPP OR NOT DEFINED OUTPUT)
message(FATAL_ERROR "HEDLEY_HPP and OUTPUT must be set")
endif()
if(NOT EXISTS "${HEDLEY_HPP}")
message(FATAL_ERROR "Hedley header not found: ${HEDLEY_HPP}")
endif()
if(NOT DEFINED MODE)
set(MODE undef)
endif()
if(NOT MODE STREQUAL "undef" AND NOT MODE STREQUAL "checks")
message(FATAL_ERROR "MODE must be undef or checks, got: ${MODE}")
endif()
# Line-anchored, like `grep -oE "^[[:blank:]]*#[[:blank:]]*define[[:blank:]]+JSON_HEDLEY_[A-Za-z0-9_]+"`.
# Unanchored matching would also pick up JSON_HEDLEY_* mentions inside
# comments or string literals elsewhere in the file, which must not turn
# into #undef lines.
file(STRINGS "${HEDLEY_HPP}" hedley_lines)
set(macro_names)
foreach(line IN LISTS hedley_lines)
if("${line}" MATCHES "^[ \t]*#[ \t]*define[ \t]+(JSON_HEDLEY_[A-Za-z0-9_]+)")
list(APPEND macro_names "${CMAKE_MATCH_1}")
endif()
endforeach()
if(NOT macro_names)
message(FATAL_ERROR "No JSON_HEDLEY_* macros found in ${HEDLEY_HPP}")
endif()
list(REMOVE_DUPLICATES macro_names)
# Lexicographic, locale-independent (ASCII-only names) -- matches `LC_ALL=C sort`.
list(SORT macro_names COMPARE STRING)
list(LENGTH macro_names macro_count)
set(generated "")
if(MODE STREQUAL "undef")
# Same banner `make update_hedley_undef` would stamp by hand, so the
# recipe is self-contained and its output is byte-stable across reruns.
# The embedded SPDX tags below are part of the *generated* file's
# content, not a REUSE header for this .cmake script itself (which is
# already covered by the blanket "Files: *" rule in .reuse/dep5) -- keep
# them wrapped in REUSE-IgnoreStart/End so `reuse lint` does not try to
# parse "MIT\n")" as this file's own SPDX-License-Identifier value.
# REUSE-IgnoreStart
string(APPEND generated "// __ _____ _____ _____\n")
string(APPEND generated "// __| | __| | | | JSON for Modern C++\n")
string(APPEND generated "// | | |__ | | | | | | version 3.12.0\n")
string(APPEND generated "// |_____|_____|_____|_|___| https://github.com/nlohmann/json\n")
string(APPEND generated "//\n")
string(APPEND generated "// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>\n")
string(APPEND generated "// SPDX-License-Identifier: MIT\n")
# REUSE-IgnoreEnd
string(APPEND generated "\n")
string(APPEND generated "#pragma once\n")
string(APPEND generated "\n")
foreach(name IN LISTS macro_names)
string(APPEND generated "#undef ${name}\n")
endforeach()
else()
string(APPEND generated "// This file is generated by cmake/scripts/gen_hedley_undef_check.cmake\n")
string(APPEND generated "// from include/nlohmann/thirdparty/hedley/hedley.hpp. Do not edit it by\n")
string(APPEND generated "// hand -- it is regenerated on every build. ${macro_count} macros checked.\n\n")
foreach(name IN LISTS macro_names)
string(APPEND generated "#ifdef ${name}\n")
string(APPEND generated " FAIL_CHECK(\"${name} leaked after including nlohmann/json.hpp\");\n")
string(APPEND generated "#endif\n")
endforeach()
endif()
get_filename_component(output_dir "${OUTPUT}" DIRECTORY)
if(output_dir)
file(MAKE_DIRECTORY "${output_dir}")
endif()
# Avoid rewriting the file (and busting downstream incremental rebuilds)
# when the content has not actually changed.
set(write_output TRUE)
if(EXISTS "${OUTPUT}")
file(READ "${OUTPUT}" existing_content)
if(existing_content STREQUAL generated)
set(write_output FALSE)
endif()
endif()
if(write_output)
file(WRITE "${OUTPUT}" "${generated}")
endif()
@@ -90,10 +90,6 @@ Linear in the length of the input. The parser is a predictive LL(1) parser.
A UTF-8 byte order mark is silently ignored.
By default, a `'\0'` (NUL) byte anywhere in the input is treated as end of input, rather than as an ordinary (and,
outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for details and the
[`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) macro to opt into rejecting it instead.
## Examples
??? example
@@ -115,8 +111,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
- [parse](parse.md) - deserialize from a compatible input
- [sax_parse](sax_parse.md) - parse input using the SAX interface
- [operator>>](../operator_gtgt.md) - deserialize from stream
- [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
instead of treating it as end of input
## Version history
@@ -126,8 +120,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
- Added `ignore_trailing_commas` in version 3.13.0.
- Extended container support (1) to include types with lvalue-only ADL `begin`/`end` (matching `std::begin`/`std::end` semantics) in version 3.13.0.
- Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
- `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
it as end of input; planned to become the default in version 4.0.0.
!!! warning "Deprecation"
+1 -6
View File
@@ -14,11 +14,7 @@ To store objects in C++, a type is defined by the template parameters explained
## Template parameters
`ArrayType`
: container type to store arrays. It must be a vector-like container: the library uses `operator[]`, `at()`, and
`resize()`, and requires random-access iterators. `#!cpp std::vector` and `#!cpp std::deque` qualify;
`#!cpp std::list` does not. See
[Template Parameter Requirements](../../features/types/template_parameters.md#arraytype) for the full list of
requirements.
: container type to store arrays (e.g., `std::vector` or `std::list`)
`AllocatorType`
: the allocator to use for objects (e.g., `std::allocator`)
@@ -70,4 +66,3 @@ Arrays are stored as pointers in a `basic_json` type. That is, for any access to
## Version history
- Added in version 1.0.0.
- Made `capacity()` optional, so that array types such as `#!cpp std::deque` can be used, in version 3.13.0.
+1 -11
View File
@@ -42,9 +42,7 @@ represent a byte array in modern C++.
`value_type` must additionally be exactly one byte wide (e.g., `std::uint8_t`/`char`/`std::byte`): the binary
serializers (CBOR, MessagePack, BSON, UBJSON) read and write the container's raw bytes via
`reinterpret_cast`, which is only correct for byte-sized elements -- a container like
`#!cpp std::vector<std::intptr_t>` will not work as `BinaryType`. The elements must be stored contiguously, and
the binary readers additionally require `resize()` and `operator[]`. See
[Template Parameter Requirements](../../features/types/template_parameters.md#binarytype) for the full list.
`#!cpp std::vector<std::intptr_t>` will not work as `BinaryType`.
## Notes
@@ -52,11 +50,6 @@ represent a byte array in modern C++.
The default values for `BinaryType` is `#!cpp std::vector<std::uint8_t>`.
#### Supported byte types
`#!cpp std::vector<std::uint8_t>`, `#!cpp std::vector<char>`, and `#!cpp std::vector<std::byte>` are supported.
Regardless of which of them is configured, [`dump`](dump.md) writes the bytes as the numbers 0..255.
#### Custom BinaryType behavior
When a custom `BinaryType` is configured (other than the default `#!cpp std::vector<std::uint8_t>`), you can assign
@@ -133,6 +126,3 @@ type `#!cpp binary_t*` must be dereferenced.
## Version history
- Added in version 3.8.0. Changed the type of subtype to `std::uint64_t` in version 3.10.0.
- Fixed [`dump`](dump.md), [`std::hash`](std_hash.md), and [`to_ubjson`](to_ubjson.md) for byte types that are not
integers (e.g., `#!cpp std::byte`) in version 3.13.0. `dump` now writes the bytes of a signed byte type (e.g.,
`#!cpp char`) as 0..255 rather than as negative numbers.
@@ -11,14 +11,6 @@ literals `#!json true` and `#!json false`.
To store boolean values in C++, a type is defined by the template parameter `BooleanType` which chooses the type to use.
## Template parameters
`BooleanType`
: the type to store booleans. As it is stored directly inside a `basic_json` value (in a union), it must be a
trivially default-constructible, trivially copyable, and trivially destructible type that is convertible to and
from `#!cpp bool`. See
[Template Parameter Requirements](../../features/types/template_parameters.md#booleantype).
## Notes
#### Default type
@@ -21,10 +21,6 @@ This overload is chosen if:
- `ValueType` is not `basic_json`,
- `json_serializer<ValueType>` has a `from_json()` method of the form `void from_json(const basic_json&, ValueType&)`
`v` must not be `const`. Passing a `const` object is a compile-time error. For types such as arithmetic types, enums,
and C arrays, the error is a `static_assert` that names the problem. For other types, the overload is not viable, and
the compiler reports that no matching `get_to` was found.
## Template parameters
`ValueType`
@@ -71,4 +67,3 @@ Depends on the `json_serializer<ValueType>::from_json()` implementation.
## Version history
- Since version 3.3.0.
- Added a `static_assert` with a clear message for `const` arguments in version 3.13.0.
-4
View File
@@ -35,10 +35,6 @@ class basic_json;
| `BinaryType` | type for binary arrays | [`binary_t`](binary_t.md) |
| `CustomBaseClass` | extension point for user code | [`json_base_class_t`](json_base_class_t.md) |
The library imposes a number of requirements on these types that are not expressed as C++ concepts, such as the
container operations `object_t` and `array_t` must provide, or the fact that `StringType` must be `char`-based. They
are collected in [Template Parameter Requirements](../../features/types/template_parameters.md).
## Specializations
- [**json**](../json.md) - default specialization
@@ -88,8 +88,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
do not belong to the same JSON value; example: `"iterators do not fit"`
- Throws [`invalid_iterator.211`](../../home/exceptions.md#jsonexceptioninvalid_iterator211) if `first` or `last`
are iterators into container for which insert is called; example: `"passed iterators may not belong to container"`
- Throws [`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202) if `first` or `last`
do not point to an array; example: `"iterators first and last must point to arrays"`
4. The function can throw the following exceptions:
- Throws [`type_error.309`](../../home/exceptions.md#jsonexceptiontype_error309) if called on JSON values other than
arrays; example: `"cannot use insert() with string"`
@@ -21,11 +21,8 @@ The default value for `CustomBaseClass` is `void`. In this case, an
#### Limitations
The type `CustomBaseClass` has to be a default-constructible, non-`final` class.
The type `CustomBaseClass` has to be a default-constructible class.
`basic_json` only supports copy/move construction/assignment if `CustomBaseClass` does so as well.
A `CustomBaseClass` with non-static data members forfeits `basic_json`'s
[standard layout](https://en.cppreference.com/w/cpp/named_req/StandardLayoutType) guarantee. See
[Template Parameter Requirements](../../features/types/template_parameters.md#custombaseclass).
## Examples
@@ -19,12 +19,6 @@ using json_serializer = JSONSerializer<T, SFINAE>;
The default values for `json_serializer` is [`adl_serializer`](../adl_serializer/index.md).
#### Requirements
A custom serializer must provide `#!cpp static void to_json(basic_json&, T)` for every type it serializes, and either
`#!cpp static void from_json(const basic_json&, T&)` or `#!cpp static T from_json(const basic_json&)` for every type it
deserializes. See [Template Parameter Requirements](../../features/types/template_parameters.md#jsonserializer).
## Examples
??? example
@@ -20,16 +20,6 @@ used.
To store floating-point numbers in C++, a type is defined by the template parameter `NumberFloatType` which chooses the
type to use.
## Template parameters
`NumberFloatType`
: the type to store floating-point numbers. Parsing and serialization are implemented in terms of
`#!cpp std::strtof`/`#!cpp std::strtod`/`#!cpp std::strtold` and `#!cpp std::snprintf`, so the type must be
`#!cpp float`, `#!cpp double`, or `#!cpp long double`. The
[binary formats](../../features/binary_formats/index.md) additionally require `#!cpp float` or `#!cpp double`,
because they have no encoding for `#!cpp long double`. See
[Template Parameter Requirements](../../features/types/template_parameters.md#numberfloattype).
## Notes
#### Default type
@@ -20,13 +20,6 @@ used.
To store integer numbers in C++, a type is defined by the template parameter `NumberIntegerType` which chooses the type
to use.
## Template parameters
`NumberIntegerType`
: the type to store signed integers. It must be a **signed integral** type (`#!cpp std::is_integral`) with a
`#!cpp std::numeric_limits` specialization, and it is stored directly inside a `basic_json` value. See
[Template Parameter Requirements](../../features/types/template_parameters.md#numberintegertype-and-numberunsignedtype).
## Notes
#### Default type
@@ -20,14 +20,6 @@ used.
To store unsigned integer numbers in C++, a type is defined by the template parameter `NumberUnsignedType` which chooses
the type to use.
## Template parameters
`NumberUnsignedType`
: the type to store unsigned integers. It must be an **unsigned integral** type (`#!cpp std::is_integral`) with a
`#!cpp std::numeric_limits` specialization, and it must be able to represent the absolute value of every
[`number_integer_t`](number_integer_t.md) value. See
[Template Parameter Requirements](../../features/types/template_parameters.md#numberintegertype-and-numberunsignedtype).
## Notes
#### Default type
@@ -30,5 +30,3 @@ and [`default_object_comparator_t`](default_object_comparator_t.md) otherwise.
- Added in version 3.0.0.
- Changed to be conditionally defined as `#!cpp typename object_t::key_compare` or `default_object_comparator_t` in
version 3.11.0.
- Fixed the fallback to `default_object_comparator_t`, which previously failed to compile for object types without a
`key_compare` member type, in version 3.13.0.
+1 -6
View File
@@ -18,11 +18,7 @@ To store objects in C++, a type is defined by the template parameters described
## Template parameters
`ObjectType`
: the container to store objects. Its template parameters must have the same order and meaning as those of
`std::map`; in particular, the third parameter is a comparator. `#!cpp std::unordered_map`, whose third parameter
is a hash function, therefore needs an adapter -- see
[Template Parameter Requirements](../../features/types/template_parameters.md#objecttype) for the full list of
requirements, an adapter example, and the containers that are known to work.
: the container to store objects (e.g., `std::map` or `std::unordered_map`)
`StringType`
: the type of the keys or names (e.g., `std::string`). The comparison function `std::less<StringType>` is used to
@@ -126,4 +122,3 @@ the object is silently converted as an array of key-value pairs, which is incorr
## Version history
- Added in version 1.0.0.
- Allowed object types whose `erase(iterator)` returns `#!cpp void` in version 3.13.0.
-8
View File
@@ -103,10 +103,6 @@ A UTF-8 byte order mark is silently ignored.
Invalid Unicode escapes and unpaired surrogates in the input are reported as
[`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101) with a detailed message.
By default, a `'\0'` (NUL) byte anywhere in the input is treated as end of input, rather than as an ordinary (and,
outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for details and the
[`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) macro to opt into rejecting it instead.
## Examples
??? example "Parsing from a character array"
@@ -240,8 +236,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
- [accept](accept.md) - check if the input is valid JSON
- [sax_parse](sax_parse.md) - parse input using the SAX interface
- [operator>>](../operator_gtgt.md) - deserialize from stream
- [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
instead of treating it as end of input
## Version history
@@ -252,8 +246,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
- Added `ignore_trailing_commas` in version 3.13.0.
- Extended container support (1) to include types with lvalue-only ADL `begin`/`end` (matching `std::begin`/`std::end` semantics) in version 3.13.0.
- Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
- `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
it as end of input; planned to become the default in version 4.0.0.
!!! warning "Deprecation"
-8
View File
@@ -34,10 +34,6 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
("add", "remove", "move")
- Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
location is a proper prefix of its "path" location.
- Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
unsuccessful.
@@ -79,7 +75,3 @@ is thrown. In any case, the original value is not changed: the patch is applied
- Added in version 2.0.0.
- Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
target location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.
@@ -30,10 +30,6 @@ No guarantees, value may be corrupted by an unsuccessful patch operation.
("add", "remove", "move")
- Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
location is a proper prefix of its "path" location.
- Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
unsuccessful.
@@ -76,7 +72,3 @@ function throws an exception.
- Added in version 3.11.0.
- Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
target location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.
+3 -4
View File
@@ -70,8 +70,7 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
`strict` (in)
: whether the input has to be consumed completely (optional, `#!cpp true` by default); when `#!cpp false` and the
input is a `#!cpp std::istream`, the character that terminates a number is consumed unless
[`JSON_PRECISE_STREAM_POSITION`](../macros/json_precise_stream_position.md) is defined to `1`; see [`operator>>`](../operator_gtgt.md#notes)
input is a `#!cpp std::istream`, the stream is left positioned right after the parsed value
`ignore_comments` (in)
: whether comments should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
@@ -138,8 +137,8 @@ A UTF-8 byte order mark is silently ignored.
- Added `ignore_trailing_commas` in version 3.13.0.
- Extended container support (1) to include types with lvalue-only ADL `begin`/`end` (matching `std::begin`/`std::end` semantics) in version 3.13.0.
- Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
- `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave a `#!cpp std::istream` positioned right
after the parsed value when `strict` is `#!cpp false`.
- Changed in version 4.0.0 to leave a `#!cpp std::istream` positioned right after the parsed value when `strict` is
`#!cpp false`; see [`operator>>`](../operator_gtgt.md#notes).
!!! warning "Deprecation"
@@ -23,11 +23,6 @@ JSON class into byte-sized characters during deserialization.
`StringType`. To work with wide-character data, convert it to/from UTF-8 at the boundary instead -- see the
FAQ's [wide string handling](../../home/faq.md#wide-string-handling) section for a conversion recipe.
Beyond the character type, the library expects a substantial part of the `#!cpp std::string` interface (contiguous
null-terminated `data()`, `substr()`, `find()`, `append()`, ...). See
[Template Parameter Requirements](../../features/types/template_parameters.md#stringtype) for the full list and
for the string types that are known to work.
## Notes
#### Default type
@@ -83,5 +78,3 @@ and an example.
## Version history
- Added in version 1.0.0.
- Removed the requirement that `string_t` be implicitly convertible from `#!cpp std::string`, which the BSON writer and
the UBJSON reader relied on, in version 3.13.0.
+2 -6
View File
@@ -34,14 +34,10 @@ void swap(typename binary_t::container_type& other);
```
1. Exchanges the contents of the JSON value with those of `other`. Does not invoke any move, copy, or swap operations on
individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. If macro
[`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) is defined to `#!cpp 1`, the
[`start_pos()`](start_pos.md)/[`end_pos()`](end_pos.md) diagnostic positions are exchanged along with the value.
individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.
2. Exchanges the contents of the JSON value from `left` with those of `right`. Does not invoke any move, copy, or swap
operations on individual elements. All iterators and references remain valid. The past-the-end iterator is
invalidated. Implemented as a friend function callable via ADL. If macro
[`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) is defined to `#!cpp 1`, the
[`start_pos()`](start_pos.md)/[`end_pos()`](end_pos.md) diagnostic positions are exchanged along with the value.
invalidated. Implemented as a friend function callable via ADL.
3. Exchanges the contents of a JSON array with those of `other`. Does not invoke any move, copy, or swap operations on
individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.
4. Exchanges the contents of a JSON object with those of `other`. Does not invoke any move, copy, or swap operations on
@@ -52,11 +52,6 @@ optional, `#!cpp bjdata_version_t::draft2` by default.
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
## Exceptions
- Throws [`other_error.502`](../../home/exceptions.md#jsonexceptionother_error502) if `use_type` is true and `use_size`
is false.
## Complexity
Linear in the size of the JSON value `j`.
+1 -3
View File
@@ -46,9 +46,7 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
## Complexity
Proportional to the size of the JSON value `j` multiplied by its maximum nesting
depth, `O(n × d)`. BSON length prefixes are computed recursively before nested
values are written.
Linear in the size of the JSON value `j`.
## Examples
@@ -45,11 +45,6 @@ The exact mapping and its limitations are described on a [dedicated page](../../
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
## Exceptions
- Throws [`other_error.502`](../../home/exceptions.md#jsonexceptionother_error502) if `use_type` is true and `use_size`
is false.
## Complexity
Linear in the size of the JSON value `j`.
+1 -9
View File
@@ -37,14 +37,7 @@ Linear in the size of the JSON value.
## Notes
Empty objects and arrays are flattened by [`flatten()`](flatten.md) to `#!json null` values and cannot unflattened to
their original type.
A flattened array and a flattened object whose keys are array indices are indistinguishable, because both are
described by the same JSON pointers. A value is therefore restored as an array if and only if one of its keys is the
reference token `0`, and as an object otherwise: `#!json {"2": 1}` is restored unchanged, whereas `#!json {"0": 1}` is
restored as `#!json [1]`. This decision does not depend on the order in which the flattened object is iterated.
Apart from these two cases, for a JSON value `j`, the following is always true:
their original type. Apart from this example, for a JSON value `j`, the following is always true:
`#!cpp j == j.flatten().unflatten()`.
## Examples
@@ -70,4 +63,3 @@ Apart from these two cases, for a JSON value `j`, the following is always true:
## Version history
- Added in version 2.0.0.
- Made the array/object decision independent of the object's iteration order in version 3.13.0.
-9
View File
@@ -14,13 +14,6 @@ header. See also the [macro overview page](../../features/macros.md).
- [**JSON_DIAGNOSTIC_POSITIONS**](json_diagnostic_positions.md) - access positions of elements
- [**JSON_NOEXCEPTION**](json_noexception.md) - switch off exceptions
## Parsing
- [**JSON_PRECISE_STREAM_POSITION**](json_precise_stream_position.md) - opt in to leaving an input stream positioned
right after a parsed number
- [**JSON_STRICT_NUL_HANDLING**](json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input instead of
treating it as end of input
## Language support
- [**JSON_HAS_CPP_11**<br>**JSON_HAS_CPP_14**<br>**JSON_HAS_CPP_17**<br>**JSON_HAS_CPP_20**](json_has_cpp_11.md) - set supported C++ standard
@@ -29,10 +22,8 @@ header. See also the [macro overview page](../../features/macros.md).
- [**JSON_HAS_STD_FORMAT**](json_has_std_format.md) - control `std::format`/`std::formatter` support
- [**JSON_HAS_THREE_WAY_COMPARISON**](json_has_three_way_comparison.md) - control 3-way comparison support
- [**JSON_NO_IO**](json_no_io.md) - switch off functions relying on certain C++ I/O headers
- [**JSON_NO_THREAD_LOCAL**](json_no_thread_local.md) - switch off the use of `thread_local` storage
- [**JSON_SKIP_UNSUPPORTED_COMPILER_CHECK**](json_skip_unsupported_compiler_check.md) - do not warn about unsupported compilers
- [**JSON_USE_GLOBAL_UDLS**](json_use_global_udls.md) - place user-defined string literals (UDLs) into the global namespace
- [**JSON_USE_SIMDUTF**](json_use_simdutf.md) - use the simdutf library to accelerate UTF-8 validation
## Library version
@@ -38,28 +38,6 @@ The default value is `0` (disabled — existing behavior is preserved).
This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no effect.
!!! warning "Applies to every single-element list"
The macro does not only affect a single JSON value in braces. **Any** single-element braced list is treated as its
element, so it no longer creates a one-element array:
```cpp
json j1 = {1}; // 1, not [1]
json j2 = {"text"}; // "text", not ["text"]
json j3 = {{1, 2}}; // [1,2], not [[1,2]]
```
Code that relies on these producing arrays must use `json::array()` instead (see below). Lists with more than one
element, and a single `[string, value]` pair such as `{{"key", "value"}}`, which still creates an object, are not
affected. The library's own conversions are not affected either: for example, `std::tuple<int>{5}` still becomes
`[5]`.
!!! note "ABI compatibility"
The value of this macro is encoded in the [namespace](../../features/namespace.md) (tag `_bics`), resulting in
distinct symbol names. Translation units compiled with and without it can therefore be linked into the same program
without One Definition Rule (ODR) violations, but they cannot exchange instances of library types.
!!! tip "Workaround without the macro"
To explicitly create a single-element array without enabling this macro, use `json::array()`:
@@ -1,48 +0,0 @@
# JSON_NO_THREAD_LOCAL
```cpp
#define JSON_NO_THREAD_LOCAL
```
When defined, the library does not use `#!cpp thread_local` storage. This is relevant for the few environments whose
toolchain does not support it.
Copying a value and comparing two values both descend into the first levels by letting the containers copy or compare
themselves, and finish whatever is nested deeper than that without the call stack, so that neither can exhaust the stack
however deeply the values are nested. Each counts the levels it has descended into in a `#!cpp thread_local` variable, as
a counter shared between threads would be raced.
Without those counters, no descent can be bounded safely, so objects and arrays are copied and compared without the call
stack right away. Both keep working exactly as they do otherwise - the same values come out, the same comparisons hold,
and deeply nested values are handled just as safely - but both are slower, because the containers no longer copy or
compare themselves. Copying the benchmark documents takes 9% (`canada.json`) to 34% (`twitter.json`) longer, and
comparing two equal ones 10% (`citm_catalog.json`) to 90% (`canada.json`) longer.
## Default definition
By default, `#!cpp JSON_NO_THREAD_LOCAL` is not defined.
```cpp
#undef JSON_NO_THREAD_LOCAL
```
The library defines it by itself for Clang targeting MinGW, which does not survive the `#!cpp thread_local` storage:
copying a value segfaults there, with both old and current Clang versions, while GCC targeting MinGW is unaffected.
Copying and comparing fall back to working without the call stack there, as they do whenever the macro is defined.
## Examples
??? example
The code below forces the library not to use `#!cpp thread_local` storage.
```cpp
#define JSON_NO_THREAD_LOCAL 1
#include <nlohmann/json.hpp>
...
```
## Version history
- Added in version 3.12.1.
@@ -1,131 +0,0 @@
# JSON_PRECISE_STREAM_POSITION
```cpp
#define JSON_PRECISE_STREAM_POSITION /* value */
```
When defined to `1`, [`operator>>`](../operator_gtgt.md) and [`sax_parse`](../basic_json/sax_parse.md) with
`strict = false` leave a `#!cpp std::istream` positioned right after the parsed value for every value type. By default,
the character that terminates a number is consumed as well.
The macro only affects reading from a `#!cpp std::istream` when the rest of the stream is not required to be consumed.
[`parse`](../basic_json/parse.md), [`accept`](../basic_json/accept.md), and all other inputs (strings, iterators,
containers, `#!cpp FILE*`) are never affected.
## Default definition
The default value is `0` (disabled — existing behavior is preserved).
```cpp
#define JSON_PRECISE_STREAM_POSITION 0
```
## Notes
!!! note "Background"
A number is the only JSON value whose end can be detected solely by reading the character that follows it. By
default, that character is consumed and not put back, so the stream is left one byte too far after a number, and
only after a number:
```cpp
std::istringstream input("1true");
json j;
input >> j; // j == 1, but the stream now starts at "rue"
```
With this macro, the character is only looked at and left in the stream, so the stream starts at `true`. This
does not require the stream buffer to support putting a character back.
This was not changed unconditionally, because code can depend on the consumed character, even unknowingly (see
[#5340](https://github.com/nlohmann/json/issues/5340)). Both of the following work by default only because the
character after each number is swallowed, and behave differently with this macro:
```cpp
std::istringstream input("1,2,3");
json j1, j2, j3;
input >> j1 >> j2 >> j3; // default: 1, 2, 3
// with the macro: throws parse_error.101 at the ','
```
```cpp
std::istringstream input("42\nfoo");
json j;
std::string line;
input >> j;
std::getline(input, line); // default: "foo"
// with the macro: "" (like after reading an int with >>)
```
In both cases, the behavior with the macro is what you already get today when the value is not a number: `"a","b"`
fails at the `,`, and `std::getline` after `{}` returns an empty string. This macro offers an opt-in path to
the consistent behavior ahead of version 4.0.0, where it is planned to become the default.
!!! warning "Opt-in only"
This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no
effect.
!!! note "ABI compatibility"
The value of this macro is encoded in the [namespace](../../features/namespace.md) (tag `_psp`), resulting in
distinct symbol names. Translation units compiled with and without it can therefore be linked into the same program
without One Definition Rule (ODR) violations, but they cannot exchange instances of library types.
!!! tip "Workaround without the macro"
Separate the values in the stream with whitespace. The character consumed after a number is then the separator,
and whitespace before the next value is skipped anyway.
## Examples
??? example "Default behavior (macro not defined)"
Without the macro, the character after a number is consumed:
```cpp
#include <iostream>
#include <sstream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::istringstream input("1true");
json j1, j2;
input >> j1; // j1 == 1
input >> j2; // throws parse_error.101: the stream now starts at "rue"
}
```
??? example "Opt-in precise stream position (macro defined to 1)"
With the macro, the stream is positioned right after the number:
```cpp
#define JSON_PRECISE_STREAM_POSITION 1
#include <iostream>
#include <sstream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::istringstream input("1true");
json j1, j2;
input >> j1; // j1 == 1
input >> j2; // j2 == true
}
```
## See also
- [**operator>>**](../operator_gtgt.md) - deserialize from stream
- [**sax_parse**](../basic_json/sax_parse.md) - generate SAX events
## Version history
- Added in version 3.13.0.
- Planned to become the default (with the macro removed) in version 4.0.0.
@@ -1,126 +0,0 @@
# JSON_STRICT_NUL_HANDLING
```cpp
#define JSON_STRICT_NUL_HANDLING /* value */
```
When defined to `1`, a `'\0'` (NUL) byte in JSON text input is rejected with `parse_error.101`, like any other
unexpected byte, instead of being silently treated as end of input.
The macro only affects the JSON text parser ([`parse`](../basic_json/parse.md), [`accept`](../basic_json/accept.md),
[`sax_parse`](../basic_json/sax_parse.md), and [`operator>>`](../operator_gtgt.md)). There are three cases where a NUL
byte is still not rejected:
- The binary formats ([`from_bjdata`](../basic_json/from_bjdata.md), [`from_bson`](../basic_json/from_bson.md),
[`from_cbor`](../basic_json/from_cbor.md), [`from_msgpack`](../basic_json/from_msgpack.md),
[`from_ubjson`](../basic_json/from_ubjson.md)) are never affected: there, `0x00` is ordinary data.
- A bare `const char*` pointer has no length of its own, so its length is still determined with `strlen()`. The first
NUL byte therefore still marks the end of the input, and nothing after it is read.
- One trailing `'\0'` at the end of a `char` array (e.g., a string literal) is trimmed; see the warning below.
## Default definition
The default value is `0` (disabled — existing behavior is preserved).
```cpp
#define JSON_STRICT_NUL_HANDLING 0
```
## Notes
!!! note "Background"
By default, a `'\0'` byte anywhere in the input is treated the same as the real end of the input, rather than as
an ordinary (and, outside of a string, invalid) byte. Everything from that byte onward is silently ignored,
without a parse error - including further, otherwise well-formed JSON:
```cpp
json::parse(std::string("123") + '\0'); // == 123, no error
json::parse(std::string("123") + '\0' + "true"); // == 123, the "true" is silently ignored too
```
This falls out of the same convention used when no explicit input length is given at all: parsing from a
`const char*` already stops at the first NUL byte via `strlen()`, since a bare pointer has no length of its own.
The library applies that same NUL-terminated-C-string convention uniformly, rather than only when a length is
genuinely unavailable - so a `std::string`, iterator range, or container whose content happens to include a NUL
byte is affected the same way a raw `const char*` would be (see the
[FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for a fuller explanation).
This was not fixed unconditionally, because doing so is backwards-incompatible for any caller who happens to
depend on the current behavior - even unknowingly, for instance because their input already contains trailing
padding they never noticed was being discarded (see [#5530](https://github.com/nlohmann/json/issues/5530)).
This macro instead offers an opt-in path to the corrected behavior ahead of version 4.0.0, where it is planned to
become the default.
!!! warning "Opt-in only"
This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no
effect.
Enabling it also changes how a `char` array (including a string literal, e.g. `json::parse("123")`) is read: such
an array normally carries a trailing `'\0'` contributed by the compiler, not by the source text. With this macro
enabled, that one trailing byte is trimmed if present so that parsing a string literal keeps working; every other
byte in the array - including any `'\0'` that is not the very last element - is read as real data and rejected
like any other unexpected byte. Arrays of any other element type (`unsigned char`, `std::uint8_t`, ...), as used
for CBOR or MessagePack, are never affected by this trimming; their full extent - including a genuine trailing
`0x00` - is always preserved, in both states of this macro.
!!! tip "Workaround without the macro"
To reject a NUL byte without enabling this macro, trim your input yourself before calling `parse()`:
```cpp
s.resize(s.find('\0')); // drop everything from the first NUL onward, if any
json::parse(s);
```
## Examples
??? example "Default behavior (macro not defined)"
Without the macro, a NUL byte silently ends parsing at that point:
```cpp
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
json j = json::parse(std::string("123") + '\0' + "true");
// j is 123 -- the '\0' and everything after it is silently ignored
}
```
??? example "Opt-in strict handling (macro defined to 1)"
With the macro, a NUL byte is rejected like any other unexpected byte:
```cpp
#define JSON_STRICT_NUL_HANDLING 1
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
json j = json::parse(std::string("123") + '\0' + "true");
// throws parse_error.101 -- the NUL byte is now invalid input,
// exactly like any other unexpected trailing byte
json ok = json::parse("123");
// ok is 123 -- parsing from a string literal still works
}
```
## See also
- [FAQ: NUL bytes in the input](../../home/faq.md#nul-bytes-in-the-input)
- [**parse**](../basic_json/parse.md) - deserialize from a compatible input
- [**accept**](../basic_json/accept.md) - check if the input is valid JSON
- [**operator>>**](../operator_gtgt.md) - deserialize from stream
## Version history
- Added in version 3.13.0.
- Planned to become the default (with the macro removed) in version 4.0.0.
@@ -12,11 +12,9 @@
Controls how exceptions are handled by the library.
1. This macro overrides [`#!cpp catch`](https://en.cppreference.com/w/cpp/language/try_catch) calls inside the library.
The argument is the type of the exception to catch. The library uses it in a single place: to swallow any exception
escaping the parent-pointer check that [`JSON_DIAGNOSTICS`](json_diagnostics.md) adds to the class invariant. The
places where the library catches its own [`json::out_of_range`](../../home/exceptions.md#out-of-range) exceptions
use `JSON_INTERNAL_CATCH` instead, which `JSON_CATCH_USER` also overrides unless `JSON_INTERNAL_CATCH_USER` is
defined. The macro is always followed by a scope.
The argument is the type of the exception to catch. As of version 3.8.0, the library only catches `std::out_of_range`
exceptions internally to rethrow them as [`json::out_of_range`](../../home/exceptions.md#out-of-range) exceptions.
The macro is always followed by a scope.
2. This macro overrides `#!cpp throw` calls inside the library. The argument is the exception to be thrown. Note that
`JSON_THROW_USER` should leave the current scope (e.g., by throwing or aborting), as continuing after it may yield
undefined behavior.
@@ -24,14 +24,6 @@ By default, implicit conversions are enabled.
You can prepare existing code by already defining `JSON_USE_IMPLICIT_CONVERSIONS` to `0` and replace any implicit
conversions with calls to [`get`](../basic_json/get.md).
!!! tip "Automatic migration"
The community-maintained clang-tidy check `modernize-nlohmann-json-explicit-conversions` rewrites implicit
conversions into explicit calls to [`get`](../basic_json/get.md); for example, `#!cpp int i = j;` becomes
`#!cpp int i = j.get<int>();`. The check is not part of clang-tidy itself, and it does not catch every case (for
example, constructing a `std::optional` from a JSON value), so review the result. See
[discussion #4610](https://github.com/nlohmann/json/discussions/4610) for how to build and use it.
!!! hint "CMake option"
Implicit conversions can also be controlled with the CMake option
@@ -1,71 +0,0 @@
# JSON_USE_SIMDUTF
```cpp
#define JSON_USE_SIMDUTF
```
When defined, the parser validates the UTF-8 content of JSON strings that come from a **contiguous byte input**
(`std::string`, `std::vector<char>`/`<std::uint8_t>`, string literals, `const char*` ranges, …) using the
[simdutf](https://github.com/simdutf/simdutf) library instead of the built-in scalar validator. On text with many
non-ASCII characters (e.g. CJK or emoji) this can validate several times faster.
This is an **opt-in external dependency**. The library itself remains header-only and its behavior is unchanged: the
same input is accepted or rejected either way, and every parse error is reported at the same position with the same
message (simdutf is only used to fast-path *valid* runs; anything it flags falls back to the scalar path so the exact
diagnostic is preserved). Streaming inputs (files, `std::istream`, wide strings, user-defined adapters) always use the
scalar path.
When `JSON_USE_SIMDUTF` is defined you must make the `simdutf.h` header available on the include path and link the
simdutf library. When it is not defined, no simdutf header is included and there is no dependency.
!!! note "Requires C++17"
simdutf requires C++17 and its header rejects older standards with an `#!cpp #error`. The backend is therefore only
compiled in from C++17 on. In C++11 and C++14 the macro has no effect and the scalar validator is used, which
accepts and rejects exactly the same input -- only throughput differs. Setting the macro project-wide is therefore
safe even when some translation units are built with an older standard.
!!! warning "Define consistently"
The macro selects between two definitions of the same inline validation function. It must therefore be defined
identically for **every** translation unit that includes the library; mixing translation units that define it with
ones that do not is an ODR violation. Prefer setting it as a compile definition on the target rather than with
`#!cpp #define` in individual source files.
## Default definition
By default, `#!cpp JSON_USE_SIMDUTF` is not defined and the portable C++11 scalar validator is used.
```cpp
#undef JSON_USE_SIMDUTF
```
## Examples
??? example
The code below enables the simdutf backend for UTF-8 validation.
```cpp
#define JSON_USE_SIMDUTF 1
#include <nlohmann/json.hpp>
...
```
The project must also link against simdutf, e.g. with CMake:
```cmake
target_compile_definitions(your_target PRIVATE JSON_USE_SIMDUTF)
target_link_libraries(your_target PRIVATE simdutf::simdutf)
```
!!! hint "Testing this configuration"
The unit tests can be built against the simdutf backend with the CMake option `JSON_TestSimdutf` (`OFF` by
default), which fetches simdutf and defines `JSON_USE_SIMDUTF` for every test target. The `ci_test_simdutf` target
runs the whole test suite in that configuration.
## Version history
- Added in version 3.13.0.
+16 -45
View File
@@ -33,54 +33,30 @@ A UTF-8 byte order mark is silently ignored.
Invalid Unicode escapes and unpaired surrogates in the input are reported as
[`parse_error.101`](../home/exceptions.md#jsonexceptionparse_error101) with a detailed message.
`operator>>` parses exactly one JSON value, so it can be called repeatedly to read a sequence of concatenated JSON
values from the same stream:
`operator>>` parses exactly one JSON value and leaves the stream positioned right after it, so it can be called
repeatedly to read a sequence of concatenated JSON values from the same stream:
```cpp
json j1, j2;
input >> j1; // parses the first value
input >> j2; // parses the next value
std::istringstream input("1true[2]");
json j1, j2, j3;
input >> j1; // j1 == 1, stream now positioned right after it
input >> j2; // j2 == true
input >> j3; // j3 == [2]
```
!!! warning "A number must be followed by whitespace"
!!! note "Changed behavior for numbers"
A number is only terminated by the character that follows it. That character is read from the stream to detect the
end of the number, and it is **not** put back. When a value that is a number is immediately followed by the next
value, the first character of that next value is lost:
A number is the only value whose end can be detected solely by reading the character that follows it. Up to
version 3.13.0 that character was consumed and not put back, so the stream was left one byte too far whenever a
number was immediately followed by another value: reading `1true` yielded `1` and left the stream at `rue`.
Values had to be separated by whitespace to work around this.
```cpp
std::istringstream input("1true");
json j1, j2;
input >> j1; // j1 == 1
input >> j2; // throws parse_error.101: the stream now starts at "rue"
```
Separating the values with whitespace avoids this, because the character that is eaten is then the separator:
```cpp
std::istringstream input("1 true");
json j1, j2;
input >> j1; // j1 == 1
input >> j2; // j2 == true
```
Only numbers are affected. Values ending in a self-delimiting character do not read past themselves, so
`truefalse`, `[1][2]`, `{"a":1}{"b":2}`, and `"a""b"` can be read back to back without a separator.
Define [`JSON_PRECISE_STREAM_POSITION`](macros/json_precise_stream_position.md) to `1` to leave the terminating character in the stream
instead, so that the stream is positioned right after the value for every value type and no separator is
needed. This is tracked in [#5340](https://github.com/nlohmann/json/issues/5340).
The terminating character is now only looked at and left in the stream, so no separator is required. Code that
relied on the extra byte being swallowed will observe it again.
Note that reading concatenated values does **not** work for [JSON Lines](../features/parsing/json_lines.md)
(newline-delimited JSON) input -- see that page for why and for the recommended alternative.
By default, a `'\0'` (NUL) byte encountered while reading a value is treated as end of input, rather than as an
ordinary (and, outside of a string, invalid) byte; see the [FAQ entry](../home/faq.md#nul-bytes-in-the-input) for
details and the [`JSON_STRICT_NUL_HANDLING`](macros/json_strict_nul_handling.md) macro to opt into rejecting it
instead. Because `operator>>` only parses a single value and does not require the rest of the stream to be consumed,
a NUL byte *after* a complete value has no effect on `operator>>` either way; it only matters while a value is still
being read.
!!! warning "Deprecation"
This function replaces function `#!cpp std::istream& operator<<(basic_json& j, std::istream& i)` which has
@@ -107,14 +83,9 @@ being read.
- [accept](basic_json/accept.md) - check if the input is valid JSON
- [parse](basic_json/parse.md) - deserialize from a compatible input
- [`JSON_STRICT_NUL_HANDLING`](macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
instead of treating it as end of input
- [`JSON_PRECISE_STREAM_POSITION`](macros/json_precise_stream_position.md) - opt in to leaving the stream positioned right after a number
## Version history
- Added in version 1.0.0.
- `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
it as end of input; planned to become the default in version 4.0.0.
- `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave the character that terminates a number in
the stream; planned to become the default in version 4.0.0.
- Changed in version 4.0.0 to leave the character that terminates a number in the stream, so that the stream is
positioned right after the parsed value for every value type.
@@ -1,70 +0,0 @@
# Assurance case
This page argues why the library meets its security requirements. It describes the threats the library faces, where the
trust boundaries lie, and how the library's design and the [quality assurance](quality_assurance.md) counter these
threats. To report a vulnerability, see the [security policy](security_policy.md).
## Threat model
The library parses, stores, and serializes JSON values in memory. It does not open network connections, does not open
files (it only reads from streams or `std::FILE*` handles that the caller has already opened), does not read environment
variables, and does not implement cryptography or handle credentials.
The primary threat is therefore **untrusted input**: JSON text or binary data (BJData, BSON, CBOR, MessagePack, UBJSON)
that an attacker controls, passed to [`parse`](../api/basic_json/parse.md), [`accept`](../api/basic_json/accept.md),
[`sax_parse`](../api/basic_json/sax_parse.md), or one of the `from_*` functions such as
[`from_cbor`](../api/basic_json/from_cbor.md). Such input may try to
- make the library read or write out of bounds (malformed lengths, truncated input, invalid UTF-8),
- trigger undefined behavior (integer overflow in sizes or numbers, invalid casts),
- exhaust memory (huge announced sizes), or
- exhaust the call stack (deeply nested arrays and objects).
## Trust boundaries
- **Untrusted:** all serialized input read by the parser, the SAX interface, and the binary readers. The library must
handle every possible input by either producing a value or throwing a [`parse_error`](../home/exceptions.md#parse-errors)
(or returning `false` when exceptions are disabled for the call).
- **Trusted:** the C++ code that calls the library. Calling a function with violated preconditions, for instance
accessing an array with [`operator[]`](../api/basic_json/operator%5B%5D.md) out of range, is a programming error and
not a security boundary. Such preconditions are checked with [runtime assertions](../features/assertions.md) in debug
builds; functions such as [`at`](../api/basic_json/at.md) offer checked access with exceptions.
## Secure design
- **Strict parsing.** The parser accepts exactly the JSON grammar of [RFC 8259](https://datatracker.ietf.org/doc/html/rfc8259).
Extensions such as [comments](../features/comments.md) and [trailing commas](../features/trailing_commas.md) must be
enabled explicitly. Invalid UTF-8 is rejected.
- **Errors are reported, not ignored.** Malformed input results in a [`parse_error`](../home/exceptions.md#parse-errors)
with the byte position of the error. Binary readers do not trust announced sizes: strings and binary values grow
only as bytes are actually read, arrays reserve at most a fixed number of elements up front, and sizes that no
container can hold are rejected.
- **Memory is owned by values.** Each `basic_json` value owns its content, and there is no manual memory management in
user code. The destructor does not recurse, so destroying a deeply nested value does not exhaust the stack.
- **Bounded recursion.** The JSON parser and the binary readers keep their state in explicit stacks instead of
recursing per nesting level. Operations that walk a value, such as [`dump`](../api/basic_json/dump.md), copying,
hashing, and [`merge_patch`](../api/basic_json/merge_patch.md), recurse only up to a fixed depth and continue with an
explicit stack below it. Some operations, such as comparison, [`diff`](../api/basic_json/diff.md),
[`flatten`](../api/basic_json/flatten.md), and the binary writers, still recurse once per nesting level; work on them
is in progress. Applications that process untrusted input can limit its nesting depth with a
[parser callback](../features/parsing/parser_callbacks.md).
- **Invariants are checked.** The class invariant (for instance, that the pointer for the stored type is never null) is
checked with runtime assertions throughout the test suite.
## Common weaknesses
The following table maps the relevant classes of the [Common Weakness Enumeration](https://cwe.mitre.org) to the
measures that counter them. The measures are described in detail in [Quality assurance](quality_assurance.md).
| Weakness | Countermeasures |
|---------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------|
| Out-of-bounds read/write ([CWE-125](https://cwe.mitre.org/data/definitions/125.html), [CWE-787](https://cwe.mitre.org/data/definitions/787.html)) | bounds checks on all reads from the input; AddressSanitizer and Valgrind on the test suite; OSS-Fuzz |
| Integer overflow ([CWE-190](https://cwe.mitre.org/data/definitions/190.html)) | UndefinedBehaviorSanitizer with integer overflow detection; Clang-Tidy; Cppcheck |
| Use after free, double free ([CWE-416](https://cwe.mitre.org/data/definitions/416.html), [CWE-415](https://cwe.mitre.org/data/definitions/415.html)) | ownership of all memory by values; AddressSanitizer and Valgrind; Clang Static Analyzer |
| Memory leaks ([CWE-401](https://cwe.mitre.org/data/definitions/401.html)) | Valgrind (Memcheck) on the test suite |
| Uncontrolled recursion ([CWE-674](https://cwe.mitre.org/data/definitions/674.html)) | iterative parser, binary readers, and destructor; bounded recursion in value operations; tests with deeply nested inputs |
| Uncontrolled resource consumption ([CWE-400](https://cwe.mitre.org/data/definitions/400.html)) | allocations based on announced sizes are capped; OSS-Fuzz with memory limits |
| Undefined behavior in general ([CWE-758](https://cwe.mitre.org/data/definitions/758.html)) | UndefinedBehaviorSanitizer; runtime assertions; Clang-Tidy, Cppcheck, Clang Static Analyzer, Infer |
In addition, every line of the library is covered by the unit tests, and all parsers are fuzz-tested around the clock
by [OSS-Fuzz](https://github.com/google/oss-fuzz/tree/master/projects/json).
-2
View File
@@ -5,6 +5,4 @@
- [Contribution Guidelines](contribution_guidelines.md) - guidelines how to contribute to this project
- [Governance](governance.md) - the governance model of this project
- [Quality Assurance](quality_assurance.md) - how the quality of this project is assured
- [Roadmap](roadmap.md) - what the project will and will not do
- [Security Policy](security_policy.md) - the security policy of the project
- [Assurance Case](assurance_case.md) - why the library meets its security requirements
@@ -164,9 +164,6 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
- [x] The parser is tested against extensive correctness suites for JSON compliance.
- [x] In addition, the library is continuously fuzz-tested at [OSS-Fuzz](https://google.github.io/oss-fuzz/) where the
library is checked against billions of inputs.
- [x] Every crash reported by OSS-Fuzz is fixed together with a unit test that reproduces it, and the fix references
the OSS-Fuzz issue. The round-trip checks of the fuzzer drivers are also part of the unit tests. See the
[fuzz testing documentation](https://github.com/nlohmann/json/blob/develop/tests/fuzzing.md#handling-oss-fuzz-reports).
## Static analysis
-43
View File
@@ -1,43 +0,0 @@
# Roadmap
This page describes what the project intends to do, and what it does not intend to do, over the next year. Concrete
work items are tracked in the [GitHub milestones](https://github.com/nlohmann/json/milestones) and the
[issue tracker](https://github.com/nlohmann/json/issues).
## What the project will do
- **Keep the C++11 baseline.** The library will continue to compile with every
[supported C++11 compiler](https://github.com/nlohmann/json/blob/develop/README.md#supported-compilers). Features of
later standards are only used when they are guarded by the `JSON_HAS_CPP_*` macros.
- **Stay conformant to JSON.** The parser and serializer follow [RFC 8259](https://datatracker.ietf.org/doc/html/rfc8259).
Extensions such as [comments](../features/comments.md) or [trailing commas](../features/trailing_commas.md) remain
opt-in.
- **Keep the 3.x public API stable.** Releases follow [semantic versioning](https://semver.org). Changes that would
break existing code are only added behind a feature macro, so users can opt in and test their code before a next
major release.
- **Support a broad range of compilers and platforms.** The [CI](quality_assurance.md) keeps testing old and new
versions of GCC, Clang, MSVC, and other compilers on Linux, macOS, and Windows.
- **Keep the quality assurance up.** Every change keeps the test coverage at 100%, passes the static and dynamic
analysis, and is fuzz-tested by OSS-Fuzz, see [Quality assurance](quality_assurance.md).
- **Harden the library against hostile input.** Handling deeply nested values without exhausting the call stack is
ongoing work.
- **Fix bugs and security issues** reported through the issue tracker and the [security policy](security_policy.md).
## What the project will not do
- **Break the public API of version 3.x.** See the
[contribution guidelines](https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md#break-the-public-api)
for what counts as a breaking change.
- **Require a newer C++ standard than C++11.**
- **Break JSON conformance** or enable non-standard extensions by default.
- **Add dependencies** or require a build step. The library remains header-only, and the single header
`json.hpp` remains a complete distribution.
- **Trade simplicity for speed or memory efficiency.** Performance improvements are welcome, but the library is not
meant to compete with the fastest JSON libraries, see [Design goals](../home/design_goals.md).
## Version 4.0
There is no decision yet on whether or when a version 4.0 with breaking changes will be released. Proposals that need
a major version, for instance stricter type conversions, are collected in issue
[#3453](https://github.com/nlohmann/json/issues/3453). Until then, such changes are only added as opt-in behavior
behind feature macros.
@@ -1,19 +0,0 @@
#include <iostream>
#include <map>
#include <nlohmann/json.hpp>
#include "custom_array_type.hpp"
using custom_json = nlohmann::basic_json<std::map, custom_array_type>;
int main()
{
custom_json j = custom_json::array();
j.push_back(1);
j.push_back(2);
j.push_back(3);
std::cout << j.dump() << std::endl;
std::cout << std::boolalpha << (custom_json::parse(j.dump()) == j) << std::endl;
}
@@ -1,152 +0,0 @@
#pragma once
#include <memory>
#include <utility>
#include <vector>
// A minimal, self-contained ArrayType built around a private std::vector.
// See https://json.nlohmann.me/features/types/template_parameters/#arraytype
template<class T, class Allocator = std::allocator<T>>
class custom_array_type
{
using vector_t = std::vector<T, Allocator>;
vector_t data_;
public:
using value_type = typename vector_t::value_type;
using size_type = typename vector_t::size_type;
using iterator = typename vector_t::iterator;
using const_iterator = typename vector_t::const_iterator;
custom_array_type() = default;
custom_array_type(const custom_array_type&) = default;
custom_array_type(custom_array_type&&) = default;
custom_array_type& operator=(const custom_array_type&) = default;
custom_array_type& operator=(custom_array_type&&) = default;
template<class InputIt>
custom_array_type(InputIt first, InputIt last) : data_(first, last) {}
custom_array_type(size_type count, const T& value) : data_(count, value) {}
iterator begin()
{
return data_.begin();
}
iterator end()
{
return data_.end();
}
const_iterator begin() const
{
return data_.begin();
}
const_iterator end() const
{
return data_.end();
}
const_iterator cbegin() const
{
return data_.cbegin();
}
const_iterator cend() const
{
return data_.cend();
}
bool empty() const
{
return data_.empty();
}
size_type size() const
{
return data_.size();
}
size_type max_size() const
{
return data_.max_size();
}
void clear()
{
data_.clear();
}
void resize(size_type n)
{
data_.resize(n);
}
T& operator[](size_type pos)
{
return data_[pos];
}
const T& operator[](size_type pos) const
{
return data_[pos];
}
T& back()
{
return data_.back();
}
const T& back() const
{
return data_.back();
}
void push_back(const T& value)
{
data_.push_back(value);
}
void push_back(T&& value)
{
data_.push_back(std::move(value));
}
template<class... Args>
void emplace_back(Args&& ... args)
{
data_.emplace_back(std::forward<Args>(args)...);
}
void pop_back()
{
data_.pop_back();
}
iterator insert(const_iterator pos, const T& value)
{
return data_.insert(pos, value);
}
iterator insert(const_iterator pos, size_type count, const T& value)
{
return data_.insert(pos, count, value);
}
template<class InputIt>
iterator insert(const_iterator pos, InputIt first, InputIt last)
{
return data_.insert(pos, first, last);
}
iterator erase(const_iterator pos)
{
return data_.erase(pos);
}
iterator erase(const_iterator first, const_iterator last)
{
return data_.erase(first, last);
}
void swap(custom_array_type& other)
{
data_.swap(other.data_);
}
friend bool operator==(const custom_array_type& lhs, const custom_array_type& rhs)
{
return lhs.data_ == rhs.data_;
}
friend bool operator<(const custom_array_type& lhs, const custom_array_type& rhs)
{
return lhs.data_ < rhs.data_;
}
};
@@ -1,2 +0,0 @@
[1,2,3]
true
@@ -1,21 +0,0 @@
#include <cstdint>
#include <iostream>
#include <map>
#include <string>
#include <vector>
#include <nlohmann/json.hpp>
#include "custom_binary_type.hpp"
using custom_json = nlohmann::basic_json<std::map, std::vector, std::string, bool,
std::int64_t, std::uint64_t, double, std::allocator,
nlohmann::adl_serializer, custom_binary_type>;
int main()
{
const auto j = custom_json::binary({0x01, 0x02, 0x03});
std::cout << j.dump() << std::endl;
std::cout << std::boolalpha << (custom_json::from_cbor(custom_json::to_cbor(j)) == j) << std::endl;
}
@@ -1,112 +0,0 @@
#pragma once
#include <cstdint>
#include <initializer_list>
#include <vector>
// A minimal, self-contained BinaryType built around a private std::vector.
// See https://json.nlohmann.me/features/types/template_parameters/#binarytype
class custom_binary_type
{
using vector_t = std::vector<std::uint8_t>;
vector_t data_;
public:
using value_type = vector_t::value_type;
using size_type = vector_t::size_type;
using iterator = vector_t::iterator;
using const_iterator = vector_t::const_iterator;
custom_binary_type() = default;
custom_binary_type(const custom_binary_type&) = default;
custom_binary_type(custom_binary_type&&) = default;
custom_binary_type& operator=(const custom_binary_type&) = default;
custom_binary_type& operator=(custom_binary_type&&) = default;
template<class InputIt>
custom_binary_type(InputIt first, InputIt last) : data_(first, last) {}
// so basic_json::binary({0x01, 0x02}) can build one directly
custom_binary_type(std::initializer_list<std::uint8_t> init) : data_(init) {}
size_type size() const
{
return data_.size();
}
bool empty() const
{
return data_.empty();
}
void clear()
{
data_.clear();
}
void resize(size_type n)
{
data_.resize(n);
}
// read-only is enough: the writers only ever read from a binary value
const std::uint8_t* data() const
{
return data_.data();
}
std::uint8_t& operator[](size_type pos)
{
return data_[pos];
}
std::uint8_t operator[](size_type pos) const
{
return data_[pos];
}
std::uint8_t& back()
{
return data_.back();
}
std::uint8_t back() const
{
return data_.back();
}
iterator begin()
{
return data_.begin();
}
iterator end()
{
return data_.end();
}
const_iterator begin() const
{
return data_.begin();
}
const_iterator end() const
{
return data_.end();
}
const_iterator cbegin() const
{
return data_.cbegin();
}
const_iterator cend() const
{
return data_.cend();
}
template<class InputIt>
iterator insert(const_iterator pos, InputIt first, InputIt last)
{
return data_.insert(pos, first, last);
}
friend bool operator==(const custom_binary_type& lhs, const custom_binary_type& rhs)
{
return lhs.data_ == rhs.data_;
}
friend bool operator<(const custom_binary_type& lhs, const custom_binary_type& rhs)
{
return lhs.data_ < rhs.data_;
}
};
@@ -1,2 +0,0 @@
{"bytes":[1,2,3],"subtype":null}
true
@@ -1,26 +0,0 @@
#include <iostream>
#include <type_traits>
#include <vector>
#include <nlohmann/json.hpp>
#include "custom_object_type.hpp"
using custom_json = nlohmann::basic_json<custom_object_type, std::vector>;
int main()
{
custom_json j;
j["pi"] = 3.141;
j["happy"] = true;
j["list"] = {1, 2, 3};
std::cout << j.dump(2) << std::endl;
std::cout << std::boolalpha << (custom_json::parse(j.dump()) == j) << std::endl;
// custom_object_type has no key_compare member, so object_comparator_t
// falls back to its default
std::cout << std::boolalpha
<< std::is_same<custom_json::object_comparator_t, custom_json::default_object_comparator_t>::value
<< std::endl;
}
@@ -1,144 +0,0 @@
#pragma once
#include <map>
#include <utility>
// A minimal, self-contained ObjectType built around a private std::map.
// key_compare is deliberately not exposed: when an ObjectType has no
// key_compare member, the library falls back to its own default comparator.
// See https://json.nlohmann.me/features/types/template_parameters/#objecttype
template<class Key, class T, class Compare, class Allocator>
class custom_object_type
{
using map_t = std::map<Key, T, Compare, Allocator>;
map_t data_;
public:
using key_type = typename map_t::key_type;
using mapped_type = typename map_t::mapped_type;
using value_type = typename map_t::value_type;
using size_type = typename map_t::size_type;
using iterator = typename map_t::iterator;
using const_iterator = typename map_t::const_iterator;
custom_object_type() = default;
custom_object_type(const custom_object_type&) = default;
custom_object_type(custom_object_type&&) = default;
custom_object_type& operator=(const custom_object_type&) = default;
custom_object_type& operator=(custom_object_type&&) = default;
template<class InputIt>
custom_object_type(InputIt first, InputIt last) : data_(first, last) {}
iterator begin()
{
return data_.begin();
}
iterator end()
{
return data_.end();
}
const_iterator begin() const
{
return data_.begin();
}
const_iterator end() const
{
return data_.end();
}
const_iterator cbegin() const
{
return data_.cbegin();
}
const_iterator cend() const
{
return data_.cend();
}
bool empty() const
{
return data_.empty();
}
size_type size() const
{
return data_.size();
}
size_type max_size() const
{
return data_.max_size();
}
void clear()
{
data_.clear();
}
iterator find(const key_type& key)
{
return data_.find(key);
}
const_iterator find(const key_type& key) const
{
return data_.find(key);
}
size_type count(const key_type& key) const
{
return data_.count(key);
}
std::pair<iterator, bool> emplace(const key_type& key, const mapped_type& value)
{
return data_.emplace(key, value);
}
std::pair<iterator, bool> insert(const value_type& value)
{
return data_.insert(value);
}
template<class InputIt>
void insert(InputIt first, InputIt last)
{
data_.insert(first, last);
}
mapped_type& operator[](const key_type& key)
{
return data_[key];
}
mapped_type& at(const key_type& key)
{
return data_.at(key);
}
const mapped_type& at(const key_type& key) const
{
return data_.at(key);
}
iterator erase(iterator pos)
{
return data_.erase(pos);
}
iterator erase(iterator first, iterator last)
{
return data_.erase(first, last);
}
size_type erase(const key_type& key)
{
return data_.erase(key);
}
void swap(custom_object_type& other)
{
data_.swap(other.data_);
}
friend bool operator==(const custom_object_type& lhs, const custom_object_type& rhs)
{
return lhs.data_ == rhs.data_;
}
friend bool operator<(const custom_object_type& lhs, const custom_object_type& rhs)
{
return lhs.data_ < rhs.data_;
}
};
@@ -1,11 +0,0 @@
{
"happy": true,
"list": [
1,
2,
3
],
"pi": 3.141
}
true
true
@@ -1,20 +0,0 @@
#include <iostream>
#include <map>
#include <vector>
#include <nlohmann/json.hpp>
#include "custom_string_type.hpp"
using custom_json = nlohmann::basic_json<std::map, std::vector, custom_string_type>;
int main()
{
custom_json j;
j["pi"] = 3.141;
j["happy"] = true;
j["list"] = {1, 2, 3};
std::cout << j.dump(2) << std::endl;
std::cout << std::boolalpha << (custom_json::parse(j.dump()) == j) << std::endl;
}
@@ -1,134 +0,0 @@
#pragma once
#include <ostream>
#include <string>
// A minimal, self-contained StringType built around a private std::string.
// Wraps rather than inherits, so it exposes exactly what the library needs
// and nothing more of std::string's interface.
//
// Covers the "Always required" members, the extras needed for the binary
// formats, and the extras needed for JSON Pointer / flatten / unflatten /
// diff. Extending it further (e.g. for std::hash<basic_json> or to_bson) is
// a matter of adding the extra members listed in the "Required for other
// functionality" table.
//
// See https://json.nlohmann.me/features/types/template_parameters/#stringtype
class custom_string_type
{
std::string data_;
public:
using value_type = char;
using size_type = std::string::size_type;
using iterator = std::string::iterator;
using const_iterator = std::string::const_iterator;
static constexpr size_type npos = std::string::npos;
custom_string_type() = default;
custom_string_type(const custom_string_type&) = default;
custom_string_type(custom_string_type&&) = default;
custom_string_type& operator=(const custom_string_type&) = default;
custom_string_type& operator=(custom_string_type&&) = default;
// not explicit: the library relies on being able to hand it a string literal
custom_string_type(const char* s) : data_(s) {}
custom_string_type(const char* s, size_type count) : data_(s, count) {}
custom_string_type(size_type count, char ch) : data_(count, ch) {}
size_type size() const
{
return data_.size();
}
bool empty() const
{
return data_.empty();
}
void clear()
{
data_.clear();
}
void resize(size_type n)
{
data_.resize(n);
}
void resize(size_type n, char c)
{
data_.resize(n, c);
}
void reserve(size_type n)
{
data_.reserve(n);
}
// must stay null-terminated -- the parser hands this to std::strtoull &
// friends; std::string::data() has guaranteed that since C++11
const char* data() const
{
return data_.data();
}
void push_back(char c)
{
data_.push_back(c);
}
char& operator[](size_type pos)
{
return data_[pos];
}
char operator[](size_type pos) const
{
return data_[pos];
}
custom_string_type& append(const char* s, size_type count)
{
data_.append(s, count);
return *this;
}
custom_string_type& append(const custom_string_type& other)
{
data_.append(other.data_);
return *this;
}
size_type find_first_of(char c, size_type pos = 0) const
{
return data_.find_first_of(c, pos);
}
iterator begin()
{
return data_.begin();
}
iterator end()
{
return data_.end();
}
const_iterator begin() const
{
return data_.begin();
}
const_iterator end() const
{
return data_.end();
}
friend bool operator==(const custom_string_type& lhs, const custom_string_type& rhs)
{
return lhs.data_ == rhs.data_;
}
friend bool operator<(const custom_string_type& lhs, const custom_string_type& rhs)
{
return lhs.data_ < rhs.data_;
}
// not required by the library itself, but dump() returns a custom_string_type
// and this makes `std::cout << j.dump()` work as expected
friend std::ostream& operator<<(std::ostream& os, const custom_string_type& s)
{
return os << s.data_;
}
};
@@ -1,10 +0,0 @@
{
"happy": true,
"list": [
1,
2,
3
],
"pi": 3.141
}
true
@@ -4,8 +4,8 @@
Hello, world!
1 2 3 4 5
string: "Hello, world!"
number: {"floating-point":17.23,"integer":42}
null: null
string: "Hello, world!"
boolean: true
array: [1,2,3,4,5]
+1 -1
View File
@@ -4,8 +4,8 @@
Hello, world!
1 2 3 4 5
string: "Hello, world!"
number: {"floating-point":17.23,"integer":42}
null: null
string: "Hello, world!"
boolean: true
array: [1,2,3,4,5]
@@ -4,9 +4,9 @@
Hello, world!
1 2 3 4 5
string: "Hello, world!"
number: {"floating-point":17.23,"integer":42}
null: null
string: "Hello, world!"
boolean: true
array: [1,2,3,4,5]
[json.exception.type_error.302] type must be boolean, but is string
@@ -9,13 +9,13 @@ int main()
auto text = R"({"IDs": [116, 943], "Width": 800})";
// discard the array when the parser reads its opening bracket
json j_array_start = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
json j_array_start = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
{
return event != json::parse_event_t::array_start;
});
// discard the same array when the parser reads its closing bracket
json j_array_end = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
json j_array_end = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
{
return event != json::parse_event_t::array_end;
});
@@ -33,7 +33,7 @@ int main()
});
// discard the top-level object
json j_root = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
json j_root = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
{
return event != json::parse_event_t::object_end;
});
@@ -116,22 +116,17 @@ The library uses the following mapping from JSON values types to BJData types ac
```
Likewise, when a JSON object in the above form is serialized using
[`to_bjdata`](../../api/basic_json/to_bjdata.md), it is automatically converted into a compact BJData ND-array.
[`to_bjdata`](../../api/basic_json/to_bjdata.md), it is automatically converted into a compact BJData ND-array. When
the 1-dimensional vector stored in `"_ArraySize_"` contains a single integer or two integers with one being 1, a
regular 1-D optimized array is generated instead.
When parsing, an ND-array whose dimension vector is empty, contains a single integer, contains two integers with the
first being 1, or contains a 0 is returned as a regular (possibly empty) array rather than an annotated object.
An object is only converted if the annotation describes a packed array that is parsed back into the same annotated
object; otherwise it is serialized as a regular JSON object, so the annotation is never lost in a round trip. This requires
all of the following:
An object is only converted if the annotation actually describes a packed array; otherwise it is serialized as a
regular JSON object. This requires all of the following:
- `"_ArrayType_"` is one of `uint8`, `int8`, `uint16`, `int16`, `uint32`, `int32`, `uint64`, `int64`, `single`,
`double`, `char`, or `byte`,
- `"_ArraySize_"` is an array, since the dimensions are written as the ND-array header's length,
- `"_ArraySize_"` has at least two entries and is not a 1×N row vector (first entry 1), since other shapes are
parsed back as a regular array,
- every entry of `"_ArraySize_"` is a positive integer, and their product is representable as a `std::size_t`,
- `"_ArrayData_"` is an array holding exactly that many elements, and
- every entry of `"_ArraySize_"` is a non-negative integer, and their product is representable as a `std::size_t`,
- `"_ArrayData_"` holds exactly that many elements, and
- every element of `"_ArrayData_"` is a number of the kind named by `"_ArrayType_"` (a floating-point number for
`single` and `double`, an integer otherwise).
@@ -208,16 +203,6 @@ The library maps BJData types to JSON value types as follows:
The mapping is **complete** in the sense that any BJData value can be converted to a JSON value.
!!! info "Round trips"
A value returned by [`from_bjdata`](../../api/basic_json/from_bjdata.md) can be serialized with
[`to_bjdata`](../../api/basic_json/to_bjdata.md) using any combination of options and parsed back into an equal
value, and serializing that value again with the same options produces the same bytes. The exception is binary
values: they are only written as an optimized binary array (`[$B`) if Draft 3 is enabled and both `use_size` and
`use_type` are set. Otherwise, they are written as arrays of integers and parsed back as such (see the notes on
binary values above), and serializing such an array again may choose different, but equally valid, type markers.
The bytes can then differ, but parsing them again yields the same value.
??? example
```cpp
@@ -98,17 +98,6 @@ The library maps BSON record types to JSON value types as follows:
This library deserializes BSON type `0x11` (Timestamp) as a `number_unsigned` value. The 64-bit value is preserved,
but the Timestamp type information is not.
!!! warning "Lenient BSON input handling"
The BSON reader is lenient in a few areas where the BSON specification is more restrictive:
- array element keys are not checked against the required decimal sequence (`0`, `1`, `2`, ...),
- any non-zero byte is accepted as `true` for the boolean type, and
- the payload for binary subtype `0x02` is returned as-is, including its inner length prefix.
If BSON input must be validated for strict specification compliance, validate it separately before passing it to
`from_bson()`.
??? example
```cpp
@@ -69,13 +69,6 @@ The library uses the following mapping from JSON values types to UBJSON types ac
Note that `use_size = true` alone may result in larger representations - the benefit of this parameter is that the
receiving side is immediately informed on the number of elements of the container.
An array whose type marker is `Z` (null), `T` (true) or `F` (false) stores no payload at all, because the marker
already is the value. Its declared count is therefore the only thing that decides how much memory the receiving side
allocates, and a handful of bytes can describe billions of elements. `from_ubjson` rejects such an array with
[`out_of_range.408`](../../home/exceptions.md#jsonexceptionout_of_range408) when the count exceeds 1,048,576
(`1 << 20`), and `to_ubjson` writes longer arrays of these types without the annotation, so any value it produces
can be read back.
!!! info "Binary values"
If the JSON data contains the binary type, the value stored is a list of integers, as suggested by the UBJSON
-24
View File
@@ -54,30 +54,6 @@ json j = {1.0, "hello", 42};
auto t = j.get<std::tuple<double, std::string, int>>(); // {1.0, "hello", 42}
```
!!! warning "Serializing a `std::pair`/`std::tuple` whose every element is a string-keyed pair"
When *every* element of a `#!cpp std::pair` or `#!cpp std::tuple` is itself a two-element array whose first
element is a string (for example `#!cpp std::pair<std::string, int>`), serializing it produces a JSON **object**
instead of the expected array:
```cpp
using kv = std::pair<std::string, int>;
json j = std::pair<kv, kv>{{"a", 1}, {"b", 2}}; // {"a":1,"b":2}, not [["a",1],["b",2]]
```
This is a consequence of the [brace-initializer object-detection rule](creating_values.md): the same rule that
lets `#!cpp json{{"a", 1}, {"b", 2}}` create an object also fires here. The resulting object cannot be read back
into the original type (`#!cpp get<std::pair<kv, kv>>()` throws [`type_error.302`](../home/exceptions.md#jsonexceptiontype_error302)),
and duplicate keys collapse into one, losing elements. This only affects `#!cpp std::pair`/`#!cpp std::tuple`
themselves; a `#!cpp std::vector<std::pair<std::string, int>>`, or a pair/tuple with at least one element that is
not a string-keyed pair, serializes to an array as expected. To force an array, build one explicitly from the
elements with [`array`](../api/basic_json/array.md):
```cpp
std::pair<kv, kv> p{{"a", 1}, {"b", 2}};
json a = json::array({p.first, p.second}); // [["a",1],["b",2]]
```
!!! info "Extracting references into a tuple"
A tuple type may also hold references (e.g. `#!cpp std::tuple<double&, std::string&>`) to avoid copying: `get`
-38
View File
@@ -91,23 +91,6 @@ security reasons (e.g., Intel Software Guard Extensions (SGX)).
See [full documentation of `JSON_NO_IO`](../api/macros/json_no_io.md).
## `JSON_NO_THREAD_LOCAL`
When defined, the library does not use `#!cpp thread_local` storage. Copying a value and comparing two values then
always avoid the call stack rather than descending into a bounded number of levels first, which is slower but yields the
same values and the same comparisons.
See [full documentation of `JSON_NO_THREAD_LOCAL`](../api/macros/json_no_thread_local.md).
## `JSON_PRECISE_STREAM_POSITION`
When defined to `1`, [`operator>>`](../api/operator_gtgt.md) and non-strict
[`sax_parse`](../api/basic_json/sax_parse.md) leave an input stream positioned right after the parsed value, instead of
also consuming the character that terminates a number. The default value is `0`, which preserves the existing behavior;
this is planned to become the default in version 4.0.0.
See [full documentation of `JSON_PRECISE_STREAM_POSITION`](../api/macros/json_precise_stream_position.md).
## `JSON_SKIP_LIBRARY_VERSION_CHECK`
When defined, the library will not create a compiler warning when a different version of the library was already
@@ -122,19 +105,6 @@ using the library with compilers that do not fully support C++11 and may only wo
See [full documentation of `JSON_SKIP_UNSUPPORTED_COMPILER_CHECK`](../api/macros/json_skip_unsupported_compiler_check.md).
## `JSON_STRICT_NUL_HANDLING`
When defined to `1`, a `'\0'` (NUL) byte anywhere in the input is rejected with `parse_error.101`, like any other
unexpected byte, instead of being silently treated as end of input (see the
[FAQ entry](../home/faq.md#nul-bytes-in-the-input) for background). The default value is `0`, which preserves the
existing behavior; this is planned to become the default in version 4.0.0.
The strict handling can also be enabled with the CMake option
[`JSON_StrictNulHandling`](../integration/cmake.md#json_strictnulhandling) (`OFF` by default) which sets
`JSON_STRICT_NUL_HANDLING` accordingly.
See [full documentation of `JSON_STRICT_NUL_HANDLING`](../api/macros/json_strict_nul_handling.md).
## `JSON_THROW_USER(exception)`
This macro overrides `#!cpp throw` calls inside the library. The argument is the exception to be thrown.
@@ -167,14 +137,6 @@ behavior is deprecated and switched off (`0`) by default.
See [full documentation of `JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON`](../api/macros/json_use_legacy_discarded_value_comparison.md).
## `JSON_USE_SIMDUTF`
When defined, UTF-8 validation of JSON strings read from contiguous byte input is delegated to the
[simdutf](https://github.com/simdutf/simdutf) library instead of the built-in scalar validator. This is an opt-in
external dependency and is not defined by default.
See [full documentation of `JSON_USE_SIMDUTF`](../api/macros/json_use_simdutf.md).
## `NLOHMANN_DEFINE_TYPE_*(...)`, `NLOHMANN_DEFINE_DERIVED_TYPE_*(...)`
The library defines 12 macros to simplify the serialization/deserialization of types. See the page on
-4
View File
@@ -15,10 +15,6 @@ The complete default namespace name is derived as follows:
- [`JSON_DIAGNOSTICS`](../api/macros/json_diagnostics.md) defined non-zero appends `_diag`.
- [`JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON`](../api/macros/json_use_legacy_discarded_value_comparison.md)
defined non-zero appends `_ldvcmp`.
- [`JSON_DIAGNOSTIC_POSITIONS`](../api/macros/json_diagnostic_positions.md) defined non-zero appends `_dp`.
- [`JSON_BRACE_INIT_COPY_SEMANTICS`](../api/macros/json_brace_init_copy_semantics.md) defined non-zero appends
`_bics`.
- [`JSON_PRECISE_STREAM_POSITION`](../api/macros/json_precise_stream_position.md) defined non-zero appends `_psp`.
- The inline namespace ends with the suffix `_v` followed by the 3 components of the version number separated by
underscores. To omit the version component, see [Disabling the version component](#disabling-the-version-component)
below.
+1 -5
View File
@@ -51,11 +51,7 @@ If you do want to preserve the **insertion order**, you can use the type [`nlohm
--8<-- "examples/ordered_json.output"
```
Alternatively, [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) also preserves the insertion order and, unlike [`ordered_map`](../api/ordered_map.md), keeps a lookup index, so it does not have the quadratic cost described below. It is used through a small adapter ([integration](https://github.com/nlohmann/json/issues/485#issuecomment-333652309)).
If the order does not matter and you only want faster lookup, `boost::unordered_flat_map`, `absl::flat_hash_map`, `absl::node_hash_map`, and several other hash maps work through an adapter that restores the template argument order `basic_json` expects; see [Template Parameter Requirements](types/template_parameters.md#objecttype). Note these are *unordered*, not insertion-ordered.
[`tsl::ordered_map`](https://github.com/Tessil/ordered-map) cannot be used: its iterators expose the mapped value as `const`, while `basic_json` needs to modify it in place.
Alternatively, you can use a more sophisticated ordered map like [`tsl::ordered_map`](https://github.com/Tessil/ordered-map) ([integration](https://github.com/nlohmann/json/issues/546#issuecomment-304447518)) or [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) ([integration](https://github.com/nlohmann/json/issues/485#issuecomment-333652309)).
The [`ordered_map`](../api/ordered_map.md) behind `nlohmann::ordered_json` is deliberately minimal and has no lookup
index, so every key access is a linear scan and building an object of `n` keys costs O(n²). This is unnoticeable at
+1 -3
View File
@@ -40,9 +40,7 @@ what makes it possible to read several concatenated values from the same stream,
document followed by trailing bytes" is accepted rather than rejected. If you are validating conformance, or need to
reject any input that is not exactly one JSON document, prefer `parse`.
When using `operator>>` to read several concatenated values this way, a value that is a number must be followed by
whitespace, because `operator>>` consumes the character that terminates a number, unless
[`JSON_PRECISE_STREAM_POSITION`](../../api/macros/json_precise_stream_position.md) is defined to `1` — see the
Values read this way do not need to be separated by whitespace; see the
[`operator>>` notes](../../api/operator_gtgt.md#notes) for details and examples.
## SAX vs. DOM parsing
@@ -49,5 +49,4 @@ JSON Lines input with more than one value is treated as invalid JSON by the [`pa
with a JSON Lines input does not work, because the parser will try to parse one value after the last one.
This is different from parsing a stream of *concatenated* (non-newline-delimited) JSON values, for which
`operator>>` does work, provided that a value that is a number is followed by whitespace -- see its
[notes](../../api/operator_gtgt.md#notes) for details.
`operator>>` does work -- see its [notes](../../api/operator_gtgt.md#notes) for details.
+1 -6
View File
@@ -79,8 +79,7 @@ template<
class NumberFloatType = double,
template<typename U> class AllocatorType = std::allocator,
template<typename T, typename SFINAE = void> class JSONSerializer = adl_serializer,
class BinaryType = std::vector<std::uint8_t>,
class CustomBaseClass = void
class BinaryType = std::vector<std::uint8_t>
>
class basic_json;
```
@@ -107,10 +106,6 @@ using number_float_t = NumberFloatType;
using binary_t = nlohmann::byte_container_with_subtype<BinaryType>;
```
Not every type can be passed for these template arguments: the library uses the resulting types in ways that imply a
number of requirements, for instance that `StringType` is `char`-based or that `ArrayType` is vector-like. These
requirements are collected in [Template Parameter Requirements](template_parameters.md).
## Objects
@@ -1,751 +0,0 @@
# Template Parameter Requirements
Class [`basic_json`](../../api/basic_json/index.md) is configurable through eleven template parameters. The library
never formally states what a type passed for one of these parameters has to provide -- the requirements are implied by
the way the library uses the resulting [`object_t`](../../api/basic_json/object_t.md),
[`array_t`](../../api/basic_json/array_t.md), [`string_t`](../../api/basic_json/string_t.md), etc. This page collects
these requirements so they do not have to be discovered by trial and error. Each section lists the concrete types
that are known to work for that parameter and the ones that do not, checked against Boost 1.83, Abseil 20250127.0,
Folly, EASTL 3.21, `ankerl::unordered_dense`, `phmap`, `gtl`, `robin_hood`, `tsl::ordered_map`, and Qt 6.
## How to read this page
Requirements are split into two groups:
- **Always required** -- needed to instantiate `basic_json` at all, or needed by functions that virtually every program
uses (construction, element access, [`dump`](../../api/basic_json/dump.md)).
- **Required for ...** -- only needed when a particular part of the API is instantiated. Member function templates are
only instantiated when they are used, so a type may be perfectly usable even though it does not satisfy these
requirements, as long as the corresponding functions are never called.
!!! warning "Requirements are not checked"
Three requirements are checked with a `#!cpp static_assert`: the array iterator category, the width of
[`BinaryType`](#binarytype)'s `value_type`, and [`NumberUnsignedType`](#numberintegertype-and-numberunsignedtype)
being at least as wide as [`NumberIntegerType`](#numberintegertype-and-numberunsignedtype). The rest are not
diagnosed with dedicated error messages, and violating most of them results in a compiler error somewhere inside
the library. Four violations are not caught at compile time at all:
- A [`StringType`](#stringtype) whose `data()` is not null-terminated compiles and silently misparses numbers,
because the lexer hands the buffer to `#!cpp std::strtoull`/`#!cpp std::strtoll`/`#!cpp std::strtod`.
- A stateful [`AllocatorType`](#allocatortype) compiles and silently ignores its state: allocation, deallocation,
and [`get_allocator()`](../../api/basic_json/get_allocator.md) each use a different default-constructed instance.
- The two [cross-specialization conversions](#cross-specialization-conversions) below. These abort on an assertion
in a normal build, and only fail silently under `#!cpp NDEBUG`.
## Overview
| Template parameter | Default | Notable substitutes |
|-------------------------------------------------------------------|-----------------------------------|-----------------------------------------------------------------------|
| [`ObjectType`](#objecttype) | `std::map` | [`nlohmann::ordered_map`](../../api/ordered_map.md), Abseil hash maps |
| [`ArrayType`](#arraytype) | `std::vector` | `#!cpp std::deque` |
| [`StringType`](#stringtype) | `std::string` | `std::string`-like types over `char` |
| [`BooleanType`](#booleantype) | `bool` | none worth using |
| [`NumberIntegerType`](#numberintegertype-and-numberunsignedtype) | `std::int64_t` | any signed integer type |
| [`NumberUnsignedType`](#numberintegertype-and-numberunsignedtype) | `std::uint64_t` | any unsigned integer type at least as wide as `NumberIntegerType` |
| [`NumberFloatType`](#numberfloattype) | `double` | `float` (`long double`: no binary formats) |
| [`AllocatorType`](#allocatortype) | `std::allocator` | stateless allocators |
| [`JSONSerializer`](#jsonserializer) | `adl_serializer` | serializers with the same interface |
| [`BinaryType`](#binarytype) | `#!cpp std::vector<std::uint8_t>` | `#!cpp std::vector<char>` |
| [`CustomBaseClass`](#custombaseclass) | `void` | any default-constructible class |
!!! warning "Third-party containers and incomplete types"
`object_t` is instantiated inside the definition of `basic_json` -- it is probed for a `key_compare` member to
form [`object_comparator_t`](../../api/basic_json/object_comparator_t.md) -- i.e. while `basic_json` is still an
incomplete type. `#!cpp std::map` is required by the standard to support incomplete mapped types; most
third-party maps are not, and inspecting the mapped type at class scope (for instance with
`#!cpp std::is_trivially_move_assignable`) makes them unusable as `ObjectType`, no matter how their template
arguments are adapted. This rules out `absl::btree_map`, `phmap::btree_map`, `gtl::btree_map`,
`robin_hood::unordered_node_map`, `folly::F14FastMap`, and `eastl::hash_map`.
`array_t` is only *named* in the class definition and is not instantiated until `basic_json` is complete, so an
`ArrayType` that inspects its value type at class scope is generally fine -- `boost::container::small_vector` and
`static_vector` both reject incomplete value types yet work here. `absl::InlinedVector` is the exception: the
`#!cpp std::is_trivially_move_assignable<basic_json>` it evaluates while instantiating itself re-enters the
library's own trait machinery mid-instantiation.
!!! note "Folly requires C++20"
Folly's headers use `#!cpp consteval` and `#!cpp std::type_identity`, so any `basic_json` specialization that
names a Folly type has to be compiled as C++20 or later, whatever the rest of the library supports.
## `ObjectType`
`ObjectType` is instantiated as
```cpp
using object_t = ObjectType<StringType, // key_type
basic_json, // mapped_type
default_object_comparator_t, // key_compare
AllocatorType<std::pair<const StringType,
basic_json>>>; // allocator_type
```
i.e., the template arguments follow the order and meaning of `std::map`.
### Always required
- The template must be usable with **four** type arguments in the order shown above. The third argument is a
**comparator**; containers that expect something else in this position (e.g., a hash function) need an alias template
or wrapper -- see [Notes](#notes).
- An optional member type `key_compare`. If it is present it becomes
[`object_comparator_t`](../../api/basic_json/object_comparator_t.md); otherwise
[`default_object_comparator_t`](../../api/basic_json/default_object_comparator_t.md) is used.
- Member types `key_type`, `mapped_type`, `value_type`, and `iterator`.
- `value_type` must behave like `#!cpp std::pair<const key_type, mapped_type>`; the library accesses `.first` and
`.second` on it.
- `iterator` must be default-constructible and satisfy
[LegacyBidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator). The type returned
by `cbegin()`/`cend()` must satisfy the same requirements.
- Constructors: default, copy, move, and from an iterator range `(first, last)`.
- Member functions `begin()`, `end()`, `cbegin()`, `cend()`, `empty()`, `size()`, `max_size()`, `clear()`,
`find(key)`, `count(key)`, `emplace(key, value)`, `insert(value_type)`, `insert(first, last)`, `operator[](key)`,
`erase(iterator)`, and `erase(first, last)`. `erase(iterator)` may return the following iterator or `#!cpp void`;
in the latter case the library computes the successor itself, before erasing.
- `erase(key)` is **optional**: if the container does not provide one, the library falls back to `find(key)` followed
by `erase(iterator)`.
- `at(key)` is required only by [`to_ubjson`](../../api/basic_json/to_ubjson.md) and
[`to_bjdata`](../../api/basic_json/to_bjdata.md), but every container tried here provides it.
- `emplace` and `insert(value_type)` must return `#!cpp std::pair<iterator, bool>` and must have **unique-key**
semantics; multimaps cannot be used.
- The type must be swappable (via `std::swap` or an ADL `swap`).
- The comparison operators `==` and `<`; `!=`, `<=`, `>`, and `>=` are derived from them. Where the library uses
three-way comparison (C++20), `==` and `<=>` are required **instead** -- the six two-way operators do not satisfy
it. They implement [`basic_json`'s comparison operators](../../api/basic_json/operator_eq.md).
### Required for heterogeneous key lookup
The overloads of [`at`](../../api/basic_json/at.md), [`operator[]`](../../api/basic_json/operator%5B%5D.md),
[`find`](../../api/basic_json/find.md), [`contains`](../../api/basic_json/contains.md),
[`count`](../../api/basic_json/count.md), [`erase`](../../api/basic_json/erase.md), and
[`value`](../../api/basic_json/value.md) that accept a key type other than `object_t::key_type` require
- a **transparent** comparator, i.e. [`object_comparator_t`](../../api/basic_json/object_comparator_t.md) has a member
type `is_transparent` (this is why the default comparator is `#!cpp std::less<>` since C++14), and
- corresponding heterogeneous `find`, `count`, `erase`, and `operator[]` overloads on the container.
### Notes
#### `std::unordered_map` needs an adapter
`#!cpp std::unordered_map` cannot be passed directly: its third template parameter is a hash function, but
`basic_json` passes a comparator in that position. An alias template or wrapper that restores the expected argument
order makes it usable:
```cpp
template<class Key, class T, class IgnoredCompare, class Allocator>
struct unordered_map_object
: std::unordered_map<Key, T, std::hash<Key>, std::equal_to<Key>, Allocator>
{
using base_t = std::unordered_map<Key, T, std::hash<Key>, std::equal_to<Key>, Allocator>;
using base_t::base_t;
};
using unordered_json = nlohmann::basic_json<unordered_map_object>;
```
Whether `#!cpp std::unordered_map` can be instantiated at all depends on the standard library: `object_t` is formed
while `basic_json` is still incomplete (see the warning above), and libstdc++ 9 needs the size of the mapped type to
instantiate the hash map's node type, so the adapter does not compile there. Newer libstdc++ versions, and the hash
maps listed below, do not have that problem.
The adapter above works verbatim for Abseil's, Boost's, `phmap`'s and `gtl`'s hash maps, which all place the hash
function third and take a `#!cpp std::pair<const Key, T>` allocator fifth. Two need a different adapter:
- `ankerl::unordered_dense` expects an allocator over `#!cpp std::pair<Key, T>` (non-const key), so the allocator has
to be rebound to that or dropped.
- `robin_hood`'s fifth parameter is the non-type `MaxLoadFactor100`, so its adapter must drop the allocator entirely.
None of these hash maps defines `key_compare`, so all of them additionally rely on `object_comparator_t` falling back
to [`default_object_comparator_t`](../../api/basic_json/default_object_comparator_t.md); see
[`object_comparator_t`](../../api/basic_json/object_comparator_t.md).
#### Abseil hash maps
`absl::flat_hash_map` and `absl::node_hash_map` tolerate an incomplete value type, but they take a hash function as
their third template argument. The same adapter as for `#!cpp std::unordered_map` makes them usable:
```cpp
template<class Key, class T, class IgnoredCompare, class Allocator>
struct flat_hash_object
: absl::flat_hash_map<Key, T, absl::Hash<Key>, std::equal_to<Key>, Allocator>
{
using base_t = absl::flat_hash_map<Key, T, absl::Hash<Key>, std::equal_to<Key>, Allocator>;
using base_t::base_t;
};
using flat_hash_json = nlohmann::basic_json<flat_hash_object>;
```
`absl::node_hash_map` keeps references to the mapped values valid across insertions; `absl::flat_hash_map` does not,
which makes it behave like [`ordered_json`](../../api/ordered_json.md) with respect to
[iterator invalidation](../../api/basic_json/index.md#iterator-invalidation). Both expose a `capacity()` member
function, so [`JSON_DIAGNOSTICS`](../../api/macros/json_diagnostics.md) treats them conservatively and keeps the
parent pointers correct either way.
#### Iteration order
The library never relies on the container's iteration order for correctness; it does determine the order in which
object keys are serialized by [`dump`](../../api/basic_json/dump.md) and visited by
[`items`](../../api/basic_json/items.md). See [Object Order](../object_order.md).
#### `capacity()` marks a container as insertion-ordered
With [`JSON_DIAGNOSTICS`](../../api/macros/json_diagnostics.md) enabled, the library detects insertion-ordered maps by
probing for a `capacity()` member function (`nlohmann::ordered_map` inherits it from `std::vector`) and refreshes all
parent pointers after every insertion. An `ObjectType` that happens to have a `capacity()` member is therefore treated
conservatively -- this is correct, but slower.
#### Key order and duplicate keys
The library does not sort or de-duplicate keys itself; the behavior described in
[`object_t`](../../api/basic_json/object_t.md) is entirely the behavior of the chosen container.
!!! tip "Reference implementation"
`docs/mkdocs/docs/examples/custom_object_type.hpp` wraps a private `#!cpp std::map` and satisfies every
requirement above. It does not define `key_compare`, so `object_comparator_t` falls back to
[`default_object_comparator_t`](../../api/basic_json/default_object_comparator_t.md) -- a good starting point for
a custom `ObjectType`.
```cpp
--8<-- "examples/custom_object_type.hpp"
```
??? example "Compiling and using it"
```cpp
--8<-- "examples/custom_object_type.cpp"
```
Output:
```json
--8<-- "examples/custom_object_type.output"
```
### Compatible containers
| Container | Notes |
|----------------------------------------------------------------------------------|-------------------------------------------------------------------------------|
| `#!cpp std::map` (default) | |
| [`nlohmann::ordered_map`](../../api/ordered_map.md) | used by [`ordered_json`](../../api/ordered_json.md); keeps insertion order |
| [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) | keeps insertion order; adapter puts `fifo_map_compare` in the comparator slot |
| `boost::container::map`, `boost::container::flat_map` | no adapter needed |
| `#!cpp std::unordered_map` | through the adapter above; not with libstdc++ 9, see the note |
| `boost::unordered_map`, `boost::unordered_flat_map`, `boost::unordered_node_map` | through the adapter above |
| `absl::flat_hash_map`, `absl::node_hash_map` | through the adapter above; `flat_hash_map` moves mapped values on rehash |
| `phmap::flat_hash_map`, `phmap::node_hash_map`, `gtl::flat_hash_map` | through the adapter above |
| `ankerl::unordered_dense::map` and `segmented_map` | adapter must rebind or drop the allocator |
| `robin_hood::unordered_flat_map` | adapter must drop the allocator |
| `folly::F14NodeMap` | through the adapter above; requires C++20, see the note above |
| `folly::sorted_vector_map` | alias must drop the allocator, whose value type it disagrees on |
### Containers that cannot be used
| Container | Reason |
|--------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------|
| `absl::btree_map`, `phmap::btree_map`, `gtl::btree_map` | require a complete mapped type |
| `robin_hood::unordered_node_map`, `folly::F14FastMap`, `eastl::hash_map` | require a complete mapped type |
| `eastl::map` | EASTL iterators do not work with `#!cpp std::iterator_traits` |
| `tsl::ordered_map` | its iterators expose the mapped value as `#!cpp const` |
| `QMap` | no `value_type` member type |
| `QHash` | its `value_type` is the mapped type rather than a key/value pair, and its iterators dereference to the mapped value |
| `#!cpp std::multimap`, `#!cpp std::unordered_multimap` | `emplace` does not return `#!cpp std::pair<iterator, bool>` |
## `ArrayType`
`ArrayType` is instantiated as
```cpp
using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
```
### Always required
- The template must be usable with **two** type arguments (value type and allocator).
- Member types `value_type` and `iterator`.
- Constructors: default, copy, and move; and from an iterator range `(first, last)`.
- Member functions `begin()`, `end()`, `cbegin()`, `cend()`, `empty()`, `size()`, `max_size()`, `clear()`,
`operator[](size_type)`, `back()`, `push_back()`, `emplace_back()`, `pop_back()`, `resize()`,
`insert()` (single element, count, and range), `erase(pos)`, and `erase(first, last)`.
`basic_json::insert(pos, initializer_list)` goes through the range overload, so no initializer-list `insert` is
needed. `at(size_type)` is **not** required: [`basic_json::at(size_type)`](../../api/basic_json/at.md) checks the
index itself and then uses `operator[]`.
- `iterator` must be default-constructible, and it as well as the type returned by `cbegin()`/`cend()` must satisfy
[LegacyRandomAccessIterator](https://en.cppreference.com/w/cpp/named_req/RandomAccessIterator).
A `#!cpp static_assert` only checks for
[LegacyBidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator), but
[`dump`](../../api/basic_json/dump.md) (`cend() - 1`),
[`erase(idx)`](../../api/basic_json/erase.md) (`begin() + idx`), and the random-access operations of
[`basic_json::iterator`](../../api/basic_json/begin.md) require random access.
- The comparison operators, as for [`ObjectType`](#objecttype): `==` and `<`, or `==` and `<=>` under C++20.
### Required for individual functions
- A member type `value_type`, for [`to_bson`](../../api/basic_json/to_bson.md) of an array.
- A constructor from `(count, value)`, for
[`basic_json(size_type, const basic_json&)`](../../api/basic_json/basic_json.md).
- Swappability, via `#!cpp std::swap` or an ADL `swap`, for [`swap(array_t&)`](../../api/basic_json/swap.md).
!!! note "`capacity()` is optional"
With [`JSON_DIAGNOSTICS`](../../api/macros/json_diagnostics.md) enabled, the library reads `array_t::capacity()`
to find out whether adding an element reallocated the array and moved its elements, which would invalidate the
parent pointers. An array type without a `capacity()` member function is handled conservatively: the parent
pointers of all elements are refreshed after every insertion, which makes adding *n* elements cost O(*n*²). Only
diagnostics builds pay this; without them `capacity()` is never called.
!!! tip "Reference implementation"
`docs/mkdocs/docs/examples/custom_array_type.hpp` wraps a private `#!cpp std::vector` and satisfies every
requirement above -- a good starting point for a custom `ArrayType`.
```cpp
--8<-- "examples/custom_array_type.hpp"
```
??? example "Compiling and using it"
```cpp
--8<-- "examples/custom_array_type.cpp"
```
Output:
```json
--8<-- "examples/custom_array_type.output"
```
### Compatible containers
| Container | Notes |
|---------------------------------------------------------|-------------------------------------------------------------------------------------------|
| `#!cpp std::vector` (default) | |
| `#!cpp std::deque` | references survive appends, but not insertions elsewhere; see the `capacity()` note above |
| `#!cpp std::pmr::vector` | through an alias, as the allocator comes from `AllocatorType` instead |
| `boost::container::vector`, `deque`, `devector` | |
| `boost::container::stable_vector` | the only one tried that keeps references valid across *every* insertion |
| `boost::container::small_vector`, `folly::small_vector` | through an alias that fixes the inline capacity |
| `boost::container::static_vector` | through the same kind of alias, for arrays that stay within the fixed capacity |
| `folly::fbvector` | requires C++20, see the note above |
### Containers that cannot be used
| Container | Reason |
|-------------------------------------|-----------------------------------------------------------------------------------------------|
| `#!cpp std::list` | no `operator[]`, and no random-access iterators |
| `eastl::vector`, `QList`, `QVector` | no `max_size()`; they handle the incomplete value type fine |
| `absl::InlinedVector` | requires a complete value type, see the note above |
| `absl::FixedArray` | the size is fixed at construction, so `resize`, `push_back`, `insert` and `erase` are missing |
## `StringType`
`StringType` is used **both** for JSON string values and for the keys of JSON objects
(`string_t` and `object_t::key_type`).
### Always required
- A member type `value_type` that is one byte wide and `char`-compatible. The library stores and processes UTF-8
encoded `char` data and hands `data()` to `#!cpp std::strtoull`/`#!cpp std::strtoll`.
`#!cpp std::wstring`, `#!cpp std::u16string`, and `#!cpp std::u32string` are **not** valid choices; see the FAQ on
[wide string handling](../../home/faq.md#wide-string-handling).
- Constructors: default, copy, move, from `#!cpp const char*` (which must not be `#!cpp explicit`), from
`#!cpp (const char*, size_type)`, and from `#!cpp (size_type, char)`; and copy or move assignment.
- Member functions `size()`, `clear()`, `resize(n, c)`, `data()`, `push_back(char)`, and `operator[]`
(const and non-const, returning references). `c_str()` and `back()` are **not** required.
- `data()` must return a pointer to a contiguous, **null-terminated** buffer -- the parser hands it to
`#!cpp std::strtoull`. A type whose `data()` is not null-terminated does not fail to compile; it silently
misparses numbers.
- `append(const char*, size_type)`, used by [`dump`](../../api/basic_json/dump.md), and `append(const StringType&)`,
used by the CBOR reader for indefinite-length strings. The library's internal string concatenation additionally has
to append a `#!cpp char` and a `#!cpp const char*`; for each it selects between `append(arg)`, `#!cpp operator+=`,
`append(first, last)`, and `append(data, size)`.
- The comparison operator `==` against another `StringType`, and `<` for use as a key of the chosen
[`ObjectType`](#objecttype) (with the default comparator, `#!cpp std::less<>` must be able to compare two
`StringType` values, and a `StringType` with the key types used for lookup). `!=` is never applied to a
`StringType`, and `==` against `#!cpp const char*` is resolved by the implicit `#!cpp const char*` constructor.
### Required for the binary formats
- `resize(n)`, used by the readers to make room for a block of bytes.
- Non-const `operator[]`, into which the readers `#!cpp std::memcpy` those bytes. A non-`#!cpp const` `data()` would
serve just as well, but `#!cpp std::string` has only had one since C++17, and the library still supports C++11.
### Required for JSON Pointer, `flatten`, and `diff`
- A static member `npos` and the member function `find_first_of(char, size_type)` -- together with `data()`,
`reserve(n)`, and `append(const char*, size_type)` they implement the escaping and unescaping of reference tokens
described in RFC 6901. Neither `find(const StringType&, size_type)`, nor `substr(pos, count)`, nor
`replace(pos, count, const StringType&)` is required.
- `empty()`.
- `begin()` and `end()` -- used by
[`operator[](const json_pointer&)`](../../api/basic_json/operator%5B%5D.md) to decide whether a reference token
denotes an array index.
### Required for other functionality
| Functionality | Additional requirement |
|-----------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [`diff`](../../api/basic_json/diff.md), [`items`](../../api/basic_json/items.md), [`std::hash`](../../api/basic_json/std_hash.md) | conversion of a `#!cpp std::size_t` to `StringType`: either assignability from the result of `#!cpp std::to_string`, or an ADL overload `#!cpp void int_to_string(StringType&, std::size_t)` |
| [`std::hash<basic_json>`](../../api/basic_json/std_hash.md) | additionally a specialization of `#!cpp std::hash<StringType>` |
| [`to_bson`](../../api/basic_json/to_bson.md) | `find(value_type)` and `npos` |
| [`parse`](../../api/basic_json/parse.md) from a `string_t` | the input adapters must accept it; otherwise pass a character range |
| `#!cpp operator<<(std::ostream&, const json_pointer&)` | streamability to `#!cpp std::ostream` |
| exception messages | `data()` and `size()`, or `begin()` and `end()` |
### Compatible types
| Type | Notes |
|-----------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `#!cpp std::string` (default) | |
| `#!cpp std::basic_string` with a custom **stateless** allocator | |
| `#!cpp std::pmr::string` | see the warning below before relying on the memory resource |
| `boost::container::string` | needs a user-supplied `#!cpp std::hash` specialization (Boost provides `boost::hash` instead) |
| `folly::fbstring` | requires C++20, see the note above |
| `eastl::string` | needs a user-supplied `#!cpp std::hash` and an ADL `int_to_string` (it is not assignable from a `#!cpp std::string`); [`parse`](../../api/basic_json/parse.md) does not accept it directly -- pass a character range or a `#!cpp std::string` |
| a custom string class in a user-defined namespace | if the requirements above are met |
### Types that cannot be used
| Type | Reason |
|----------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------|
| `#!cpp std::wstring`, `#!cpp std::u16string`, `#!cpp std::u32string` | the character type is not one byte wide |
| `#!cpp std::u8string` | one byte wide, but `#!cpp char8_t` is not `#!cpp char`-compatible |
| `absl::Cord` | no `value_type`, and the storage is not contiguous |
| `QString` | no `append(const char*, size_type)`; its `QChar` is also two bytes wide, though that is never diagnosed |
!!! warning "A `std::pmr::string` mostly does not use the memory resource you choose"
`basic_json` cannot be given an allocator or a memory resource. `AllocatorType` is default-constructed at every
allocation and has to be stateless (see [`AllocatorType`](#allocatortype)), and string values the library creates
are constructed with their own default allocator. So:
- Every string the library itself produces -- from [`parse`](../../api/basic_json/parse.md), from
[`dump`](../../api/basic_json/dump.md), or by default construction -- allocates from
`#!cpp std::pmr::get_default_resource()`.
- **Copying** an arena-backed string into a value silently drops its memory resource: the copy lands on the
default resource, because `#!cpp std::pmr::polymorphic_allocator` does not propagate on copy construction.
Nothing warns about this.
- **Moving** one in does keep it, and later growth still allocates from that arena -- but it does not survive a
copy of the enclosing `basic_json`.
- Passing `#!cpp std::pmr::polymorphic_allocator` as `AllocatorType` does not work around any of this; it does
not compile.
Apart from moving a string in, the only way to redirect these allocations is the process-global
`#!cpp std::pmr::set_default_resource()`.
!!! tip "Reference implementation"
`docs/mkdocs/docs/examples/custom_string_type.hpp` wraps a private `#!cpp std::string` and satisfies every
requirement above -- a good starting point for a custom `StringType`. The unit test
`tests/src/unit-alt-string.cpp` contains a more thorough variant, `alt_string`, exercised against a larger part
of the API.
```cpp
--8<-- "examples/custom_string_type.hpp"
```
??? example "Compiling and using it"
```cpp
--8<-- "examples/custom_string_type.cpp"
```
Output:
```json
--8<-- "examples/custom_string_type.output"
```
## `BooleanType`
`boolean_t` is stored **directly** inside `basic_json`, as a member of an anonymous union.
### Always required
- A literal type that is trivially default-constructible, trivially copyable, and trivially destructible; otherwise the
union's special member functions are deleted.
- **Implicitly** convertible from `#!cpp bool` -- an `#!cpp explicit` constructor is not enough, because the
`to_json` overload for a custom `BooleanType` is constrained on `#!cpp std::is_convertible` -- and contextually
convertible to `#!cpp bool` (here an `#!cpp explicit operator bool` is fine).
- Comparison operators `==`, `!=`, `<`, `<=`, `>`, `>=` (or `<=>`).
- Convertible from and to `#!cpp bool` through the serializer, because
[`get<bool>()`](../../api/basic_json/get.md) is used internally.
There is little reason to use anything other than `#!cpp bool` here.
### Compatible types
`#!cpp bool` is the only usable choice. Another trivially copyable type that is implicitly convertible to and from
`#!cpp bool` -- `#!cpp std::uint8_t`, say -- does compile, and JSON booleans still round-trip, but the type then
serves as both `boolean_t` and an ordinary integer: `basic_json` can no longer be constructed or assigned from a
`#!cpp std::uint8_t` at all (the boolean and unsigned-integer `to_json` overloads become ambiguous), and
[`get<std::uint8_t>()`](../../api/basic_json/get.md) on a number throws
[`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) instead of returning the value.
## `NumberIntegerType` and `NumberUnsignedType`
Both types are stored **directly** inside `basic_json`'s union.
### Always required
- `#!cpp std::is_integral` must be satisfied: `NumberIntegerType` must be a **signed** integer type,
`NumberUnsignedType` an **unsigned** integer type. Class types are not supported -- among others, the constructors
taking integer values are constrained on `#!cpp std::is_integral`.
- Trivially default-constructible, trivially copyable, and trivially destructible (union member).
- `#!cpp std::numeric_limits` must be specialized for both types.
- `NumberUnsignedType` must be able to represent the absolute value of every `NumberIntegerType` value; serialization
of negative numbers converts the value to `NumberUnsignedType`. A `#!cpp static_assert` requires it to be at least as
wide as `NumberIntegerType`, which is what that amounts to for the standard integer types.
- Both types must fit into the internal 64-character number buffer used by
[`dump`](../../api/basic_json/dump.md), which is the case for all standard integer types.
- [`std::hash<basic_json>`](../../api/basic_json/std_hash.md) additionally requires `#!cpp std::hash` specializations.
### Notes
The number types influence what the parser accepts: an integer literal that does not round-trip through the chosen type
is stored as [`number_float_t`](../../api/basic_json/number_float_t.md) instead. Choosing types narrower than 64 bits
therefore silently changes parse results rather than raising an error. See
[Number Handling](number_handling.md) for details.
### Compatible types
| Type pair | Support |
|----------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `#!cpp std::int64_t` / `#!cpp std::uint64_t` (default) | full |
| `#!cpp std::int32_t` / `#!cpp std::uint32_t`, `#!cpp long long` / `#!cpp unsigned long long` | full; narrower types change which literals the parser can represent |
| any other pair of standard signed/unsigned integer types | full |
| class types, enumerations | not usable; `#!cpp std::is_integral` must hold |
| `#!cpp bool`, or a type already used for another member of the union | not usable; `#!cpp std::is_integral<bool>` is in fact `#!cpp true`, but the `get_impl_ptr` overloads for `boolean_t`, `number_integer_t`, `number_unsigned_t` and `number_float_t` would collide |
## `NumberFloatType`
`number_float_t` is stored **directly** inside `basic_json`'s union.
### Always required
- Trivially default-constructible, trivially copyable, and trivially destructible (union member).
- `#!cpp std::numeric_limits` must be specialized; `max_digits10` is used to size the conversion.
- `#!cpp std::isfinite` must be applicable to the type.
### Required for parsing and serialization
`NumberFloatType` must be one of `#!cpp float`, `#!cpp double`, or `#!cpp long double`:
- The [parser](../parsing/index.md) converts number literals with `#!cpp std::strtof`, `#!cpp std::strtod`, or
`#!cpp std::strtold`; the library provides overloads for exactly these three types.
- [`dump`](../../api/basic_json/dump.md) falls back to `#!cpp std::snprintf` with the `%g` and `%Lg` conversion
specifiers, for which the library likewise provides only `#!cpp double` and `#!cpp long double` overloads
(`#!cpp float` is promoted to `#!cpp double`).
If `#!cpp std::numeric_limits<NumberFloatType>` describes an IEEE 754 binary32 or binary64 number, `dump` uses the
Grisu2 algorithm, which produces the shortest representation that round-trips. Otherwise the `snprintf` fallback with
`max_digits10` digits is used.
### Required for the binary formats
`NumberFloatType` must be `#!cpp float` or `#!cpp double`. The writers for
[CBOR, MessagePack, UBJSON, BJData, and BSON](../binary_formats/index.md) map a floating-point value onto an IEEE 754
binary32 or binary64 field and have no encoding for `#!cpp long double`.
### Compatible types
| Type | Support |
|--------------------------|-----------------------------------------------------------------------------------------------------------------------|
| `#!cpp double` (default) | full; short round-trip output through Grisu2 |
| `#!cpp float` | full; short round-trip output through Grisu2 |
| `#!cpp long double` | `dump` and `parse` only; the binary format writers do not compile, as they only handle IEEE 754 binary32 and binary64 |
| any other type | not usable |
## `AllocatorType`
`AllocatorType` is instantiated with **one** argument, for each of `object_t`, `array_t`, `string_t`, `binary_t`,
`basic_json`, `#!cpp std::pair<const StringType, basic_json>`, and `#!cpp std::pair<StringType, basic_json>`.
`AllocatorType` is not the only allocator a `basic_json` uses. It allocates the JSON values themselves, but most
temporary storage is allocated with `#!cpp std::allocator`. This includes the parser's stacks and the stacks that
process deeply nested values without recursion.
### Always required
- The template must be usable with exactly one type argument. The library instantiates `AllocatorType<T>` directly and
never uses `#!cpp std::allocator_traits<...>::rebind_alloc`.
- It must satisfy the [Allocator](https://en.cppreference.com/w/cpp/named_req/Allocator) named requirement so that
`#!cpp std::allocator_traits` can be used with it.
- It must be **default-constructible and stateless**. Objects are allocated with a default-constructed allocator and
deallocated with a *different* default-constructed allocator, and
[`get_allocator()`](../../api/basic_json/get_allocator.md) returns a default-constructed instance. Allocators
carrying state are not supported, so there is no way to tell a `basic_json` where to allocate from; see the note
under [`StringType`](#stringtype) for what that means in practice. A stateful allocator is **not diagnosed**: it
compiles and silently ignores the state.
- It must support **incomplete types**: `AllocatorType<basic_json>` is instantiated inside the definition of
`basic_json` itself.
- `#!cpp std::allocator_traits<AllocatorType<basic_json>>::pointer` becomes
[`basic_json::pointer`](../../api/basic_json/index.md#container-types), and iterators are constructed from raw
`#!cpp basic_json*` values. The `pointer` type must therefore be a plain pointer; fancy pointers are not supported.
### Compatible types
| Type | Support |
|-------------------------------------------------------------------|----------------------------------------|
| `#!cpp std::allocator` (default) | full |
| a custom stateless allocator template | full |
| stateful allocators, e.g. `#!cpp std::pmr::polymorphic_allocator` | not usable; see the requirements above |
## `JSONSerializer`
`JSONSerializer` is instantiated as `JSONSerializer<T, void>` and defaults to
[`adl_serializer`](../../api/adl_serializer/index.md).
### Always required
- The template must accept **two** type arguments. It does not have to give the second one a default -- `basic_json`
declares the parameter as `#!cpp template<typename T, typename SFINAE = void> class JSONSerializer`, so uses such as
`#!cpp JSONSerializer<T>` inside the library supply `#!cpp void` themselves. The second parameter exists so that
partial specializations can be constrained by SFINAE.
- For every type `T` that is converted **to** a JSON value, a static member function
`#!cpp static void to_json(basic_json&, T)` must exist.
- For every type `T` that is converted **from** a JSON value, either
`#!cpp static void from_json(const basic_json&, T&)` or `#!cpp static T from_json(const basic_json&)` must exist.
The latter form is required for types that are not default-constructible; see
[Arbitrary Types Conversions](../arbitrary_types.md).
- To support the [converting constructor](../../api/basic_json/basic_json.md) between different `basic_json`
specializations, `to_json` must be available for `boolean_t`, `number_integer_t`, `number_unsigned_t`,
`number_float_t`, `string_t`, `object_t`, `array_t`, and `binary_t` of the *source* specialization.
### Compatible types
| Type | Support |
|---------------------------------------------------------------------------|-------------------------------------------------------------------|
| [`nlohmann::adl_serializer`](../../api/adl_serializer/index.md) (default) | full |
| a class template deriving from `adl_serializer` | full; the usual way to change behavior while keeping the defaults |
| an unrelated template with the same interface | full, but it has to handle every type the library converts |
## `BinaryType`
`BinaryType` is not a JSON type; it is used for the byte strings of the
[binary formats](../binary_formats/index.md). It is wrapped as
```cpp
using binary_t = nlohmann::byte_container_with_subtype<BinaryType>;
```
### Always required
- A non-`final` class type -- [`byte_container_with_subtype`](../../api/byte_container_with_subtype/index.md) derives
from it publicly.
- A member type `value_type` that is **exactly one byte** wide (e.g., `#!cpp std::uint8_t`, `#!cpp char`, or
`#!cpp std::byte`). Readers and writers reinterpret the container's storage as raw bytes, so a wider `value_type` is
rejected with a `#!cpp static_assert`.
- Contiguous storage: the binary readers `#!cpp std::memcpy` into `#!cpp &binary[n]`, the writers `reinterpret_cast`
`data()`. `#!cpp data() + n` would do for the readers too, but they share one helper with
[`StringType`](#stringtype), whose non-`#!cpp const` `data()` is C++17 and later only.
- Default-constructible, copy-constructible, and move-constructible.
- Member functions `size()`, `empty()`, `data()`, `resize()`, `operator[]`, `back()`, `begin()`, `end()`, `cbegin()`,
and `cend()` with random-access iterators, and `insert(pos, first, last)`, which the CBOR reader uses to join the
chunks of an indefinite-length byte string. `push_back()` is **not** required.
- Comparison operators: `==` is used by
[`byte_container_with_subtype`](../../api/byte_container_with_subtype/index.md), the relational operators by
[`basic_json`'s comparison operators](../../api/basic_json/operator_le.md).
### Required for individual functions
- `clear()`, for [`basic_json::clear()`](../../api/basic_json/clear.md).
`max_size()`, `at()`, `reserve()`, `erase()`, `pop_back()`, and `emplace_back()` are **not** used at all.
See [`binary_t`](../../api/basic_json/binary_t.md) for how a non-default `BinaryType` changes the meaning of assigning
such a container to a `basic_json` value.
!!! tip "Reference implementation"
`docs/mkdocs/docs/examples/custom_binary_type.hpp` wraps a private `#!cpp std::vector<std::uint8_t>` and satisfies
every requirement above -- a good starting point for a custom `BinaryType`.
```cpp
--8<-- "examples/custom_binary_type.hpp"
```
??? example "Compiling and using it"
```cpp
--8<-- "examples/custom_binary_type.cpp"
```
Output:
```json
--8<-- "examples/custom_binary_type.output"
```
### Compatible containers
| Container | Notes |
|---------------------------------------------------------------------------------------------|---------------------------------------------------------------------------|
| `#!cpp std::vector<std::uint8_t>` (default) | |
| `#!cpp std::vector<char>`, `#!cpp std::vector<std::byte>` | `dump()` writes the bytes as 0..255 whichever is used |
| `boost::container::vector<std::uint8_t>`, `boost::container::small_vector<std::uint8_t, N>` | |
| `absl::InlinedVector<std::uint8_t, N>` | usable here, unlike as an `ArrayType`, because the value type is complete |
| `eastl::vector<std::uint8_t>` | usable here, unlike as an `ArrayType`, because `max_size()` is not needed |
| `folly::fbvector<std::uint8_t>` | requires C++20, see the note above |
### Containers that cannot be used
| Container | Reason |
|------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `QByteArray` | no `empty()` (it spells that `isEmpty()`); its `insert` takes an index rather than an iterator; and it converts to `string_t`, which makes `to_json` ambiguous between a string and a binary value |
| `#!cpp std::string` | `binary_t::container_type` and `string_t` would be the same type, so the two [`swap`](../../api/basic_json/swap.md) overloads collide and `basic_json` cannot be instantiated at all |
| `#!cpp std::deque<std::uint8_t>` | storage is not contiguous, so there is no `data()` |
| containers whose `value_type` is wider than one byte | see above -- accepted by the compiler, wrong at runtime |
## `CustomBaseClass`
`CustomBaseClass` is an extension point: unless it is `#!cpp void` (the default, which selects the empty
`nlohmann::json_default_base`), `basic_json` publicly derives from it.
### Always required
- A non-`final`, default-constructible class type.
- `basic_json` is copy-/move-constructible and copy-/move-assignable only if `CustomBaseClass` is.
### Notes
`basic_json` is documented to be a
[StandardLayoutType](https://en.cppreference.com/w/cpp/named_req/StandardLayoutType). Because `basic_json` has
non-static data members of its own, a `CustomBaseClass` with non-static data members forfeits this guarantee.
Note the namespace of `CustomBaseClass` becomes an associated namespace of `basic_json` for the purpose of
argument-dependent lookup.
See [`json_base_class_t`](../../api/basic_json/json_base_class_t.md) for an example.
### Compatible types
| Type | Support |
|----------------------------------------------|----------------------------------------------------------------------------|
| `#!cpp void` (default) | an empty base class is used; no effect on `basic_json` |
| any default-constructible, non-`final` class | full; see [`json_base_class_t`](../../api/basic_json/json_base_class_t.md) |
## Cross-specialization conversions
Converting a value from one `basic_json` specialization into another (see the
[converting constructor](../../api/basic_json/basic_json.md)) imposes two additional requirements that are not
diagnosed at compile time. With assertions enabled they abort on the `#!cpp JSON_ASSERT` at the end of the converting
constructor; under `#!cpp NDEBUG` they fail **silently** at runtime:
- The target `string_t` must be directly constructible from the source `string_t`. Otherwise the string is converted to
an array of character codes.
- The target `object_t::key_type` must be directly constructible from the source object's key type. Otherwise the
object is converted to an array of key/value pairs.
See [issue #3425](https://github.com/nlohmann/json/issues/3425), [`string_t`](../../api/basic_json/string_t.md), and
[`object_t`](../../api/basic_json/object_t.md).
## See also
- [Types](index.md) -- overview of how JSON values are stored
- [Number Handling](number_handling.md) -- how the number types affect parsing and serialization
- [Object Order](../object_order.md) -- using an insertion-ordered `ObjectType`
- [`basic_json`](../../api/basic_json/index.md) -- API documentation of the class template
+35 -177
View File
@@ -1,125 +1,34 @@
# Architecture
This page gives a high-level overview of the library's architecture. It should help new contributors to get an idea of
the used concepts and where to make changes.
!!! info
This page is still under construction. Its goal is to provide a high-level overview of the library's architecture.
This should help new contributors to get an idea of the used concepts and where to make changes.
## Overview
The library is built around a single class template, [`nlohmann::basic_json`](../api/basic_json/index.md). A
`basic_json` value is a node in a tree of JSON values. All other components either create such a tree from an input
(parsing), write a tree to an output (serialization), or give access to it (iterators, JSON Pointer, conversions).
The main structure is class [nlohmann::basic_json](../api/basic_json/index.md).
```mermaid
flowchart LR
input[/"input<br>(string, stream,<br>iterator range, file)"/]
ia["input adapter"]
lexer["lexer"]
parser["parser"]
breader["binary_reader"]
sax["SAX interface"]
value[("basic_json<br>value tree")]
serializer["serializer"]
bwriter["binary_writer"]
oa["output adapter"]
output[/"output<br>(string, stream,<br>vector)"/]
- public API
- container interface
- iterators
input --> ia
ia --> lexer --> parser --> sax
ia --> breader --> sax
sax --> value
value --> serializer --> oa
value --> bwriter --> oa
oa --> output
```
## Template specializations
- **JSON text** is read by an [input adapter](#input-adapters), tokenized by the lexer, and turned into SAX events by
the parser.
- **Binary formats** (BJData, BSON, CBOR, MessagePack, UBJSON) are read by an input adapter and turned into the same SAX
events by the `binary_reader`.
- A [SAX consumer](#sax-interface) receives the events. The one used by [`parse`](../api/basic_json/parse.md) builds a
`basic_json` value tree.
- The `serializer` (JSON text) or the `binary_writer` (binary formats) writes a value tree to an
[output adapter](#output-adapters).
## Source layout
The public headers are in [`include/nlohmann`](https://github.com/nlohmann/json/tree/develop/include/nlohmann):
- [`json.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/json.hpp) defines class [`basic_json`](../api/basic_json/index.md).
- [`json_fwd.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/json_fwd.hpp) contains forward declarations.
- [`adl_serializer.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/adl_serializer.hpp), [`byte_container_with_subtype.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/byte_container_with_subtype.hpp), and [`ordered_map.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/ordered_map.hpp) define
[`adl_serializer`](../api/adl_serializer/index.md),
[`byte_container_with_subtype`](../api/byte_container_with_subtype/index.md), and
[`ordered_map`](../api/ordered_map.md).
Everything else lives in [`detail/`](https://github.com/nlohmann/json/tree/develop/include/nlohmann/detail) and namespace `nlohmann::detail`, which is not part of the public API. Paths
below are relative to `include/nlohmann`.
| Component | Location |
|-----------|----------|
| Value type enumeration | [`detail/value_t.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/value_t.hpp) |
| Input adapters | [`detail/input/input_adapters.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/input_adapters.hpp) |
| Lexer | [`detail/input/lexer.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/lexer.hpp), [`detail/input/number_parse.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/number_parse.hpp), [`detail/input/string_scan.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/string_scan.hpp) |
| Parser | [`detail/input/parser.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/parser.hpp) |
| SAX interface and DOM builders | [`detail/input/json_sax.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/json_sax.hpp) |
| Binary format readers | [`detail/input/binary_reader.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/binary_reader.hpp) |
| JSON serializer | [`detail/output/serializer.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/output/serializer.hpp), [`detail/conversions/to_chars.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/conversions/to_chars.hpp) |
| Binary format writers | [`detail/output/binary_writer.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/output/binary_writer.hpp) |
| Output adapters | [`detail/output/output_adapters.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/output/output_adapters.hpp) |
| Iterators | [`detail/iterators/`](https://github.com/nlohmann/json/tree/develop/include/nlohmann/detail/iterators) |
| Conversions from/to arbitrary types | [`detail/conversions/from_json.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/conversions/from_json.hpp), [`detail/conversions/to_json.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/conversions/to_json.hpp) |
| JSON Pointer | [`detail/json_pointer.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/json_pointer.hpp) |
| Exceptions | [`detail/exceptions.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/exceptions.hpp) |
| Type traits and C++ feature backports | [`detail/meta/`](https://github.com/nlohmann/json/tree/develop/include/nlohmann/detail/meta) |
| Macros | [`detail/macro_scope.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/macro_scope.hpp), [`detail/macro_unscope.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/macro_unscope.hpp), [`detail/abi_macros.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/abi_macros.hpp) |
The single-header version [`single_include/nlohmann/json.hpp`](https://github.com/nlohmann/json/blob/develop/single_include/nlohmann/json.hpp)
is generated from these files with `make amalgamate` and must not be edited by hand.
## Template parameters
[`basic_json`](../api/basic_json/index.md) is parameterized by the types it uses to store values and to convert from and to other types:
| Template parameter | Default | Used for |
|----------------------|-----------------------------|-------------------------------------------------------------------|
| `ObjectType` | `std::map` | objects, see [`object_t`](../api/basic_json/object_t.md) |
| `ArrayType` | `std::vector` | arrays, see [`array_t`](../api/basic_json/array_t.md) |
| `StringType` | `std::string` | strings and object keys, see [`string_t`](../api/basic_json/string_t.md) |
| `BooleanType` | `bool` | Booleans, see [`boolean_t`](../api/basic_json/boolean_t.md) |
| `NumberIntegerType` | `std::int64_t` | signed integers, see [`number_integer_t`](../api/basic_json/number_integer_t.md) |
| `NumberUnsignedType` | `std::uint64_t` | unsigned integers, see [`number_unsigned_t`](../api/basic_json/number_unsigned_t.md) |
| `NumberFloatType` | `double` | floating-point numbers, see [`number_float_t`](../api/basic_json/number_float_t.md) |
| `AllocatorType` | `std::allocator` | allocating objects, arrays, strings, and binary values |
| `JSONSerializer` | `adl_serializer` | conversions from/to other types, see [`adl_serializer`](../api/adl_serializer/index.md) |
| `BinaryType` | `std::vector<std::uint8_t>` | binary values, see [`binary_t`](../api/basic_json/binary_t.md) |
| `CustomBaseClass` | `void` | an optional base class, see [`json_base_class_t`](../api/basic_json/json_base_class_t.md) |
The library provides two specializations:
- [`json`](../api/json.md) uses all default template arguments.
- [`ordered_json`](../api/ordered_json.md) uses [`ordered_map`](../api/ordered_map.md) as `ObjectType` to keep the
insertion order of object keys.
The requirements on the template arguments are listed in
[Template Parameter Requirements](../features/types/template_parameters.md).
- describe template parameters of `basic_json`
- [`json`](../api/json.md)
- [`ordered_json`](../api/ordered_json.md) via [`ordered_map`](../api/ordered_map.md)
## Value storage
Each [`basic_json`](../api/basic_json/index.md) value stores its content as a tagged union: an enumeration [`value_t`](../api/basic_json/value_t.md)
names the type of the value, and a union `json_value` holds the value itself. Both are members of the nested struct
`data`, which is the only data member `m_data` of `basic_json`:
Values are stored as a tagged union of [value_t](../api/basic_json/value_t.md) and json_value.
```cpp
struct data
{
/// the type of the current element
value_t m_type = value_t::null;
/// the type of the current element
value_t m_type = value_t::null;
/// the value of the current element
json_value m_value = {};
};
data m_data = {};
/// the value of the current element
json_value m_value = {};
```
with
@@ -159,83 +68,42 @@ union json_value {
};
```
Objects, arrays, strings, and binary values are allocated on the heap with `AllocatorType`, and the union only stores a
pointer to them. This keeps a `basic_json` value small: one pointer-sized union and one byte for the type. The class
maintains the invariant that the pointer matching `m_type` is never null; `assert_invariant()` checks it with
[runtime assertions](../features/assertions.md).
## Parsing inputs (deserialization)
## Input adapters
Input is read via **input adapters** that abstract a source. Every input adapter provides this interface:
Input is read via **input adapters** that abstract a source with a common interface:
```cpp
/// the type of the characters in the input
using char_type = ...;
/// read a single character
std::char_traits<char>::int_type get_character() noexcept;
/// read a single character; returns std::char_traits<char_type>::eof() at the end of the input
typename std::char_traits<char_type>::int_type get_character();
/// read up to count * sizeof(T) bytes into dest and return the number of bytes read
/// (used by the binary readers)
/// read multiple characters to a destination buffer and
/// returns the number of characters successfully read
template<class T>
std::size_t get_elements(T* dest, std::size_t count = 1);
```
The lexer detects two optional extensions at compile time. Only `iterator_input_adapter` provides them, and only for
random-access input of single-byte characters:
List examples of input adapters.
- `supports_seek`, `get_consumed_count()`, and `copy_consumed_range()` let the lexer reconstruct already consumed input
for error messages instead of copying every character it reads.
- `supports_bulk_scan`, `bulk_data()`, `bulk_remaining()`, and `bulk_skip()` let the lexer scan strings directly in
contiguous memory, several bytes at a time.
## SAX Interface
The function `input_adapter` picks the right adapter for the argument passed to `parse`, `accept`, `sax_parse`, or the
`from_*` functions:
TODO
- `iterator_input_adapter` reads from an iterator range, which also covers strings, containers, and pointers.
- `wide_string_input_adapter` reads from ranges of `wchar_t`, `char16_t`, or `char32_t` and converts them to UTF-8.
It cannot be used for binary formats; its `get_elements()` throws.
- `input_stream_adapter` reads from a `std::istream`.
- `file_input_adapter` reads from a `std::FILE*`.
## SAX interface
The parser does not build values itself. It reports what it reads as events to a [SAX](../features/parsing/sax_interface.md)
consumer, which implements the interface [`json_sax`](../api/json_sax/index.md): `null`, `boolean`, `number_integer`,
`number_unsigned`, `number_float`, `string`, `binary`, `start_object`, `key`, `end_object`, `start_array`, `end_array`,
and `parse_error`.
The library comes with two consumers in `detail/input/json_sax.hpp`:
- `json_sax_dom_parser` builds a [`basic_json`](../api/basic_json/index.md) value tree. [`parse`](../api/basic_json/parse.md) uses it.
- `json_sax_dom_callback_parser` does the same, but calls a [parser callback](../features/parsing/parser_callbacks.md)
for each event, which can skip values. `parse` uses it when a callback is given.
The `binary_reader` emits the same events for binary formats, so [`sax_parse`](../api/basic_json/sax_parse.md) works
with a user-defined consumer for JSON and for all binary formats alike.
## Output adapters
## Writing outputs (serialization)
Output is written via **output adapters**:
```cpp
template<typename T>
void write_character(CharType c);
template<typename CharType>
void write_characters(const CharType* s, std::size_t length);
```
The `serializer` (used by [`dump`](../api/basic_json/dump.md) and [`operator<<`](../api/operator_ltlt.md)) and the
`binary_writer` (used by the `to_*` functions) write to one of these adapters:
- `output_vector_adapter` appends to a `std::vector`.
- `output_stream_adapter` writes to a `std::ostream`.
- `output_string_adapter` appends to a string.
List examples of output adapters.
## Value conversion
Values are converted from and to other types with the `JSONSerializer` template parameter. The default,
[`adl_serializer`](../api/adl_serializer/index.md), calls the free functions
```cpp
template<class T>
void to_json(basic_json& j, const T& t);
@@ -244,23 +112,13 @@ template<class T>
void from_json(const basic_json& j, T& t);
```
found by argument-dependent lookup. The library defines them for standard types in `detail/conversions`; users add them
for their own types, see [Arbitrary Type Conversions](../features/arbitrary_types.md). The
[serialization macros](../features/macros.md) generate these functions.
## Additional features
- [JSON Pointer](../features/json_pointer.md) (class `json_pointer`) addresses values inside a tree. It is also the
basis of [JSON Patch](../features/json_patch.md).
- [Binary formats](../features/binary_formats/index.md) are read by `binary_reader` and written by `binary_writer`.
- A [custom base class](../api/basic_json/json_base_class_t.md) can add members to every [`basic_json`](../api/basic_json/index.md) value.
- [Serialization macros](../features/macros.md) generate `to_json` and `from_json` functions for user-defined types.
- JSON Pointers
- Binary formats
- Custom base class
- Conversion macros
## Details namespace
Namespace `nlohmann::detail` contains all implementation details. It is not part of the public API and may change in any
release. Besides the components above, it contains:
- type traits to detect the capabilities of user-defined types (`detail/meta/type_traits.hpp`),
- backports of C++14/17 features to C++11 (`detail/meta/cpp_future.hpp`), and
- helpers such as `string_concat` and `string_escape`.
- C++ feature backports
+8 -138
View File
@@ -8,72 +8,41 @@ the result of an internet search. If you know further customers of the library,
## Space Exploration
- [**Peregrine Lunar Lander Flight 01**](https://en.wikipedia.org/wiki/Peregrine_Mission_One) - The library was used for payload management in the **Peregrine Moon Lander**, developed by **Astrobotic Technology** and launched as part of NASA's **Commercial Lunar Payload Services (CLPS)** program. After six days in orbit, the spacecraft was intentionally redirected into Earth's atmosphere, where it burned up over the Pacific Ocean on **January 18, 2024**.
- [**NASA Unsteady Pressure-Sensitive Paint Processing**](https://github.com/nasa/upsp-processing), NASA software for processing high-speed video recordings of wind tunnel tests on launch vehicle and aircraft models
- [**Terma TEMU**](https://temu.terma.com/docs/public/temu-release-notes/latest/copying/json-for-modern-cpp.html), an emulator of spacecraft on-board computers used to develop and validate flight software for European space missions
## Automotive
- [**Alexa Auto SDK**](https://github.com/alexa/alexa-auto-sdk), a software development kit enabling the integration of Alexa into automotive systems
- [**Apollo**](https://github.com/ApolloAuto/apollo), a framework for building autonomous driving systems
- [**Automotive Grade Linux (AGL)**](https://download.automotivelinux.org/AGL/release/jellyfish/latest/qemux86-64/deploy/licenses/nlohmann-json/), a collaborative open-source platform for automotive software development
- [**Autoware**](https://github.com/autowarefoundation/autoware_universe), an open-source software stack for autonomous driving built on ROS 2
- [**Eclipse S-CORE**](https://github.com/eclipse-score/nlohmann_json), an open-source software platform for the software-defined vehicle backed by major automotive manufacturers and suppliers
- [**Genesis Motor** (infotainment)](http://webmanual.genesis.com/ccIC/AVNT/JW/KOR/English/reference010.html), a luxury automotive brand
- [**Hyundai** (infotainment)](https://www.hyundai.com/wsvc/ww/download.file.do?id=/content/hyundai/ww/data/opensource/data/GN7-2022/licenseCode/info), a global automotive brand
- [**Kia** (infotainment)](http://webmanual.kia.com/PREM_GEN6/AVNT/RJPE/KOR/Korean/reference010.html), a global automotive brand
- [**Mercedes-Benz Operating System (MB.OS)**](https://group.mercedes-benz.com/careers/about-us/mercedes-benz-operating-system/), a core component of the vehicle software ecosystem from Mercedes-Benz
- [**NVIDIA DRIVE OS**](https://developer.nvidia.com/docs/drive/drive-os/6.0.5/public/driveworks-nvcgf/dwx_open_source_attribution.html), the operating system and DriveWorks SDK powering NVIDIA's platform for autonomous vehicles
- [**Rivian** (infotainment)](https://assets.ctfassets.net/2md5qhoeajym/3cwyo4eoufk4yingUwusFt/ded2c47da620fdfc99c88c7156d2c1d8/In-Vehicle_OSS_Attribution_2024__11-24_.pdf), an electric vehicle manufacturer
- [**Suzuki** (infotainment)](https://www.globalsuzuki.com/motorcycle/ipc/oss/oss_48KA_00.pdf), a global automotive and motorcycle manufacturer
## Gaming and Entertainment
- [**Anno 117: Pax Romana**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a city-building strategy game set in the Roman Empire
- [**Assassin's Creed: Mirage**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a stealth-action game set in the Middle East, focusing on the journey of a young assassin with classic parkour and stealth mechanics
- [**Battlefield 6**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a military first-person shooter known for its large-scale multiplayer battles
- [**Battlefield: REDSEC**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a free-to-play battle royale experience set in the Battlefield universe
- [**BioMenace: Remastered**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a remaster of the classic side-scrolling platform shooter
- [**Chasm: The Rift**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a first-person shooter blending horror and adventure, where players navigate dark realms and battle monsters
- [**College Football 25**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a college football simulation game featuring gameplay that mimics real-life college teams and competitions
- [**College Football 26**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a college football simulation game featuring licensed teams and stadiums
- [**College Football 27**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), the latest installment of the college football simulation series
- [**Concepts**](https://concepts.app/en/licenses), a digital sketching app designed for creative professionals, offering flexible drawing tools for illustration, design, and brainstorming
- [**Depthkit**](https://www.depthkit.tv/third-party-licenses), a tool for creating and capturing volumetric video, enabling immersive 3D experiences and interactive content
- [**Dune: Awakening**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), an open-world survival MMO set on the desert planet Arrakis
- [**EA Sports FC 25**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), an association football simulation with club, career, and online modes
- [**EA Sports FC 26**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), the latest installment of the association football simulation series
- [**EA Sports UFC 6**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a mixed martial arts fighting simulation
- [**FiveM**](https://github.com/citizenfx/fivem), a modification framework for Grand Theft Auto V that powers custom multiplayer servers
- [**FLUX:: Immersive**](https://doc.flux.audio/syrah/Credits.html), a suite of professional audio processing and immersive mixing plugins used in music and post-production
- [**IMG.LY**](https://img.ly/acknowledgements), a platform offering creative tools and SDKs for integrating advanced image and video editing in applications
- [**immersivetech**](https://immersitech.io/open-source-third-party-software/), a technology company focused on immersive experiences, providing tools and solutions for virtual and augmented reality applications
- [**Kodi**](https://github.com/xbmc/xbmc/blob/master/xbmc/utils/JSONVariantWriter.cpp), a home theater and media center application
- [**LOOT**](https://loot.readthedocs.io/_/downloads/en/0.13.0/pdf/), a tool for optimizing the load order of game plugins, commonly used in The Elder Scrolls and Fallout series
- [**LunaTranslator**](https://github.com/HIllya51/LunaTranslator/blob/main/src/NativeImpl/LunaSubprocess/aspatch.cpp), a real-time translation tool for visual novels
- [**MaaAssistantArknights**](https://github.com/MaaAssistantArknights/MaaAssistantArknights/blob/dev-v2/src/MaaCore/Vision/Roguelike/BlackFlow/BlackFlowMapAnalyzer.cpp), an automation assistant for the mobile game Arknights
- [**Madden NFL 25**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a sports simulation game capturing the excitement of American football with realistic gameplay and team management features
- [**Madden NFL 26**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), an American football simulation with franchise and team management modes
- [**Madden NFL 27**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), the latest installment of the American football simulation series
- [**Marne**](https://marne.io/licenses), an unofficial private server platform for hosting custom Battlefield 1 game experiences
- [**Minecraft**](https://www.minecraft.net/zh-hant/attribution), a popular sandbox video game
- [**Mumble**](https://github.com/mumble-voip/mumble), a low-latency, open-source voice chat application widely used by gaming communities
- [**NHL 22**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a hockey simulation game offering realistic gameplay, team management, and various modes to enhance the hockey experience
- [**OBS Studio**](https://github.com/obsproject/obs-studio), a free and open-source suite for video recording and live streaming
- [**OpenRCT2**](https://github.com/OpenRCT2/OpenRCT2/blob/develop/src/openrct2/core/JsonFwd.hpp), an open source re-implementation of RollerCoaster Tycoon 2
- [**Pixelpart**](https://pixelpart.net/documentation/book/third-party.html), a 2D animation and video compositing software that allows users to create animated graphics and visual effects with a focus on simplicity and ease of use
- [**Razer Cortex**](https://mysupport.razer.com/app/answers/detail/a_id/14146/~/open-source-software-for-razer-software), a gaming performance optimizer and system booster designed to enhance the gaming experience
- [**Red Dead Redemption II**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), an open-world action-adventure game following an outlaw's story in the late 1800s, emphasizing deep storytelling and immersive gameplay
- [**RetroArch**](https://github.com/libretro/RetroArch), a frontend for emulators, game engines, and media players built on the libretro API
- [**shadPS4**](https://github.com/shadps4-emu/shadPS4/blob/main/src/core/user_manager.h), a PlayStation 4 emulator for Windows, Linux and macOS
- [**skate.**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a free-to-play skateboarding game set in an open world
- [**Snapchat**](https://www.snap.com/terms/license-android), a multimedia messaging and augmented reality app for communication and entertainment
- [**Steel Century Groove**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), an action game released in 2026
- [**Sunshine**](https://github.com/LizardByte/Sunshine/blob/master/src/confighttp.h), a self-hosted game streaming host compatible with Moonlight clients
- [**Tactics Ogre: Reborn**](https://www.square-enix-games.com/en_US/documents/tactics-ogre-reborn-pc-installer-software-and-associated-plug-ins-disclosure), a tactical role-playing game featuring strategic battles and deep storytelling elements
- [**Throne and Liberty**](https://www.amazon.com/gp/help/customer/display.html?nodeId=T7fLNw5oAevCMtJFPj&pop-up=1), an MMORPG that offers an expansive fantasy world with dynamic gameplay and immersive storytelling
- [**Unity Vivox**](https://docs.unity3d.com/Packages/com.unity.services.vivox@15.1/license/Third%20Party%20Notices.html), a communication service that enables voice and text chat functionality in multiplayer games developed with Unity
- [**xemu**](https://github.com/xemu-project/xemu), an emulator of the original Xbox console
- [**Zool: Redimensioned**](https://www.mobygames.com/person/1195889/niels-lohmann/credits/), a modern reimagining of the classic platformer featuring fast-paced gameplay and vibrant environments
- [**immersivetech**](https://immersitech.io/open-source-third-party-software/), a technology company focused on immersive experiences, providing tools and solutions for virtual and augmented reality applications
## Consumer Electronics
@@ -81,195 +50,109 @@ the result of an internet search. If you know further customers of the library,
- [**Canon CanoScan LIDE**](https://carolburo.com/wp-content/uploads/2024/06/LiDE400_OnlineManual_Win_FR_V02.pdf), a series of flatbed scanners offering high-resolution image scanning for home and office use
- [**Canon PIXMA Printers**](https://www.mediaexpert.pl/products/files/73/7338196/Instrukcja-obslugi-CANON-Pixma-TS7450i.pdf), a line of all-in-one inkjet printers known for high-quality printing and wireless connectivity
- [**Cisco Webex Desk Camera**](https://www.cisco.com/c/dam/en_us/about/doing_business/open_source/docs/CiscoWebexDeskCamera-23-1622100417.pdf), a video camera designed for professional-quality video conferencing and remote collaboration
- [**DJI Edge SDK**](https://github.com/dji-sdk/Edge-SDK-V2-Demo), the reference applications for DJI's Edge SDK, used to build edge computing services on DJI drone docks
- [**Elgato Stream Deck**](https://github.com/elgatosf/streamdeck-obs-plugin2), a family of programmable control surfaces for content creators and their plugin ecosystem
- [**Instagrid**](https://instagrid.co/intellectual-property/foss), a manufacturer of portable, high-performance battery systems for professional mobile power supply
- [**iRobot**](https://iot-content.irobot.com/iw/sfsites/c/cms/delivery/media/MCKRLTPDJSSJBNJKDA5SG5UVVIIQ), a manufacturer of autonomous home robots including the Roomba vacuum cleaner range
- [**Logitech Logi Bolt**](https://opensource.logitech.com/wiki/Logi_BoltApp/), the management application for Logitech's secure wireless connectivity technology
- [**Novitus**](https://novitus.pl/licencjepensource), a manufacturer of fiscal cash registers and point-of-sale devices
- [**Philips Hue Personal Wireless Lighting**](http://2ak5ape.257.cz/), a smart lighting system for customizable and wireless home illumination
- [**Ray-Ban Meta Smart glasses**](https://www.meta.com/de/en/legal/smart-glasses/third-party-notices-android/03/), a pair of smart glasses designed for capturing photos and videos with integrated connectivity and social features
- [**Razer Synapse**](https://mysupport.razer.com/app/answers/detail/a_id/14146/~/open-source-software-for-razer-software), a unified configuration software enabling hardware customization for Razer devices
- [**Sharp Professional Displays**](https://jp.sharp/restricted/business/lcd-display/cms/images/source_pnla862/PN-LA652_752_862_LicenseInformation.pdf), a range of large-format interactive displays for business and education
- [**Siemens SINEMA Remote Connect**](https://cache.industry.siemens.com/dl/files/790/109793790/att_1054961/v2/OSS_SINEMA-RC_86.pdf), a remote connectivity solution for monitoring and managing industrial networks and devices securely
- [**Skydio**](https://pages.skydio.com/rs/784-TUF-591/images/Open%20Source%20Software%20Notice%20v0.2.html), a manufacturer of autonomous drones for inspection, public safety, and defense applications
- [**Sony PlayStation 4**](https://doc.dl.playstation.net/doc/ps4-oss/index.html), a gaming console developed by Sony that offers a wide range of games and multimedia entertainment features
- [**Sony Spatial Reality Display**](https://www.sony.co.jp/en/Products/Developer-Spatial-Reality-display/download/dcc-tools/blender-plugin/SpatiaRealityDisplayPluginforPreviewBL_Manual.pdf), a glasses-free stereoscopic 3D display and its plugins for Blender, 3ds Max, and ZBrush
- [**Sony Virtual Webcam Driver for Remote Camera**](https://helpguide.sony.net/rc/vwd/v1/zh-cn/print.pdf), a software driver that enables the use of Sony cameras as virtual webcams for video conferencing and streaming
- [**Yamaha Clavinova**](https://usa.yamaha.com/files/download/other_assets/1/2298171/CLP-800_oss_license.pdf), a series of digital pianos combining acoustic piano feel with digital sound technology
## Operating Systems and Platforms
## Operating Systems
- [**Apple iOS and macOS**](https://www.apple.com/macos), a family of operating systems developed by Apple, including iOS for mobile devices and macOS for desktop computers
- [**Chromium**](https://chromium.googlesource.com/chromium/src/+/main/third_party/nlohmann_json/), the open-source browser project that Google Chrome, Microsoft Edge, and many other browsers are built on, where the library is used as data container for on-device model execution
- [**Google Fuchsia**](https://fuchsia.googlesource.com/third_party/json/), an open-source operating system developed by Google, designed to be secure, updatable, and adaptable across various devices
- [**LG webOS**](https://github.com/webosose/com.webos.service.camera), a Linux-based operating system used in LG smart TVs, signage, and embedded devices
- [**Microsoft Azure Linux**](https://github.com/microsoft/azurelinux), a Linux distribution developed by Microsoft for Azure infrastructure and edge workloads
- [**OpenHarmony**](https://github.com/openharmony/third_party_json), an open-source operating system for smart devices and the foundation of HarmonyOS
- [**SerenityOS**](https://github.com/SerenityOS/serenity), an open-source operating system that aims to provide a simple and beautiful user experience with a focus on simplicity and elegance
- [**Windows Subsystem for Linux**](https://github.com/microsoft/WSL), a compatibility layer that runs Linux environments natively on Windows
- [**Yocto**](http://ftp.emacinc.com/openembedded-sw/kirkstone-icop-5.15-kirkstone-6.0/archive-2024-10/pn8m-090t-ppc/licenses/nlohmann-json/), a Linux-based build system for creating custom operating systems and software distributions, tailored for embedded devices and IoT applications
## Development Tools and IDEs
- [**Accentize SpectralBalance**](https://www.accentize.com/products/SpectralBalanceManual.pdf), an adaptive speech analysis tool designed to enhance audio quality by optimizing frequency balance in recordings
- [**Airbus Ghidralligator**](https://www.cyber.airbus.com/en/newsroom/stories/2025-06-ghidralligator), a Ghidra-based emulator from Airbus CyberSecurity used to fuzz and analyse embedded firmware
- [**Apache brpc**](https://github.com/apache/brpc/blob/master/src/butil/iobuf.h), an industrial-grade remote procedure call framework for C++
- [**Arm Compiler for Linux**](https://documentation-service.arm.com/static/66558e9d876c8d213b7843e4), a software development toolchain for compiling and optimizing applications on Arm-based Linux systems
- [**BBEdit**](https://s3.amazonaws.com/BBSW-download/BBEdit_15.1.2_User_Manual.pdf), a professional text and code editor for macOS
- [**CoderPad**](https://coderpad.io), a collaborative coding platform that enables real-time code interviews and assessments for developers; the library is included in every CoderPad instance and can be accessed with a simple `#include "json.hpp"`
- [**Codon**](https://github.com/exaloop/codon/blob/develop/jupyter/jupyter.h), an ahead-of-time compiler for a Python-like language
- [**Compiler Explorer**](https://godbolt.org), a web-based tool that allows users to write, compile, and visualize the assembly output of code in various programming languages; the library is readily available and accessible with the directive `#include <nlohmann/json.hpp>`.
- [**Flutter**](https://github.com/flutter/flutter/blob/master/engine/src/flutter/impeller/compiler/reflector.cc), a UI toolkit for building natively compiled applications for mobile, web, and desktop from a single codebase
- [**Fraunhofer VVenC**](https://github.com/fraunhoferhhi/vvenc), a fast and efficient encoder for the Versatile Video Coding (H.266/VVC) standard
- [**GitHub CodeQL**](https://github.com/github/codeql/blob/main/shared/cpp/Diagnostics.h), a code analysis tool used for identifying security vulnerabilities and bugs in software through semantic queries
- [**GoPro ngfx**](https://github.com/gopro/ngfx), a low-level graphics abstraction and profiling framework developed by GoPro
- [**gRPC**](https://github.com/grpc/grpc/blob/master/tools/artifact_gen/utils.h), a high-performance universal remote procedure call framework
- [**GitHub CodeQL**](https://github.com/github/codeql), a code analysis tool used for identifying security vulnerabilities and bugs in software through semantic queries
- [**Hex-Rays**](https://docs.hex-rays.com/user-guide/user-interface/licenses), a reverse engineering toolset for analyzing and decompiling binaries, primarily used for security research and vulnerability analysis
- [**ImHex**](https://github.com/WerWolv/ImHex), a hex editor designed for reverse engineering, providing advanced features for data analysis and manipulation
- [**Intel GITS**](https://github.com/intel/gits), a tool for capturing and replaying graphics API calls for debugging and performance analysis
- [**Intel GPA Framework**](https://intel.github.io/gpasdk-doc/src/licenses.html), a suite of cross-platform tools for capturing, analyzing, and optimizing graphics applications across different APIs
- [**Intopix**](https://www.intopix.com/software-licensing), a provider of advanced image processing and compression solutions used in software development and AV workflows
- [**Java SE**](https://www.oracle.com/a/tech/docs/jdk8-lium.pdf), the core Java platform that provides the libraries and runtime needed to build and run general-purpose Java applications
- [**Meta Yoga**](https://github.com/facebook/yoga), a layout engine that facilitates flexible and efficient user interface design across multiple platforms
- [**MKVToolNix**](https://mkvtoolnix.download/doc/README.md), a set of tools for creating, editing, and inspecting MKV (Matroska) multimedia container files
- [**MRTech IFF SDK**](https://mr-technologies.com/pub/iff-sdk-manual-2-0-1/iff-sdk-manual-2-0-1.pdf), an image processing SDK for machine vision applications with GPU-accelerated pipelines
- [**Nix**](https://github.com/NixOS/nix/blob/master/src/nix/build.cc), a purely functional package manager
- [**Notepad++**](https://github.com/notepad-plus-plus/notepad-plus-plus), a free source code editor that supports various programming languages
- [**Meta Yoga**](https://github.com/facebook/yoga), a layout engine that facilitates flexible and efficient user interface design across multiple platforms
- [**NVIDIA Nsight Compute**](https://docs.nvidia.com/nsight-compute/2022.2/pdf/CopyrightAndLicenses.pdf), a performance analysis tool for CUDA applications that provides detailed insights into GPU performance metrics
- [**openFrameworks**](https://github.com/openframeworks/openFrameworks/blob/master/libs/openFrameworks/utils/ofJson.h), a community-developed C++ toolkit for creative coding
- [**Notepad++**](https://github.com/notepad-plus-plus/notepad-plus-plus), a free source code editor that supports various programming languages
- [**OpenRGB**](https://gitlab.com/CalcProgrammer1/OpenRGB), an open source RGB lighting control that doesn't depend on manufacturer software
- [**OpenTelemetry C++**](https://github.com/open-telemetry/opentelemetry-cpp), a library for collecting and exporting observability data in C++, enabling developers to implement distributed tracing and metrics in their application
- [**Oracle GraalVM**](https://docs.oracle.com/en/graalvm/jdk/21/docs/licensing-information/), a high-performance JDK distribution with ahead-of-time compilation and polyglot runtime support
- [**Philips amp-cucumber-cpp-runner**](https://github.com/philips-software/amp-cucumber-cpp-runner), a behaviour-driven development test runner for embedded C++ software developed at Philips
- [**Qt Creator**](https://doc.qt.io/qtcreator/qtcreator-attribution-json-nlohmann.html), an IDE for developing applications using the Qt application framework
- [**Qt for MCUs**](https://doc.qt.io/QtForMCUs/quickultralite-attribution-nlohmann-json.html), a graphics framework for building fluid user interfaces on microcontrollers
- [**React Native**](https://github.com/react/react-native/blob/main/packages/react-native/ReactCxxPlatform/react/devsupport/PackagerConnection.cpp), a framework for building native mobile applications using React
- [**Scanbot SDK**](https://docs.scanbot.io/barcode-scanner-sdk/web/third-party-libraries/), a software development kit (SDK) that provides tools for integrating advanced document scanning and barcode scanning capabilities into applications
- [**STMicroelectronics TouchGFX**](https://www.st.com/resource/en/additional_license_terms/additional-license-terms-x-cube-touchgfx.html), a graphical user interface framework shipped with STM32 microcontrollers for building embedded HMIs
- [**swagger-codegen**](https://github.com/swagger-api/swagger-codegen/blob/master/samples/server/petstore/pistache-server/model/Pet.h), a template-driven engine that generates API clients and server stubs from an OpenAPI specification
- [**Swoole**](https://github.com/swoole/swoole-src/blob/master/ext-src/swoole_admin_server.cc), a coroutine-based concurrency engine for PHP
- [**Tracy Profiler**](https://github.com/wolfpld/tracy/blob/master/profiler/src/profiler/TracyLlm.hpp), a real-time frame profiler for games and other applications
- [**WasmEdge**](https://github.com/WasmEdge/WasmEdge/blob/master/plugins/wasi_nn/GGML/tts/tts_core.cpp), a lightweight WebAssembly runtime for edge and cloud workloads
- [**x64dbg**](https://github.com/x64dbg/x64dbg/blob/development/src/cross/remote_table/TableRpcData.h), an open source user mode debugger for Windows, aimed at reverse engineering and malware analysis
## Machine Learning and AI
- [**Alibaba MNN**](https://github.com/alibaba/MNN), a lightweight deep learning inference engine for mobile and embedded devices
- [**AMD Gaia**](https://github.com/amd/gaia), an open-source framework for running generative AI applications locally on AMD hardware
- [**AMD Vitis AI (VAIP)**](https://github.com/amd/vaip), the execution provider stack that runs AI models on AMD Ryzen AI and adaptive computing devices
- [**Apple Core ML Tools**](https://github.com/apple/coremltools), a set of tools for converting and configuring machine learning models for deployment in Apple's Core ML framework
- [**Avular Mobile Robotics**](https://www.avular.com/licenses/nlohmann-json-3.9.1.txt), a platform for developing and deploying mobile robotics solutions
- [**FunASR**](https://github.com/modelscope/FunASR/blob/main/runtime/http/bin/asr_sessions.h), a speech recognition toolkit for training and deploying end-to-end models
- [**Google gemma.cpp**](https://github.com/google/gemma.cpp), a lightweight C++ inference engine designed for running AI models from the Gemma family
- [**Google Magenta The Infinite Crate**](https://github.com/magenta/the-infinite-crate), an open-source generative AI plugin for digital audio workstations from Google's Magenta research team
- [**GPT4All**](https://github.com/nomic-ai/gpt4all/blob/main/gpt4all-chat/src/tool.h), a desktop application for running local large language models on consumer hardware
- [**Huawei MindSpore**](https://github.com/mindspore-ai/mindspore/blob/master/Third_Party_Open_Source_Software_Notice), a deep learning framework for training and inference across device, edge, and cloud
- [**KTransformers**](https://github.com/kvcache-ai/ktransformers/blob/main/archive/csrc/balance_serve/sched/model_config.h), a framework for heterogeneous large language model inference
- [**llama.cpp**](https://github.com/ggerganov/llama.cpp), a C++ library designed for efficient inference of large language models (LLMs), enabling streamlined integration into applications
- [**LocalAI**](https://github.com/mudler/LocalAI/blob/master/backend/cpp/ds4/dsml_renderer.cpp), a self-hosted inference engine that exposes local models through an OpenAI-compatible API
- [**MLX**](https://github.com/ml-explore/mlx), an array framework for machine learning on Apple Silicon
- [**Mozilla llamafile**](https://github.com/Mozilla-Ocho/llamafile), a tool designed for distributing and executing large language models (LLMs) efficiently using a single file format
- [**NVIDIA ACE**](https://docs.nvidia.com/ace/latest/index.html), a suite of real-time AI solutions designed for the development of interactive avatars and digital human applications, enabling scalable and sophisticated user interactions
- [**NVIDIA Instant NGP**](https://github.com/NVlabs/instant-ngp/blob/master/src/nerf_loader.cu), an implementation of instant neural graphics primitives for rapid scene reconstruction
- [**NVIDIA TensorRT**](https://github.com/NVIDIA/TensorRT), an SDK for high-performance deep learning inference, including its TensorRT-LLM extension for large language models
- [**NVIDIA TensorRT-LLM**](https://github.com/NVIDIA/TensorRT-LLM/blob/main/cpp/tensorrt_llm/common/safetensors.cpp), a toolkit for optimizing and serving large language model inference on GPUs
- [**ONNX Runtime**](https://github.com/microsoft/onnxruntime), a cross-platform inference and training accelerator for machine learning models
- [**OpenVINO**](https://github.com/openvinotoolkit/openvino), Intel's toolkit for optimizing and deploying deep learning inference across CPUs, GPUs, and NPUs
- [**PaddleOCR**](https://github.com/PaddlePaddle/PaddleOCR/blob/main/deploy/cpp_infer/src/modules/text_detection/result.cc), an optical character recognition toolkit that turns documents and images into structured data
- [**PaddlePaddle**](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/ap/src/axpr/anf_expr.cc), a deep learning framework for distributed training and inference
- [**Peer**](https://support.peer.inc/hc/en-us/articles/17261335054235-Licenses), a platform offering personalized AI assistants for interactive learning and creative collaboration
- [**PyTorch**](https://github.com/pytorch/pytorch), a machine learning framework for building and training neural networks, widely used in research and production
- [**Qualcomm AI Engine Direct**](https://github.com/qualcomm/qai-appbuilder), a toolchain for building and running generative AI applications on Snapdragon devices
- [**sherpa-onnx**](https://github.com/k2-fsa/sherpa-onnx/blob/master/sherpa-onnx/csrc/sentence-piece-tokenizer.cc), a speech toolkit for on-device recognition, synthesis and speaker diarization
- [**stable-diffusion.cpp**](https://github.com/leejet/stable-diffusion.cpp), a C++ implementation of the Stable Diffusion image generation model
- [**TanvasTouch**](https://tanvas.co/tanvastouch-sdk-third-party-acknowledgments), a software development kit (SDK) that enables developers to create tactile experiences on touchscreens, allowing users to feel textures and physical sensations in a digital environment
- [**TensorFlow**](https://github.com/tensorflow/tensorflow), a machine learning framework that facilitates the development and training of models, supporting data serialization and efficient data exchange between components
- [**whisper.cpp**](https://github.com/ggml-org/whisper.cpp), a C++ implementation of OpenAI's Whisper automatic speech recognition model
## Scientific Research and Analysis
- [**BLACK**](https://www.black-sat.org/en/stable/installation/linux.html), a bounded linear temporal logic (LTL) satisfiability checker
- [**CERN ALICE O2**](https://github.com/AliceO2Group/AliceO2), the online-offline computing framework of the ALICE heavy-ion experiment at the Large Hadron Collider
- [**CERN Atlas Athena**](https://gitlab.cern.ch/atlas/athena/-/blob/main/Control/PerformanceMonitoring/PerfMonComps/src/PerfMonMTSvc.h), a software framework used in the ATLAS experiment at the Large Hadron Collider (LHC) for performance monitoring
- [**CERN CMSSW**](https://github.com/cms-sw/cmssw), the offline software framework of the CMS experiment at the Large Hadron Collider
- [**CERN Gaudi**](https://gitlab.cern.ch/gaudi/Gaudi), the event-processing framework used by the LHCb and ATLAS experiments at the Large Hadron Collider
- [**ICU**](https://github.com/unicode-org/icu), the International Components for Unicode, a mature library for software globalization and multilingual support
- [**KAMERA**](https://github.com/Kitware/kamera), a platform for synchronized data collection and real-time deep learning to map marine species like polar bears and seals, aiding Arctic ecosystem research
- [**KiCad**](https://gitlab.com/kicad/code/kicad/-/tree/master/thirdparty/nlohmann_json), a free and open-source software suite for electronic design automation
- [**LLNL ROSE**](https://github.com/llnl/rose), a compiler infrastructure from Lawrence Livermore National Laboratory for building source-to-source program analysis and transformation tools
- [**Maple**](https://www.maplesoft.com/support/help/Maple/view.aspx?path=copyright), a symbolic and numeric computing environment for advanced mathematical modeling and analysis
- [**MeVisLab**](https://mevislabdownloads.mevis.de/docs/current/MeVis/ThirdParty/Documentation/Publish/ThirdPartyReference/index.html), a software framework for medical image processing and visualization.
- [**MITK**](https://github.com/MITK/MITK), the Medical Imaging Interaction Toolkit, a framework for developing interactive medical image processing software
- [**OpenPMD API**](https://openpmd-api.readthedocs.io/en/0.8.0-alpha/backends/json.html), a versatile programming interface for accessing and managing scientific data, designed to facilitate the efficient storage, retrieval, and sharing of simulation data across various applications and platforms
- [**ORNL DataFed**](https://github.com/ORNL/DataFed), a federated scientific data management system developed at Oak Ridge National Laboratory
- [**ParaView**](https://github.com/Kitware/ParaView), an open-source tool for large-scale data visualization and analysis across various scientific domains
- [**QGIS**](https://gitlab.b-data.ch/qgis/qgis/-/blob/backport-57658-to-release-3_34/external/nlohmann/json.hpp), a free and open-source geographic information system (GIS) application that allows users to create, edit, visualize, and analyze geospatial data across a variety of formats
- [**Sandia InterSpec**](https://github.com/sandialabs/InterSpec), spectral radiation analysis software from Sandia National Laboratories for identifying radioactive isotopes
- [**VolView**](https://github.com/Kitware/VolView), a lightweight application for interactive visualization and analysis of 3D medical imaging data.
- [**VTK**](https://github.com/Kitware/VTK), a software library for 3D computer graphics, image processing, and visualization
- [**VolView**](https://github.com/Kitware/VolView), a lightweight application for interactive visualization and analysis of 3D medical imaging data.
## Business and Productivity Software
- [**ArcGIS PRO**](https://www.esri.com/content/dam/esrisites/en-us/media/legal/open-source-acknowledgements/arcgis-pro-2-8-attribution-report.html), a desktop geographic information system (GIS) application developed by Esri for mapping and spatial analysis
- [**Autodesk Desktop**](https://damassets.autodesk.net/content/dam/autodesk/www/Company/legal-notices-trademarks/autodesk-desktop-platform-components/internal-autodesk-components-web-page-2023.pdf), a software platform developed by Autodesk for creating and managing desktop applications and services
- [**Check Point**](https://www.checkpoint.com/about-us/copyright-and-trademarks/), a cybersecurity company specializing in threat prevention and network security solutions, offering a range of products designed to protect enterprises from cyber threats and ensure data integrity
- [**EasyEffects**](https://github.com/wwmm/easyeffects/blob/master/src/presets_manager.hpp), an audio effects processor for PipeWire offering limiting, compression and equalization
- [**espanso**](https://github.com/espanso/espanso/blob/dev/espanso-ui/src/win32/native.cpp), a cross-platform text expander
- [**Karabiner-Elements**](https://github.com/pqrs-org/Karabiner-Elements/blob/main/src/share/app_icon.hpp), a keyboard customizer for macOS
- [**MacType**](https://github.com/snowie2000/mactype/blob/directwrite/settings.h), a font rendering engine for Windows
- [**magicplan**](https://help.magicplan.app/acknowledgments), a mobile application for creating floor plans and interior designs using augmented reality
- [**Microsoft Office for Mac**](https://officecdnmac.microsoft.com/pr/legal/mac/OfficeforMacAttributions.html), a suite of productivity applications developed by Microsoft for macOS, including tools for word processing, spreadsheets, and presentations
- [**Microsoft Teams**](https://www.microsoft.com/microsoft-teams/), a team collaboration application offering workspace chat and video conferencing, file storage, and integration of proprietary and third-party applications and services
- [**MuseScore**](https://github.com/musescore/MuseScore), a free and open-source music notation and composition application
- [**NanaZip**](https://github.com/M2Team/NanaZip/blob/main/NanaZip.Codecs/NanaZip.Codecs.Archive.ElectronAsar.cpp), a 7-Zip derivative built for modern Windows
- [**Nexthink Infinity**](https://docs.nexthink.com/legal/services-terms/experience-open-source-software-licenses/infinity-2022.8-software-licenses), a digital employee experience management platform for monitoring and improving IT performance
- [**Sophos Connect Client**](https://docs.sophos.com/nsg/licenses/SophosConnect/SophosConnectAttribution.html), a secure VPN client from Sophos that allows remote users to connect to their corporate network, ensuring secure access to resources and data
- [**Stonebranch**](https://stonebranchdocs.atlassian.net/wiki/spaces/UA77/pages/799545647/Licenses+for+Third-Party+Libraries), a cloud-based cybersecurity solution that integrates backup, disaster recovery, and cybersecurity features to protect data and ensure business continuity for organizations
- [**Tablecruncher**](https://tablecruncher.com/), a data analysis tool that allows users to import, analyze, and visualize spreadsheet data, offering interactive features for better insights and decision-making
- [**VNote**](https://github.com/vnotex/vnote/blob/master/src/core/services/notebookcoreservice.cpp), a Markdown-based note-taking application written in C++
- [**magicplan**](https://help.magicplan.app/acknowledgments), a mobile application for creating floor plans and interior designs using augmented reality
## Databases and Big Data
- [**ADIOS2**](https://code.ornl.gov/ecpcitest/adios2/-/tree/pr4285_FFSUpstream/thirdparty/nlohmann_json?ref_type=heads), a data management framework designed for high-performance input and output operations
- [**Apache Doris**](https://github.com/apache/doris/blob/master/be/src/runtime/be_proc_monitor.cpp), a real-time analytical database for high-concurrency queries
- [**Claris FileMaker Server**](https://www.claris.com/company/legal/docs/acknowledgements/filemaker-server-macwin/claris_fms2025_acknowledgements_en.pdf), the server platform hosting FileMaker custom apps and databases, developed by Apple subsidiary Claris
- [**ClickHouse**](https://github.com/ClickHouse/ClickHouse), a column-oriented database management system for real-time analytical queries
- [**Cribl Stream**](https://docs.cribl.io/stream/third-party-current-list/), a real-time data processing platform that enables organizations to collect, route, and transform observability data, enhancing visibility and insights into their systems
- [**DB Browser for SQLite**](https://github.com/sqlitebrowser/sqlitebrowser), a visual open-source tool for creating, designing, and editing SQLite database files
- [**Manticore Search**](https://github.com/manticoresoftware/manticoresearch/blob/main/src/searchdhttpcompat.cpp), a database for search, offering full-text and vector queries
- [**Milvus**](https://github.com/milvus-io/milvus/blob/master/internal/core/src/query/PlanImpl.h), a cloud-native vector database built for embedding similarity search
- [**MongoDB**](https://github.com/mongodb/mongo/blob/master/src/mongo/replay/config_handler.cpp), a general-purpose document database
- [**MySQL Connector/C++**](https://docs.oracle.com/cd/E17952_01/connector-cpp-9.1-license-com-en/license-opentelemetry-cpp-com.html), a C++ library for connecting and interacting with MySQL databases
- [**MySQL NDB Cluster**](https://downloads.mysql.com/docs/licenses/cluster-9.0-com-en.pdf), a distributed database system that provides high availability and scalability for MySQL databases
- [**MySQL Shell**](https://downloads.mysql.com/docs/licenses/mysql-shell-8.0-gpl-en.pdf), an advanced client and code editor for interacting with MySQL servers, supporting SQL, Python, and JavaScript
- [**PrestoDB**](https://github.com/prestodb/presto/blob/master/presto-native-execution/presto_cpp/main/Announcer.cpp), a distributed SQL query engine designed for large-scale data analytics, originally developed by Facebook
- [**PrestoDB**](https://github.com/prestodb/presto), a distributed SQL query engine designed for large-scale data analytics, originally developed by Facebook
- [**ROOT Data Analysis Framework**](https://root.cern/doc/v614/classnlohmann_1_1basic__json.html), an open-source data analysis framework widely used in high-energy physics and other fields for data processing and visualization
- [**Typesense**](https://github.com/typesense/typesense/blob/v31/include/join.h), an open source typo-tolerant search engine
- [**Vearch**](https://github.com/jd-opensource/vearch), a distributed vector database developed at JD.com for similarity search and retrieval-augmented generation
- [**WiredTiger**](https://github.com/wiredtiger/wiredtiger), a high-performance storage engine for databases, offering support for compression, concurrency, and checkpointing
## Simulation and Modeling
- [**Adobe Lagrange**](https://github.com/adobe/lagrange), a geometry processing library developed by Adobe for mesh manipulation and analysis
- [**Arcturus HoloSuite**](https://www.datocms-assets.com/104353/1698904597-holosuite-third-party-software-credits-and-attributions-2.pdf), a software toolset for capturing, editing, and streaming volumetric video, featuring advanced compression technologies for high-quality 3D content creation
- [**azul**](https://pure.tudelft.nl/ws/files/85338589/tgis.12673.pdf), a fast and efficient 3D city model viewer designed for visualizing urban environments and spatial data
- [**Bambu Studio**](https://github.com/bambulab/BambuStudio), a slicing and print management application for Bambu Lab 3D printers
- [**Blender**](https://projects.blender.org/blender/blender/search?q=nlohmann), a free and open-source 3D creation suite for modeling, animation, rendering, and more
- [**cpplot**](https://cpplot.readthedocs.io/en/latest/library_api/function_eigen_8h_1ac080eac0541014c5892a55e41bf785e6.html), a library for creating interactive graphs and charts in C++, which can be viewed in web browsers
- [**Foundry Nuke**](https://learn.foundry.com/nuke/content/misc/studio_third_party_libraries.html), a powerful node-based digital compositing and visual effects application used in film and television post-production
- [**FreeCAD**](https://github.com/FreeCAD/FreeCAD), a free and open-source parametric 3D CAD modeler for product design and engineering
- [**GAMS**](https://www.gams.com/47/docs/THIRDPARTY.html), a high-performance mathematical modeling system for optimization and decision support
- [**Keysight WirelessPro**](https://docs.keysight.com/display/engdocwirelesspro/WirelessPro+2026+Release+Notes), a simulation platform for 5G, 5G-Advanced, and 6G cellular network research
- [**Kitware SMTK**](https://github.com/Kitware/SMTK), a software toolkit for managing simulation models and workflows in scientific and engineering applications
- [**M-Star**](https://docs.mstarcfd.com/3_Licensing/thirdparty-licenses.html), a computational fluid dynamics software for simulating and analyzing fluid flow
- [**MapleSim CAD Toolbox**](https://www.maplesoft.com/support/help/MapleSim/view.aspx?path=CADToolbox/copyright), a software extension for MapleSim that integrates CAD models, allowing users to import, manipulate, and analyze 3D CAD data within the MapleSim environment for enhanced modeling and simulation
- [**Microsoft AirSim**](https://github.com/microsoft/AirSim/blob/main/AirLib/include/common/Settings.hpp), a simulator for autonomous vehicles and drones built on Unreal Engine
- [**NVIDIA Omniverse**](https://docs.omniverse.nvidia.com/composer/latest/common/product-licenses/usd-explorer/usd-explorer-2023.2.0-licenses-manifest.html), a platform for 3D content creation and collaboration that enables real-time simulations and interactive experiences across various industries
- [**OpenSCAD**](https://github.com/openscad/openscad/blob/master/src/core/AIClient.cc), a script-driven solid 3D CAD modeller
- [**OrcaSlicer**](https://github.com/SoftFever/OrcaSlicer), an open-source slicer supporting a wide range of consumer 3D printers
- [**Pixar Renderman**](https://rmanwiki-26.pixar.com/space/REN26/19662083/Legal+Notice), a photorealistic 3D rendering software developed by Pixar, widely used in the film industry for creating high-quality visual effects and animations
- [**PrusaSlicer**](https://github.com/prusa3d/PrusaSlicer), the slicing software developed by Prusa Research for its 3D printers
- [**ROS - Robot Operating System**](http://docs.ros.org/en/noetic/api/behaviortree_cpp/html/json_8hpp_source.html), a set of software libraries and tools that assist in developing robot applications
- [**UBS**](https://www.ubs.com/), a multinational financial services and banking company
@@ -278,31 +161,18 @@ the result of an internet search. If you know further customers of the library,
- [**Acronis Cyber Protect Cloud**](https://care.acronis.com/s/article/59533-Third-party-software-used-in-Acronis-Cyber-Protect-Cloud?language=en_US), an all-in-one data protection solution that combines backup, disaster recovery, and cybersecurity to safeguard business data from threats like ransomware
- [**Baereos**](https://gitlab.tiger-computing.co.uk/packages/bareos/-/blob/tiger/bullseye/third-party/CLI11/examples/json.cpp), a backup solution that provides data protection and recovery options for various environments, including physical and virtual systems
- [**Bitdefender Home Scanner**](https://www.bitdefender.de/site/Main/view/home-scanner-open-source.html), a tool from Bitdefender that scans devices for malware and security threats, providing a safeguard against potential online dangers
- [**Cisco MLS++**](https://github.com/cisco/mlspp), an implementation of the Messaging Layer Security protocol for end-to-end encrypted group messaging
- [**Citrix Provisioning**](https://docs.citrix.com/en-us/provisioning/2203-ltsr/downloads/pvs-third-party-notices-2203.pdf), a solution that streamlines the delivery of virtual desktops and applications by allowing administrators to manage and provision resources efficiently across multiple environments
- [**Citrix Virtual Apps and Desktops**](https://docs.citrix.com/en-us/citrix-virtual-apps-desktops/2305/downloads/third-party-notices-apps-and-desktops.pdf), a solution from Citrix that delivers virtual apps and desktops
- [**Cyberarc**](https://docs.cyberark.com/Downloads/Legal/Privileged%20Session%20Manager%20for%20SSH%20Third-Party%20Notices.pdf), a security solution that specializes in privileged access management, enabling organizations to control and monitor access to critical systems and data, thereby enhancing overall cybersecurity posture
- [**Deutsche Telekom sysrepo-plugins**](https://github.com/telekom/sysrepo-plugins), a collection of YANG datastore plugins used to manage network devices
- [**Egnyte Desktop**](https://helpdesk.egnyte.com/hc/en-us/articles/360007071732-Third-Party-Software-Acknowledgements), a secure cloud storage solution designed for businesses, enabling file sharing, collaboration, and data management across teams while ensuring compliance and data protection
- [**Elster**](https://www.secunet.com/en/about-us/press/article/elstersecure-bietet-komfortablen-login-ohne-passwort-dank-secunet-protect4use), a digital platform developed by German tax authorities for secure and efficient electronic tax filing and management using secunet protect4use
- [**Envoy**](https://github.com/envoyproxy/envoy), a cloud-native edge and service proxy that forms the data plane of many service meshes
- [**Ethereum Solidity**](https://github.com/ethereum/solidity), a high-level, object-oriented programming language designed for implementing smart contracts on the Ethereum platform
- [**gVisor**](https://github.com/google/gvisor), an application kernel that provides a secure sandbox for running untrusted containers
- [**IBM Storage Virtualize**](https://public.dhe.ibm.com/systems/support/warranty/pdfs/stgoilc/SV_for_FS_7300_v8_7_0_Base_OILC.pdf), the software powering IBM FlashSystem enterprise storage arrays
- [**Inciga**](https://fossies.org/linux/icinga2/third-party/nlohmann_json/json.hpp), a monitoring tool for IT infrastructure, designed to provide insights into system performance and availability through customizable dashboards and alerts
- [**Intel Accelerator Management Daemon for VMware ESXi**](https://downloadmirror.intel.com/772507/THIRD-PARTY.txt), a management tool designed for monitoring and controlling Intel hardware accelerators within VMware ESXi environments, optimizing performance and resource allocation
- [**Juniper Identity Management Service**](https://www.juniper.net/documentation/us/en/software/jims/jims-guide/jims-guide.pdf)
- [**Meta FBOSS**](https://github.com/facebook/fboss), the software stack that controls the network switches in Meta's data centers
- [**Microsoft Azure IoT SDK**](https://library.e.abb.com/public/2779c5f85f30484192eb3cb3f666a201/IP%20Gateway%20Open%20License%20Declaration_9AKK108467A4095_Rev_C.pdf), a collection of tools and libraries to help developers connect, build, and deploy Internet of Things (IoT) solutions on the Azure cloud platform
- [**Microsoft Confidential Consortium Framework**](https://github.com/microsoft/CCF), a framework for building secure, highly available applications on trusted execution environments
- [**Microsoft WinGet**](https://github.com/microsoft/winget-cli), a command-line utility included in the Windows Package Manager
- [**Mitsubishi Electric SECS/GEM**](https://dl.mitsubishielectric.com/dl/fa/document/manual/plc/sh082483eng/sh082483engi.pdf), the semiconductor equipment communication software running on Mitsubishi Electric C Controller and C intelligent function modules
- [**Moxa**](https://www.moxa.com/getmedia/fbe2a0c7-8dda-4b5b-a501-15e45adebb1f/moxa-foss-statement-for-da-720-series-win-10-ltsc-21h2-declaration-v1.0.pdf), a provider of industrial networking, computing, and automation infrastructure
- [**plexusAV**](https://www.sisme.com/media/10994/manual_plexusav-p-avn-4-form8244-c.pdf), a high-performance AV-over-IP transceiver device capable of video encoding and decoding using the IPMX standard
- [**Pointr**](https://docs-dev.pointr.tech/docs/8.x/Developer%20Portal/Open%20Source%20Licenses/), a platform for indoor positioning and navigation solutions, offering tools and SDKs for developers to create location-based applications
- [**secunet protect4use**](https://www.secunet.com/en/about-us/press/article/elstersecure-bietet-komfortablen-login-ohne-passwort-dank-secunet-protect4use), a secure, passwordless multifactor authentication solution that transforms smartphones into digital keyrings, ensuring high security for online services and digital identities
- [**Sencore MRD 7000**](https://www.foccusdigital.com/wp-content/uploads/2025/03/MRD-7000-Manual-8175V.pdf), a professional multi-channel receiver and decoder supporting UHD and HD stream decoding
- [**Siemens SINEC**](https://cache.industry.siemens.com/dl/files/917/109974917/att_1298783/v2/OSS_SINEC-NMS_99.pdf), a family of network management and infrastructure services for industrial networks
- [**Toshiba Industrial Servers**](https://www.global.toshiba/content/dam/toshiba/jp/products-solutions/industrial/computer/product/server/fs20000r/pdf/FS20000R_OSS_License_6E8C5817_rev0.pdf), the FS20000R series of industrial servers for factory automation and control systems
- [**Wazuh**](https://github.com/wazuh/wazuh/blob/main/src/data_provider/src/sysInfo.cpp), a security platform for threat detection, integrity monitoring and incident response
- [**ZeroTier**](https://github.com/zerotier/ZeroTierOne/blob/dev/osdep/OSUtils.hpp), a software-defined networking service that creates virtual Ethernet networks
-68
View File
@@ -868,12 +868,6 @@ The size of an array or object in a [binary format](../features/binary_formats/i
the size following `#` for [UBJSON](../features/binary_formats/ubjson.md)/[BJData](../features/binary_formats/bjdata.md),
or the encoded length for [CBOR](../features/binary_formats/cbor.md).
The exception is also thrown for a [UBJSON](../features/binary_formats/ubjson.md) array of a type that is encoded by its
marker alone (`Z`, `T` or `F`) whose declared count exceeds 1,048,576 (`1 << 20`). Such an array has no payload, so its
count alone decides how much memory is allocated, and a handful of bytes would otherwise describe billions of values.
[`to_ubjson`](../api/basic_json/to_ubjson.md) writes longer arrays of these types without the size and type annotation,
so any value it produces can still be read back.
!!! failure "Example messages"
```
@@ -885,9 +879,6 @@ so any value it produces can still be read back.
```
[json.exception.out_of_range.408] syntax error while parsing CBOR size: excessive map size
```
```
[json.exception.out_of_range.408] syntax error while parsing UBJSON size: excessive array size
```
### json.exception.out_of_range.409
@@ -942,49 +933,6 @@ BSON stores the length of documents, arrays, strings, and binary values in a sig
[`to_bson`](../api/basic_json/to_bson.md) produced documents with negative length prefixes that
[`from_bson`](../api/basic_json/from_bson.md) rejected.
### json.exception.out_of_range.413
A JSON Patch `remove` operation cannot be applied because the target location's parent is neither an object nor an array. Per [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902), a `remove` target must reference a member of an existing object or an element of an existing array; a primitive value (string, number, boolean, etc.) or `null` has no members or elements to remove.
!!! failure "Example message"
```
cannot remove value: the JSON Patch 'remove' target's parent is of type number, but must be an object or array
```
!!! note
This exception was added in version 3.13.0. Before that, this situation was silently ignored (the `remove` operation had no effect).
### json.exception.out_of_range.414
A JSON Patch `move` operation's `"from"` location is a proper prefix of its `"path"` location. Per [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902) (section 4.4), a location cannot be moved into one of its own children.
!!! failure "Example message"
```
cannot move value: 'from' path '/0' is a proper prefix of 'path' '/0/0'
```
!!! note
This exception was added in version 3.13.0. Before that, this situation could succeed with a corrupted result: for an array target, removing the "from" element before the "add" step shifted subsequent indices, so "path" silently re-resolved to a different element than intended.
### json.exception.out_of_range.415
MessagePack's ext type and BSON's binary subtype are each stored in a single byte. This exception is thrown when serializing a
[`byte_container_with_subtype`](../api/byte_container_with_subtype/index.md) whose subtype exceeds 255.
!!! failure "Example message"
```
[json.exception.out_of_range.415] subtype 70000 is too large for the MessagePack ext type (max 255)
```
!!! note
This exception was added in version 3.13.0. Before that, subtypes above 255 were silently truncated modulo 256 instead of raising an error.
## Further exceptions
This exception is thrown in case of errors that cannot be classified with the
@@ -1017,19 +965,3 @@ A JSON Patch operation 'test' failed. The unsuccessful operation is also printed
```
[json.exception.other_error.501] unsuccessful: {"op":"test","path":"/baz","value":"bar"}
```
### json.exception.other_error.502
[`to_ubjson`](../api/basic_json/to_ubjson.md) and [`to_bjdata`](../api/basic_json/to_bjdata.md) were called with
`use_type = true` but `use_size = false`. UBJSON requires a size marker (`#`) after a type marker (`$`).
!!! failure "Example message"
```
[json.exception.other_error.502] use_type requires use_size = true
```
!!! note
This exception was added in version 3.13.0. Before that, debug builds aborted on an assertion and release builds
wrote a `$` marker without `#`, which [`from_ubjson`](../api/basic_json/from_ubjson.md) then rejected.
+7 -40
View File
@@ -92,51 +92,18 @@ In most cases, the parser is right to complain, because the input is not UTF-8 e
### NUL bytes in the input
!!! question "Questions"
!!! question
- Why does `json::parse()` silently ignore part of my input?
- Why does a `std::string`/buffer with extra data after the JSON text parse without error, while a similar-looking string with extra text does not?
Why does parsing fail with "invalid literal" or "unexpected additional data" when my input contains a `'\0'` (NUL) byte?
A `'\0'` (NUL) byte anywhere in the input is treated the same as the real end of the input, rather than as an ordinary (and, outside of a string, invalid) byte. Everything from that byte onward is silently ignored, without a parse error — including further, otherwise well-formed JSON:
A `'\0'` byte that occurs inside or at the end of the input is **not** treated as end-of-input; it is treated as an ordinary, invalid byte, exactly like any other unexpected byte in that position. [RFC 8259](https://tools.ietf.org/html/rfc8259.html) does not give the NUL byte any special end-of-text meaning, so a JSON text that is embedded in a larger byte sequence (for instance, a `std::string` with a trailing `'\0'` appended, or a buffer that happens to be zero-padded) will yield a `parse_error.101`, the same error you would get for any other unexpected trailing or misplaced byte:
```cpp
json::parse(std::string("123") + '\0'); // == 123, no error
json::parse(std::string("123") + '\0' + "true"); // == 123, the "true" is silently ignored too
```
- If the NUL byte follows a complete value, parsing fails with the usual "expected end of input" message the library also gives for any other unexpected trailing byte (e.g., `json::parse(std::string("123") + '\0')` fails the same way `json::parse("123x")` does).
- If the NUL byte occurs where a value is expected (for instance, at the very start of the input, or right after a `:` or `,`), the library reports "invalid literal".
- A NUL byte inside a quoted string still needs to be escaped as `\u0000`, as required by [RFC 8259](https://tools.ietf.org/html/rfc8259.html#section-7); an unescaped NUL there is reported separately as a control character that must be escaped.
This is different from any other unexpected trailing byte, which *does* raise [`parse_error.101`](../home/exceptions.md#jsonexceptionparse_error101):
Only the length actually passed to the parser matters here: parsing a `const char*` (for example, a string literal) uses `strlen()`-like semantics and therefore never sees the terminating NUL, so `json::parse("[1,2,3]")` is unaffected. What is affected is input that explicitly includes a NUL byte as data, such as a `std::string` with `'\0'` appended, or an iterator range/container whose end includes it.
```cpp
json::parse("123x"); // throws parse_error.101: unexpected additional data
```
This falls out of the same convention used when no explicit input length is given at all: `json::parse(const char*)` already stops at the first NUL byte via `strlen()`, since a bare pointer has no length of its own. The library applies that same NUL-terminated-C-string convention uniformly, rather than only when a length is genuinely unavailable — so a `std::string`, iterator range, or container whose content happens to include a NUL byte is affected the same way a raw `const char*` would be.
If your input may contain a trailing or embedded NUL that is **not** meant to signal the end of the JSON text — for instance, a fixed-size, zero-padded buffer — trim it yourself before calling `parse()`, since the library will otherwise silently stop there instead of raising an error:
```cpp
s.resize(s.find('\0')); // drop everything from the first NUL onward, if any
json::parse(s);
```
**Opt-in strict handling (since version 3.13.0)**
Manually trimming every input is easy to forget. If you define [`JSON_STRICT_NUL_HANDLING`](../api/macros/json_strict_nul_handling.md) to `1` before including the library, a `'\0'` byte is instead rejected like any other unexpected byte and raises `parse_error.101`, instead of being treated as end of input:
```cpp
#define JSON_STRICT_NUL_HANDLING 1
#include <nlohmann/json.hpp>
json::parse(std::string("123") + '\0'); // throws parse_error.101 instead of silently returning 123
```
This macro defaults to `0` (disabled, preserving the behavior described above) to avoid breaking existing code that may depend on it, even unknowingly; it is planned to become the default in version 4.0.0. See [its documentation](../api/macros/json_strict_nul_handling.md) for details, including how it also affects `char` arrays such as string literals.
Note that this is unrelated to an *unescaped* NUL byte occurring **inside** a quoted JSON string, which is a different, already-invalid case and is correctly rejected either way:
```cpp
json::parse(std::string("\"") + '\0' + "\""); // throws parse_error.101: control character U+0000 (NUL) must be escaped to \u0000
```
### Wide string handling
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@@ -198,11 +198,6 @@ Use the non-amalgamated version of the library. This option is `ON` by default.
Treat the library headers like system headers (i.e., adding `SYSTEM` to the [`target_include_directories`](https://cmake.org/cmake/help/latest/command/target_include_directories.html) call) to check for this library by tools like Clang-Tidy. This option is `OFF` by default.
### `JSON_StrictNulHandling`
Reject a `'\0'` (NUL) byte in the input instead of treating it as end of input, by defining the macro
[`JSON_STRICT_NUL_HANDLING`](../api/macros/json_strict_nul_handling.md). This option is `OFF` by default.
### `JSON_Valgrind`
Execute the test suite with [Valgrind](https://valgrind.org). This option is `OFF` by default. Depends on `JSON_BuildTests`.
@@ -176,12 +176,6 @@ You can prepare existing code by already defining
conversions with calls to [`get`](../api/basic_json/get.md), [`get_to`](../api/basic_json/get_to.md),
[`get_ref`](../api/basic_json/get_ref.md), or [`get_ptr`](../api/basic_json/get_ptr.md).
!!! tip "Automatic migration"
The community-maintained clang-tidy check `modernize-nlohmann-json-explicit-conversions` rewrites most implicit
conversions into calls to [`get`](../api/basic_json/get.md). It is not part of clang-tidy itself; see
[discussion #4610](https://github.com/nlohmann/json/discussions/4610) for how to build and use it.
=== "Deprecated"
```cpp
+1 -15
View File
@@ -98,7 +98,6 @@ nav:
- Types:
- features/types/index.md
- features/types/number_handling.md
- features/types/template_parameters.md
- Integration:
- integration/index.md
- integration/migration_guide.md
@@ -292,15 +291,11 @@ nav:
- 'JSON_HAS_THREE_WAY_COMPARISON': api/macros/json_has_three_way_comparison.md
- 'JSON_NOEXCEPTION': api/macros/json_noexception.md
- 'JSON_NO_IO': api/macros/json_no_io.md
- 'JSON_NO_THREAD_LOCAL': api/macros/json_no_thread_local.md
- 'JSON_PRECISE_STREAM_POSITION': api/macros/json_precise_stream_position.md
- 'JSON_SKIP_LIBRARY_VERSION_CHECK': api/macros/json_skip_library_version_check.md
- 'JSON_SKIP_UNSUPPORTED_COMPILER_CHECK': api/macros/json_skip_unsupported_compiler_check.md
- 'JSON_STRICT_NUL_HANDLING': api/macros/json_strict_nul_handling.md
- 'JSON_USE_GLOBAL_UDLS': api/macros/json_use_global_udls.md
- 'JSON_USE_IMPLICIT_CONVERSIONS': api/macros/json_use_implicit_conversions.md
- 'JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON': api/macros/json_use_legacy_discarded_value_comparison.md
- 'JSON_USE_SIMDUTF': api/macros/json_use_simdutf.md
- 'NLOHMANN_DEFINE_DERIVED_TYPE_INTRUSIVE, NLOHMANN_DEFINE_DERIVED_TYPE_INTRUSIVE_WITH_DEFAULT, NLOHMANN_DEFINE_DERIVED_TYPE_INTRUSIVE_ONLY_SERIALIZE, NLOHMANN_DEFINE_DERIVED_TYPE_NON_INTRUSIVE, NLOHMANN_DEFINE_DERIVED_TYPE_NON_INTRUSIVE_WITH_DEFAULT, NLOHMANN_DEFINE_DERIVED_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE': api/macros/nlohmann_define_derived_type.md
- 'NLOHMANN_DEFINE_TYPE_INTRUSIVE, NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT, NLOHMANN_DEFINE_TYPE_INTRUSIVE_ONLY_SERIALIZE': api/macros/nlohmann_define_type_intrusive.md
- 'NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE, NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT, NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE': api/macros/nlohmann_define_type_non_intrusive.md
@@ -318,9 +313,7 @@ nav:
- community/contribution_guidelines.md
- community/quality_assurance.md
- community/governance.md
- community/roadmap.md
- community/security_policy.md
- community/assurance_case.md
# Extras
extra:
@@ -400,14 +393,7 @@ plugins:
- http://nlohmann.github.io/json/*
- https://nlohmann.github.io/json/*
- mailto:*
- privacy:
# repology.org refuses requests from GitHub Actions runners, which made
# the privacy plugin abort the whole build when it could not download the
# package badges (the fetch fails, then reading the missing cache entry
# raises FileNotFoundError). Readers' browsers are served normally, so
# leave these badges as external references instead of self-hosting them.
assets_exclude:
- repology.org/*
- privacy
- llmstxt:
markdown_description: >
JSON for Modern C++ is a C++11 header-only library implementing a JSON
+2 -2
View File
@@ -1,7 +1,7 @@
wheel==0.48.0
wheel==0.47.0
mkdocs==1.6.1 # documentation framework
mkdocs-git-revision-date-localized-plugin==1.6.0 # plugin "git-revision-date-localized"
mkdocs-git-revision-date-localized-plugin==1.5.3 # plugin "git-revision-date-localized"
mkdocs-material==9.7.7 # theme for mkdocs
mkdocs-material-extensions==1.3.1 # extensions
mkdocs-minify-plugin==0.8.0 # plugin "minify"
+4 -26
View File
@@ -34,14 +34,6 @@
#define JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON 0
#endif
#ifndef JSON_BRACE_INIT_COPY_SEMANTICS
#define JSON_BRACE_INIT_COPY_SEMANTICS 0
#endif
#ifndef JSON_PRECISE_STREAM_POSITION
#define JSON_PRECISE_STREAM_POSITION 0
#endif
#if JSON_DIAGNOSTICS
#define NLOHMANN_JSON_ABI_TAG_DIAGNOSTICS _diag
#else
@@ -60,34 +52,20 @@
#define NLOHMANN_JSON_ABI_TAG_LEGACY_DISCARDED_VALUE_COMPARISON
#endif
#if JSON_BRACE_INIT_COPY_SEMANTICS
#define NLOHMANN_JSON_ABI_TAG_BRACE_INIT_COPY_SEMANTICS _bics
#else
#define NLOHMANN_JSON_ABI_TAG_BRACE_INIT_COPY_SEMANTICS
#endif
#if JSON_PRECISE_STREAM_POSITION
#define NLOHMANN_JSON_ABI_TAG_PRECISE_STREAM_POSITION _psp
#else
#define NLOHMANN_JSON_ABI_TAG_PRECISE_STREAM_POSITION
#endif
#ifndef NLOHMANN_JSON_NAMESPACE_NO_VERSION
#define NLOHMANN_JSON_NAMESPACE_NO_VERSION 0
#endif
// Construct the namespace ABI tags component
#define NLOHMANN_JSON_ABI_TAGS_CONCAT_EX(a, b, c, d, e) json_abi ## a ## b ## c ## d ## e
#define NLOHMANN_JSON_ABI_TAGS_CONCAT(a, b, c, d, e) \
NLOHMANN_JSON_ABI_TAGS_CONCAT_EX(a, b, c, d, e)
#define NLOHMANN_JSON_ABI_TAGS_CONCAT_EX(a, b, c) json_abi ## a ## b ## c
#define NLOHMANN_JSON_ABI_TAGS_CONCAT(a, b, c) \
NLOHMANN_JSON_ABI_TAGS_CONCAT_EX(a, b, c)
#define NLOHMANN_JSON_ABI_TAGS \
NLOHMANN_JSON_ABI_TAGS_CONCAT( \
NLOHMANN_JSON_ABI_TAG_DIAGNOSTICS, \
NLOHMANN_JSON_ABI_TAG_LEGACY_DISCARDED_VALUE_COMPARISON, \
NLOHMANN_JSON_ABI_TAG_DIAGNOSTIC_POSITIONS, \
NLOHMANN_JSON_ABI_TAG_BRACE_INIT_COPY_SEMANTICS, \
NLOHMANN_JSON_ABI_TAG_PRECISE_STREAM_POSITION)
NLOHMANN_JSON_ABI_TAG_DIAGNOSTIC_POSITIONS)
// Construct the namespace version component
#define NLOHMANN_JSON_NAMESPACE_VERSION_CONCAT_EX(major, minor, patch) \
@@ -398,17 +398,6 @@ inline void from_json(const BasicJsonType& j, CompatibleArrayType& bin)
}
}
template<typename ConstructibleObjectType>
auto from_json_object_reserve(ConstructibleObjectType& obj, typename ConstructibleObjectType::size_type size, priority_tag<1> /*unused*/)
-> decltype(obj.reserve(size), void())
{
obj.reserve(size);
}
template<typename ConstructibleObjectType>
inline void from_json_object_reserve(ConstructibleObjectType& /*obj*/, std::size_t /*size*/, priority_tag<0> /*unused*/)
{}
template<typename BasicJsonType, typename ConstructibleObjectType,
enable_if_t<is_constructible_object_type<BasicJsonType, ConstructibleObjectType>::value, int> = 0>
inline void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
@@ -420,7 +409,6 @@ inline void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
ConstructibleObjectType ret;
const auto* inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
from_json_object_reserve(ret, inner_object->size(), priority_tag<1> {});
for (const auto& p : *inner_object)
{
ret.emplace(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
@@ -1075,8 +1075,8 @@ char* to_chars(char* first, const char* last, FloatType value)
}
#ifdef __GNUC__
JSON_HEDLEY_DIAGNOSTIC_PUSH
JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wfloat-equal"
#endif
if (value == 0) // +-0
{
@@ -1087,7 +1087,7 @@ char* to_chars(char* first, const char* last, FloatType value)
return first;
}
#ifdef __GNUC__
JSON_HEDLEY_DIAGNOSTIC_POP
#pragma GCC diagnostic pop
#endif
JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);

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