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Author SHA1 Message Date
Niels LohmannandClaude Sonnet 5 a27065bd12 Regenerate api_surface.json after merging develop
develop gained iterator+sentinel support for accept()/parse()/sax_parse()/
from_cbor()/from_msgpack()/from_ubjson()/from_bjdata()/from_bson() (#5205)
since this branch was created, which check_api_docs.yml's drift check caught
immediately: GitHub's pull_request trigger checks out the PR-vs-base merge
commit, not the PR branch in isolation, so CI was comparing the committed
api_surface.json (generated before that upstream change existed) against a
fresh extraction of a json.hpp that already had it.

This superseded an earlier, incorrect diagnosis of the same symptom (a
JSON_HAS_RANGES cross-environment pin) -- that fix remains in place since it's
still a real, independent determinism improvement for three other
JSON_HAS_RANGES-gated locations in type_traits.hpp, but it wasn't the actual
cause of this particular mismatch: these new overloads turned out to be
unconditional (SFINAE-gated via can_compare_ne, not preprocessor-gated), so
no environment-detection difference was involved here at all.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-07-11 23:45:46 +02:00
Niels Lohmann 3940f4b730 Merge remote-tracking branch 'origin/develop' into claude/todo-191-plan-508110 2026-07-11 23:43:30 +02:00
Niels LohmannandClaude Sonnet 5 0663907b68 Fix cross-environment API-surface drift and lint findings from CI
extract_api.py's own extraction wasn't deterministic across machines, which
CI's drift check caught immediately: JSON_HAS_RANGES auto-detects via the
standard library's __cpp_lib_ranges feature-test macro, which isn't reliably
gated to C++20 mode by every stdlib -- undefined under -std=c++17 with macOS's
libc++, but defined under the identical flag with the Ubuntu stdlib CI uses,
so parse()/accept()/from_*() extracted different signatures purely depending
on which machine ran the extraction. Pinned to -DJSON_HAS_RANGES=0: the
deterministic and safe choice, since pinning to 1 was tried first and found to
fail to parse on a stdlib without full <ranges> support even when the macro
claims otherwise.

Also found and fixed a second, independent source of the same class of drift:
get_identity_name() used cursor.spelling verbatim for CONVERSION_FUNCTION
cursors, which libclang renders as its own internally-canonicalized form of
the return type rather than what's literally written. Confirmed for
json_pointer::operator string_t() spelling differently on two machines
pinned to the identical libclang==18.1.1 wheel, with the JSON_HAS_RANGES fix
above ruled out as the cause. Now derived from the cursor's own raw source
text instead, immune to libclang's dependent-type resolution differences and
incidentally more readable than the libclang-internal forms it replaces.

Bumped SURFACE_FORMAT_VERSION to 3 and regenerated all 27 history snapshots
and the committed api_surface.json; both fixes are documented in
tools/api_checker/history/README.md's format-history log.

Also fixes diff_api.py's format_version guard, which only compared the two
loaded surfaces against each other and never against SURFACE_FORMAT_VERSION
(what this build actually understands) -- two surfaces on the same,
newer-than-expected format_version would have silently passed the guard.

Remaining fixes are the concretely actionable findings from Codacy's review
of the new tools/api_checker/ files: unused imports/variables, a stray
f-string with no placeholders. Left the docstring-formatting nitpicks
(pydocstyle D2xx/D4xx) and generic subprocess-usage notices alone -- the
former has no established convention elsewhere in this codebase's Python
tooling to conform to, and the latter are inherent to a dev tool that shells
out to git/clang with developer-controlled arguments, not user input.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-07-11 18:59:19 +02:00
Niels LohmannandClaude Sonnet 5 f23b3c63a2 Add AST-based public API checker and fix documentation gaps it found (#3691)
Adds tools/api_checker/: extract_api.py derives the public API surface directly
from the libclang AST (independent of documentation status), check_docs.py flags
public entries missing @sa links (and @sa on non-public ones), diff_api.py does
an overload-aware breaking/feature diff between two refs, check_macros.py cross-
checks documented macros against #define sites, and snapshot_release.py backfills
immutable per-release surface snapshots into tools/api_checker/history/ (v3.1.0
through v3.12.0) so diff_api.py can compare releases without live extraction.
POLICY.md documents what counts as public API and what stability is guaranteed.

Running this tooling against the current tree found and fixed a real documentation
backlog: ~25 new API doc pages (ordered_map's methods, json_sax's ctor/dtor/
operator=, byte_container_with_subtype's comparison operators, several orphaned
type aliases), each with a compiled and output-verified example, plus missing
@sa comments and stale/incorrect Version History entries on several existing
pages (found by diffing consecutive release pairs and checking whether the
resulting change was actually reflected in the target page's history section).

Also adds docs/home/api_changes.md, a per-release, per-function reference of
public API changes (v3.1.0 through v3.12.0) generated from the history/
snapshots, complementing (not replacing) the existing release notes.

Along the way, found and fixed several extractor bugs by testing against real
release tags rather than trusting the algorithm in isolation -- most notably an
identity-key scheme based on libclang's USR that encoded the enclosing class
template's own arity, and a since-renamed ABI inline-namespace pattern
(json_v3_11_0 vs. today's json_abi_v3_11_2) that neither of two earlier regex
attempts stripped correctly. Both are documented in extract_api.py's docstrings
and tools/api_checker/history/README.md so the failure mode doesn't recur
silently.

.github/workflows/check_api_docs.yml runs extract_api.py + check_docs.py in CI,
advisory-only for now (documented backlog may not be at zero for entities this
PR didn't touch), plus a blocking drift check on the committed
tools/api_checker/api_surface.json.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-07-11 18:59:00 +02:00
153 changed files with 72513 additions and 2660 deletions
+81
View File
@@ -0,0 +1,81 @@
name: "Check API documentation"
on:
pull_request:
permissions:
contents: read
jobs:
check_api_docs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
with:
egress-policy: audit
- name: Checkout pull request
uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
- name: Install clang
# Used only as a subprocess for `clang++ -E -v` system-include-path discovery in
# extract_api.py; it does not need to version-match the pinned libclang pip wheel
# below, which does the actual AST parsing. Do not "fix" this to be version-matched.
run: sudo apt-get update && sudo apt-get install -y clang
- name: Install Python dependencies
run: pip install -r tools/api_checker/requirements.txt
- name: Extract API and regenerate the committed surface file
run: |
python3 tools/api_checker/extract_api.py \
--header include/nlohmann/json.hpp \
--include include \
--output /tmp/api_snapshot.json \
--surface-output tools/api_checker/api_surface.json
- name: "Check API documentation (Phase 1: advisory)"
# Surfaces missing/broken @sa links without failing the job while the backlog from the
# initial AST-based rollout is burned down. See tools/api_checker/POLICY.md and the PR
# that introduced this workflow for the two-phase rollout plan.
continue-on-error: true
run: |
python3 tools/api_checker/check_docs.py \
--snapshot /tmp/api_snapshot.json
- name: Check macro documentation (advisory only)
# Cross-checks docs/mkdocs/docs/api/macros/ pages against #define sites. Only checks the
# documented-macro-still-exists direction; never blocks CI. See POLICY.md.
run: python3 tools/api_checker/check_macros.py
- name: Check for uncommitted API surface changes
id: diff
run: |
mkdir -p ${{ github.workspace }}/patch
git diff --patch --no-color -- tools/api_checker/api_surface.json > ${{ github.workspace }}/patch/api_surface.patch
if [ -s ${{ github.workspace }}/patch/api_surface.patch ]; then
echo "tools/api_checker/api_surface.json is out of date. Diff:"
cat ${{ github.workspace }}/patch/api_surface.patch
echo "has_diff=true" >> "$GITHUB_OUTPUT"
else
echo "has_diff=false" >> "$GITHUB_OUTPUT"
fi
# Uploaded so contributors can fix their PR with `git apply api_surface.patch`
# instead of installing libclang locally.
- name: Upload patch
if: steps.diff.outputs.has_diff == 'true'
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
with:
name: api-surface-patch
path: patch/api_surface.patch
- name: Fail if API surface file is not up to date
# Unlike the doc-backlog check above, this is purely mechanical regeneration with no
# backlog to phase in -- blocking from the start, matching check_amalgamation.yml's
# precedent. Contributors who add/remove/rename public API must regenerate and commit
# tools/api_checker/api_surface.json as part of their PR.
if: steps.diff.outputs.has_diff == 'true'
run: exit 1
+3 -3
View File
@@ -38,14 +38,14 @@ jobs:
# Initializes the CodeQL tools for scanning.
- name: Initialize CodeQL
uses: github/codeql-action/init@99df26d4f13ea111d4ec1a7dddef6063f76b97e9 # v4.37.0
uses: github/codeql-action/init@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
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@99df26d4f13ea111d4ec1a7dddef6063f76b97e9 # v4.37.0
uses: github/codeql-action/autobuild@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
- name: Perform CodeQL Analysis
uses: github/codeql-action/analyze@99df26d4f13ea111d4ec1a7dddef6063f76b97e9 # v4.37.0
uses: github/codeql-action/analyze@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
+1 -1
View File
@@ -43,6 +43,6 @@ jobs:
output: 'flawfinder_results.sarif'
- name: Upload analysis results to GitHub Security tab
uses: github/codeql-action/upload-sarif@99df26d4f13ea111d4ec1a7dddef6063f76b97e9 # v4.37.0
uses: github/codeql-action/upload-sarif@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
with:
sarif_file: ${{github.workspace}}/flawfinder_results.sarif
+1 -1
View File
@@ -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@99df26d4f13ea111d4ec1a7dddef6063f76b97e9 # v4.37.0
uses: github/codeql-action/upload-sarif@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
with:
sarif_file: results.sarif
+1 -1
View File
@@ -61,7 +61,7 @@ jobs:
# Upload SARIF file generated in previous step
- name: Upload SARIF file
uses: github/codeql-action/upload-sarif@99df26d4f13ea111d4ec1a7dddef6063f76b97e9 # v4.37.0
uses: github/codeql-action/upload-sarif@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
with:
sarif_file: semgrep.sarif
if: always()
+1 -1
View File
@@ -20,7 +20,7 @@ jobs:
with:
egress-policy: audit
- uses: actions/stale@1e223db275d687790206a7acac4d1a11bd6fe629 # v10.4.0
- uses: actions/stale@eb5cf3af3ac0a1aa4c9c45633dd1ae542a27a899 # v10.3.0
with:
stale-issue-label: 'state: stale'
stale-pr-label: 'state: stale'
+5
View File
@@ -3,6 +3,7 @@
*.gcno
*.gcda
.DS_Store
__pycache__/
/.idea
/cmake-build-*
@@ -43,5 +44,9 @@ venv
nlohmann_json.spdx
# api_checker: ephemeral, location/doc-status-sensitive working file (not the committed
# release-tracking artifact -- see tools/api_checker/api_surface.json for that)
/tools/api_checker/api_snapshot.json
# Bazel-related
MODULE.bazel.lock
+1 -1
View File
@@ -106,7 +106,7 @@ Thanks everyone!
:books: If you want to **learn more** about how to use the library, check out the rest of the [**README**](#examples), have a look at [**code examples**](https://github.com/nlohmann/json/tree/develop/docs/mkdocs/docs/examples), or browse through the [**help pages**](https://json.nlohmann.me).
:construction: If you want to understand the **API** better, check out the [**API Reference**](https://json.nlohmann.me/api/basic_json/) or have a look at the [quick reference](#quick-reference) below.
:construction: If you want to understand the **API** better, check out the [**API Reference**](https://json.nlohmann.me/api/basic_json/) or have a look at the [quick reference](#quick-reference) below. The public API surface is derived mechanically and checked for documentation coverage by the tooling in [`tools/api_checker/`](tools/api_checker/), whose [POLICY.md](tools/api_checker/POLICY.md) defines what counts as public API and what stability is guaranteed.
:bug: If you found a **bug**, please check the [**FAQ**](https://json.nlohmann.me/home/faq/) if it is a known issue or the result of a design decision. Please also have a look at the [**issue list**](https://github.com/nlohmann/json/issues) before you [**create a new issue**](https://github.com/nlohmann/json/issues/new/choose). Please provide as much information as possible to help us understand and reproduce your issue.
+1 -1
View File
@@ -49,7 +49,7 @@ Unlike the [`parse()`](parse.md) function, this function neither throws an excep
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
- `std::counted_iterator` with a different sentinel type
## Parameters
@@ -420,7 +420,9 @@ basic_json(basic_json&& other) noexcept;
1. Since version 1.0.0.
2. Since version 1.0.0.
3. Since version 2.1.0.
4. Since version 3.2.0.
4. Since version 3.2.0. Also initializes the position reported by
[`start_pos()`](start_pos.md)/[`end_pos()`](end_pos.md) from `val` when
[`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) is enabled, since version 3.12.0.
5. Since version 1.0.0.
6. Since version 1.0.0.
7. Since version 1.0.0.
@@ -0,0 +1,38 @@
# <small>nlohmann::basic_json::</small>bjdata_version_t
```cpp
enum class bjdata_version_t
{
draft2,
draft3,
};
```
This enumeration is used in the [`to_bjdata`](to_bjdata.md) function to choose which draft version of
the BJData specification to encode ND-array extensions for:
draft2
: encode using the BJData Draft 2 ND-array format
draft3
: encode using the BJData Draft 3 ND-array format
## Examples
??? example
The example shows how `bjdata_version_t` selects the BJData draft used by `to_bjdata`.
```cpp
--8<-- "examples/bjdata_version_t.cpp"
```
Output:
```
--8<-- "examples/bjdata_version_t.output"
```
## Version history
- Added in version 3.12.0.
@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
: a compatible iterator type
`SentinelType`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
custom sentinel type for C++20 ranges
## Parameters
+2 -4
View File
@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
: a compatible iterator type
`SentinelType`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
custom sentinel type for C++20 ranges
## Parameters
+2 -4
View File
@@ -39,10 +39,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
: a compatible iterator type
`SentinelType`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
custom sentinel type for C++20 ranges
## Parameters
@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
: a compatible iterator type
`SentinelType`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
custom sentinel type for C++20 ranges
## Parameters
@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
: a compatible iterator type
`SentinelType`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
custom sentinel type for C++20 ranges
## Parameters
@@ -0,0 +1,32 @@
# <small>nlohmann::basic_json::</small>initializer_list_t
```cpp
using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;
```
The type used for the initializer-list [constructor](basic_json.md) (overload 5) and for functions
such as [`operator=`](operator=.md) that accept a braced-init-list of JSON values. Each element wraps a
`basic_json` value or something convertible to one, deferring the decision of whether the list should be
parsed as a JSON array or a JSON object to the constructor itself.
See the [constructor](basic_json.md) documentation for how `initializer_list_t` values are interpreted.
## Examples
??? example
The example shows how an `initializer_list_t` is used to construct a JSON value.
```cpp
--8<-- "examples/initializer_list_t.cpp"
```
Output:
```
--8<-- "examples/initializer_list_t.output"
```
## Version history
- Since version 1.0.0.
@@ -0,0 +1,31 @@
# <small>nlohmann::basic_json::</small>json_sax_t
```cpp
using json_sax_t = json_sax<basic_json>;
```
The [`json_sax`](../json_sax/index.md) interface bound to this `basic_json` specialization, i.e. with
`BasicJsonType` fixed to `basic_json`. Used as the SAX interface type by [`sax_parse`](sax_parse.md) and
other SAX-based parsing functions.
See [`nlohmann::json_sax`](../json_sax/index.md) for more information.
## Examples
??? example
The example shows the type `json_sax_t`.
```cpp
--8<-- "examples/json_sax_t.cpp"
```
Output:
```
--8<-- "examples/json_sax_t.output"
```
## Version history
- Added in version 3.2.0.
@@ -51,3 +51,5 @@ Linear.
## Version history
- Added in version 1.0.0.
- The `noexcept` specification was extended to also depend on
[`json_base_class_t`](json_base_class_t.md)'s move-assignment in version 3.11.3.
@@ -85,3 +85,8 @@ Linear in the size of the JSON value.
- Since version 1.0.0.
- Macros `JSON_EXPLICIT`/[`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) added
in version 3.9.0.
- The exclusion of `std::any` from this conversion became conditional on
[`JSON_HAS_STATIC_RTTI`](../macros/json_has_static_rtti.md) in version 3.11.3.
- `std::optional<T>` excluded from this conversion in version 3.13.0; use
[`get<std::optional<T>>()`](get.md)/[`get_to()`](get_to.md) instead (see
[Converting values](../../features/conversions.md)).
+1 -1
View File
@@ -48,7 +48,7 @@ static basic_json parse(IteratorType first, SentinelType last,
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
- `std::counted_iterator` with a different sentinel type
## Parameters
+1 -4
View File
@@ -48,10 +48,7 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
with a size of 1, 2, or 4 bytes (interpreted respectively as UTF-8, UTF-16, and UTF-32)
`SentinelType`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for overload (2), for instance.
- a custom sentinel type for C++20 ranges
- `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
: defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for overload (2)
`SAX`
: a class fulfilling the SAX event listener interface; see [`json_sax`](../json_sax/index.md)
@@ -0,0 +1,32 @@
# <small>nlohmann::byte_container_with_subtype::</small>container_type
```cpp
using container_type = BinaryType;
```
The type of the underlying binary container, forwarded from the `BinaryType` template parameter that
`byte_container_with_subtype` is instantiated with. `byte_container_with_subtype` publicly inherits from
`container_type`.
See [`basic_json::binary_t`](../basic_json/binary_t.md) for the type typically used to instantiate
`BinaryType`.
## Examples
??? example
The example shows the type `container_type`.
```cpp
--8<-- "examples/byte_container_with_subtype__container_type.cpp"
```
Output:
```
--8<-- "examples/byte_container_with_subtype__container_type.output"
```
## Version history
- Since version 3.8.0.
@@ -0,0 +1,45 @@
# <small>nlohmann::byte_container_with_subtype::</small>operator==
```cpp
bool operator==(const byte_container_with_subtype& rhs) const;
```
Compares two `byte_container_with_subtype` values for equality by comparing the underlying binary
container, the subtype, and whether a subtype is set.
## Parameters
`rhs` (in)
: value to compare `*this` against
## Return value
whether `*this` and `rhs` are equal
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Linear in the size of the underlying binary container.
## Examples
??? example
The example demonstrates comparing `byte_container_with_subtype` values.
```cpp
--8<-- "examples/byte_container_with_subtype__operator_eq.cpp"
```
Output:
```
--8<-- "examples/byte_container_with_subtype__operator_eq.output"
```
## Version history
- Since version 3.8.0.
@@ -0,0 +1,45 @@
# <small>nlohmann::byte_container_with_subtype::</small>operator!=
```cpp
bool operator!=(const byte_container_with_subtype& rhs) const;
```
Compares two `byte_container_with_subtype` values for inequality. Implemented as the negation of
[`operator==`](operator_eq.md).
## Parameters
`rhs` (in)
: value to compare `*this` against
## Return value
whether `*this` and `rhs` are not equal
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Linear in the size of the underlying binary container.
## Examples
??? example
The example demonstrates comparing `byte_container_with_subtype` values.
```cpp
--8<-- "examples/byte_container_with_subtype__operator_ne.cpp"
```
Output:
```
--8<-- "examples/byte_container_with_subtype__operator_ne.output"
```
## Version history
- Since version 3.8.0.
@@ -0,0 +1,28 @@
# <small>nlohmann::byte_container_with_subtype::</small>subtype_type
```cpp
using subtype_type = std::uint64_t;
```
The type used to store the optional binary subtype tag. See [`subtype`](subtype.md) and
[`set_subtype`](set_subtype.md).
## Examples
??? example
The example shows the type `subtype_type`.
```cpp
--8<-- "examples/byte_container_with_subtype__subtype_type.cpp"
```
Output:
```
--8<-- "examples/byte_container_with_subtype__subtype_type.output"
```
## Version history
- Since version 3.8.0.
+30
View File
@@ -0,0 +1,30 @@
# <small>nlohmann::json_sax::</small>binary_t
```cpp
using binary_t = typename BasicJsonType::binary_t;
```
The type used by the [`binary`](binary.md) callback for JSON binary values, forwarded from the
`BasicJsonType` template parameter.
See [`basic_json::binary_t`](../basic_json/binary_t.md) for more information.
## Examples
??? example
The example shows the type `binary_t` and its relation to `basic_json::binary_t`.
```cpp
--8<-- "examples/json_sax__binary_t.cpp"
```
Output:
```
--8<-- "examples/json_sax__binary_t.output"
```
## Version history
- Added in version 3.8.0.
+33
View File
@@ -0,0 +1,33 @@
# <small>nlohmann::json_sax::</small>json_sax
```cpp
// (1)
json_sax() = default;
// (2)
json_sax(const json_sax&) = default;
// (3)
json_sax(json_sax&&) noexcept = default;
```
1. Default constructor.
2. Copy constructor.
3. Move constructor.
`json_sax` is a pure abstract base class with no data members of its own, so all three constructors are
defaulted and only exist to make derived SAX consumers explicitly copyable/movable.
## Exception safety
No-throw guarantee: none of these constructors throw exceptions.
## Complexity
Constant.
<!-- NOLINT Examples -->
## Version history
- Added in version 3.2.0.
@@ -0,0 +1,30 @@
# <small>nlohmann::json_sax::</small>number_float_t
```cpp
using number_float_t = typename BasicJsonType::number_float_t;
```
The type used by the [`number_float`](number_float.md) callback for JSON floating-point numbers,
forwarded from the `BasicJsonType` template parameter.
See [`basic_json::number_float_t`](../basic_json/number_float_t.md) for more information.
## Examples
??? example
The example shows the type `number_float_t` and its relation to `basic_json::number_float_t`.
```cpp
--8<-- "examples/json_sax__number_float_t.cpp"
```
Output:
```
--8<-- "examples/json_sax__number_float_t.output"
```
## Version history
- Added in version 3.2.0.
@@ -0,0 +1,30 @@
# <small>nlohmann::json_sax::</small>number_integer_t
```cpp
using number_integer_t = typename BasicJsonType::number_integer_t;
```
The type used by the [`number_integer`](number_integer.md) callback for JSON integer numbers, forwarded
from the `BasicJsonType` template parameter.
See [`basic_json::number_integer_t`](../basic_json/number_integer_t.md) for more information.
## Examples
??? example
The example shows the type `number_integer_t` and its relation to `basic_json::number_integer_t`.
```cpp
--8<-- "examples/json_sax__number_integer_t.cpp"
```
Output:
```
--8<-- "examples/json_sax__number_integer_t.output"
```
## Version history
- Added in version 3.2.0.
@@ -0,0 +1,30 @@
# <small>nlohmann::json_sax::</small>number_unsigned_t
```cpp
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
```
The type used by the [`number_unsigned`](number_unsigned.md) callback for JSON unsigned integer numbers,
forwarded from the `BasicJsonType` template parameter.
See [`basic_json::number_unsigned_t`](../basic_json/number_unsigned_t.md) for more information.
## Examples
??? example
The example shows the type `number_unsigned_t` and its relation to `basic_json::number_unsigned_t`.
```cpp
--8<-- "examples/json_sax__number_unsigned_t.cpp"
```
Output:
```
--8<-- "examples/json_sax__number_unsigned_t.output"
```
## Version history
- Added in version 3.2.0.
@@ -0,0 +1,29 @@
# <small>nlohmann::json_sax::</small>operator=
```cpp
// (1)
json_sax& operator=(const json_sax&) = default;
// (2)
json_sax& operator=(json_sax&&) noexcept = default;
```
1. Copy assignment operator.
2. Move assignment operator.
`json_sax` is a pure abstract base class with no data members of its own, so both assignment operators
are defaulted and only exist to make derived SAX consumers explicitly copy-/move-assignable.
## Exception safety
No-throw guarantee: neither operator throws exceptions.
## Complexity
Constant.
<!-- NOLINT Examples -->
## Version history
- Added in version 3.2.0.
+30
View File
@@ -0,0 +1,30 @@
# <small>nlohmann::json_sax::</small>string_t
```cpp
using string_t = typename BasicJsonType::string_t;
```
The type used by the [`string`](string.md) and [`key`](key.md) callbacks for JSON strings and object
keys, forwarded from the `BasicJsonType` template parameter.
See [`basic_json::string_t`](../basic_json/string_t.md) for more information.
## Examples
??? example
The example shows the type `string_t` and its relation to `basic_json::string_t`.
```cpp
--8<-- "examples/json_sax__string_t.cpp"
```
Output:
```
--8<-- "examples/json_sax__string_t.output"
```
## Version history
- Added in version 3.2.0.
@@ -0,0 +1,22 @@
# <small>nlohmann::json_sax::</small>~json_sax
```cpp
virtual ~json_sax() = default;
```
Destructor. Virtual to allow proper destruction of derived SAX consumer classes through a
pointer/reference to `json_sax`.
## Exception safety
No-throw guarantee: this destructor never throws exceptions.
## Complexity
Constant.
<!-- NOLINT Examples -->
## Version history
- Added in version 3.2.0.
-1
View File
@@ -24,7 +24,6 @@ header. See also the [macro overview page](../../features/macros.md).
- [**JSON_NO_IO**](json_no_io.md) - switch off functions relying on certain C++ I/O headers
- [**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
@@ -38,8 +38,7 @@ When the macro is not defined, the library will define it to its default value.
Diagnostic messages can also be controlled with the CMake option
[`JSON_Diagnostics`](../../integration/cmake.md#json_diagnostics) (`OFF` by default)
which defines `JSON_DIAGNOSTICS` accordingly. Note this only applies when building the
library from source — see the pre-installed-package caveat on that page.
which defines `JSON_DIAGNOSTICS` accordingly.
## Examples
@@ -1,52 +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.
## 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 <simdutf.h>
#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)
```
## Version history
- Added in version 3.12.1.
+2 -2
View File
@@ -8,7 +8,7 @@ This type preserves the insertion order of object keys.
## Iterator invalidation
The type is based on [`ordered_map`](ordered_map.md) which in turn uses a `std::vector` to store object elements.
The type is based on [`ordered_map`](ordered_map/index.md) which in turn uses a `std::vector` to store object elements.
Therefore, adding object elements can yield a reallocation in which case all iterators (including the
[`end()`](basic_json/end.md) iterator) and all references to the elements are invalidated. Also, any iterator or
reference after the insertion point will point to the same index, which is now a different value.
@@ -31,7 +31,7 @@ reference after the insertion point will point to the same index, which is now a
## See also
- [ordered_map](ordered_map.md)
- [ordered_map](ordered_map/index.md)
- [Object Order](../features/object_order.md)
## Version history
@@ -0,0 +1,28 @@
# <small>nlohmann::ordered_map::</small>Container
```cpp
using Container = std::vector<std::pair<const Key, T>, Allocator>;
```
The base container type that `ordered_map` publicly inherits from. Elements are stored in insertion
order as `#!cpp std::pair<const Key, T>` entries in a `std::vector`.
## Examples
??? example
The example shows the type `Container`.
```cpp
--8<-- "examples/ordered_map__Container.cpp"
```
Output:
```
--8<-- "examples/ordered_map__Container.output"
```
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+61
View File
@@ -0,0 +1,61 @@
# <small>nlohmann::ordered_map::</small>at
```cpp
// (1)
T& at(const key_type& key);
const T& at(const key_type& key) const;
// (2)
template<class KeyType>
T& at(KeyType&& key);
template<class KeyType>
const T& at(KeyType&& key) const;
```
1. Returns a reference to the value mapped to `key`.
2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
(heterogeneous lookup, e.g. looking up by a `#!cpp const char*` without constructing a temporary
`key_type`). Only participates in overload resolution if `KeyType` is usable as a key type.
## Template parameters
`KeyType`
: a type comparable to `key_type` via [`key_compare`](key_compare.md)
## Parameters
`key` (in)
: key of the element to find
## Return value
reference to the mapped value of the element with key equal to `key`
## Exceptions
Throws `std::out_of_range` if no element with key `key` exists.
## Complexity
Linear in the number of elements.
## Examples
??? example
The example shows how `at` is used.
```cpp
--8<-- "examples/ordered_map__at.cpp"
```
Output:
```
--8<-- "examples/ordered_map__at.output"
```
## Version history
- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
- Overload (2) added in version 3.11.0.
+53
View File
@@ -0,0 +1,53 @@
# <small>nlohmann::ordered_map::</small>count
```cpp
// (1)
size_type count(const key_type& key) const;
// (2)
template<class KeyType>
size_type count(KeyType&& key) const;
```
1. Returns the number of elements with key equal to `key` (0 or 1, since keys are unique).
2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
(heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
## Template parameters
`KeyType`
: a type comparable to `key_type` via [`key_compare`](key_compare.md)
## Parameters
`key` (in)
: key of the elements to count
## Return value
number of elements with key equal to `key` (0 or 1)
## Complexity
Linear in the number of elements.
## Examples
??? example
The example shows how `count` is used.
```cpp
--8<-- "examples/ordered_map__count.cpp"
```
Output:
```
--8<-- "examples/ordered_map__count.output"
```
## Version history
- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
- Overload (2) added in version 3.11.0.
@@ -0,0 +1,58 @@
# <small>nlohmann::ordered_map::</small>emplace
```cpp
// (1)
std::pair<iterator, bool> emplace(const key_type& key, T&& t);
// (2)
template<class KeyType>
std::pair<iterator, bool> emplace(KeyType&& key, T&& t);
```
1. Inserts `#!cpp {key, t}` if no element with an equal key already exists (per [`key_compare`](key_compare.md)),
appending it at the end to preserve insertion order. If an equal key already exists, does nothing.
2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
(heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
## Template parameters
`KeyType`
: a type comparable to `key_type` via [`key_compare`](key_compare.md)
## Parameters
`key` (in)
: key of the element to insert
`t` (in)
: value of the element to insert
## Return value
pair of an iterator to the (possibly newly inserted) element, and a `bool` that is `true` if insertion
took place and `false` if an element with an equal key already existed
## Complexity
Linear in the number of elements.
## Examples
??? example
The example shows how `emplace` is used.
```cpp
--8<-- "examples/ordered_map__emplace.cpp"
```
Output:
```
--8<-- "examples/ordered_map__emplace.output"
```
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
- Overload (2) added in version 3.11.0.
+75
View File
@@ -0,0 +1,75 @@
# <small>nlohmann::ordered_map::</small>erase
```cpp
// (1)
size_type erase(const key_type& key);
// (2)
template<class KeyType>
size_type erase(KeyType&& key);
// (3)
iterator erase(iterator pos);
// (4)
iterator erase(iterator first, iterator last);
```
1. Removes the element with key equal to `key`, if any, preserving the relative order of the remaining
elements.
2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
(heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
3. Removes the element at `pos`.
4. Removes the elements in range `[first, last)`.
## Template parameters
`KeyType`
: a type comparable to `key_type` via [`key_compare`](key_compare.md)
## Parameters
`key` (in)
: key of the element to remove
`pos` (in)
: iterator to the element to remove
`first` (in)
: iterator to the first element to remove
`last` (in)
: iterator one past the last element to remove
## Return value
1. number of elements removed (0 or 1)
2. number of elements removed (0 or 1)
3. iterator following the removed element
4. iterator following the last removed element
## Complexity
Linear in the number of elements (elements after the removed one(s) are shifted to keep storage
contiguous).
## Examples
??? example
The example shows how `erase` is used.
```cpp
--8<-- "examples/ordered_map__erase.cpp"
```
Output:
```
--8<-- "examples/ordered_map__erase.output"
```
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
- Overload (2) added in version 3.11.0.
+56
View File
@@ -0,0 +1,56 @@
# <small>nlohmann::ordered_map::</small>find
```cpp
// (1)
iterator find(const key_type& key);
const_iterator find(const key_type& key) const;
// (2)
template<class KeyType>
iterator find(KeyType&& key);
template<class KeyType>
const_iterator find(KeyType&& key) const;
```
1. Returns an iterator to the element with key equal to `key`, or `end()` if no such element exists.
2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
(heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
## Template parameters
`KeyType`
: a type comparable to `key_type` via [`key_compare`](key_compare.md)
## Parameters
`key` (in)
: key of the element to find
## Return value
iterator to the element with key equal to `key`, or `end()` if not found
## Complexity
Linear in the number of elements.
## Examples
??? example
The example shows how `find` is used.
```cpp
--8<-- "examples/ordered_map__find.cpp"
```
Output:
```
--8<-- "examples/ordered_map__find.output"
```
## Version history
- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
- Overload (2) added in version 3.11.0.
@@ -6,7 +6,7 @@ template<class Key, class T, class IgnoredLess = std::less<Key>,
struct ordered_map : std::vector<std::pair<const Key, T>, Allocator>;
```
A minimal map-like container that preserves insertion order for use within [`nlohmann::ordered_json`](ordered_json.md)
A minimal map-like container that preserves insertion order for use within [`nlohmann::ordered_json`](../ordered_json.md)
(`nlohmann::basic_json<ordered_map>`).
## Template parameters
@@ -32,12 +32,12 @@ case all iterators (including the `end()` iterator) and all references to the el
- **key_type** - key type (`Key`)
- **mapped_type** - mapped type (`T`)
- **Container** - base container type (`#!cpp std::vector<std::pair<const Key, T>, Allocator>`)
- [**Container**](Container.md) - base container type (`#!cpp std::vector<std::pair<const Key, T>, Allocator>`)
- **iterator**
- **const_iterator**
- **size_type**
- **value_type**
- **key_compare** - key comparison function
- [**key_compare**](key_compare.md) - key comparison function
```cpp
std::equal_to<Key> // until C++14
@@ -46,15 +46,16 @@ std::equal_to<> // since C++14
## Member functions
- (constructor)
- (destructor)
- **emplace**
- **operator\[\]**
- **at**
- **erase**
- **count**
- **find**
- **insert**
- [(constructor)](ordered_map.md)
- [(destructor)](~ordered_map.md)
- [**operator=**](operator=.md)
- [**emplace**](emplace.md)
- [**operator\[\]**](operator[].md)
- [**at**](at.md)
- [**erase**](erase.md)
- [**count**](count.md)
- [**find**](find.md)
- [**insert**](insert.md)
## Examples
@@ -74,9 +75,9 @@ std::equal_to<> // since C++14
## See also
- [ordered_json](ordered_json.md)
- [ordered_json](../ordered_json.md)
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](ordered_json.md).
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
- Added **key_compare** member in version 3.11.0.
@@ -0,0 +1,63 @@
# <small>nlohmann::ordered_map::</small>insert
```cpp
// (1)
std::pair<iterator, bool> insert(value_type&& value);
std::pair<iterator, bool> insert(const value_type& value);
// (2)
template<typename InputIt>
void insert(InputIt first, InputIt last);
```
1. Inserts `value` if no element with an equal key already exists (per [`key_compare`](key_compare.md)),
appending it at the end to preserve insertion order. If an equal key already exists, does nothing.
2. Inserts the elements from range `[first, last)`, in iteration order, applying the same equal-key rule
as (1) to each element.
## Template parameters
`InputIt`
: an input iterator type
## Parameters
`value` (in)
: value to insert
`first` (in)
: iterator to the first element to insert
`last` (in)
: iterator one past the last element to insert
## Return value
1. pair of an iterator to the (possibly newly inserted) element, and a `bool` that is `true` if insertion
took place and `false` if an element with an equal key already existed
2. (none)
## Complexity
1. Linear in the number of elements.
2. Linear in the distance between `first` and `last`, times linear in the number of elements.
## Examples
??? example
The example shows how `insert` is used.
```cpp
--8<-- "examples/ordered_map__insert.cpp"
```
Output:
```
--8<-- "examples/ordered_map__insert.output"
```
## Version history
- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,34 @@
# <small>nlohmann::ordered_map::</small>key_compare
```cpp
using key_compare = std::equal_to<Key>; // until C++14
using key_compare = std::equal_to<>; // since C++14
```
The comparator used to determine key equality when looking up elements. Unlike `std::map`, `ordered_map`
uses linear search with `key_compare` rather than an ordering relation, since element order reflects
insertion order rather than key order.
Since C++14, the transparent `#!cpp std::equal_to<>` is used, which enables heterogeneous lookup (e.g.
looking up by a `#!cpp const char*` key without constructing a temporary `Key`).
## Examples
??? example
The example shows how `key_compare` is used.
```cpp
--8<-- "examples/ordered_map__key_compare.cpp"
```
Output:
```
--8<-- "examples/ordered_map__key_compare.output"
```
## Version history
- Added in version 3.11.0.
@@ -0,0 +1,32 @@
# <small>nlohmann::ordered_map::</small>operator=
```cpp
// (1)
ordered_map& operator=(const ordered_map& other);
// (2)
ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value);
```
1. Copy assignment operator.
2. Move assignment operator.
## Parameters
`other` (in)
: value to assign from
## Return value
`*this`
## Complexity
1. Linear in the size of `other`.
2. Constant.
<!-- NOLINT Examples -->
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,62 @@
# <small>nlohmann::ordered_map::</small>operator[]
```cpp
// (1)
T& operator[](const key_type& key);
const T& operator[](const key_type& key) const;
// (2)
template<class KeyType>
T& operator[](KeyType&& key);
template<class KeyType>
const T& operator[](KeyType&& key) const;
```
1. Returns a reference to the value mapped to `key`, inserting a default-constructed `T` (non-`const`
overload only) if no such element exists yet.
2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
(heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
## Template parameters
`KeyType`
: a type comparable to `key_type` via [`key_compare`](key_compare.md)
## Parameters
`key` (in)
: key of the element to find or insert
## Return value
reference to the mapped value of the element with key equal to `key`
## Exceptions
The `const` overloads throw `std::out_of_range` if no element with key `key` exists (they delegate to
[`at`](at.md)).
## Complexity
Linear in the number of elements.
## Examples
??? example
The example shows how `operator[]` is used.
```cpp
--8<-- "examples/ordered_map__operator_idx.cpp"
```
Output:
```
--8<-- "examples/ordered_map__operator_idx.output"
```
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
- Overload (2) added in version 3.11.0.
@@ -0,0 +1,66 @@
# <small>nlohmann::ordered_map::</small>ordered_map
```cpp
// (1)
ordered_map() noexcept(noexcept(Container()));
// (2)
explicit ordered_map(const Allocator& alloc) noexcept(noexcept(Container(alloc)));
// (3)
template <class It>
ordered_map(It first, It last, const Allocator& alloc = Allocator());
// (4)
ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator());
// (5)
ordered_map(const ordered_map&) = default;
// (6)
ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
```
1. Default constructor. Creates an empty `ordered_map`.
2. Creates an empty `ordered_map` using the given allocator.
3. Creates an `ordered_map` from the elements in range `[first, last)`, inserted in iteration order.
4. Creates an `ordered_map` from an initializer list of key/value pairs, inserted in list order.
5. Copy constructor.
6. Move constructor.
These constructors are declared explicitly (rather than inherited via `#!cpp using Container::Container`)
because older compilers (GCC <= 5.5, Xcode <= 9.4) do not handle the inherited constructors correctly.
## Template parameters
`It`
: an input iterator type
## Parameters
`alloc` (in)
: allocator to use for the underlying container
`first` (in)
: iterator to the first element to insert
`last` (in)
: iterator one past the last element to insert
`init` (in)
: initializer list of key/value pairs to insert
## Complexity
1. Constant.
2. Constant.
3. Linear in the distance between `first` and `last`.
4. Linear in the size of `init`.
5. Linear in the size of `other`.
6. Constant.
<!-- NOLINT Examples -->
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,17 @@
# <small>nlohmann::ordered_map::</small>~ordered_map
```cpp
~ordered_map() = default;
```
Destroys the `ordered_map` and frees all allocated memory.
## Complexity
Linear in the number of elements.
<!-- NOLINT Examples -->
## Version history
- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,21 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// an empty binary value is encoded differently by the two drafts:
// draft2 omits the optimized type marker for an empty byte array,
// while draft3 always writes it
json j = json::binary({});
// encode using BJData draft2 (the default)
auto v_draft2 = json::to_bjdata(j, true, true, json::bjdata_version_t::draft2);
// encode using BJData draft3
auto v_draft3 = json::to_bjdata(j, true, true, json::bjdata_version_t::draft3);
std::cout << "draft2 size: " << v_draft2.size() << '\n'
<< "draft3 size: " << v_draft3.size() << std::endl;
}
@@ -0,0 +1,2 @@
draft2 size: 4
draft3 size: 6
@@ -0,0 +1,11 @@
#include <iostream>
#include <nlohmann/json.hpp>
using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
int main()
{
std::cout << std::boolalpha
<< std::is_same<byte_container_with_subtype::container_type, std::vector<std::uint8_t>>::value
<< std::endl;
}
@@ -0,0 +1,15 @@
#include <iostream>
#include <nlohmann/json.hpp>
using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
int main()
{
byte_container_with_subtype c1({0xca, 0xfe});
byte_container_with_subtype c2({0xca, 0xfe});
byte_container_with_subtype c3({0xca, 0xfe}, 42);
std::cout << std::boolalpha
<< "c1 == c2: " << (c1 == c2) << '\n'
<< "c1 == c3: " << (c1 == c3) << std::endl;
}
@@ -0,0 +1,2 @@
c1 == c2: true
c1 == c3: false
@@ -0,0 +1,15 @@
#include <iostream>
#include <nlohmann/json.hpp>
using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
int main()
{
byte_container_with_subtype c1({0xca, 0xfe});
byte_container_with_subtype c2({0xca, 0xfe});
byte_container_with_subtype c3({0xca, 0xfe}, 42);
std::cout << std::boolalpha
<< "c1 != c2: " << (c1 != c2) << '\n'
<< "c1 != c3: " << (c1 != c3) << std::endl;
}
@@ -0,0 +1,2 @@
c1 != c2: false
c1 != c3: true
@@ -0,0 +1,10 @@
#include <iostream>
#include <nlohmann/json.hpp>
using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
int main()
{
std::cout << std::boolalpha
<< std::is_same<byte_container_with_subtype::subtype_type, std::uint64_t>::value << std::endl;
}
@@ -0,0 +1,13 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// an initializer_list_t is what a braced-init-list of JSON values is deduced as
json::initializer_list_t init = {"a", 1, 2.0, false};
json j(init);
std::cout << j.dump() << std::endl;
}
@@ -0,0 +1 @@
["a",1,2.0,false]
@@ -0,0 +1,10 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::cout << std::boolalpha
<< std::is_same<json::json_sax_t::binary_t, json::binary_t>::value << std::endl;
}
@@ -0,0 +1 @@
true
@@ -0,0 +1,10 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::cout << std::boolalpha
<< std::is_same<json::json_sax_t::number_float_t, json::number_float_t>::value << std::endl;
}
@@ -0,0 +1 @@
true
@@ -0,0 +1,10 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::cout << std::boolalpha
<< std::is_same<json::json_sax_t::number_integer_t, json::number_integer_t>::value << std::endl;
}
@@ -0,0 +1 @@
true
@@ -0,0 +1,10 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::cout << std::boolalpha
<< std::is_same<json::json_sax_t::number_unsigned_t, json::number_unsigned_t>::value << std::endl;
}
@@ -0,0 +1 @@
true
@@ -0,0 +1,10 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::cout << std::boolalpha
<< std::is_same<json::json_sax_t::string_t, json::string_t>::value << std::endl;
}
@@ -0,0 +1 @@
true
+10
View File
@@ -0,0 +1,10 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
std::cout << std::boolalpha
<< std::is_same<json::json_sax_t, nlohmann::json_sax<json>>::value << std::endl;
}
@@ -0,0 +1 @@
true
@@ -0,0 +1,12 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
using Map = nlohmann::ordered_map<std::string, int>;
std::cout << std::boolalpha
<< "Container is std::vector<std::pair<const Key, T>>: "
<< std::is_same<Map::Container, std::vector<std::pair<const std::string, int>>>::value
<< std::endl;
}
@@ -0,0 +1 @@
Container is std::vector<std::pair<const Key, T>>: true
@@ -0,0 +1,26 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
nlohmann::ordered_map<std::string, int> m;
m["one"] = 1;
m["two"] = 2;
// access an existing element
std::cout << "m.at(\"one\") = " << m.at("one") << std::endl;
// modify through the reference returned by at()
m.at("two") = 22;
std::cout << "m.at(\"two\") = " << m.at("two") << std::endl;
// accessing a missing key throws
try
{
m.at("three");
}
catch (const std::out_of_range& e)
{
std::cout << "exception: " << e.what() << std::endl;
}
}
@@ -0,0 +1,3 @@
m.at("one") = 1
m.at("two") = 22
exception: key not found
@@ -0,0 +1,12 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
nlohmann::ordered_map<std::string, int> m;
m["one"] = 1;
std::cout << std::boolalpha
<< "m.count(\"one\") = " << m.count("one") << '\n'
<< "m.count(\"two\") = " << m.count("two") << std::endl;
}
@@ -0,0 +1,2 @@
m.count("one") = 1
m.count("two") = 0
@@ -0,0 +1,15 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
nlohmann::ordered_map<std::string, std::string> m;
// emplace a new element
auto res1 = m.emplace("one", "eins");
std::cout << std::boolalpha << "inserted: " << res1.second << ", value: " << res1.first->second << std::endl;
// emplace with an already-existing key: no-op, returns the existing element
auto res2 = m.emplace("one", "uno");
std::cout << std::boolalpha << "inserted: " << res2.second << ", value: " << res2.first->second << std::endl;
}
@@ -0,0 +1,2 @@
inserted: true, value: eins
inserted: false, value: eins
@@ -0,0 +1,24 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
nlohmann::ordered_map<std::string, int> m;
m["one"] = 1;
m["two"] = 2;
m["three"] = 3;
// erase by key
std::size_t removed = m.erase("two");
std::cout << "removed by key: " << removed << std::endl;
// erase by iterator
m.erase(m.begin());
std::cout << "remaining: ";
for (const auto& element : m)
{
std::cout << element.first << ' ';
}
std::cout << std::endl;
}
@@ -0,0 +1,2 @@
removed by key: 1
remaining: three
@@ -0,0 +1,19 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
nlohmann::ordered_map<std::string, int> m;
m["one"] = 1;
auto it = m.find("one");
if (it != m.end())
{
std::cout << "found: " << it->first << " = " << it->second << std::endl;
}
if (m.find("two") == m.end())
{
std::cout << "\"two\" not found" << std::endl;
}
}
@@ -0,0 +1,2 @@
found: one = 1
"two" not found
@@ -0,0 +1,21 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
nlohmann::ordered_map<std::string, int> m;
// insert a single value
auto res = m.insert({"one", 1});
std::cout << std::boolalpha << "inserted: " << res.second << std::endl;
// insert a range from another container
std::vector<std::pair<const std::string, int>> more = {{"two", 2}, {"three", 3}};
m.insert(more.begin(), more.end());
for (const auto& element : m)
{
std::cout << element.first << ':' << element.second << ' ';
}
std::cout << std::endl;
}
@@ -0,0 +1,2 @@
inserted: true
one:1 two:2 three:3
@@ -0,0 +1,12 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
using Map = nlohmann::ordered_map<std::string, int>;
Map::key_compare compare{};
std::cout << std::boolalpha
<< "compare(\"a\", \"a\") = " << compare("a", "a") << '\n'
<< "compare(\"a\", \"b\") = " << compare("a", "b") << std::endl;
}
@@ -0,0 +1,2 @@
compare("a", "a") = true
compare("a", "b") = false
@@ -0,0 +1,14 @@
#include <iostream>
#include <nlohmann/json.hpp>
int main()
{
nlohmann::ordered_map<std::string, int> m;
// operator[] inserts a default-constructed value if the key doesn't exist yet
m["one"] = 1;
std::cout << "m[\"one\"] = " << m["one"] << std::endl;
// accessing again just returns the existing value
std::cout << "m[\"one\"] = " << m["one"] << std::endl;
}
@@ -0,0 +1,2 @@
m["one"] = 1
m["one"] = 1
-36
View File
@@ -47,28 +47,6 @@ json j = {{"one", 1}, {"two", 2}};
auto m = j.get<std::map<std::string, int>>(); // {{"one", 1}, {"two", 2}}
```
`#!cpp std::pair` and `#!cpp std::tuple` are also supported, converting positionally to and from a JSON array:
```cpp
json j = {1.0, "hello", 42};
auto t = j.get<std::tuple<double, std::string, int>>(); // {1.0, "hello", 42}
```
!!! 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`
then returns a tuple of references pointing directly at the elements stored inside the `basic_json` array,
rather than a tuple of copies:
```cpp
json j = {1.0, "hello"};
auto refs = j.get<std::tuple<double&, std::string&>>();
std::get<1>(refs) = "world"; // modifies j[1] in place
```
A referenced type must be one the library actually stores (or an arithmetic type it can convert to/from);
otherwise this is a compile error.
## Implicit conversions
By default, a JSON value implicitly converts to a compatible C++ type, so the explicit `get` call can often be omitted:
@@ -158,20 +136,6 @@ std::vector<int> numbers = {1, 2, 3};
json j = numbers; // [1,2,3]
```
!!! info "Constructing from a C++20 range view"
A `json` array can also be constructed directly from a C++20 range view (`std::ranges::view`), such as the result
of `std::views::filter` or `std::views::transform` -- no intermediate container is needed:
```cpp
std::vector<int> nums{1, 2, 37, 42, 21};
auto filtered = nums | std::views::filter([](int i) { return i > 10; });
json j(filtered); // [37,42,21]
```
This requires [`JSON_HAS_RANGES`](../api/macros/json_has_ranges.md) to be enabled and is unavailable on MinGW due
to incomplete C++20 ranges support there.
## Your own types
The conversions above are built in for standard types. To make the same syntax work for **your own** types, provide
File diff suppressed because it is too large Load Diff
+1 -1
View File
@@ -17,7 +17,7 @@ The main structure is class [nlohmann::basic_json](../api/basic_json/index.md).
- describe template parameters of `basic_json`
- [`json`](../api/json.md)
- [`ordered_json`](../api/ordered_json.md) via [`ordered_map`](../api/ordered_map.md)
- [`ordered_json`](../api/ordered_json.md) via [`ordered_map`](../api/ordered_map/index.md)
## Value storage
+2 -1
View File
@@ -2,7 +2,8 @@
This page summarizes the notable changes of every release and links to the relevant documentation.
The **complete release notes** — including all changes, the download files, and their checksums — are
published on the [GitHub releases page](https://github.com/nlohmann/json/releases).
published on the [GitHub releases page](https://github.com/nlohmann/json/releases). For a raw,
signature-level diff of the public API between releases, see [API Changes](api_changes.md).
## v3.12.0 (2025-04-11)
-25
View File
@@ -135,31 +135,6 @@ Enable CI build targets. The exact targets are used during the several CI steps
Enable [extended diagnostic messages](../home/exceptions.md#extended-diagnostic-messages) by defining macro [`JSON_DIAGNOSTICS`](../api/macros/json_diagnostics.md). This option is `OFF` by default.
!!! warning "Does not apply to a pre-installed package"
This option only takes effect when building nlohmann/json from source as part of your own
CMake project (e.g. via [`FetchContent`](#fetchcontent) or [`add_subdirectory`](#external)).
It has **no effect** on a package that was already built and installed elsewhere (Homebrew,
vcpkg, a system package, etc.) — the resulting compile definition is baked into the exported
`nlohmann_jsonTargets.cmake` at install time, and `set(JSON_Diagnostics ON)` before
`find_package()` does not change it (verified against the Homebrew-installed package: the
exported target still carries a fixed `$<$<BOOL:OFF>:JSON_DIAGNOSTICS=1>`, regardless of any
variable set in the consuming project).
To enable extended diagnostics for a pre-installed package, override the imported target's
property directly after `find_package()`:
```cmake
find_package(nlohmann_json REQUIRED)
set_target_properties(nlohmann_json::nlohmann_json PROPERTIES
INTERFACE_COMPILE_DEFINITIONS "JSON_DIAGNOSTICS=1")
```
This only works cleanly when your project is the sole consumer of that imported target. If
nlohmann_json is pulled in from more than one place in your dependency graph with different
`JSON_DIAGNOSTICS` values, you may see a `"JSON_DIAGNOSTICS" redefined` compiler error, since
conflicting `-D` flags can end up on the same compile command line.
### `JSON_Diagnostic_Positions`
Enable position diagnostics by defining macro [`JSON_DIAGNOSTIC_POSITIONS`](../api/macros/json_diagnostic_positions.md). This option is `OFF` by default.
+30 -2
View File
@@ -52,6 +52,7 @@ nav:
- "FAQ": home/faq.md
- home/exceptions.md
- home/releases.md
- home/api_changes.md
- home/design_goals.md
- home/architecture.md
- home/customers.md
@@ -117,6 +118,7 @@ nav:
- 'begin': api/basic_json/begin.md
- 'binary': api/basic_json/binary.md
- 'binary_t': api/basic_json/binary_t.md
- 'bjdata_version_t': api/basic_json/bjdata_version_t.md
- 'boolean_t': api/basic_json/boolean_t.md
- 'cbegin': api/basic_json/cbegin.md
- 'cbor_tag_handler_t': api/basic_json/cbor_tag_handler_t.md
@@ -154,6 +156,7 @@ nav:
- 'get_to': api/basic_json/get_to.md
- 'std::formatter&lt;basic_json&gt;': api/basic_json/std_formatter.md
- 'std::hash&lt;basic_json&gt;': api/basic_json/std_hash.md
- 'initializer_list_t': api/basic_json/initializer_list_t.md
- 'input_format_t': api/basic_json/input_format_t.md
- 'insert': api/basic_json/insert.md
- 'invalid_iterator': api/basic_json/invalid_iterator.md
@@ -172,6 +175,7 @@ nav:
- 'is_structured': api/basic_json/is_structured.md
- 'items': api/basic_json/items.md
- 'json_base_class_t': api/basic_json/json_base_class_t.md
- 'json_sax_t': api/basic_json/json_sax_t.md
- 'json_serializer': api/basic_json/json_serializer.md
- 'max_size': api/basic_json/max_size.md
- 'meta': api/basic_json/meta.md
@@ -228,9 +232,13 @@ nav:
- 'Overview': api/byte_container_with_subtype/index.md
- '(constructor)': api/byte_container_with_subtype/byte_container_with_subtype.md
- 'clear_subtype': api/byte_container_with_subtype/clear_subtype.md
- 'container_type': api/byte_container_with_subtype/container_type.md
- 'has_subtype': api/byte_container_with_subtype/has_subtype.md
- 'operator==': api/byte_container_with_subtype/operator_eq.md
- 'operator!=': api/byte_container_with_subtype/operator_ne.md
- 'set_subtype': api/byte_container_with_subtype/set_subtype.md
- 'subtype': api/byte_container_with_subtype/subtype.md
- 'subtype_type': api/byte_container_with_subtype/subtype_type.md
- adl_serializer:
- 'Overview': api/adl_serializer/index.md
- 'from_json': api/adl_serializer/from_json.md
@@ -256,25 +264,46 @@ nav:
- 'to_string': api/json_pointer/to_string.md
- json_sax:
- 'Overview': api/json_sax/index.md
- '(Constructor)': api/json_sax/json_sax.md
- '(Destructor)': api/json_sax/~json_sax.md
- 'operator=': api/json_sax/operator=.md
- 'binary': api/json_sax/binary.md
- 'binary_t': api/json_sax/binary_t.md
- 'boolean': api/json_sax/boolean.md
- 'end_array': api/json_sax/end_array.md
- 'end_object': api/json_sax/end_object.md
- 'key': api/json_sax/key.md
- 'null': api/json_sax/null.md
- 'number_float': api/json_sax/number_float.md
- 'number_float_t': api/json_sax/number_float_t.md
- 'number_integer': api/json_sax/number_integer.md
- 'number_integer_t': api/json_sax/number_integer_t.md
- 'number_unsigned': api/json_sax/number_unsigned.md
- 'number_unsigned_t': api/json_sax/number_unsigned_t.md
- 'parse_error': api/json_sax/parse_error.md
- 'start_array': api/json_sax/start_array.md
- 'start_object': api/json_sax/start_object.md
- 'string': api/json_sax/string.md
- 'string_t': api/json_sax/string_t.md
- 'operator<<(basic_json), operator<<(json_pointer)': api/operator_ltlt.md
- 'operator>>(basic_json)': api/operator_gtgt.md
- 'operator""_json': api/operator_literal_json.md
- 'operator""_json_pointer': api/operator_literal_json_pointer.md
- 'ordered_json': api/ordered_json.md
- 'ordered_map': api/ordered_map.md
- ordered_map:
- 'Overview': api/ordered_map/index.md
- '(Constructor)': api/ordered_map/ordered_map.md
- '(Destructor)': api/ordered_map/~ordered_map.md
- 'operator=': api/ordered_map/operator=.md
- 'at': api/ordered_map/at.md
- 'Container': api/ordered_map/Container.md
- 'count': api/ordered_map/count.md
- 'emplace': api/ordered_map/emplace.md
- 'erase': api/ordered_map/erase.md
- 'find': api/ordered_map/find.md
- 'insert': api/ordered_map/insert.md
- 'key_compare': api/ordered_map/key_compare.md
- 'operator[]': api/ordered_map/operator[].md
- macros:
- 'Overview': api/macros/index.md
- 'JSON_ASSERT': api/macros/json_assert.md
@@ -296,7 +325,6 @@ nav:
- '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
@@ -22,7 +22,9 @@ template<typename BinaryType>
class byte_container_with_subtype : public BinaryType
{
public:
/// @sa https://json.nlohmann.me/api/byte_container_with_subtype/container_type/
using container_type = BinaryType;
/// @sa https://json.nlohmann.me/api/byte_container_with_subtype/subtype_type/
using subtype_type = std::uint64_t;
/// @sa https://json.nlohmann.me/api/byte_container_with_subtype/byte_container_with_subtype/
@@ -54,12 +56,14 @@ class byte_container_with_subtype : public BinaryType
, m_has_subtype(true)
{}
/// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_eq/
bool operator==(const byte_container_with_subtype& rhs) const
{
return std::tie(static_cast<const BinaryType&>(*this), m_subtype, m_has_subtype) ==
std::tie(static_cast<const BinaryType&>(rhs), rhs.m_subtype, rhs.m_has_subtype);
}
/// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_ne/
bool operator!=(const byte_container_with_subtype& rhs) const
{
return !(rhs == *this);

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