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Author SHA1 Message Date
Niels Lohmann 8fb114e45f Bump Semgrep to 1.182.1 and allow two unfixable advisories
Semgrep 1.168.0 pins pyjwt~=2.13.0, which dependency-review flags
(GHSA-ffc3-869f-jxw9 and 14 more). Semgrep 1.182.1 requires
pyjwt>=2.15.0; the lock file now has pyjwt 2.15.1, mcp 1.29.0 and
click 8.4.2.

Semgrep 1.182.1 still pins mcp==1.29.0 (GHSA-84m7-p3x7-pcfv) and
opentelemetry-api~=1.37.0 (GHSA-xcq7-p3pf-p88h). Neither code path is
used by `semgrep scan` in CI, so dependency-review allows both until
Semgrep lifts its pins.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-23 17:14:25 +02:00
Niels Lohmann d1235cecc9 Pin CI pip installs by hash and update KaTeX/DOMPurify
The pip installs in check_amalgamation.yml, ubuntu.yml (Meson) and
semgrep.yml now use --require-hashes with requirements files compiled by
pip-compile --generate-hashes (Python 3.14, as on ubuntu-26.04). The
astyle and generate_natvis requirements move to requirements.in, and
Meson and Semgrep get theirs in .github/requirements, which Dependabot
now watches. check_amalgamation.yml installs the natvis requirements
from the PR tree, as it already does for astyle.

The Mermaid checker overrides KaTeX to 0.18.11 (GHSA-238p-pmpm-9mq7;
Mermaid 11 still requires ^0.16.47) and updates DOMPurify to 3.4.17
(GHSA-cg2g-xh64-v4q7, GHSA-mrv2-3pqr-j5jr, GHSA-c6gr-qvv4-5v3f).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-23 07:20:44 +02:00
243 changed files with 10564 additions and 11744 deletions

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+8 -1
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@@ -29,6 +29,13 @@ updates:
- dependency-name: mermaid
update-types: ["version-update:semver-major"]
- package-ecosystem: pip
directory: /.github/requirements
schedule:
interval: daily
cooldown:
default-days: 7
- package-ecosystem: pip
directory: /tools/astyle
schedule:
@@ -36,7 +43,7 @@ updates:
cooldown:
default-days: 7
ignore:
# astyle is deliberately pinned (see tools/astyle/requirements.txt): newer versions
# astyle is deliberately pinned (see tools/astyle/requirements.in): newer versions
# reformat the code, and the pinned version defines the formatting CI enforces
- dependency-name: astyle
+1
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@@ -0,0 +1 @@
meson==1.12.1
+10
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@@ -0,0 +1,10 @@
#
# This file is autogenerated by pip-compile with Python 3.14
# by the following command:
#
# pip-compile --generate-hashes --no-emit-index-url --output-file=.github/requirements/meson.txt --strip-extras .github/requirements/meson.in
#
meson==1.12.1 \
--hash=sha256:930bc7542cbd9f57009e182fd014eba48cf1a0180a7b9006d2d32d8f168d8b02 \
--hash=sha256:ab0a6ca09f8ef70c564c8241fb5a23957886a0b53fb58412b5e07eaf07dba743
# via -r .github/requirements/meson.in
+1
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@@ -0,0 +1 @@
semgrep==1.182.1
File diff suppressed because it is too large. Load diff
+5 -5
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@@ -67,10 +67,10 @@ jobs:
- name: Install astyle
run: |
python3 -mvenv venv
venv/bin/pip3 install -r $MAIN_DIR/tools/astyle/requirements.txt
venv/bin/pip3 install --require-hashes -r $MAIN_DIR/tools/astyle/requirements.txt
- name: Install generate_natvis dependencies
run: pip3 install -r $NATVIS_TOOL_DIR/requirements.txt
run: pip3 install --require-hashes -r $MAIN_DIR/tools/generate_natvis/requirements.txt
- name: Regenerate the tools/macro_builder tables in macro_scope.hpp
run: |
@@ -163,9 +163,9 @@ jobs:
python3 $GENERATOR --list-tags
TAG_COUNT=$(python3 $GENERATOR --list-tags | wc -l)
python3 $GENERATOR --abi-tags diag,_dp,_ns --abi-tags _diag --output $RUNNER_TEMP/abi_tags.natvis
grep -q '<!-- Namespace nlohmann::json_abi_diag_dp_ns -->' $RUNNER_TEMP/abi_tags.natvis
grep -q '<!-- Namespace nlohmann::json_abi_diag_dp_ns_v[0-9_]* -->' $RUNNER_TEMP/abi_tags.natvis
python3 $GENERATOR --abi-tags diag,_dp,_vns --abi-tags _diag --output $RUNNER_TEMP/abi_tags.natvis
grep -q '<!-- Namespace nlohmann::json_abi_diag_dp_vns -->' $RUNNER_TEMP/abi_tags.natvis
grep -q '<!-- Namespace nlohmann::json_abi_diag_dp_vns_v[0-9_]* -->' $RUNNER_TEMP/abi_tags.natvis
test $(grep -c '<!-- Namespace ' $RUNNER_TEMP/abi_tags.natvis) -eq $(( $(grep -c '<!-- Namespace ' nlohmann_json.natvis) + 2 ))
python3 $GENERATOR --all --output $RUNNER_TEMP/all.natvis
+9
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@@ -31,3 +31,12 @@ jobs:
persist-credentials: false
- name: 'Dependency Review'
uses: actions/dependency-review-action@a1d282b36b6f3519aa1f3fc636f609c47dddb294 # v5.0.0
with:
# Semgrep pins mcp==1.29.0 and opentelemetry-api~=1.37.0 exactly
# (.github/requirements/semgrep.txt), so these cannot be upgraded
# until Semgrep lifts its pins. They do not apply to our use: CI
# only runs `semgrep scan` on the checkout and never starts the MCP
# server (GHSA-84m7-p3x7-pcfv, StreamableHTTP sessions) or parses
# incoming trace context (GHSA-xcq7-p3pf-p88h, tracestate parsing).
# Remove the entries once a Semgrep release allows the fixed versions.
allow-ghsas: GHSA-84m7-p3x7-pcfv, GHSA-xcq7-p3pf-p88h
+1 -1
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@@ -53,7 +53,7 @@ jobs:
# SEMGREP_APP_TOKEN is still passed through so registry auth works if a
# token is ever added.
- name: Install Semgrep
run: python3 -m pip install --user semgrep==1.168.0
run: python3 -m pip install --user --require-hashes -r .github/requirements/semgrep.txt
# `semgrep scan --sarif` always exits 0 even with findings; continue-on-error
# is a safety net so the SARIF upload still runs if the scan itself errors.
+1 -1
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@@ -42,7 +42,7 @@ jobs:
- name: Check that Meson and pkg-config offer the CMake options
run: make check_build_options
- name: Install Meson
run: pip install meson
run: pip install --require-hashes -r .github/requirements/meson.txt
- name: Install with Meson
run: |
meson setup build-meson --prefix=${{ github.workspace }}/install
-1
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@@ -90,7 +90,6 @@ cc_library(
"include/nlohmann/detail/view/simd.hpp",
"include/nlohmann/detail/view/string_ref.hpp",
"include/nlohmann/detail/view/value.hpp",
"include/nlohmann/detail/view/view_mode.hpp",
"include/nlohmann/json.hpp",
"include/nlohmann/json_fwd.hpp",
"include/nlohmann/json_literals.hpp",
+1 -1
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@@ -309,7 +309,7 @@ The "Check amalgamation" workflow fails if the file is out of date.
The file covers the namespace variants with up to two ABI tags. A Natvis file for other configurations can be
generated with the `--abi-tags` or `--all` options, for example
`make natvis NATVIS_ARGS="--abi-tags _diag,_dp,_ns --output my_nlohmann_json.natvis"`; see
`make natvis NATVIS_ARGS="--abi-tags _diag,_dp,_vns --output my_nlohmann_json.natvis"`; see
[`tools/generate_natvis`](tools/generate_natvis/README.md). With MSVC, CMake adds the file to the `nlohmann_json`
target and installs it.
+1 -1
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@@ -120,7 +120,7 @@ $(AMALGAMATED_VIEW_FILE): $(SRCS)
tools/amalgamate/amalgamate.py -c tools/amalgamate/config_json_view.json -s . --verbose=yes
NATVIS_VENV=tools/generate_natvis/venv
# extra options for generate_natvis.py, e.g. NATVIS_ARGS="--abi-tags _diag,_dp,_ns --output my.natvis"
# extra options for generate_natvis.py, e.g. NATVIS_ARGS="--abi-tags _diag,_dp,_vns --output my.natvis"
NATVIS_ARGS=
# regenerate nlohmann_json.natvis from the ABI tags and version in include/nlohmann/detail/abi_macros.hpp
+1 -2
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@@ -341,14 +341,13 @@ def download(url, docs) -> str:
raise ValueError(f'not an http(s) URL: {url}')
req = urllib.request.Request(u.geturl(), headers={'User-Agent': USER_AGENT})
# (the scheme is checked above)
# nosemgrep: python.lang.security.audit.dynamic-urllib-use-detected.dynamic-urllib-use-detected
with urllib.request.urlopen(req, timeout=20) as r: # nosec B310
data = r.read()
ctype = r.headers.get_content_type()
path = urllib.parse.unquote(u.path).lstrip('/')
ext = os.path.splitext(path)[1]
if u.query or not ext or path.endswith('/'):
digest = hashlib.sha256(url.encode()).hexdigest()[:12]
digest = hashlib.sha1(url.encode(), usedforsecurity=False).hexdigest()[:12]
path = os.path.join(os.path.dirname(path), digest + CONTENT_TYPE_EXT.get(ctype, ext or '.bin'))
rel = os.path.normpath(os.path.join('assets', 'external', u.hostname, path))
out = os.path.join(docs, rel)
@@ -30,14 +30,6 @@ struct adl_serializer {
- [**from_json**](from_json.md) - convert a JSON value to any value type
- [**to_json**](to_json.md) - convert any value type to a JSON value
## See also
- [Arbitrary type conversions](../../features/arbitrary_types.md) - how to make your types convertible
- [**get**](../basic_json/get.md) / [**get_to**](../basic_json/get_to.md) - convert a JSON value to a C++ type
- [**basic_json**](../basic_json/basic_json.md) - construct a JSON value from a C++ value
- [**NLOHMANN_DEFINE_TYPE_INTRUSIVE**](../macros/nlohmann_define_type_intrusive.md) - generate the conversion functions for a type
- [Specializing enum conversion](../../features/enum_conversion.md)
## Version history
- Added in version 2.1.0.
+1 -25
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@@ -23,9 +23,6 @@ Checks whether the input is valid JSON.
respectively as UTF-8, UTF-16, and UTF-32. If `SentinelType` differs from `IteratorType`, it must be comparable to
the iterator type with `operator!=`.
Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its
low surrogate, and a code point above `U+10FFFF` all make this function return `false`.
Unlike the [`parse()`](parse.md) function, this function neither throws an exception in case of invalid JSON input
(i.e., a parse error) nor creates diagnostic information.
@@ -38,12 +35,9 @@ Unlike the [`parse()`](parse.md) function, this function neither throws an excep
- a `#!c FILE` pointer (throws if null)
- a C-style array of characters
- a pointer to a null-terminated string of single byte characters (throws if null)
- a `std::string` or a `std::string_view` (C++17)
- a `std::string`
- a container `obj` for which `begin(obj)` and `end(obj)` produce a valid pair of iterators
(as found via ADL or member functions, with semantics compatible to `std::begin` and `std::end`)
- wide characters (`wchar_t`, `char16_t`, `char32_t`), which are converted to UTF-8: a wide string object
(`std::wstring`, `std::u16string`, `std::u32string`) or an array (e.g. a wide string literal); a pointer to a
null-terminated wide string (e.g. `std::u16string::c_str()`) is not supported
`IteratorType`
: a compatible iterator type, for instance.
@@ -131,21 +125,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
--8<-- "examples/accept__iterator_pair.output"
```
??? example "Example: (3) reading from UTF-16 strings"
The encoding is deduced from the character type of the input. String literals like `u"..."`, `U"..."`, and
`L"..."` work as well.
```cpp
--8<-- "examples/accept__wide_string.cpp"
```
Output:
```json
--8<-- "examples/accept__wide_string.output"
```
## See also
- [parse](parse.md) - deserialize from a compatible input
@@ -172,9 +151,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md)).
- Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md)).
- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
a code point above `U+10FFFF`) is rejected in version 3.13.0; before that, some such sequences were accepted or
ended the input silently.
!!! warning "Deprecation"
+3 -2
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@@ -239,8 +239,9 @@ Strong exception safety: if an exception occurs, the original value stays intact
1. Added in version 1.0.0.
2. Added in version 1.0.0.
3. Added in version 3.11.0. Support for keys convertible to `std::string_view` added in version 3.13.0, consistently
across the lookup functions.
3. Added in version 3.11.0. Fixed in version 3.13.0 to consistently accept `std::string_view`-convertible keys, as
already supported by [`operator[]`](operator[].md), [`value`](value.md), [`find`](find.md), and other lookup
functions.
4. Added in version 2.0.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) instead of
[`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) for a one-character array index that is not
a digit (e.g., `/x`) in version 3.13.0, as it already did for longer ones.
+1 -1
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@@ -63,4 +63,4 @@ Constant.
## Version history
- Added in version 1.0.0.
- Binary values are supported since version 3.8.0.
- Adjusted code to return reference to binary values in version 3.8.0.
@@ -482,15 +482,15 @@ basic_json(basic_json&& other) noexcept;
## Version history
1. Added in version 1.0.0.
2. Added in version 1.0.0.
3. Added in version 2.1.0.
4. Added in version 3.1.2. Explicit for different string types if `JSON_USE_IMPLICIT_CONVERSIONS` is `0` since
1. Since version 1.0.0.
2. Since version 1.0.0.
3. Since version 2.1.0.
4. Since version 3.2.0. Explicit for different string types if `JSON_USE_IMPLICIT_CONVERSIONS` is `0` since
version 3.13.0.
5. Added in version 1.0.0.
6. Added in version 1.0.0.
7. Added in version 1.0.0. Fixed in version 3.13.0 to also check the iterator range for binary values; before, a range
5. Since version 1.0.0.
6. Since version 1.0.0.
7. Since version 1.0.0. Fixed in version 3.13.0 to also check the iterator range for binary values; before, a range
that did not cover the whole value (such as `(end(), end())`) was accepted and the whole binary value was copied,
unlike the other primitive types.
8. Added in version 1.0.0.
9. Added in version 1.0.0.
8. Since version 1.0.0.
9. Since version 1.0.0.
+3 -2
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@@ -141,8 +141,9 @@ Logarithmic in the size of the JSON object.
## Version history
1. Added in version 3.11.0.
2. Added in version 3.6.0. Extended template `KeyType` to support comparable types in version 3.11.0. Support for keys
convertible to `std::string_view` added in version 3.13.0, consistently across the lookup functions.
2. Added in version 3.6.0. Extended template `KeyType` to support comparable types in version 3.11.0. Fixed in
version 3.13.0 to consistently accept `std::string_view`-convertible keys, as already supported by
[`operator[]`](operator[].md), [`at`](at.md), [`value`](value.md), and other lookup functions.
3. Added in version 3.7.0.
4. Deleted overloads for integral key types added in version 3.13.0 to reject such calls at compile time instead of
causing undefined behavior at runtime.
+3 -2
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@@ -92,7 +92,8 @@ Logarithmic in the size of the JSON object.
## Version history
1. Added in version 3.11.0.
2. Added in version 1.0.0. Changed to support comparable key types in version 3.11.0. Support for keys convertible to
`std::string_view` added in version 3.13.0, consistently across the lookup functions.
2. Added in version 1.0.0. Changed parameter `key` type to `KeyType&&` in version 3.11.0. Fixed in version 3.13.0 to
consistently accept `std::string_view`-convertible keys, as already supported by [`operator[]`](operator[].md),
[`at`](at.md), [`value`](value.md), and other lookup functions.
3. Deleted overload for integral key types added in version 3.13.0 to reject such calls at compile time instead of
causing undefined behavior at runtime.
+1 -1
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@@ -69,6 +69,6 @@ Logarithmic in the size of the container, O(log(`size()`)).
## Version history
- Added in version 2.0.8.
- Since version 2.0.8.
- Fixed in version 3.13.0: for [`ordered_json`](../ordered_json.md), the value could previously only be passed as an
rvalue; it can now also be passed as an lvalue or a `#!cpp const` lvalue, matching the behavior of `json`.
@@ -67,5 +67,5 @@ Amortized constant.
## Version history
- Added in version 2.0.8.
- Since version 2.0.8.
- Returns reference since 3.7.0.
+3 -2
View File
@@ -213,6 +213,7 @@ Strong exception safety: if an exception occurs, the original value stays intact
1. Added in version 1.0.0. Added support for binary types in version 3.8.0.
2. Added in version 1.0.0. Added support for binary types in version 3.8.0.
3. Added in version 1.0.0.
4. Added in version 3.11.0. Support for keys convertible to `std::string_view` added in version 3.13.0, consistently
across the lookup functions.
4. Added in version 3.11.0. Fixed in version 3.13.0 to consistently accept `std::string_view`-convertible keys, as
already supported by [`operator[]`](operator[].md), [`at`](at.md), [`value`](value.md), and other lookup
functions.
5. Added in version 1.0.0.
+1 -1
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@@ -84,4 +84,4 @@ constructor.
## Version history
- Added in version 3.0.0.
- Since version 3.0.0.
+3 -2
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@@ -99,7 +99,8 @@ Logarithmic in the size of the JSON object.
## Version history
1. Added in version 3.11.0.
2. Added in version 1.0.0. Changed to support comparable types in version 3.11.0. Support for keys convertible to
`std::string_view` added in version 3.13.0, consistently across the lookup functions.
2. Added in version 1.0.0. Changed to support comparable types in version 3.11.0. Fixed in version 3.13.0 to
consistently accept `std::string_view`-convertible keys, as already supported by [`operator[]`](operator[].md),
[`at`](at.md), [`value`](value.md), and other lookup functions.
3. Deleted overloads for integral key types added in version 3.13.0 to reject such calls at compile time instead of
causing undefined behavior at runtime.
+1 -1
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@@ -57,4 +57,4 @@ Constant.
## Version history
- Added in version 1.0.0.
- Binary values are supported since version 3.8.0.
- Adjusted code to return reference to binary values in version 3.8.0.
+3 -3
View File
@@ -188,6 +188,6 @@ overload (3).
## Version history
1. Added in version 2.1.0.
2. Added in version 2.1.0. Extended to work with other specializations of `basic_json` in version 3.1.2.
3. Added in version 1.0.0.
1. Since version 2.1.0.
2. Since version 2.1.0. Extended to work with other specializations of `basic_json` in version 3.2.0.
3. Since version 1.0.0.
+1 -1
View File
@@ -76,5 +76,5 @@ Depends on the `json_serializer<ValueType>::from_json()` implementation.
## Version history
- Added in version 3.3.0.
- Since version 3.3.0.
- Added a `static_assert` with a clear message for `const` arguments in version 3.13.0.
-19
View File
@@ -44,22 +44,6 @@ are collected in [Template Parameter Requirements](../../features/types/template
- [**json**](../json.md) - default specialization
- [**ordered_json**](../ordered_json.md) - a specialization that maintains the insertion order of object keys
## Documents and views
Besides `basic_json`, the library offers a second way to hold a parsed JSON text: a
[`basic_json_document`](../basic_json_document/index.md), which owns or borrows the text and holds a flat index of the
values in it, and a [`basic_json_view`](../basic_json_view/index.md), a read-only handle to one value of such a document.
Both are defined in the header `<nlohmann/json_view.hpp>`; see
[Zero-copy JSON views](../../features/json_view.md) for the concept and the trade-offs.
- [**json_document**](../json_document.md) / [**ordered_json_document**](../ordered_json_document.md) - read-only
documents of the `basic_json` specialization they belong to
- [**json_editable_document**](../json_editable_document.md) /
[**ordered_json_editable_document**](../ordered_json_editable_document.md) - documents that can be modified in place
- [**json_view**](../json_view.md) / [**ordered_json_view**](../ordered_json_view.md) - views of a document
- [**json_editable_view**](../json_editable_view.md) /
[**ordered_json_editable_view**](../ordered_json_editable_view.md) - views of an editable document
## Iterator invalidation
All operations that add values to an **array** ([`push_back`](push_back.md) , [`operator+=`](operator+=.md),
@@ -359,9 +343,6 @@ Access to the JSON value
## See also
- [RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format](https://tools.ietf.org/html/rfc8259)
- [basic_json_document](../basic_json_document/index.md) / [basic_json_view](../basic_json_view/index.md) - parse a JSON
text into a flat index and read it through a view
- [Zero-copy JSON views](../../features/json_view.md) - when to use a document and a view instead of a `basic_json`
## Version history
@@ -75,4 +75,4 @@ classDiagram
## Version history
- Added in version 3.0.0.
- Since version 3.0.0.
+2 -2
View File
@@ -104,8 +104,8 @@ When iterating over an array, `key()` will return the index of the element as st
## Version history
- Added in version 3.1.0 as the replacement of the static function `iterator_wrapper`, which was available since
version 1.0.0 and is deprecated since version 3.1.0.
- Added `iterator_wrapper` in version 3.0.0.
- Added `items` and deprecated `iterator_wrapper` in version 3.1.0.
- Added structured binding support in version 3.5.0.
!!! warning "Deprecation"
@@ -51,4 +51,4 @@ deserializes. See [Template Parameter Requirements](../../features/types/templat
## Version history
- Added in version 2.1.0.
- Since version 2.0.0.
@@ -71,6 +71,6 @@ returned by `#!cpp (*this)[key]`); it is read as it was when `merge_patch()` was
## Version history
- Added in version 3.1.0.
- Added in version 3.0.0.
- Fixed use of freed or relocated memory when `apply_patch` is `#!cpp *this` or refers to a value contained in
`#!cpp *this`, in version 3.13.0.
@@ -128,6 +128,6 @@ interpreted as `object_t::value_type` or `std::initializer_list<basic_json>`, se
## Version history
1. Added in version 1.0.0.
2. Added in version 1.0.0.
3. Added in version 2.0.0.
1. Since version 1.0.0.
2. Since version 1.0.0.
3. Since version 2.0.0.
@@ -284,10 +284,10 @@ Strong exception safety: if an exception occurs, the original value stays intact
1. Added in version 1.0.0. Fixed in version 3.13.0 to throw `#!cpp std::length_error` instead of emptying the array and
accessing it out of bounds when `idx` equals the maximum value of `size_type`. A missing index in the const version
is guarded by a runtime assertion since version 3.13.0.
2. Added in version 1.0.0. Added overloads for `T* key` in version 1.1.0. The `T* key` overloads forward to
overload 3 since version 3.11.0.
3. Added in version 3.11.0. Support for keys convertible to `std::string_view` added in version 3.13.0, consistently
across the lookup functions.
2. Added in version 1.0.0. Added overloads for `T* key` in version 1.1.0. Removed overloads for `T* key` (replaced by 3)
in version 3.11.0.
3. Added in version 3.11.0. Fixed in version 3.13.0 to consistently accept `std::string_view`-convertible keys, as
already supported by [`at`](at.md), [`value`](value.md), [`find`](find.md), and other lookup functions.
4. Added in version 2.0.0. A missing array index in the const version is guarded by a runtime assertion since
version 3.13.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) instead of
[`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) for a one-character array index that is not
@@ -89,6 +89,6 @@ Linear in the size of the JSON value.
## Version history
- Added in version 1.0.0.
- Since version 1.0.0.
- Macros `JSON_EXPLICIT`/[`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) added
in version 3.9.0.
@@ -75,4 +75,4 @@ classDiagram
## Version history
- Added in version 3.0.0.
- Since version 3.0.0.
@@ -76,4 +76,4 @@ classDiagram
## Version history
- Added in version 3.0.0.
- Since version 3.0.0.
+1 -34
View File
@@ -25,10 +25,6 @@ static basic_json parse(IteratorType first, SentinelType last,
respectively as UTF-8, UTF-16, and UTF-32. If `SentinelType` differs from `IteratorType`, it must be comparable to
the iterator type with `operator!=`.
Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its
low surrogate, and a code point above `U+10FFFF` all yield a
[`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101).
## Template parameters
`InputType`
@@ -38,12 +34,9 @@ static basic_json parse(IteratorType first, SentinelType last,
- a `FILE` pointer (throws if null)
- a C-style array of characters
- a pointer to a null-terminated string of single byte characters (throws if null)
- a `std::string` or a `std::string_view` (C++17)
- a `std::string`
- a container `obj` for which `begin(obj)` and `end(obj)` produce a valid pair of iterators
(as found via ADL or member functions, with semantics compatible to `std::begin` and `std::end`)
- wide characters (`wchar_t`, `char16_t`, `char32_t`), which are converted to UTF-8: a wide string object
(`std::wstring`, `std::u16string`, `std::u32string`) or an array (e.g. a wide string literal); a pointer to a
null-terminated wide string (e.g. `std::u16string::c_str()`) is not supported
`IteratorType`
: a compatible iterator type, for instance.
@@ -119,13 +112,6 @@ By default, a `'\0'` (NUL) byte anywhere in the input is treated as end of input
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.
!!! tip "Parsing into a document instead of a value"
[`basic_json_document::parse`](../basic_json_document/parse.md) accepts the same inputs and the same options, but
keeps the result as a flat index of the parsed values instead of a tree of `basic_json` values. It is faster and uses
less memory when only parts of the document are read, and it also accepts a pointer to a null-terminated wide string,
which `parse()` does not. See [Zero-copy JSON views](../../features/json_view.md).
!!! tip "Performance"
Contiguous inputs (strings, string views, vectors, arrays, pointer ranges) are the fastest to parse. A
@@ -264,22 +250,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
--8<-- "examples/trailing_commas.output"
```
??? example "Example: parse from UTF-16, UTF-32, and wide strings"
The encoding is deduced from the character type of the input; `std::u16string` and `std::u32string` are interpreted
as UTF-16 and UTF-32, and `std::wstring` uses the platform's `wchar_t` width. String literals like `u"..."`,
`U"..."`, and `L"..."` work as well, as do iterators over wide characters.
```cpp
--8<-- "examples/parse__wide_string.cpp"
```
Output:
```json
--8<-- "examples/parse__wide_string.output"
```
## See also
- [accept](accept.md) - check if the input is valid JSON
@@ -310,9 +280,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
time).
- Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) restores `std::fgetc`).
- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
a code point above `U+10FFFF`) is rejected with `parse_error.101` in version 3.13.0; before that, some such
sequences were accepted or ended the input silently.
!!! warning "Deprecation"
@@ -84,4 +84,4 @@ or the end of file. This also holds true when reading a byte vector for binary f
## Version history
- Added in version 3.0.0.
- Since version 3.0.0.
+3 -3
View File
@@ -125,6 +125,6 @@ throws.
## Version history
1. Added in version 1.0.0.
2. Added in version 1.0.0.
3. Added in version 2.0.0.
1. Since version 1.0.0.
2. Since version 1.0.0.
3. Since version 2.0.0.
@@ -31,10 +31,6 @@ Read from input and generate SAX events
respectively as UTF-8, UTF-16, and UTF-32. If `SentinelType` differs from `IteratorType`, it must be comparable to
the iterator type with `operator!=`.
Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its
low surrogate, and a code point above `U+10FFFF` all yield a
[`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101).
The SAX event lister must follow the interface of [`json_sax`](../json_sax/index.md).
## Template parameters
@@ -46,12 +42,8 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
- a `FILE` pointer
- a C-style array of characters
- a pointer to a null-terminated string of single byte characters
- a `std::string` or a `std::string_view` (C++17)
- a container `obj` for which `begin(obj)` and `end(obj)` produce a valid pair of iterators
(as found via ADL or member functions, with semantics compatible to `std::begin` and `std::end`)
- wide characters (`wchar_t`, `char16_t`, `char32_t`), which are converted to UTF-8: a wide string object
(`std::wstring`, `std::u16string`, `std::u32string`) or an array (e.g. a wide string literal); a pointer to a
null-terminated wide string (e.g. `std::u16string::c_str()`) is not supported
`IteratorType`
: a compatible iterator type for overload (2); a pair of character iterators whose `value_type` is an integral type
@@ -168,9 +160,6 @@ use the same file with stdio functions, but it must not wait for another thread
([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md)).
- Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md)).
- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
a code point above `U+10FFFF`) is rejected with `parse_error.101` in version 3.13.0; before that, some such
sequences were accepted or ended the input silently.
!!! warning "Deprecation"
+7 -7
View File
@@ -182,10 +182,10 @@ Constant.
## Version history
1. Added in version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
2. Added in version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
3. Added in version 1.0.0.
4. Added in version 1.0.0.
5. Added in version 1.0.0.
6. Added in version 3.8.0.
7. Added in version 3.8.0.
1. Since version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
2. Since version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
3. Since version 1.0.0.
4. Since version 1.0.0.
5. Since version 1.0.0.
6. Since version 3.8.0.
7. Since version 3.8.0.
@@ -124,3 +124,5 @@ Linear in the size of the JSON value `j`.
[`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled) throws `type_error.316`.
- Throws `type_error.321` for a discarded value since version 3.13.0; previously, a discarded value nested in an
array or object was silently skipped, producing invalid BJData.
- Writes unsigned integers wider than 64 bits as high-precision numbers since version 3.13.0; previously, they were
silently truncated to 64 bits.
@@ -76,4 +76,4 @@ classDiagram
## Version history
- Added in version 3.0.0.
- Since version 3.0.0.
+6 -3
View File
@@ -231,8 +231,11 @@ changes to any JSON value.
1. Added in version 1.0.0. Changed parameter `default_value` type from `const ValueType&` to `ValueType&&` in version
3.11.0. Deleted overload for integral key types added in version 3.13.0 to reject such calls at compile time
instead of causing undefined behavior at runtime.
2. Added in version 3.11.0. Made `ValueType` the first template parameter in version 3.11.2. Support for keys
convertible to `std::string_view` added in version 3.13.0, consistently across the lookup functions.
3. Added in version 2.0.2. Extended to work with arrays in version 3.13.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109)
2. Added in version 3.11.0. Made `ValueType` the first template parameter in version 3.11.2. Fixed in version 3.13.0
to consistently accept `std::string_view`-convertible keys, as already supported by
[`operator[]`](operator[].md), [`at`](at.md), [`find`](find.md), and other lookup functions.
3. Added in version 2.0.2. Extended to work with arrays in version 3.13.0, including fixing an issue where resolving
`ptr` through an array unexpectedly threw `out_of_range` instead of returning the resolved element (or
`default_value`, as documented). Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109)
instead of returning `default_value` for a one-character array index that is not a digit (e.g., `/x`) in version
3.13.0, as it already did for longer ones.
@@ -12,7 +12,7 @@ void erase(view_type array, I idx);
std::size_t erase(const json_pointer& ptr);
```
Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
has `erase`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
1. Removes every member of `object` whose key is `key` (see [Notes](#notes) on duplicate keys) and returns how many
@@ -3,14 +3,14 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
template<typename BasicJsonType, view_mode Mode = view_mode::read_only>
template<typename BasicJsonType, bool Editable = false>
class basic_json_document;
```
A parsed JSON text, held as a flat index of its values
([16 bytes per value](../../home/architecture.md#node-index-of-json-views)) instead of a tree of `BasicJsonType` values.
Strings and floating-point numbers stay in the source text; integers are converted while parsing, and strings that
contain escapes are decoded into one buffer owned by the document. [`basic_json_view`](../basic_json_view/index.md) is a read-only handle to one value of a
Strings and numbers stay in the source text; only strings that contain escapes are decoded, into one buffer owned by
the document. [`basic_json_view`](../basic_json_view/index.md) is a read-only handle to one value of a
`basic_json_document`; [`materialize()`](../basic_json_view/materialize.md) turns a subtree into the
`BasicJsonType` value that [`BasicJsonType::parse()`](../basic_json/parse.md) would have produced for it.
@@ -20,9 +20,9 @@ is move-only: a copy would duplicate the whole index, the decoded-string buffer,
enough in every use we know of. The index, the decoded strings, and the owned text live in one heap block that the
document holds through a `#!cpp std::unique_ptr`; this is also why views survive a move of the document.
With `#!cpp Mode == view_mode::editable`, the document also offers [`set`](set.md), [`push_back`](push_back.md),
With `#!cpp Editable == true`, the document also offers [`set`](set.md), [`push_back`](push_back.md),
[`insert`](insert.md), and [`erase`](erase.md) to change values in place, see [Edits](#edits) below. The source text
itself is never written; a read-only document (`#!cpp view_mode::read_only`, the default) does not carry any of the
itself is never written; a read-only document (`#!cpp Editable == false`, the default) does not carry any of the
bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp static_assert`).
## Template parameters
@@ -32,10 +32,9 @@ bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp
[`ordered_json`](../ordered_json.md). Only 64-bit `number_integer_t`/`number_unsigned_t` types are supported; this
is checked with a `static_assert`.
`Mode`
: a [`view_mode`](../view_mode.md): `#!cpp view_mode::editable` if the document supports [`set`](set.md),
[`push_back`](push_back.md), [`insert`](insert.md), and [`erase`](erase.md) (optional, `#!cpp view_mode::read_only`
by default). See [Edits](#edits) below.
`Editable`
: whether the document supports [`set`](set.md), [`push_back`](push_back.md), [`insert`](insert.md), and
[`erase`](erase.md) (optional, `#!cpp false` by default). See [Edits](#edits) below.
## Specializations
@@ -48,7 +47,7 @@ bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp
## Member types
- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType, Mode>`)
- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType, Editable>`)
- **value_t** - the JSON type enumeration, see [`basic_json::value_t`](../basic_json/value_t.md)
- **image_check** - how [`load()`](load.md) validates an image (`full`, `bounds`, `none`), see [`image_check`](load.md#image_check)
@@ -81,15 +80,15 @@ bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp
### Edits
- [**set**](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers
to (editable documents only)
- [**push_back**](push_back.md) - append to an array (editable documents only)
- [**insert**](insert.md) - insert an element into an array before a given position (editable documents only)
to (`#!cpp Editable` documents only)
- [**push_back**](push_back.md) - append to an array (`#!cpp Editable` documents only)
- [**insert**](insert.md) - insert an element into an array before a given position (`#!cpp Editable` documents only)
- [**erase**](erase.md) - remove an object member, an array element, or the value a JSON pointer refers to
(editable documents only)
(`#!cpp Editable` documents only)
## Edits
An editable document (`#!cpp view_mode::editable`) can be changed after parsing, with [`set`](set.md),
An editable document (`#!cpp Editable == true`) can be changed after parsing, with [`set`](set.md),
[`push_back`](push_back.md), [`insert`](insert.md), and [`erase`](erase.md);
[`json_editable_document`](../json_editable_document.md) and
[`ordered_json_editable_document`](../ordered_json_editable_document.md) are the corresponding specializations. A few
@@ -116,13 +115,6 @@ points apply to every edit:
[`source_offset()`](../basic_json_view/source_offset.md) of a value introduced by an edit is
`#!cpp static_cast<std::size_t>(-1)`, the same value it reports for a decoded string.
## See also
- [Zero-copy JSON views](../../features/json_view.md) - guide to documents and views
- [**basic_json_view**](../basic_json_view/index.md) - the non-owning handle to a value in a document
- [**json_document**](../json_document.md) and [**json_editable_document**](../json_editable_document.md) - the default specializations
- [**materialize**](../basic_json_view/materialize.md) - build a `basic_json` value from a view
## Version history
- Added in version 3.13.0.
@@ -5,7 +5,7 @@ template<typename I, typename V>
view_type insert(view_type array, I idx, V&& value);
```
Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
has `insert`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
Inserts `value` into `array` as a new element before position `idx`, which must not be past the end
@@ -55,7 +55,10 @@ validate with overload 2 first, if the original vector must survive a failed loa
## Exceptions
Throws [`parse_error.116`](../../home/exceptions.md#jsonexceptionparse_error116) if `image` is not one
On a big-endian target, throws [`type_error.320`](../../home/exceptions.md#jsonexceptiontype_error320) -- the same
exception [`save()`](save.md#exceptions) throws there, since the image format is little-endian only.
Otherwise throws [`parse_error.116`](../../home/exceptions.md#jsonexceptionparse_error116) if `image` is not one
`save()` could have written, or fails the requested `check`:
| message | when |
@@ -92,9 +95,6 @@ are checked once, however many nodes refer to it.
## Notes
**Little-endian targets only.** On a big-endian target, `load()` does not exist, just like
[`save()`](save.md#notes): the image format is little-endian, so a call fails to compile.
### `image_check` { #image_check }
```cpp
@@ -21,19 +21,17 @@ static basic_json_document parse(IteratorType first, IteratorType last,
Both overloads accept the same JSON text as [`BasicJsonType::parse()`](../basic_json/parse.md), with the same
`ignore_comments`/`ignore_trailing_commas` options, but build a [`basic_json_document`](index.md) (a flat index into
the input) instead of a tree of `BasicJsonType` values. They accept every input `BasicJsonType::parse()` takes, and in
addition a pointer to a null-terminated wide string (which `BasicJsonType::parse()` rejects). Contiguous inputs of
single-byte characters that stay alive can be borrowed; all others (streams, `#!cpp FILE*`, wide characters, which
must be converted to UTF-8, and non-contiguous iterators) are read into a copy that the document owns -- see the
Notes. Use [`parse_copy()`](parse_copy.md) to get an owned copy of a borrowable input
as well.
the input) instead of a tree of `BasicJsonType` values. They take the same inputs as `BasicJsonType::parse()`. Byte
inputs that stay alive can be borrowed; all others (streams, `#!cpp FILE*`, wide characters, non-contiguous
iterators) are read into a copy that the document owns -- see the Notes. Use [`parse_copy()`](parse_copy.md) to get an
owned copy of a borrowable input as well.
## Template parameters
`InputType`
: A compatible input, for instance:
- a `#!cpp std::string`, a `#!cpp std::string_view` (C++17), or a C-style array of single-byte characters
- a `#!cpp std::string`, `#!cpp std::string_view`, or a C-style array of single-byte characters
- a pointer to a null-terminated string of single-byte characters (`#!cpp char`, `#!cpp signed char`,
`#!cpp unsigned char`, `#!cpp std::uint8_t`)
- a container for which `#!cpp obj.data()` and `#!cpp obj.size()` give contiguous single-byte access, e.g.
@@ -49,10 +47,6 @@ as well.
`#!cpp std::string::iterator`; the iterators of single-byte characters are borrowed or read like the byte inputs
above, those of wide characters are converted to UTF-8
Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its low
surrogate, and a code point above `U+10FFFF` all yield a
[`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101).
## Parameters
`input` (in)
@@ -161,5 +155,3 @@ buffer of a given length, pass a pair of pointers: `#!cpp parse(ptr, ptr + len)`
## Version history
- Added in version 3.13.0.
- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
a code point above `U+10FFFF`) is rejected with `parse_error.101`.
@@ -13,7 +13,7 @@ editable, and it does not have to be `array`'s own document -- which is copied s
source document afterward; a `BasicJsonType` value; or anything `BasicJsonType` can be constructed from (numbers,
strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
has `push_back`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
## Template parameters
@@ -12,7 +12,7 @@ An edited document is written in its *current* state, with its values in documen
parser would have produced them for that JSON text: a member [`set`](set.md) added goes at the end, an
[`erase`](erase.md)d member leaves no trace, and a float that is not finite (NaN or positive/negative infinity)
becomes null, the same substitution [`dump()`](../basic_json_view/dump.md) makes. The same document always saves to
the same bytes -- also across `BasicJsonType` and the [`view_mode`](../view_mode.md), since the image reflects document order and
the same bytes -- also across `BasicJsonType` and `#!cpp Editable`, since the image reflects document order and
values only, not which specialization produced them.
## Return value
@@ -31,6 +31,9 @@ Throws [`type_error.320`](../../home/exceptions.md#jsonexceptiontype_error320) i
[discarded](is_discarded.md) -- a default-constructed document, or one a failed [`parse()`](parse.md)/
[`read()`](read.md) with `allow_exceptions == false` left discarded.
On a big-endian target, throws `type_error.320` with a different message instead: the image format is little-endian
only (see [Notes](#notes)).
Throws [`out_of_range.416`](../../home/exceptions.md#jsonexceptionout_of_range416) if the node count, the text, or
the decoded strings of the image would individually reach 4 GiB -- the same 32-bit offsets
[`parse()`](parse.md#exceptions) and, for edits, [`set`](set.md)/[`push_back`](push_back.md) are already limited to.
@@ -41,6 +44,9 @@ the decoded strings of the image would individually reach 4 GiB -- the same 32-b
[json.exception.type_error.320] cannot save a discarded json_document
```
```
[json.exception.type_error.320] json_document images need a little-endian target
```
```
[json.exception.out_of_range.416] images of 4 GiB or more are not supported by json_document
```
@@ -64,9 +70,9 @@ else -- see [`load`'s Exceptions](load.md#exceptions).
the *same* build on the *same* (little-endian) machine -- not as a long-term storage format. Keep the original
JSON text if you need to read a saved document back with a future library version.
**Little-endian targets only.** The image is written as raw little-endian bytes, with no byte-swapping. On a
big-endian target, `save()` and [`load`](load.md) do not exist: a call fails to compile rather than produce bytes a
big-endian reader could not interpret correctly.
**Little-endian only.** The image is written as raw little-endian bytes, with no byte-swapping. `save()` (and
[`load`](load.md)) throw `type_error.320` on a big-endian target rather than silently produce bytes a big-endian
reader could not interpret correctly.
## Examples
@@ -18,7 +18,7 @@ template<typename V>
view_type set(const json_pointer& ptr, V&& value);
```
Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
has `set`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
1. Replaces the value `target` refers to with `value`.
+1 -2
View File
@@ -80,8 +80,7 @@ None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics
Objects with 128 or more members get a hash index of their keys while parsing, so that a lookup in them takes
constant time on average.
2. Linear in `idx`: elements are skipped one at a time from the first one, since they are not a fixed size in the
index (unlike `BasicJsonType`'s array, which is random-access). Constant if no element of the array is an array
or object, since the elements are then adjacent in the index.
index (unlike `BasicJsonType`'s array, which is random-access).
3. Linear in the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
that level (as 1.) or the index into the array (as 2.).
+1 -2
View File
@@ -28,8 +28,7 @@ This exception does not carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.
Linear in the size of the array or object: unlike [`front()`](front.md), which only ever looks at the first
element, `back()` has to walk every element to find where they end, since elements are not a fixed size in the
index. Constant if no element of the array is an array or object, since the elements are then adjacent
in the index.
index.
## Notes
+3 -25
View File
@@ -27,25 +27,8 @@ For the types below, the conversion works directly on the flat index -- no `Basi
[`materialize()`](materialize.md)) does; `#!cpp std::map<std::string, basic_json_view>` keeps views of the members
instead of values
A default-constructible `T` whose `from_json()` accepts views reads the view directly as well, member by member, without
building a `BasicJsonType` value. This covers the types of the
[`NLOHMANN_DEFINE_TYPE_*`](../macros/nlohmann_define_type_intrusive.md) and
[`NLOHMANN_DEFINE_DERIVED_TYPE_*`](../macros/nlohmann_define_derived_type.md) macros and the enumerations of
[`NLOHMANN_JSON_SERIALIZE_ENUM`](../macros/nlohmann_json_serialize_enum.md), and any `from_json()` constrained to
accept views, e.g. with [`is_json_view`](../is_json_view.md). A `from_json()` that also accepts types that are no JSON
values at all, such as the unconstrained `#!cpp template<typename BasicJsonType> void from_json(const BasicJsonType&,
T&)` of [arbitrary type conversions](../../features/arbitrary_types.md), is not called with a view: it may use
`BasicJsonType` functions a view does not have. See [json_view](../../features/json_view.md).
!!! warning "Duplicate keys"
Such a `from_json()` looks members up in the view, where a repeated key finds the **first** member, while
`#!cpp materialize().get<T>()` sees the **last** one, as [`BasicJsonType::parse()`](../basic_json/parse.md)
keeps it: for `#!cpp {"x":1,"x":2}`, `#!cpp get<point>()` reads `#!cpp x == 1`. See
[Duplicate keys](../../features/json_view.md#duplicate-keys).
Every other `T` -- `#!cpp std::list`, `#!cpp std::pair`, `#!cpp std::array`, user types whose `from_json()` is
written for `BasicJsonType` only, ... -- is converted by `#!cpp materialize().get<T>()`: the subtree is built into a real `BasicJsonType`
Every other `T` -- `#!cpp std::list`, `#!cpp std::pair`, `#!cpp std::array`, enumerations, user types with a
`from_json()`, ... -- is converted by `#!cpp materialize().get<T>()`: the subtree is built into a real `BasicJsonType`
value first (as [`BasicJsonType::parse()`](../basic_json/parse.md) would), and converted from there exactly as
[`BasicJsonType::get<T>()`](../basic_json/get.md) would convert it.
@@ -72,13 +55,10 @@ Strong guarantee: there are no changes to the view or the document it refers to.
an element to `U` throws.
- For `#!cpp std::map`/`#!cpp std::unordered_map`: throws `type_error.302` if the value is not an object; otherwise,
whatever converting a member to the mapped type throws.
- For a `T` whose `from_json()` reads the view: whatever that `from_json()` throws; for the macros, the same
exceptions with the same messages as [`BasicJsonType::get<T>()`](../basic_json/get.md) of the same value.
- For every other `T`: whatever [`materialize().get<T>()`](../basic_json/get.md) throws -- typically `type_error.302`,
or whatever a user-provided `from_json()` throws.
None of the exceptions thrown directly by this function or by a `from_json()` that reads the view (the first four
bullets above) carry a
None of the exceptions thrown directly by this function (the first three bullets above) carry a
[`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) path: the view has no `BasicJsonType` value to point at. An
exception thrown while converting through `materialize()` (the last bullet) is different: it is thrown by a real
`BasicJsonType` value, so it **does** carry a `JSON_DIAGNOSTICS` path if `BasicJsonType` was built with it enabled.
@@ -96,8 +76,6 @@ document.
- `#!cpp std::map`/`#!cpp std::unordered_map`: linear in the number of members for walking them, plus the container's
own insertion cost per member (logarithmic for `#!cpp std::map`, amortized constant for `#!cpp
std::unordered_map`), times the complexity of converting one member to the mapped type.
- a `T` whose `from_json()` reads the view: the cost of that `from_json()`; for the macros, linear in the number of
members times the cost of a lookup, plus the cost of converting the members.
- every other `T`: the cost of [`materialize()`](materialize.md) and of destroying the `BasicJsonType` value
afterwards, plus that of [`BasicJsonType::get<T>()`](../basic_json/get.md).
@@ -5,14 +5,12 @@ template<typename T>
T& get_to(T& v) const;
```
Converts the value to `T` and stores it in `v`, in one of three ways:
Converts the value to `T` and stores it in `v`, in one of two ways:
- For the types that [`get<T>()`](get.md) converts directly -- arithmetic types, `#!cpp bool`,
`#!cpp std::nullptr_t`, [`string_view_t`](index.md#member-types), `#!cpp std::basic_string`, `BasicJsonType`,
`basic_json_view`, `#!cpp std::vector`, and `#!cpp std::map`/`#!cpp std::unordered_map` with string keys -- `v` is
assigned: `#!cpp v = get<T>()`.
- For a type whose `from_json()` accepts views (see [`get<T>()`](get.md)), that `from_json()` is called with the
view and the existing `v`, without building a `BasicJsonType` value.
- For every other type, the subtree is built into a `BasicJsonType` value and `#!cpp materialize().get_to(v)` is
called, i.e. `from_json()` is invoked with the existing `v`, exactly as
[`BasicJsonType::get_to()`](../basic_json/get_to.md) does.
+5 -14
View File
@@ -3,7 +3,7 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
template<typename BasicJsonType, view_mode Mode = view_mode::read_only>
template<typename BasicJsonType, bool Editable = false>
class basic_json_view;
```
@@ -37,7 +37,7 @@ Moving the document itself does not invalidate its views: the index is heap-allo
`#!cpp operator ValueType()`), and no `#!cpp get_ptr()` or `#!cpp get_ref()`; see [`get`](get.md).
`basic_json_view` itself is always read-only -- it never has a `set` or `push_back` of its own. A view of an
**editable** document (`#!cpp view_mode::editable`) sees every edit made through
**editable** document (`#!cpp Editable == true`) sees every edit made through
[`basic_json_document::set`](../basic_json_document/set.md) and
[`basic_json_document::push_back`](../basic_json_document/push_back.md): once a value is changed, every view that
still refers to it -- including ones taken before the change -- reads the new value. See
@@ -49,10 +49,9 @@ still refers to it -- including ones taken before the change -- reads the new va
: a specialization of [`basic_json`](../basic_json/index.md), matching the
[`basic_json_document`](../basic_json_document/index.md) the view was taken from.
`Mode`
: a [`view_mode`](../view_mode.md): whether the view is of an editable document, matching the
[`basic_json_document`](../basic_json_document/index.md) it was taken from (optional, `#!cpp view_mode::read_only` by
default). See [Edits](../basic_json_document/index.md#edits).
`Editable`
: whether the view is of an editable document, matching the [`basic_json_document`](../basic_json_document/index.md)
it was taken from (optional, `#!cpp false` by default). See [Edits](../basic_json_document/index.md#edits).
## Specializations
@@ -64,7 +63,6 @@ still refers to it -- including ones taken before the change -- reads the new va
## Member types
- **basic_json_type** - `BasicJsonType` (it also marks the class for [`is_json_view`](../is_json_view.md))
- **value_t** - the JSON type enumeration, see [`basic_json::value_t`](../basic_json/value_t.md)
- **string_t**, **number_integer_t**, **number_unsigned_t**, **number_float_t**, **json_pointer** - the corresponding
member types of `BasicJsonType`
@@ -145,13 +143,6 @@ still refers to it -- including ones taken before the change -- reads the new va
- [**source_offset**](source_offset.md) - byte offset of this value in the document's source text
## See also
- [Zero-copy JSON views](../../features/json_view.md) - guide to documents and views
- [**basic_json_document**](../basic_json_document/index.md) - the document that owns the parsed data
- [**json_view**](../json_view.md) and [**json_editable_view**](../json_editable_view.md) - the default specializations
- [**materialize**](materialize.md) - build a `basic_json` value from a view
## Version history
- Added in version 3.13.0.
@@ -86,8 +86,7 @@ None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics
Objects with 128 or more members get a hash index of their keys while parsing, so that a lookup in them takes
constant time on average.
2. Linear in `idx`: elements are skipped one at a time from the first one, since they are not a fixed size in the
index (unlike `BasicJsonType`'s array, which is random-access). Constant if no element of the array is an array
or object, since the elements are then adjacent in the index.
index (unlike `BasicJsonType`'s array, which is random-access).
3. Linear in the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
that level (as 1.) or the index into the array (as 2.).
@@ -51,4 +51,4 @@ byte_container_with_subtype(container_type&& container, subtype_type subtype);
## Version history
Added in version 3.8.0.
Since version 3.8.0.
@@ -39,4 +39,4 @@ Constant.
## Version history
Added in version 3.8.0.
Since version 3.8.0.
@@ -42,4 +42,4 @@ Constant.
## Version history
Added in version 3.8.0.
Since version 3.8.0.
@@ -29,14 +29,6 @@ specific naming scheme in order to override the binary type.
- [**has_subtype**](has_subtype.md) - return whether the value has a subtype
- [**clear_subtype**](clear_subtype.md) - clears the binary subtype
## See also
- [Binary values](../../features/binary_values.md) - how binary values and subtypes are handled
- [**binary**](../basic_json/binary.md) - create a binary array value
- [**get_binary**](../basic_json/get_binary.md) - get a reference to the stored binary value
- [**binary_t**](../basic_json/binary_t.md) - type for binary arrays
- [Binary formats](../../features/binary_formats/index.md) - formats that can store binary values
## Version history
- Added in version 3.8.0.
@@ -44,4 +44,4 @@ Constant.
## Version history
Added in version 3.8.0.
Since version 3.8.0.
-55
View File
@@ -1,55 +0,0 @@
# <small>nlohmann::</small>is_json_view
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
template<typename T>
struct is_json_view;
```
A type trait: `#!cpp is_json_view<T>::value` is `#!cpp true` if `T` is a [`basic_json_view`](basic_json_view/index.md)
of any `BasicJsonType` and any [`view_mode`](view_mode.md) -- [`json_view`](json_view.md),
[`json_editable_view`](json_editable_view.md), [`ordered_json_view`](ordered_json_view.md), ... -- and
`#!cpp false` otherwise, for [`basic_json`](basic_json/index.md) as well.
It is meant for constraining templates that accept views, in particular a `from_json()` that should read views
directly: [`get<T>()`](basic_json_view/get.md) on a view calls a `from_json()` with the view only if that `from_json()`
accepts views but not arbitrary types.
## Template parameters
`T`
: the type to check (without cv-qualifiers or references)
## Notes
A view is recognized by its member type `basic_json_type` (a [`basic_json`](basic_json/index.md) specialization) and
its [`materialize()`](basic_json_view/materialize.md) returning that type, so the trait needs no declaration of the
view class.
## Examples
??? example
The example below shows the trait, and a `from_json()` constrained to `json` values and views: `get<T>()` on a view
reads the view directly.
```cpp
--8<-- "examples/is_json_view.cpp"
```
Output:
```
--8<-- "examples/is_json_view.output"
```
## See also
- [basic_json_view](basic_json_view/index.md) - a handle to one value of a document
- [get](basic_json_view/get.md) - which conversions read the view directly
- [view_mode](view_mode.md) - read-only or editable
## Version history
Added in version 3.13.0.
+1 -1
View File
@@ -30,4 +30,4 @@ types.
## Version history
Added in version 1.0.0.
Since version 1.0.0.
+1 -1
View File
@@ -32,4 +32,4 @@ specialization.
## Version history
Added in version 3.13.0.
Since version 3.13.0.
@@ -3,7 +3,7 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
using json_editable_document = basic_json_document<json, view_mode::editable>;
using json_editable_document = basic_json_document<json, true>;
```
This type is an **editable** [`basic_json_document`](basic_json_document/index.md) of the default
@@ -40,4 +40,4 @@ parsing, without ever rewriting the source text -- see [Edits](basic_json_docume
## Version history
Added in version 3.13.0.
Since version 3.13.0.
+2 -2
View File
@@ -3,7 +3,7 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
using json_editable_view = basic_json_view<json, view_mode::editable>;
using json_editable_view = basic_json_view<json, true>;
```
This type is a [`basic_json_view`](basic_json_view/index.md) of a value of a
@@ -38,4 +38,4 @@ still referring to it seeing the change, see [Edits](basic_json_document/index.m
## Version history
Added in version 3.13.0.
Since version 3.13.0.
@@ -51,5 +51,5 @@ operator string_t() const
## Version history
- Added in version 2.0.0.
- Since version 2.0.0.
- Changed type to `string_t` and deprecated in version 3.11.0.
@@ -49,5 +49,5 @@ ptr == json_pointer(ptr.to_string());
## Version history
- Added in version 2.0.0.
- Since version 2.0.0.
- Changed return type to `string_t` in version 3.11.0.
-7
View File
@@ -59,13 +59,6 @@ leading `-` sign.
- [**start_object**](start_object.md) (_virtual_) - the beginning of an object was read
- [**string**](string.md) (_virtual_) - a string value was read
## See also
- [SAX interface](../../features/parsing/sax_interface.md) - guide to event-based parsing
- [**sax_parse**](../basic_json/sax_parse.md) - generate SAX events from an input
- [**parse**](../basic_json/parse.md) - DOM parsing, with optional [parser callbacks](../../features/parsing/parser_callbacks.md)
- [Parse exceptions](../../features/parsing/parse_exceptions.md)
## Version history
- Added in version 3.2.0.
+1 -1
View File
@@ -31,4 +31,4 @@ This type is a [`basic_json_view`](basic_json_view/index.md) of a value of a [`j
## Version history
Added in version 3.13.0.
Since version 3.13.0.
+3 -10
View File
@@ -43,6 +43,8 @@ header. See also the [macro overview page](../../features/macros.md).
- [**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
- [**JSON_VIEW_NO_SIMD**](json_view_no_simd.md) - use only portable code in the parser of `json_view.hpp`
- [**JSON_VIEW_USE_SSSE3**](json_view_use_ssse3.md) - validate non-ASCII strings with SSSE3 in the parser of `json_view.hpp`
## Library version
@@ -135,13 +137,4 @@ header. See also the [macro overview page](../../features/macros.md).
- [**NLOHMANN_DEFINE_DERIVED_TYPE_NON_INTRUSIVE_WITH_DEFAULT_WITH_NAMES**](nlohmann_define_type_with_names.md) - serialize/deserialize
a derived class; uses default values; uses custom names
- [**NLOHMANN_DEFINE_DERIVED_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE_WITH_NAMES**](nlohmann_define_type_with_names.md) - serialize a derived
class; uses custom names
## See also
- [Macros](../../features/macros.md) - guide to the supported macros
- [Runtime assertions](../../features/assertions.md)
- [Arbitrary type conversions](../../features/arbitrary_types.md) - using the `NLOHMANN_DEFINE_TYPE_*` macros
- [Enum conversion](../../features/enum_conversion.md) - using `NLOHMANN_JSON_SERIALIZE_ENUM`
- [The `nlohmann` namespace](../../features/namespace.md)
- [CMake integration](../../integration/cmake.md) - setting macros from the build system
class; uses custom names
+1 -3
View File
@@ -5,8 +5,7 @@
```
When defined, the library uses only portable C++ code where it would otherwise use vector instructions: when scanning
strings during parsing, and when writing floating-point numbers during serialization. This includes the parser of
[`basic_json_document`](../basic_json_document/index.md) (`<nlohmann/json_view.hpp>`).
strings during parsing, and when writing floating-point numbers during serialization.
The macro is an escape hatch, for example for toolchains that cannot compile the vector code, for sanitizers or
analyzers that do not understand it, or to compare the speed of both variants. It does not change any result: values,
@@ -78,7 +77,6 @@ By default, `#!cpp JSON_NO_SIMD` is not defined, and vector instructions are use
- [**JSON_USE_SIMDUTF**](json_use_simdutf.md) - use the simdutf library to accelerate UTF-8 validation
- [**JSON_DISABLE_STREAM_BULK_SCAN**](json_disable_stream_bulk_scan.md) - read a `std::istream` one character at a time
- [Parsing: input sources and performance](../../features/parsing/index.md#input-sources-and-performance)
- [json_view](../../features/json_view.md) - the zero-copy view, whose parser the macro also affects
## Version history
@@ -0,0 +1,52 @@
# JSON_VIEW_NO_SIMD
```cpp
#define JSON_VIEW_NO_SIMD
```
When defined, the parser of [`basic_json_document`](../basic_json_document/index.md) (`<nlohmann/json_view.hpp>`)
uses only portable C++ to scan strings. By default, it scans long runs of string bytes 16 at a time with NEON on
AArch64 (with GCC and Clang) and SSE2 on x86-64, which are part of the baseline instruction sets of these
architectures, and validates non-ASCII text with NEON (or SSSE3, see
[`JSON_VIEW_USE_SSSE3`](json_view_use_ssse3.md)).
The same input is accepted or rejected either way, with the same values, and errors are reported the same way; only
the speed differs. The macro exists for platforms whose compilers lack the intrinsics headers, and to test the portable
code.
!!! note "ABI compatibility"
The macro selects between two definitions of the same inline functions. Whether it is defined is encoded in the
[namespace](../../features/namespace.md) (tag `_vns`), 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.
## Default definition
By default, `#!cpp JSON_VIEW_NO_SIMD` is not defined, and the vector code is used where available.
```cpp
#undef JSON_VIEW_NO_SIMD
```
## Examples
??? example
The code below uses the portable string scanning of the view.
```cpp
#define JSON_VIEW_NO_SIMD
#include <nlohmann/json_view.hpp>
...
```
## See also
- [JSON_VIEW_USE_SSSE3](json_view_use_ssse3.md) - validate non-ASCII strings with SSSE3 on x86-64
- [json_view](../../features/json_view.md) - the zero-copy view
## Version history
- Added in version 3.13.0.
@@ -0,0 +1,53 @@
# JSON_VIEW_USE_SSSE3
```cpp
#define JSON_VIEW_USE_SSSE3
```
When defined on x86-64, the parser of [`basic_json_document`](../basic_json_document/index.md)
(`<nlohmann/json_view.hpp>`) validates non-ASCII text in strings with SSSE3 without asking the CPU first.
By default, the parser checks once at run time whether the CPU has SSSE3 (all x86-64 CPUs since about 2011 have it)
and then validates non-ASCII text 16 bytes at a time, using the "lookup4" algorithm of
[simdjson](https://github.com/simdjson/simdjson); on CPUs without SSSE3, it validates one UTF-8 sequence at a time.
The vector check is compiled for SSSE3 with a function attribute (GCC 4.9 and later, Clang), so this needs no compiler
option. With MSVC, the check uses `__cpuid`. On AArch64, the vector check uses NEON and is always on.
Define the macro only together with a compiler option that enables SSSE3 (e.g. `-mssse3`, or `-march=` with a CPU that
has it), and only for programs that run on such CPUs. It saves the check of the CPU, which costs little. The same
input is accepted or rejected either way; only the speed of non-ASCII text differs.
!!! note "ABI compatibility"
The macro selects between two definitions of the same inline functions. Whether it is defined is encoded in the
[namespace](../../features/namespace.md) (tag `_vssse3`, on every architecture), 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.
## Default definition
By default, `#!cpp JSON_VIEW_USE_SSSE3` is not defined.
```cpp
#undef JSON_VIEW_USE_SSSE3
```
## Examples
??? example
With CMake, for a program that only runs on CPUs with SSSE3:
```cmake
target_compile_definitions(your_target PRIVATE JSON_VIEW_USE_SSSE3)
target_compile_options(your_target PRIVATE -mssse3)
```
## See also
- [JSON_VIEW_NO_SIMD](json_view_no_simd.md) - use only portable code in the view's parser
- [JSON_USE_SIMDUTF](json_use_simdutf.md) - validate UTF-8 with simdutf in `basic_json`'s parser
## Version history
- Added in version 3.13.0.
@@ -147,13 +147,6 @@ void to_json(BasicJsonType& j, const B& b) {
See Implementation limits for [NLOHMANN_DEFINE_TYPE_INTRUSIVE](nlohmann_define_type_intrusive.md) and
[NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE](nlohmann_define_type_non_intrusive.md), respectively.
!!! info "Views"
The generated `from_json()` also reads the views of [`json_document`](../json_document.md)s
(`<nlohmann/json_view.hpp>`): [`get<T>()`](../basic_json_view/get.md) on a view looks the members up in the
view, without building a `json` value first. The base part is read from the view as well if the base's
`from_json()` accepts views, and from [`materialize()`](../basic_json_view/materialize.md) otherwise.
## Examples
??? example "Example: (1) NLOHMANN_DEFINE_DERIVED_TYPE_INTRUSIVE"
@@ -199,5 +192,3 @@ void to_json(BasicJsonType& j, const B& b) {
6. Added in version 3.12.0.
All six macros were changed to allow an empty member list in version 3.13.0.
The generated `from_json()` reads the views of `json_document`s since version 3.13.0.
@@ -81,12 +81,6 @@ See the examples below for the concrete generated code.
that serializes a struct's members positionally into a JSON array; for that, write `to_json`/`from_json` by
hand, building/reading a `json::array()` of the members in order.
!!! info "Views"
The generated `from_json()` also reads the views of [`json_document`](../json_document.md)s
(`<nlohmann/json_view.hpp>`): [`get<T>()`](../basic_json_view/get.md) on a view looks the members up in the
view, without building a `json` value first.
## Examples
??? example "Example: (1) NLOHMANN_DEFINE_TYPE_INTRUSIVE"
@@ -195,5 +189,3 @@ See the examples below for the concrete generated code.
All three macros were changed to work with any `basic_json` specialization (not only `nlohmann::json`) in version 3.12.0,
and to allow an empty member list in version 3.13.0.
The generated `from_json()` reads the views of `json_document`s since version 3.13.0.
@@ -80,12 +80,6 @@ See the examples below for the concrete generated code.
that serializes a struct's members positionally into a JSON array; for that, write `to_json`/`from_json` by
hand, building/reading a `json::array()` of the members in order.
!!! info "Views"
The generated `from_json()` also reads the views of [`json_document`](../json_document.md)s
(`<nlohmann/json_view.hpp>`): [`get<T>()`](../basic_json_view/get.md) on a view looks the members up in the
view, without building a `json` value first.
## Examples
??? example "Example: (1) NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE"
@@ -194,5 +188,3 @@ See the examples below for the concrete generated code.
All three macros were changed to work with any `basic_json` specialization (not only `nlohmann::json`) in version 3.12.0,
and to allow an empty member list in version 3.13.0.
The generated `from_json()` reads the views of `json_document`s since version 3.13.0.
@@ -39,6 +39,6 @@ the library.
## Version history
- Added in version 3.11.0. Changed inline namespace name in version 3.11.2. Added the ABI tag `_dp` in
version 3.12.0, and the ABI tags `_bics`, `_psp`, `_snul`, `_sbu8`, `_ekmo`, `_dsbs`, `_dufio`, and `_ns` in
version 3.13.0; see
version 3.12.0, and the ABI tags `_bics`, `_psp`, `_snul`, `_sbu8`, `_ekmo`, `_dsbs`, `_dufio`, `_ns`, `_vns`,
and `_vssse3` in version 3.13.0; see
[`nlohmann` Namespace](../../features/namespace.md#structure).
@@ -45,12 +45,6 @@ inline void from_json(const BasicJsonType& j, type& e);
Define [`JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS`](json_use_objects_for_enum_keyed_maps.md) to store them as objects
with the converted keys. Such maps can be read from both forms.
!!! info "Views"
The generated `from_json()` also reads the views of [`json_document`](../json_document.md)s
(`<nlohmann/json_view.hpp>`), comparing the view with the entries of the mapping, without building a `json` value
first.
## Examples
??? example "Example: Basic usage"
@@ -94,5 +88,3 @@ inline void from_json(const BasicJsonType& j, type& e);
## Version history
Added in version 3.4.0.
The generated `from_json()` reads the views of `json_document`s since version 3.13.0.
@@ -48,12 +48,6 @@ inline void from_json(const BasicJsonType& j, type& e);
Define [`JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS`](json_use_objects_for_enum_keyed_maps.md) to store them as objects
with the converted keys. Such maps can be read from both forms.
!!! info "Views"
The generated `from_json()` also reads the views of [`json_document`](../json_document.md)s
(`<nlohmann/json_view.hpp>`), comparing the view with the entries of the mapping, without building a `json` value
first.
## Examples
??? example "Example: Basic usage"
+1 -1
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@@ -42,4 +42,4 @@ parsing an object of `n` keys costs O(n²) rather than O(n log n). See
## Version history
Added in version 3.9.0.
Since version 3.9.0.
@@ -35,4 +35,4 @@ of object keys, instead of sorting them like [`json_document`](json_document.md)
## Version history
Added in version 3.13.0.
Since version 3.13.0.
@@ -3,7 +3,7 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
using ordered_json_editable_document = basic_json_document<ordered_json, view_mode::editable>;
using ordered_json_editable_document = basic_json_document<ordered_json, true>;
```
This type is an **editable** [`basic_json_document`](basic_json_document/index.md) of the
@@ -44,4 +44,4 @@ members [`set`](basic_json_document/set.md) added -- instead of sorting them lik
## Version history
Added in version 3.13.0.
Since version 3.13.0.
@@ -3,7 +3,7 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
using ordered_json_editable_view = basic_json_view<ordered_json, view_mode::editable>;
using ordered_json_editable_view = basic_json_view<ordered_json, true>;
```
This type is a [`basic_json_view`](basic_json_view/index.md) of a value of an
@@ -37,4 +37,4 @@ This type is a [`basic_json_view`](basic_json_view/index.md) of a value of an
## Version history
Added in version 3.13.0.
Since version 3.13.0.
+1 -1
View File
@@ -32,4 +32,4 @@ This type is a [`basic_json_view`](basic_json_view/index.md) of a value of an
## Version history
Added in version 3.13.0.
Since version 3.13.0.
-80
View File
@@ -1,80 +0,0 @@
# <small>nlohmann::</small>view_mode
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
enum class view_mode : std::uint8_t
{
read_only,
editable
};
```
The second template parameter of [`basic_json_document`](basic_json_document/index.md) and
[`basic_json_view`](basic_json_view/index.md): whether a document can be changed after parsing, and whether a view is
of such a document.
`read_only`
: the default: the document is parsed once and then only read. It carries none of the bookkeeping edits need, and
calling [`set`](basic_json_document/set.md), [`push_back`](basic_json_document/push_back.md),
[`insert`](basic_json_document/insert.md), or [`erase`](basic_json_document/erase.md) on it fails to compile.
`editable`
: the document also offers [`set`](basic_json_document/set.md), [`push_back`](basic_json_document/push_back.md),
[`insert`](basic_json_document/insert.md), and [`erase`](basic_json_document/erase.md); its views see every edit,
see [Edits](basic_json_document/index.md#edits).
The shortcuts name both modes: [`json_document`](json_document.md) and [`json_view`](json_view.md) are read-only,
[`json_editable_document`](json_editable_document.md) and [`json_editable_view`](json_editable_view.md) are editable
(and likewise for `ordered_json`).
## Notes
The mode is part of the view's type, and there is no conversion between the two modes: a read-only view reads a
container in place, while a view of an editable document follows the links that edits leave behind. A function that
accepts views therefore names the modes it accepts in its signature:
```cpp
// views of editable documents only
template<typename BasicJsonType>
void f(basic_json_view<BasicJsonType, view_mode::editable> v);
// views of read-only documents only
template<typename BasicJsonType>
void f(basic_json_view<BasicJsonType, view_mode::read_only> v);
// either
template<typename BasicJsonType, view_mode Mode>
void f(basic_json_view<BasicJsonType, Mode> v);
```
A function that takes a [`json_view`](json_view.md) accepts neither an [`ordered_json_view`](ordered_json_view.md)
nor a [`json_editable_view`](json_editable_view.md). Views of the two modes still compare with
[`operator==`](basic_json_view/operator_eq.md).
## Examples
??? example
The example below shows a function template that accepts the views of both modes, and one that accepts only
views of editable documents.
```cpp
--8<-- "examples/view_mode.cpp"
```
Output:
```
--8<-- "examples/view_mode.output"
```
## See also
- [basic_json_document](basic_json_document/index.md) - a parsed JSON text
- [basic_json_view](basic_json_view/index.md) - a handle to one value of a document
- [json_editable_document](json_editable_document.md) - an editable document of `json`
## Version history
Added in version 3.13.0.
+1 -1
View File
@@ -58,7 +58,7 @@ particular, a 3.x release does not:
- remove or rename a documented macro, CMake option, CMake target, or header, or change what a documented macro does.
Exceptions to these rules, for instance when fixing a bug requires changing the exception a function throws, are
documented in the [release notes](../home/releases/index.md).
documented in the [release notes](../home/releases.md).
The following are **not** part of the public API and may change in any release, including patch releases:
-29
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@@ -18,32 +18,3 @@
white-space: nowrap;
cursor: help;
}
/* byte layout tables of the binary formats */
.md-typeset .byte-layout td code {
white-space: pre-wrap;
}
.md-typeset .bl {
display: inline-block;
padding: 0 .25em;
border-radius: .2em;
font-family: var(--md-code-font-family);
font-size: .85em;
white-space: nowrap;
}
.md-typeset .bl-t {
background-color: rgba(66, 133, 244, .25);
box-shadow: inset 0 -.12em 0 rgba(66, 133, 244, .8);
}
.md-typeset .bl-l {
background-color: rgba(251, 140, 0, .25);
box-shadow: inset 0 -.12em 0 rgba(251, 140, 0, .8);
}
.md-typeset .bl-d {
background-color: rgba(67, 160, 71, .25);
box-shadow: inset 0 -.12em 0 rgba(67, 160, 71, .8);
}
@@ -1,18 +0,0 @@
#include <iostream>
#include <string>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// a valid JSON text, given as UTF-16
const std::u16string valid_text = u"{\"name\":\"\u00e9\"}";
// an invalid JSON text, given as UTF-16
const std::u16string invalid_text = u"{\"name\":\"\u00e9\",}";
std::cout << std::boolalpha
<< json::accept(valid_text) << ' '
<< json::accept(invalid_text) << '\n';
}
@@ -1 +0,0 @@
true false
@@ -1,34 +0,0 @@
#include <iostream>
#include <type_traits>
#include <nlohmann/json_view.hpp>
using nlohmann::json;
namespace ns
{
struct person
{
std::string name;
int age = 0;
};
// reads json values and views (of any document type), but nothing else
template < typename J, typename std::enable_if < nlohmann::is_json_view<J>::value || std::is_same<J, json>::value, int >::type = 0 >
void from_json(const J& j, person& p)
{
p.name = j.at("name").template get<std::string>();
p.age = j.at("age").template get<int>();
}
} // namespace ns
int main()
{
std::cout << std::boolalpha
<< nlohmann::is_json_view<nlohmann::json_view>::value << ' '
<< nlohmann::is_json_view<nlohmann::ordered_json_editable_view>::value << ' '
<< nlohmann::is_json_view<json>::value << '\n';
const nlohmann::json_document doc = nlohmann::json_document::parse(R"({"name": "Ada", "age": 36})");
const auto p = doc.root().get<ns::person>(); // reads the view, no json value is built
std::cout << p.name << ' ' << p.age << '\n';
}
@@ -1,2 +0,0 @@
true true false
Ada 36
@@ -5,7 +5,7 @@ using ordered_json_editable_document = nlohmann::ordered_json_editable_document;
int main()
{
// ordered_json_editable_document is basic_json_document<nlohmann::ordered_json, nlohmann::view_mode::editable>
// ordered_json_editable_document is basic_json_document<nlohmann::ordered_json, true>
ordered_json_editable_document doc = ordered_json_editable_document::parse(R"({"z": 1, "a": 2, "m": 3})");
doc.set(doc.root(), "b", 4); // set() always appends a new member at the end
@@ -1,27 +0,0 @@
#include <iostream>
#include <string>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// the same JSON text, given in different encodings
const std::string utf8 = "{\"name\":\"\u00e9\"}";
const std::u16string utf16 = u"{\"name\":\"\u00e9\"}";
const std::u32string utf32 = U"{\"name\":\"\u00e9\"}";
const std::wstring wide = L"{\"name\":\"\u00e9\"}";
// the encoding is deduced from the character type of the input, and all
// of them yield the same value
std::cout << json::parse(utf8) << '\n'
<< json::parse(utf16) << '\n'
<< json::parse(utf32) << '\n'
<< json::parse(wide) << '\n';
// a wide string literal works as well: u"..." is UTF-16, U"..." is UTF-32
std::cout << json::parse(u"[1, 2, 3]") << '\n';
// iterators over wide characters work as well
std::cout << json::parse(utf16.begin(), utf16.end()) << '\n';
}
@@ -1,6 +0,0 @@
{"name":"é"}
{"name":"é"}
{"name":"é"}
{"name":"é"}
[1,2,3]
{"name":"é"}
-29
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@@ -1,29 +0,0 @@
#include <iostream>
#include <nlohmann/json_view.hpp>
using nlohmann::basic_json_view;
using nlohmann::view_mode;
// accepts the views of read-only and of editable documents, of json and of ordered_json
template<typename BasicJsonType, view_mode Mode>
std::size_t count_members(basic_json_view<BasicJsonType, Mode> v)
{
return v.is_object() ? v.size() : 0;
}
// accepts only the views of editable documents
template<typename BasicJsonType>
bool is_edited(basic_json_view<BasicJsonType, view_mode::editable> v)
{
return v.is_string() && v.get_string() == "edited";
}
int main()
{
const nlohmann::json_document doc = nlohmann::json_document::parse(R"({"a": 1, "b": 2})");
nlohmann::json_editable_document edoc = nlohmann::json_editable_document::parse(R"({"a": 1})");
edoc.set(edoc.root()["a"], "edited");
std::cout << count_members(doc.root()) << ' ' << count_members(edoc.root()) << '\n';
std::cout << std::boolalpha << is_edited(edoc.root()["a"]) << '\n';
}
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