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Author SHA1 Message Date
Niels Lohmann 42ab1fa573 Regenerate the amalgamated headers
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:22 +02:00
Niels Lohmann 624f4b030d Silence a clang-tidy use-after-move finding in the json_view test
const_text is const, so std::move does not move from it; the second call
is part of the const rvalue test.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:21 +02:00
Niels Lohmann 758b6a76fe Read the node array base after emit() in the view builder's open()
emit() moves the node array when it grows, and the subtraction read base
in the same expression, so the order was unspecified. MSVC Release builds
without forced inlining read the old base; the container index then
pointed outside the array and close() wrote out of bounds.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:20 +02:00
Niels Lohmann 6052e793c0 Make json_view.hpp pass include-what-you-use
ci_single_binaries runs IWYU with --error on every header. For json_view.hpp
it suggested adding <array> (std::array is used), the headers that json.hpp
already provides (abi_config, abi_macros, input_adapters, json_pointer,
cpp_future, string_concat, value_t, json_fwd), and <version> for
std::nullptr_t, and removing <cstddef>.

- include <array>
- keep <cstddef> (nullptr_t, size_t; IWYU attributes them to <version> and <cstring>)
- tell IWYU not to suggest the headers that json.hpp provides: the amalgamated
  json_view.hpp only includes json.hpp, so including them here would duplicate
  their definitions
- export json.hpp, keep macro_unscope.hpp, and drop the unused forward declaration of the document class

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:19 +02:00
Niels Lohmann 0c3caee646 Make max_input_size a function (GCC -Wunused-const-variable)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:18 +02:00
Niels Lohmann 624660b04e Check the steps of the deep-nesting test separately
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:17 +02:00
Niels Lohmann d7f97d140d Suppress Flawfinder's read() finding on the deleted overload
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:17 +02:00
Niels Lohmann e587d3e5fd Annotate intentional patterns in unit-json_view.cpp for clang-tidy
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:16 +02:00
Niels Lohmann bed7ff801e Fix clang-tidy findings in unit-json_view_builder.cpp
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:15 +02:00
Niels Lohmann cd787fb0f7 Give document_data a user-provided constructor
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:14 +02:00
Niels Lohmann 88dc1e6ae2 Fuzz json_document with exact-size buffers and parse options
The fuzzer only parsed a std::string with default options. Also parse an
exact-size byte vector, which has no NUL after its last byte and takes the
bounds-checked path, and derive ignore_comments and ignore_trailing_commas
from the first input byte, comparing against json::parse and json::accept
with the same options.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:13 +02:00
Niels Lohmann 18c4935d99 Align the banner comment of json_view.hpp
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:12 +02:00
Niels Lohmann f0fc46fa03 Remove the unused legacy_discarded_value_comparison from abi_config
Nothing reads it: the view does not compare values.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:12 +02:00
Niels Lohmann 4dcba03757 State the exact input size limit of json_document
The check rejects inputs of 0xFFFFFFF0 bytes or more, but the exception
message and the documentation said 4 GiB. Name the limit once
(max_input_size), and state 4 GiB minus 16 bytes in the message and the
documentation. Test the limit with a container that only claims the size.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:11 +02:00
Niels Lohmann 402cb4f835 Check the node array size for overflow
reserve(n) and the growth of the index computed n * sizeof(node) without a
check, which wraps around on 32-bit targets for inputs of about 1 GiB and
allocates a too small array. Throw std::bad_alloc for a count beyond the
address space and clamp the growth step to it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:10 +02:00
Niels Lohmann 32d4f7fa33 Store node integers by halves on big-endian targets
The non-little-endian path of the node writer wrote the integer's native
word over len and next, so len got the high half there. Compose and split
the value explicitly (len is the low half, next the high half); the
little-endian path stays a plain memcpy.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:09 +02:00
Niels Lohmann f4aceabef3 Delete json_document::root() on temporary documents
auto v = json_document::parse(text).root() compiled and left the view
dangling. Delete the overload for rvalue documents, take a named document
in the tests, and document the lifetime rule.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:08 +02:00
Niels Lohmann 6952ff6363 Remove the conversion to bool from json_view
explicit operator bool meant "refers to a value", which silently differs
from what a basic_json converts to. Use !v.is_discarded() instead.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:07 +02:00
Niels Lohmann f5f864298c Copy const rvalue strings and document the accepted inputs
json_document::parse(std::move(const_string)) failed to compile with
"no matching read_kind": only a non-const rvalue std::string can be moved
from. Treat a const rvalue as a copied byte container.

parse() does not accept everything BasicJsonType::parse() does: a FILE*
and pointers to or arrays of wide characters are rejected at compile time.
List the supported inputs instead.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:06 +02:00
Niels Lohmann 40dbea3de2 Reject integer lengths in json_document::parse
parse(ptr, len) compiled: len converted to allow_exceptions, and ptr was
read as a C string, past the end of a buffer without a terminating NUL.
Delete the overloads of parse, parse_copy, accept, and read that take an
integer other than bool where the flags are expected.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:06 +02:00
Niels Lohmann 80e2aae3e2 Exclude libstdc++'s string_view comparison from the sign-change check
basic_string_view::_S_compare stores the difference of two lengths in a
signed difference_type on purpose, which -fsanitize=integer reports for
every comparison with a shorter view (test-json_view_cpp17).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:05 +02:00
Niels Lohmann f56f36c188 Fix document_data for old Clang (3.4-3.6)
Drop the empty braced NSDMIs of the std::string members: old Clang
rejects the defaulted constructor when it is used by a member
initializer before the end of the class definition.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:04 +02:00
Niels Lohmann 0f6c4dda11 Add json_document and json_view: node index, parser, and document
Add json_document and json_view, a read-only, zero-copy index of a
JSON text, as the first public slice of the zero-copy view (#5295).

A parse produces a flat array of 16-byte nodes in document order,
one per value and one per object key. Strings stay in the source
text; escaped strings are decoded into an arena. Integers are
converted while their digits are in the cache; floats keep only
their digit layout and are converted on read. Containers store the
size of their subtree, so a reader can step over one in constant
time. A document makes a handful of allocations, however many
values it has.

The parser accepts exactly what json::parse accepts, with every
combination of ignore_comments and ignore_trailing_commas, with and
without a trailing NUL, and under JSON_STRICT_NUL_HANDLING. It is
portable C++11 and does not depend on byte order.

basic_json_document adds parse, parse_copy, accept, read (reuses a
document's memory), root, is_discarded, source, owns_source,
node_count, memory_usage, and shrink_to_fit. basic_json_view adds
type, the is_* queries, operator bool, size, empty, materialize,
and source_offset. A parse error throws the same exception
basic_json::parse would throw for the same input, message and
position included.

detail::abi_config keeps JSON_STRICT_NUL_HANDLING and
JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON readable after json.hpp
undefines them, in the ABI namespace so they always match the
basic_json in use.

A NUL byte that ends a // comment is the end of the input, as in
parse() since #5696.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:53:03 +02:00
347 changed files with 6058 additions and 607292 deletions

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+3 -10
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@@ -108,16 +108,9 @@ The tests are located in [`tests/src/unit-*.cpp`](https://github.com/nlohmann/js
are structured along the features of the library or the nature of the tests. Usually, it should be clear from the
context which existing file needs to be extended, and only very few cases require creating new test files.
When fixing a bug, edit `unit-regression3.cpp` and add a section referencing the fixed issue. Tests that need C++17 or
C++20 go into `unit-regression3-cpp17.cpp` or `unit-regression3-cpp20.cpp` instead, so the large file is not rebuilt
for every C++ standard. `unit-regression2.cpp` holds the older tests; the two files exist because a single one grew
large enough for the MinGW linker to fail relocating it, so please keep adding to the smaller file rather than growing
the larger one.
To keep compile times down, several test files are compiled together as one translation unit. This sets a few rules
for test files, such as giving file-scope helpers file-specific names. See the README in the
[`tests`](https://github.com/nlohmann/json/tree/develop/tests) folder for how the tests are built and what to keep in
mind when adding them.
When fixing a bug, edit `unit-regression3.cpp` and add a section referencing the fixed issue.
`unit-regression2.cpp` holds the older tests; the two files exist because a single one grew large enough for the
MinGW linker to fail relocating it, so please keep adding to the smaller file rather than growing the larger one.
#### Exceptions
+3 -4
View File
@@ -62,13 +62,12 @@ labels:
- "include/nlohmann/detail/view/.*"
- "single_include/nlohmann/json_view\\.hpp"
- "tests/src/unit-json_view.*"
- "tests/src/json_view_test_helpers\\.hpp"
- "tests/src/fuzzer-(parse_json_view|json_view_image)\\.cpp"
- "tests/src/fuzzer-parse_json_view\\.cpp"
- "tools/amalgamate/config_json_view\\.json"
- "docs/mkdocs/docs/features/json_view\\.md"
- "docs/mkdocs/docs/api/basic_json_(document|view)/.*"
- "docs/mkdocs/docs/api/(ordered_)?json_(editable_)?(document|view)\\.md"
- "docs/mkdocs/docs/examples/(basic_json_(document|view)__|(ordered_)?json_(editable_)?(document|view)).*"
- "docs/mkdocs/docs/api/(ordered_)?json_(document|view)\\.md"
- "docs/mkdocs/docs/examples/(basic_json_(document|view)__|(ordered_)?json_(document|view)).*"
- "tests/benchmarks/src/benchmarks_view\\.cpp"
- label: "aspect: json_view"
+1 -1
View File
@@ -28,7 +28,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
+20 -19
View File
@@ -22,7 +22,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -31,13 +31,13 @@ jobs:
mkdir -p ./pr
echo ${{ github.event.number }} > ./pr/number
echo ${{ github.event.pull_request.user.login }} > ./pr/author
- uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
- uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
with:
name: pr
path: pr/
check:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
env:
MAIN_DIR: ${{ github.workspace }}/main
INCLUDE_DIR: ${{ github.workspace }}/main/single_include/nlohmann
@@ -46,7 +46,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -77,12 +77,13 @@ jobs:
cd $MAIN_DIR
# Built from this PR's own tools/macro_builder/main.cpp, not a
# develop checkout: unlike amalgamate.py, this tool has no other
# source of truth to check against (its own README documents that
# it must reproduce macro_scope.hpp byte for byte), so there is
# nothing to gain from checking out a separate copy, and doing so
# would make this step fail on a PR that adds support for a new
# dispatch table until that PR itself merges to develop.
# develop checkout: unlike amalgamate.py and generate_natvis.py,
# this tool has no other source of truth to check against (its
# own README documents that it must reproduce macro_scope.hpp
# byte for byte), so there is nothing to gain from checking out a
# separate copy, and doing so would make this step fail on a PR
# that adds support for a new dispatch table until that PR itself
# merges to develop.
TMPDIR=$(mktemp -d ./macro_builder_check.XXXXXX)
c++ -std=c++11 tools/macro_builder/main.cpp -o "$TMPDIR/macro_builder"
"$TMPDIR/macro_builder" > "$TMPDIR/paste.hpp"
@@ -145,14 +146,14 @@ jobs:
- name: Regenerate nlohmann_json.natvis
run: |
cd $MAIN_DIR
# The generator and its template are what this check verifies the
# committed natvis file against (which namespaces it lists, and
# what each entry looks like), so run this PR's copy rather than
# the develop checkout's: with develop's, a PR that changes either
# could never pass. generate_natvis.py loads the template from its
# own directory. Like the macro_builder step above, this only runs
# PR content in a job without credentials.
python3 tools/generate_natvis/generate_natvis.py $MAIN_DIR
# The template is what this check verifies the committed natvis
# file against, so take it from this PR rather than from the
# develop checkout: generate_natvis.py loads the template from its
# own directory, and with develop's copy a PR that changes the
# template could never pass. Like the macro_builder step above,
# this only renders PR content in a job without credentials.
cp tools/generate_natvis/nlohmann_json.natvis.j2 $NATVIS_TOOL_DIR/
python3 $NATVIS_TOOL_DIR/generate_natvis.py $MAIN_DIR
- name: Build patch and check for differences
id: diff
@@ -172,7 +173,7 @@ jobs:
# instead of installing the pinned astyle version locally.
- name: Upload patch
if: steps.diff.outputs.has_diff == 'true'
uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
with:
name: amalgamation-patch
path: patch/amalgamation.patch
+1 -1
View File
@@ -20,7 +20,7 @@ jobs:
timeout-minutes: 30
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
+2 -2
View File
@@ -13,7 +13,7 @@ jobs:
runs-on: ubuntu-22.04
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -35,7 +35,7 @@ jobs:
dry-run: false
language: c++
- name: Upload Crash
uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
if: failure() && steps.build.outcome == 'success'
with:
name: artifacts
+5 -5
View File
@@ -21,13 +21,13 @@ permissions:
jobs:
CodeQL-Build:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
permissions:
security-events: write
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -38,14 +38,14 @@ jobs:
# Initializes the CodeQL tools for scanning.
- name: Initialize CodeQL
uses: github/codeql-action/init@24c54180a607b1449ed407dd24f251e4e9147c8d # v4.38.3
uses: github/codeql-action/init@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
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@24c54180a607b1449ed407dd24f251e4e9147c8d # v4.38.3
uses: github/codeql-action/autobuild@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
- name: Perform CodeQL Analysis
uses: github/codeql-action/analyze@24c54180a607b1449ed407dd24f251e4e9147c8d # v4.38.3
uses: github/codeql-action/analyze@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
@@ -20,7 +20,7 @@ jobs:
pull-requests: write
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
+1 -1
View File
@@ -21,7 +21,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
+2 -2
View File
@@ -31,7 +31,7 @@ jobs:
security-events: write
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -47,6 +47,6 @@ jobs:
output: 'flawfinder_results.sarif'
- name: Upload analysis results to GitHub Security tab
uses: github/codeql-action/upload-sarif@24c54180a607b1449ed407dd24f251e4e9147c8d # v4.38.3
uses: github/codeql-action/upload-sarif@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
with:
sarif_file: ${{github.workspace}}/flawfinder_results.sarif
+1 -1
View File
@@ -23,7 +23,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
+1 -1
View File
@@ -37,7 +37,7 @@ jobs:
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
+4 -4
View File
@@ -40,7 +40,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -50,7 +50,7 @@ jobs:
persist-credentials: false
- name: "Run analysis"
uses: ossf/scorecard-action@fa7117db83c52d787ae5a89f350999701505d78e # v2.5.0
uses: ossf/scorecard-action@2d1146689b8cda280b9bc96326124645441f03bc # v2.4.4
with:
results_file: results.sarif
results_format: sarif
@@ -72,7 +72,7 @@ jobs:
# Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
# format to the repository Actions tab.
- name: "Upload artifact"
uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
with:
name: SARIF file
path: results.sarif
@@ -80,6 +80,6 @@ jobs:
# Upload the results to GitHub's code scanning dashboard.
- name: "Upload to code-scanning"
uses: github/codeql-action/upload-sarif@24c54180a607b1449ed407dd24f251e4e9147c8d # v4.38.3
uses: github/codeql-action/upload-sarif@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
with:
sarif_file: results.sarif
+3 -3
View File
@@ -33,10 +33,10 @@ jobs:
security-events: write # for github/codeql-action/upload-sarif to upload SARIF results
actions: read # only required for a private repository by github/codeql-action/upload-sarif to get the Action run status
name: Scan
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -65,7 +65,7 @@ jobs:
# Upload SARIF file generated in previous step
- name: Upload SARIF file
uses: github/codeql-action/upload-sarif@24c54180a607b1449ed407dd24f251e4e9147c8d # v4.38.3
uses: github/codeql-action/upload-sarif@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
with:
sarif_file: semgrep.sarif
if: always()
+1 -1
View File
@@ -16,7 +16,7 @@ jobs:
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
+32 -32
View File
@@ -25,20 +25,20 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
run: cmake --build build --target ci_test_gcc
ci_meson_install:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Check that Meson and pkg-config offer the CMake options
run: make check_build_options
- name: Install Meson
@@ -77,10 +77,10 @@ jobs:
cmake --build build-import-split
ci_infer:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -92,27 +92,27 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
run: cmake --build build --target ci_infer
- name: Archive Infer report
if: always()
uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
with:
name: infer-report
path: ${{ github.workspace }}/build/build_infer/infer-out/report.txt
if-no-files-found: ignore
ci_static_analysis_ubuntu:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
strategy:
matrix:
target: [ci_test_single_header, ci_cppcheck, ci_cpplint, ci_reproducible_tests, ci_non_git_tests, ci_offline_testdata, ci_reuse_compliance, ci_test_valgrind]
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -123,7 +123,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -142,7 +142,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -168,17 +168,17 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
run: cmake --build build --target ${{ matrix.target }}
ci_test_coverage:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -197,7 +197,7 @@ jobs:
- name: Build
run: cmake --build build --target ci_test_coverage
- name: Archive coverage report
uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
with:
name: code-coverage-report
path: ${{ github.workspace }}/build/html
@@ -244,7 +244,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: CXX=g++-${{ matrix.compiler }} cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -262,7 +262,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -279,7 +279,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Disable filesystem support (std::filesystem is unusable) for clang 7 / 8 / 9 / 10
run: echo "JSON_FORCED_GLOBAL_COMPILE_OPTIONS=-DJSON_HAS_FILESYSTEM=0;-DJSON_HAS_EXPERIMENTAL_FILESYSTEM=0" >> "$GITHUB_ENV"
if: ${{ matrix.compiler == '7' || matrix.compiler == '8' || matrix.compiler == '9' || matrix.compiler == '10' }}
@@ -299,7 +299,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -319,7 +319,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build with libc++
@@ -346,7 +346,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -366,7 +366,7 @@ jobs:
# import-std support. Its opt-in token is CMake-version-specific, so pin
# CMake to the version whose token is set in tests/module_cpp20/CMakeLists.txt.
- name: Get pinned CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
with:
cmakeVersion: 4.3.4
# Clang: the std library module is provided by libc++ (the image's libstdc++
@@ -392,7 +392,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -409,7 +409,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
@@ -423,17 +423,17 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DJSON_CI=On
- name: Build
run: cmake --build build --target ci_nvhpc
ci_emscripten:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -443,20 +443,20 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Run CMake
run: cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=$EMSDK/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -GNinja
- name: Build
run: cmake --build build
ci_test_documentation:
runs-on: ubuntu-26.04
runs-on: ubuntu-latest
strategy:
matrix:
target: [ci_test_examples, ci_test_build_documentation, ci_test_documentation_mermaid]
steps:
- name: Harden Runner
uses: step-security/harden-runner@ccd8616d44fd3846e67624a50d5aad6d37bf2d25 # v2.22.1
uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
with:
egress-policy: audit
@@ -465,7 +465,7 @@ jobs:
persist-credentials: false
# the git-revision-date-localized plugin needs the history; a shallow clone makes the strict build fail
fetch-depth: ${{ matrix.target == 'ci_test_build_documentation' && '0' || '1' }}
- uses: actions/setup-node@949feb2413d6458794dcd2491c4babbbce0c15c1 # v7.1.0
- uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
if: matrix.target == 'ci_test_documentation_mermaid'
with:
node-version: 24
@@ -484,7 +484,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Check that the job runs natively on arm64
run: uname -m && test "$(uname -m)" = aarch64
- name: Run CMake
+10 -12
View File
@@ -90,7 +90,7 @@ jobs:
with:
persist-credentials: false
- name: Get latest CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
- name: Set extra CXX_FLAGS for latest std_version
# /wd5285 silences C5285 emitted by the bundled third-party doctest.h, which
# specializes std::tuple (newly diagnosed by the VS2026 v145 toolset)
@@ -166,21 +166,19 @@ jobs:
# link, but the binaries clang 11.0.1 and clang 18.1.8 then produce crash
# before doctest prints its first line - 39 of 102 tests on clang 18.
# Keep the objects small by splitting the test files instead.
# The tests link with LLD: GNU ld fails on objects with more than 32767
# sections with "relocation truncated to fit: IMAGE_REL_AMD64_REL32
# against `.rdata'", as it stores the section an associative COMDAT
# section belongs to in 16 bits (x_associated in binutils'
# include/coff/internal.h) and so discards the jump tables of inline
# functions together with the wrong function. Each basic_json
# specialization and input type a test file instantiates adds many
# sections, so unit-msgpack.cpp and unit-regression2.cpp kept crossing
# that limit as the library grew.
# Objects with more than 65535 sections fail to link with "relocation
# truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'": the MinGW
# linker stores the section an associative COMDAT section belongs to in
# 16 bits (x_associated in binutils' include/coff/internal.h), so it
# discards the jump tables of inline functions together with the wrong
# function. Each basic_json specialization a test file instantiates adds
# many sections, so test a second one in a file of its own.
- name: Run CMake
run: cmake -S . -B build ^
-DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" ^
-DCMAKE_CXX_FLAGS="--target=x86_64-w64-mingw32 -stdlib=libstdc++ -pthread" ^
-DCMAKE_CXX_FLAGS_DEBUG="-g0" ^
-DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld -lwinpthread" ^
-DCMAKE_EXE_LINKER_FLAGS="-lwinpthread" ^
-G"MinGW Makefiles" ^
-DCMAKE_BUILD_TYPE=Debug ^
-DJSON_BuildTests=On
@@ -216,7 +214,7 @@ jobs:
# import-std support. Its opt-in token is CMake-version-specific, so pin
# CMake to the version whose token is set in tests/module_cpp20/CMakeLists.txt.
- name: Get pinned CMake and ninja
uses: lukka/get-cmake@a89e43e22a96abafcd7a62db652a65ecd33052c9 # v4.4.4
uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
with:
cmakeVersion: 4.3.4
# CMAKE_CXX_FLAGS replaces CMake's MSVC defaults (which include /EHsc), and
-3
View File
@@ -60,6 +60,3 @@ MODULE.bazel.lock
/json.tar.xz.asc
/release_files/
/single_include/nlohmann/*.asc
# GCC module cache
/gcm.cache/
-4
View File
@@ -1,7 +1,6 @@
{
"_comment": "Used by the ci_infer CMake target (#5715 item 4b). fail-on-issue makes CI fail on Infer findings; disable-issue-type is a type-level baseline for the ~174 pre-existing findings (all PULSE_UNNECESSARY_COPY*/PULSE_RESOURCE_LEAK/PULSE_CONST_REFABLE, mostly in test code) triaged in run https://github.com/nlohmann/json/actions/runs/35829411620 on commit 1054b2097, so CI fails only on a NEW issue type. Remove an entry here once its findings have been fixed or explicitly accepted.",
"_comment_pulse": "Pulse stops exploring paths after pulse-max-disjuncts (default 20). With the default, basic_json::replace_value() (destroy + assert_invariant) exceeds the limit, Pulse loses the stored type, and reports false NULLPTR_DEREFERENCE findings for get_ptr() results in tests/src/unit-pointer_access.cpp.",
"_comment_view": "Infer's model of std::unique_ptr mixes up values that are returned by value and own one: basic_json_document (parse() results) and the `built` values of the build() helper in tests/src/unit-json_view_builder.cpp. It reports USE_AFTER_DELETE for one of them after the destructor of an unrelated object (e.g. ~built() on line 345 invalidating `shallow` on line 350 of that file, or two documents parsed in one lambda in tests/src/unit-json_view_dump.cpp). AddressSanitizer and Valgrind are clean on the same tests, so reports for the json_view test files are excluded; findings reported in the library headers are still reported.",
"pulse-max-disjuncts": 40,
"fail-on-issue": true,
"disable-issue-type": [
@@ -11,8 +10,5 @@
"PULSE_UNNECESSARY_COPY_OPTIONAL",
"PULSE_RESOURCE_LEAK",
"PULSE_CONST_REFABLE"
],
"report-block-list-path-regex": [
"tests/src/unit-json_view.*\\.cpp"
]
}
-11
View File
@@ -68,27 +68,16 @@ cc_library(
"include/nlohmann/detail/string_utils.hpp",
"include/nlohmann/detail/value_t.hpp",
"include/nlohmann/detail/view/builder.hpp",
"include/nlohmann/detail/view/compare.hpp",
"include/nlohmann/detail/view/document_data.hpp",
"include/nlohmann/detail/view/edit.hpp",
"include/nlohmann/detail/view/edit_storage.hpp",
"include/nlohmann/detail/view/errors.hpp",
"include/nlohmann/detail/view/image.hpp",
"include/nlohmann/detail/view/input.hpp",
"include/nlohmann/detail/view/iterator.hpp",
"include/nlohmann/detail/view/lookup.hpp",
"include/nlohmann/detail/view/macro_scope.hpp",
"include/nlohmann/detail/view/macro_unscope.hpp",
"include/nlohmann/detail/view/materialize.hpp",
"include/nlohmann/detail/view/node.hpp",
"include/nlohmann/detail/view/number.hpp",
"include/nlohmann/detail/view/object_index.hpp",
"include/nlohmann/detail/view/pointer.hpp",
"include/nlohmann/detail/view/scan.hpp",
"include/nlohmann/detail/view/serializer.hpp",
"include/nlohmann/detail/view/simd.hpp",
"include/nlohmann/detail/view/string_ref.hpp",
"include/nlohmann/detail/view/value.hpp",
"include/nlohmann/json.hpp",
"include/nlohmann/json_fwd.hpp",
"include/nlohmann/json_literals.hpp",
-1
View File
@@ -1410,7 +1410,6 @@ THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR I
- The class contains parts of [Google Abseil](https://github.com/abseil/abseil-cpp) which is licensed under the [Apache 2.0 License](https://opensource.org/licenses/Apache-2.0).
- The class contains an adapted version of the Eisel-Lemire algorithm, its table of powers of five, and its digit comparison for long numbers from [fast_float](https://github.com/fastfloat/fast_float) by Daniel Lemire and contributors, which is available under the [MIT License](https://opensource.org/licenses/MIT) (used here), the Apache 2.0 License, and the Boost Software License. Copyright &copy; 2021 The fast_float authors
- The view's parser (`<nlohmann/json_view.hpp>`) contains techniques and code adapted from [yyjson](https://github.com/ibireme/yyjson) by YaoYuan, which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above): table-driven decoding of `\u` escapes and fixed-offset unrolled checks.
- The view's parser (`<nlohmann/json_view.hpp>`) validates non-ASCII strings with the vector UTF-8 check of [simdjson](https://github.com/simdjson/simdjson) by Daniel Lemire, Geoff Langdale, John Keiser, and contributors (its "lookup4" algorithm and tables, after J. Keiser and D. Lemire, "Validating UTF-8 In Less Than One Instruction Per Byte", 2021), which is available under the [MIT License](https://opensource.org/licenses/MIT) (used here) and the Apache 2.0 License. Copyright &copy; 2018-2025 The simdjson authors
<img align="right" src="https://git.fsfe.org/reuse/reuse-ci/raw/branch/master/reuse-horizontal.png" alt="REUSE Software">
+7 -14
View File
@@ -361,10 +361,10 @@ add_custom_target(ci_test_coverage
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_coverage32
COMMAND cd ${PROJECT_BINARY_DIR}/build_coverage32 && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
COMMAND ${LCOV_TOOL} --directory . --capture --output-file json.info --rc branch_coverage=1 --rc geninfo_unexecuted_blocks=1 --ignore-errors mismatch --ignore-errors unused --ignore-errors inconsistent
COMMAND ${LCOV_TOOL} -e json.info ${SRC_FILES} --output-file json.info.filtered --rc branch_coverage=1 --ignore-errors unused --ignore-errors inconsistent
COMMAND ${LCOV_TOOL} --directory . --capture --output-file json.info --rc branch_coverage=1 --rc geninfo_unexecuted_blocks=1 --ignore-errors mismatch --ignore-errors unused
COMMAND ${LCOV_TOOL} -e json.info ${SRC_FILES} --output-file json.info.filtered --rc branch_coverage=1 --ignore-errors unused
COMMAND ${CMAKE_SOURCE_DIR}/tests/thirdparty/imapdl/filterbr.py json.info.filtered > json.info.filtered.noexcept
COMMAND ${GENHTML_TOOL} --title "JSON for Modern C++" --legend --demangle-cpp --output-directory html --show-details --branch-coverage --ignore-errors inconsistent json.info.filtered.noexcept
COMMAND ${GENHTML_TOOL} --title "JSON for Modern C++" --legend --demangle-cpp --output-directory html --show-details --branch-coverage json.info.filtered.noexcept
COMMENT "Compile and test with coverage"
)
@@ -488,13 +488,6 @@ add_custom_target(ci_clang_analyze
# Check code with Cppcheck.
###############################################################################
# default_defines.hpp expands the Hedley macros to the compiler's feature-test operators, which Cppcheck does not know.
# Since Cppcheck 2.20, it rejects their invocations in #if conditions instead of evaluating them as 0.
file(WRITE ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "")
foreach(OPERATOR __has_attribute __has_builtin __has_cpp_attribute __has_declspec_attribute __has_extension __has_feature __has_include __has_warning)
file(APPEND ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "#define ${OPERATOR}(x) 0\n")
endforeach()
add_custom_target(ci_cppcheck
COMMAND mkdir -p cppcheck
COMMAND clang -dM -E -x c++ -std=c++11 ${CMAKE_SOURCE_DIR}/include/nlohmann/thirdparty/hedley/hedley.hpp > default_defines.hpp 2> /dev/null
@@ -503,7 +496,7 @@ add_custom_target(ci_cppcheck
COMMAND venv_cppcheck/bin/cppcheck --enable=warning --check-level=exhaustive --inline-suppr --inconclusive --force
--std=c++11 ${PROJECT_SOURCE_DIR}/include/nlohmann/json.hpp -I ${CMAKE_SOURCE_DIR}/include
--error-exitcode=1 --relative-paths=${PROJECT_SOURCE_DIR} -j ${N} --include=default_defines.hpp
--include=${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp --cppcheck-build-dir=cppcheck
--cppcheck-build-dir=cppcheck
-UJSON_CATCH_USER -UJSON_TRY_USER -UJSON_ASSERT -UJSON_INTERNAL_CATCH -UJSON_THROW
-DJSON_HAS_CPP_11 -UJSON_HAS_CPP_14 -UJSON_HAS_CPP_17 -UJSON_HAS_CPP_20 -UJSON_HAS_THREE_WAY_COMPARISON
COMMENT "Check code with Cppcheck"
@@ -890,11 +883,11 @@ add_custom_target(ci_icpx
# The following tests are excluded as they trigger known nvc++ 25.5 defects (not
# library bugs); see https://github.com/nlohmann/json for tracking. Only the
# affected language-standard variants are excluded so coverage is otherwise kept:
# - test-comparison-cpp20_cpp20, test-comparison_legacy-cpp20_cpp20
# - test-comparison_cpp20, test-comparison_legacy_cpp20
# miscompiles cross-type/<=> comparison (e.g. `-17 <= null`)
# - test-constructor1_cpp11
# std::initializer_list lifetime bug -> SIGSEGV
# - test-deserialization-cpp20_cpp20
# - test-deserialization_cpp20
# mangles the UTF-8 u8"" string literal in the char8_t (C++20) section
add_custom_target(ci_nvhpc
COMMAND ${CMAKE_COMMAND}
@@ -906,7 +899,7 @@ add_custom_target(ci_nvhpc
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_nvhpc
# the pipes are escaped so the surrounding shell passes them to ctest verbatim
# instead of treating them as shell pipe operators
COMMAND cd ${PROJECT_BINARY_DIR}/build_nvhpc && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-comparison-cpp20_cpp20\\|test-comparison_legacy-cpp20_cpp20\\|test-constructor1_cpp11\\|test-deserialization-cpp20_cpp20" --output-on-failure
COMMAND cd ${PROJECT_BINARY_DIR}/build_nvhpc && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-comparison_cpp20\\|test-comparison_legacy_cpp20\\|test-constructor1_cpp11\\|test-deserialization_cpp20" --output-on-failure
COMMENT "Compile and test with NVIDIA HPC SDK (nvc++)"
)
+1 -1
View File
@@ -1 +1 @@
cppcheck==1.5.3
cppcheck==1.5.1
+39 -366
View File
@@ -109,55 +109,6 @@ function(_json_test_apply_test_properties test_target properties_target)
endif()
endfunction()
# for internal use by _json_test_add_test() and _json_test_add_unity_batch():
# registers the CTest test <test_name>_cpp<cxx_standard> (plus its Valgrind
# variant), which runs the executable target <test_target> with the arguments
# in ARGN, and applies the test properties of the test- and standard-specific
# interface targets
function(_json_test_register_test test_name test_target cxx_standard)
set(ctest_name ${test_name}_cpp${cxx_standard})
if (JSON_FastTests)
add_test(NAME ${ctest_name}
COMMAND ${test_target} ${DOCTEST_TEST_FILTER} ${ARGN}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
)
else()
add_test(NAME ${ctest_name}
COMMAND ${test_target} ${DOCTEST_TEST_FILTER} ${ARGN} --no-skip
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
)
endif()
set_tests_properties(${ctest_name} PROPERTIES LABELS "all" FIXTURES_REQUIRED TEST_DATA)
# apply standard-specific test properties
if(TARGET _json_test_interface__cpp_${cxx_standard})
_json_test_apply_test_properties(${ctest_name} _json_test_interface__cpp_${cxx_standard})
endif()
# apply test-specific test properties
if(TARGET _json_test_interface_${test_name})
_json_test_apply_test_properties(${ctest_name} _json_test_interface_${test_name})
endif()
# apply test- and standard-specific test properties
if(TARGET _json_test_interface_${test_name}_cpp_${cxx_standard})
_json_test_apply_test_properties(${ctest_name}
_json_test_interface_${test_name}_cpp_${cxx_standard}
)
endif()
if(JSON_Valgrind)
add_test(NAME ${ctest_name}_valgrind
COMMAND ${memcheck_command} $<TARGET_FILE:${test_target}> ${DOCTEST_TEST_FILTER} ${ARGN}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
)
set_tests_properties(${ctest_name}_valgrind PROPERTIES
LABELS "valgrind" FIXTURES_REQUIRED TEST_DATA
)
endif()
endfunction()
# for internal use by json_test_add_test_for()
function(_json_test_add_test test_name file main cxx_standard)
set(test_target ${test_name}_cpp${cxx_standard})
@@ -192,7 +143,45 @@ function(_json_test_add_test test_name file main cxx_standard)
)
endif()
_json_test_register_test(${test_name} ${test_target} ${cxx_standard})
if (JSON_FastTests)
add_test(NAME ${test_target}
COMMAND ${test_target} ${DOCTEST_TEST_FILTER}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
)
else()
add_test(NAME ${test_target}
COMMAND ${test_target} ${DOCTEST_TEST_FILTER} --no-skip
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
)
endif()
set_tests_properties(${test_target} PROPERTIES LABELS "all" FIXTURES_REQUIRED TEST_DATA)
# apply standard-specific test properties
if(TARGET _json_test_interface__cpp_${cxx_standard})
_json_test_apply_test_properties(${test_target} _json_test_interface__cpp_${cxx_standard})
endif()
# apply test-specific test properties
if(TARGET _json_test_interface_${test_name})
_json_test_apply_test_properties(${test_target} _json_test_interface_${test_name})
endif()
# apply test- and standard-specific test properties
if(TARGET _json_test_interface_${test_name}_cpp_${cxx_standard})
_json_test_apply_test_properties(${test_target}
_json_test_interface_${test_name}_cpp_${cxx_standard}
)
endif()
if(JSON_Valgrind)
add_test(NAME ${test_target}_valgrind
COMMAND ${memcheck_command} $<TARGET_FILE:${test_target}> ${DOCTEST_TEST_FILTER}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
)
set_tests_properties(${test_target}_valgrind PROPERTIES
LABELS "valgrind" FIXTURES_REQUIRED TEST_DATA
)
endif()
endfunction()
#############################################################################
@@ -211,14 +200,6 @@ endfunction()
# Use NAME <name> to override the filename-derived test name.
# Use FORCE to create the test regardless of the file containing
# JSON_HAS_CPP_<version_number>.
#
# Tests that depend on the C++ standard (e.g., because they use the macros
# JSON_HAS_FILESYSTEM, JSON_HAS_RANGES, or JSON_HAS_THREE_WAY_COMPARISON)
# should not make the whole of a large unit-foo.cpp be rebuilt for every
# standard. Put them into a separate file unit-foo-cpp<NN>.cpp (see, e.g.,
# unit-items-cpp17.cpp) which wraps its content in #ifdef JSON_HAS_CPP_<NN>.
# Then, unit-foo.cpp itself contains no JSON_HAS_CPP_<NN> and is only built for
# C++11.
# Test targets are linked against <main>.
# CXX_STANDARDS defaults to "11".
#############################################################################
@@ -262,314 +243,6 @@ function(json_test_add_test_for file)
endforeach()
endfunction()
# for internal use by json_test_add_unity_tests(): sets <result> to whether the
# (absolute) <file> is built for <cxx_standard>; same rule as in
# json_test_add_test_for(): C++11 always, others only if the file contains
# JSON_HAS_CPP_<cxx_standard> or <force> is set
function(_json_test_unity_applies file cxx_standard force result)
set(${result} TRUE PARENT_SCOPE)
if(NOT ("${cxx_standard}" STREQUAL 11 OR force))
file(READ ${file} file_content)
string(FIND "${file_content}" JSON_HAS_CPP_${cxx_standard} has_cpp_found)
if(${has_cpp_found} EQUAL -1)
set(${result} FALSE PARENT_SCOPE)
endif()
endif()
endfunction()
# for internal use by json_test_add_unity_tests(): creates the executable
# test-unity-<batch_name>_cpp<cxx_standard> from the (absolute) source files
# in ARGN, which are #include-d by a generated source file, and registers one
# CTest test per source file that runs only the test cases of that file; if
# <private> is true, the generated file defines JSON_TESTS_PRIVATE first
function(_json_test_add_unity_batch batch_name cxx_standard main private)
set(batch_target test-unity-${batch_name}_cpp${cxx_standard})
set(batch_source ${PROJECT_BINARY_DIR}/tests/unity/${batch_target}.cpp)
set(batch_content "// generated by cmake/test.cmake; do not edit\n")
if(private)
string(APPEND batch_content "// at least one file of this batch needs access to private members of the library\n")
string(APPEND batch_content "#define JSON_TESTS_PRIVATE\n")
# the files define the macro again; mark this definition as used, as
# -Wunused-macros reports an unused definition when it is redefined
string(APPEND batch_content "#ifdef JSON_TESTS_PRIVATE\n#endif\n")
endif()
foreach(file ${ARGN})
string(APPEND batch_content "#include \"${file}\" // NOLINT(bugprone-suspicious-include)\n")
endforeach()
# only touch the generated file if it changed to keep incremental builds incremental
set(old_content "")
if(EXISTS ${batch_source})
file(READ ${batch_source} old_content)
endif()
if(NOT "${old_content}" STREQUAL "${batch_content}")
file(WRITE ${batch_source} "${batch_content}")
endif()
add_executable(${batch_target} ${batch_source})
target_link_libraries(${batch_target} PRIVATE ${main})
set_target_properties(${batch_target} PROPERTIES
CXX_STANDARD ${cxx_standard}
CXX_STANDARD_REQUIRED ON
)
if(TARGET _json_test_interface__cpp_${cxx_standard})
target_link_libraries(${batch_target} PRIVATE _json_test_interface__cpp_${cxx_standard})
endif()
# rebuild the batch when one of its files changes, and show the files in IDEs;
# files that are also built standalone (VARIANT_FILES) are left out, as
# HEADER_FILE_ONLY is a per-file property and would also affect those targets
set_source_files_properties(${batch_source} PROPERTIES OBJECT_DEPENDS "${ARGN}")
foreach(file ${ARGN})
if(NOT file IN_LIST _json_test_unity_variant_files)
set_source_files_properties(${file} PROPERTIES HEADER_FILE_ONLY ON)
target_sources(${batch_target} PRIVATE ${file})
endif()
endforeach()
foreach(file ${ARGN})
get_filename_component(file_basename ${file} NAME_WE)
string(REGEX REPLACE "unit-(.+)" "test-\\1" test_name ${file_basename})
# run only the test cases defined in this file (and in the shared
# make_test_data_available.hpp if the file uses it)
file(READ ${file} file_content)
set(source_filter "--source-file=*${file_basename}.cpp")
string(FIND "${file_content}" make_test_data_available.hpp uses_test_data)
if(NOT ${uses_test_data} EQUAL -1)
string(APPEND source_filter ",*make_test_data_available.hpp")
endif()
_json_test_register_test(${test_name} ${batch_target} ${cxx_standard} "${source_filter}")
endforeach()
endfunction()
#############################################################################
# json_test_add_unity_tests(
# FILES <files>...
# MAIN <main>
# [CXX_STANDARDS <version_number>...] [FORCE]
# [BATCH_SIZE <size>]
# [GROUPS <group>...]
# [VARIANT_FILES <files>...])
#
# Like calling json_test_add_test_for(<file> MAIN <main> ...) for each of the
# <files>, but compiles several files together to speed up the build: for each
# C++ standard, the files are split into batches of <size> files (default: 8)
# and each batch is built as a single executable
#
# test-unity-<pool><index>_cpp<version_number>
#
# whose generated source file #include-s the files of the batch (so they share
# the template instantiations of the library). The tests are still named
# test-foo_cpp<version_number>, one per file, but run the batch executable with
# a doctest filter that selects the test cases of that file only.
#
# Files are only batched with files that agree on the macros defined before
# the library is included: files that define at most JSON_TESTS_PRIVATE (or
# macros derived from global compile definitions) form the pools "plain" and
# "private". All other files are added with json_test_add_test_for() as usual,
# as are files with test-specific build settings (see
# json_test_set_test_options()) and the files listed in the explicit
# exclusion list below.
# Each <group> names a list variable json_test_unity_group_<group> of test file
# stems (file names without "unit-" and ".cpp"). The batchable files of a group
# are compiled together (regardless of BATCH_SIZE) as one executable
#
# test-unity-<group>_cpp<version_number>
#
# so that related tests, which instantiate the same templates, share one
# translation unit. A group may mix the pools "plain" and "private"; if any of
# its files needs JSON_TESTS_PRIVATE, the whole group is built with it. Files
# that cannot be batched stay standalone even if they are listed in a group.
# Files in no group are batched by BATCH_SIZE as described above.
# <files> in VARIANT_FILES are also built standalone with other settings, so
# they are not marked as header-only sources of the batch.
#############################################################################
function(json_test_add_unity_tests)
cmake_parse_arguments(args "FORCE" "MAIN;BATCH_SIZE" "FILES;CXX_STANDARDS;VARIANT_FILES;GROUPS" ${ARGN})
if("${args_MAIN}" STREQUAL "")
message(FATAL_ERROR "Required argument MAIN <main> missing.")
endif()
if("${args_BATCH_SIZE}" STREQUAL "")
set(args_BATCH_SIZE 8)
endif()
if("${args_CXX_STANDARDS}" STREQUAL "")
set(args_CXX_STANDARDS 11)
endif()
if(args_FORCE)
set(force FORCE)
else()
set(force "")
endif()
set(_json_test_unity_variant_files "")
foreach(file ${args_VARIANT_FILES})
get_filename_component(file ${file} ABSOLUTE)
list(APPEND _json_test_unity_variant_files ${file})
endforeach()
# files that must not be merged into a batch: unit-32bit.cpp is only built
# for 32bit targets, and unit-no-macro-leak.cpp checks that including the
# library defines no unprefixed macro, which any other file would disturb
set(standalone_files unit-32bit.cpp unit-no-macro-leak.cpp)
set(harmless_macros "^(DOCTEST_.*|SKIP_TESTS_FOR_.*|JSON_TEST_DEPRECATED_FUNCTIONS_DELETED|JSON_TEST_STRICT_NUL_HANDLING_ENABLED|JSON_TEST_STRINGIZE)$")
# classify the files
set(plain_files "")
set(private_files "")
set(standalone_abs_files "")
foreach(file ${args_FILES})
get_filename_component(file_name ${file} NAME)
get_filename_component(file_basename ${file} NAME_WE)
string(REGEX REPLACE "unit-(.+)" "test-\\1" test_name ${file_basename})
set(batchable TRUE)
if(file_name IN_LIST standalone_files)
set(batchable FALSE)
endif()
if(TARGET _json_test_interface_${test_name})
set(batchable FALSE)
endif()
foreach(cxx_standard ${args_CXX_STANDARDS})
if(TARGET _json_test_interface_${test_name}_cpp_${cxx_standard})
set(batchable FALSE)
endif()
endforeach()
# files that suppress GCC's -Wnoexcept around their include of the
# library: the suppression has no effect once another file of the
# batch included the library first
if(batchable)
file(READ ${file} file_content)
string(FIND "${file_content}" "SUPPRESS_WARNING(\"-Wnoexcept\")" suppresses_noexcept)
if(NOT ${suppresses_noexcept} EQUAL -1)
set(batchable FALSE)
endif()
endif()
set(pool plain)
if(batchable)
# collect the macros (un)defined before the library is included
file(READ ${file} file_content)
string(FIND "${file_content}" "#include <nlohmann/" include_position)
if(NOT ${include_position} EQUAL -1)
string(SUBSTRING "${file_content}" 0 ${include_position} file_content)
endif()
string(REGEX MATCHALL "(^|\n)[ \t]*#[ \t]*(define|undef)[ \t]+[A-Za-z_0-9]+" directives "${file_content}")
foreach(directive ${directives})
string(REGEX REPLACE "^.*[ \t]([A-Za-z_0-9]+)$" "\\1" macro "${directive}")
if(macro MATCHES "${harmless_macros}")
continue()
elseif("${macro}" STREQUAL JSON_TESTS_PRIVATE)
set(pool private)
else()
set(batchable FALSE)
endif()
endforeach()
endif()
get_filename_component(file_abs ${file} ABSOLUTE)
if(NOT batchable)
list(APPEND standalone_abs_files ${file_abs})
json_test_add_test_for(${file} MAIN ${args_MAIN} CXX_STANDARDS ${args_CXX_STANDARDS} ${force})
continue()
endif()
get_filename_component(file ${file} ABSOLUTE)
list(APPEND ${pool}_files ${file})
endforeach()
# resolve the explicit groups: group_<name>_files are the (absolute) files
# of the group, group_<name>_private tells whether one of them is private
set(grouped_files "")
foreach(group ${args_GROUPS})
if(NOT DEFINED json_test_unity_group_${group})
message(FATAL_ERROR "Unity test group '${group}' is not defined (json_test_unity_group_${group}).")
endif()
set(group_${group}_files "")
set(group_${group}_private FALSE)
foreach(stem ${json_test_unity_group_${group}})
# check against the source directory, because FILES may be filtered (JSON_TestShard)
get_filename_component(file ${CMAKE_CURRENT_SOURCE_DIR}/src/unit-${stem}.cpp ABSOLUTE)
if(NOT EXISTS ${file})
message(FATAL_ERROR "Unity test group '${group}' lists '${stem}', but ${file} does not exist.")
endif()
if(file IN_LIST grouped_files)
message(FATAL_ERROR "Unity test file unit-${stem}.cpp is listed in more than one group (second: '${group}').")
endif()
list(APPEND grouped_files ${file})
if(file IN_LIST standalone_abs_files)
message(STATUS "Unity test group '${group}': unit-${stem}.cpp cannot be batched and stays standalone")
elseif(file IN_LIST plain_files)
list(APPEND group_${group}_files ${file})
list(REMOVE_ITEM plain_files ${file})
elseif(file IN_LIST private_files)
list(APPEND group_${group}_files ${file})
list(REMOVE_ITEM private_files ${file})
set(group_${group}_private TRUE)
endif()
endforeach()
endforeach()
foreach(cxx_standard ${args_CXX_STANDARDS})
if(NOT compiler_supports_cpp_${cxx_standard})
continue()
endif()
# explicit groups: one batch per group
foreach(group ${args_GROUPS})
set(batch_files "")
foreach(file ${group_${group}_files})
_json_test_unity_applies(${file} ${cxx_standard} "${force}" applies)
if(applies)
list(APPEND batch_files ${file})
endif()
endforeach()
if(batch_files)
_json_test_add_unity_batch(${group} ${cxx_standard} ${args_MAIN} ${group_${group}_private} ${batch_files})
endif()
endforeach()
# remaining files: batches of BATCH_SIZE files per pool
foreach(pool plain private)
set(is_private FALSE)
if(pool STREQUAL private)
set(is_private TRUE)
endif()
set(batch_files "")
set(batch_count 0)
set(batch_index 0)
foreach(file ${${pool}_files})
_json_test_unity_applies(${file} ${cxx_standard} "${force}" applies)
if(NOT applies)
continue()
endif()
list(APPEND batch_files ${file})
math(EXPR batch_count "${batch_count} + 1")
if(batch_count EQUAL args_BATCH_SIZE)
_json_test_add_unity_batch(${pool}${batch_index} ${cxx_standard} ${args_MAIN} ${is_private} ${batch_files})
set(batch_files "")
set(batch_count 0)
math(EXPR batch_index "${batch_index} + 1")
endif()
endforeach()
if(batch_files)
_json_test_add_unity_batch(${pool}${batch_index} ${cxx_standard} ${args_MAIN} ${is_private} ${batch_files})
endif()
endforeach()
endforeach()
endfunction()
#############################################################################
# json_test_should_build_32bit_test(
# <build_32bit_var> <build_32bit_only_var> <input>)
@@ -132,10 +132,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
- [operator>>](../operator_gtgt.md) - deserialize from stream
- [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
instead of treating it as end of input
- [`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) - read a `std::istream` one character
at a time
- [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) - read a `FILE*` with the locking stdio
functions
## Version history
@@ -147,10 +143,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
- Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
- `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
it as end of input; planned to become the default in version 4.0.0.
- Parsing from an `std::istream` scans the characters in its stream buffer in bulk in version 3.13.0
([`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)).
!!! warning "Deprecation"
+1 -1
View File
@@ -27,7 +27,7 @@ To store objects in C++, a type is defined by the template parameters explained
### Default type
With the default values for `ArrayType` (`std::vector`) and `AllocatorType` (`std::allocator`), the default type for
With the default values for `ArrayType` (`std::vector`) and `AllocatorType` (`std::allocator`), the default value for
`array_t` is:
```cpp
-1
View File
@@ -233,7 +233,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
- documentation on [checked access](../../features/element_access/checked_access.md)
- [`operator[]`](operator%5B%5D.md) for unchecked access by reference
- [`value`](value.md) for access with default value
- [basic_json_view::at](../basic_json_view/at.md) - the same access on a zero-copy view
## Version history
-1
View File
@@ -58,7 +58,6 @@ Constant.
## See also
- [front](front.md) to access the first element
- [basic_json_view::back](../basic_json_view/back.md) - the same access on a zero-copy view
## Version history
+1 -11
View File
@@ -68,14 +68,6 @@ basic_json(basic_json&& other) noexcept;
`std::unordered_map`, `std::multimap`, and `std::unordered_multimap` with a `key_type` compatible to `string_t`
and a `value_type` from which a `basic_json` value can be constructed.
- **strings**: `string_t`, string literals, and all compatible string containers can be used.
!!! note "Rvalue containers are moved from"
If `val` is an rvalue of a compatible array-like or object-like container other than `array_t`/`object_t`
(e.g., `json j = std::move(vec);` or `json j(std::vector<std::string>{...});`), the elements are moved into
the JSON value instead of copied. Afterwards, the elements of the source container are in a valid but
unspecified state (**moved-from**). Keys of associative containers are `const` and therefore still copied.
Lvalues and `const` rvalues are copied, and the source is left unchanged.
- **numbers**: [`number_integer_t`](number_integer_t.md), [`number_unsigned_t`](number_unsigned_t.md),
[`number_float_t`](number_float_t.md), and all convertible number types such as `int`, `size_t`, `int64_t`, `float`
or `double` can be used.
@@ -244,9 +236,7 @@ basic_json(basic_json&& other) noexcept;
2. No-throw guarantee: this constructor never throws exceptions.
3. Depends on the called constructor. For types directly supported by the library (i.e., all types for which no
`to_json()` function was provided), a strong guarantee holds: if an exception is thrown, there are no changes to any
JSON value. **Exception:** when `val` is an rvalue array-like or object-like container, its elements are moved one
by one; if an exception is thrown in the middle of the conversion (e.g., an allocation failure), the JSON value is
unchanged, but the source container may be left partially moved-from.
JSON value.
4. Depends on the called constructor. For types directly supported by the library (i.e., all types for which no
`to_json()` function was provided), a strong guarantee holds: if an exception is thrown, there are no changes to any
JSON value.
-2
View File
@@ -44,8 +44,6 @@ Constant.
- [rbegin](rbegin.md) returns a reverse iterator to the last element
- [items](items.md) returns an iteration proxy to access keys and values during range-based for loops
- [Iterators](../../features/iterators.md) - the article on iterators
- [basic_json_view::begin](../basic_json_view/begin.md) - the same iteration on a zero-copy view (in document order,
not sorted by key)
## Version history
+1 -1
View File
@@ -23,7 +23,7 @@ To store boolean values in C++, a type is defined by the template parameter `Bo
### Default type
With the default values for `BooleanType` (`#!cpp bool`), the default type for `boolean_t` is `#!cpp bool`.
With the default values for `BooleanType` (`#!cpp bool`), the default value for `boolean_t` is `#!cpp bool`.
### Storage
@@ -42,7 +42,6 @@ Constant.
- [cend](cend.md) returns a const iterator to one past the last element
- [crbegin](crbegin.md) returns a const reverse iterator to the last element
- [Iterators](../../features/iterators.md) - the article on iterators
- [basic_json_view::cbegin](../basic_json_view/cbegin.md) - the same iteration on a zero-copy view
## Version history
-1
View File
@@ -42,7 +42,6 @@ Constant.
- [cbegin](cbegin.md) returns a const iterator to the first element
- [crend](crend.md) returns a const reverse iterator to one before the first element
- [Iterators](../../features/iterators.md) - the article on iterators
- [basic_json_view::cend](../basic_json_view/cend.md) - the same iteration on a zero-copy view
## Version history
@@ -136,7 +136,6 @@ Logarithmic in the size of the JSON object.
- [find](find.md) find a value in an object
- [count](count.md) returns the number of occurrences of a key
- [basic_json_view::contains](../basic_json_view/contains.md) - the same check on a zero-copy view
## Version history
-1
View File
@@ -87,7 +87,6 @@ Logarithmic in the size of the JSON object.
- [find](find.md) find a value in an object
- [contains](contains.md) checks whether a key exists
- [basic_json_view::count](../basic_json_view/count.md) - the same check on a zero-copy view
## Version history
-2
View File
@@ -91,8 +91,6 @@ Binary values are serialized as an object containing two keys:
- [to_string](to_string.md) returns a string representation of a JSON value
- [operator<<](../operator_ltlt.md) serialize to stream
- [`basic_json_view::dump`](../basic_json_view/dump.md) the corresponding function of `basic_json_view`, serializing
directly from a flat index without building a `basic_json` value
- [Serialization](../../features/serialization.md) - the serialization article
## Version history
-1
View File
@@ -43,7 +43,6 @@ Constant.
- [cend](cend.md) returns a const iterator to one past the last element
- [rend](rend.md) returns a reverse iterator to one before the first element
- [Iterators](../../features/iterators.md) - the article on iterators
- [basic_json_view::end](../basic_json_view/end.md) - the same iteration on a zero-copy view
## Version history
-2
View File
@@ -93,8 +93,6 @@ Logarithmic in the size of the JSON object.
- [count](count.md) returns the number of occurrences of a key
- [contains](contains.md) checks whether a key exists
- [basic_json_view::find](../basic_json_view/find.md) - the same lookup on a zero-copy view (a duplicate key resolves
to the first member, whereas `parse()` keeps the last)
## Version history
-2
View File
@@ -51,8 +51,6 @@ Constant.
## See also
- [back](back.md) to access the last element
- [basic_json_view::front](../basic_json_view/front.md) - the same access on a zero-copy view (document order, not
sorted; duplicate keys are visited)
## Version history
-2
View File
@@ -183,8 +183,6 @@ overload (3).
- [get_ref](get_ref.md) get a reference to the stored value
- [operator ValueType](operator_ValueType.md) get a value via implicit conversion
- [Converting values](../../features/conversions.md) - the type conversions article
- [basic_json_view::get](../basic_json_view/get.md) - the same conversion on a zero-copy view (many types are
converted without ever building a `basic_json` value)
## Version history
@@ -61,8 +61,6 @@ Constant.
## See also
- [get_ptr()](get_ptr.md) get a pointer value
- [basic_json_view::get_string](../basic_json_view/get_string.md) - the closest counterpart on a zero-copy view: a
string without a copy, but as a view rather than a reference to a value that must already exist
## Version history
@@ -72,7 +72,6 @@ Depends on the `json_serializer<ValueType>::from_json()` implementation.
- [get_ref](get_ref.md) get a reference to the stored value
- [get_ptr](get_ptr.md) get a pointer to the stored value
- [Converting values](../../features/conversions.md) - the type conversions article
- [basic_json_view::get_to](../basic_json_view/get_to.md) - the same conversion on a zero-copy view
## Version history
@@ -6,9 +6,6 @@ constexpr bool is_number_unsigned() const noexcept;
This function returns `#!cpp true` if and only if the JSON value is an unsigned integer number. This excludes
floating-point and signed integer values.
If [`number_unsigned_t`](number_unsigned_t.md) is the same type as [`number_integer_t`](number_integer_t.md), every
integer is stored as `number_integer_t`, and this function always returns `#!cpp false`.
## Return value
-2
View File
@@ -99,8 +99,6 @@ When iterating over an array, `key()` will return the index of the element as st
- [begin](begin.md) returns an iterator to the first element
- [end](end.md) returns an iterator to one past the last element
- [basic_json_view::items](../basic_json_view/items.md) - the same range on a zero-copy view (`#!cpp const auto`,
not `#!cpp const auto&`: items are produced on the fly; document order, not sorted; duplicate keys are visited)
## Version history
@@ -35,7 +35,7 @@ type to use.
### Default type
With the default values for `NumberFloatType` (`double`), the default type for `number_float_t` is `#!cpp double`.
With the default values for `NumberFloatType` (`double`), the default value for `number_float_t` is `#!cpp double`.
### Default behavior
@@ -52,9 +52,8 @@ With the default values for `NumberFloatType` (`double`), the default type for `
> interoperability can be achieved by implementations that expect no more precision or range than these provide, in the
> sense that implementations will approximate JSON numbers within the expected precision.
This implementation does exactly follow this approach, as it uses double precision floating-point numbers by default.
Note that with the default `double`, numbers smaller than `-1.79769313486232e+308` or greater than
`1.79769313486232e+308` are rejected during parsing with
This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note that
numbers smaller than `-1.79769313486232e+308` or greater than `1.79769313486232e+308` are rejected during parsing with
[`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can
only be stored by assigning them directly and are serialized to `null`.
@@ -31,7 +31,7 @@ to use.
### Default type
With the default values for `NumberIntegerType` (`std::int64_t`), the default type for `number_integer_t` is
With the default values for `NumberIntegerType` (`std::int64_t`), the default value for `number_integer_t` is
`#!cpp std::int64_t`.
### Default behavior
@@ -25,15 +25,14 @@ the type to use.
`NumberUnsignedType`
: the type to store unsigned integers. It must be an **unsigned integral** type (`#!cpp std::is_integral`) with a
`#!cpp std::numeric_limits` specialization, and it must be able to represent the absolute value of every
[`number_integer_t`](number_integer_t.md) value. Alternatively, it can be the same type as
[`number_integer_t`](number_integer_t.md); then every integer is stored as `number_integer_t`. See
[`number_integer_t`](number_integer_t.md) value. See
[Template Parameter Requirements](../../features/types/template_parameters.md#numberintegertype-and-numberunsignedtype).
## Notes
### Default type
With the default values for `NumberUnsignedType` (`std::uint64_t`), the default type for `number_unsigned_t` is
With the default values for `NumberUnsignedType` (`std::uint64_t`), the default value for `number_unsigned_t` is
`#!cpp std::uint64_t`.
### Default behavior
@@ -90,4 +89,3 @@ Integer number values are stored directly inside a `basic_json` type.
## Version history
- Added in version 2.0.0.
- Can be the same type as `number_integer_t` since version 3.13.0.
+1 -1
View File
@@ -36,7 +36,7 @@ To store objects in C++, a type is defined by the template parameters described
### Default type
With the default values for `ObjectType` (`std::map`), `StringType` (`std::string`), and `AllocatorType`
(`std::allocator`), the default type for `object_t` is:
(`std::allocator`), the default value for `object_t` is:
```cpp
// until C++14
@@ -275,9 +275,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
- documentation on [runtime assertions](../../features/assertions.md)
- see [`at`](at.md) for access by reference with range checking
- see [`value`](value.md) for access with default value
- [basic_json_view::operator[]](../basic_json_view/operator%5B%5D.md) - the same access on a zero-copy view (a duplicate
key resolves to the first member, whereas `parse()` keeps the last; a missing key gives a discarded view instead of
undefined behavior)
## Version history
@@ -170,8 +170,6 @@ Linear.
- [operator!=](operator_ne.md) compare for inequality
- [operator<=>](operator_spaceship.md) comparison: 3-way (C++20)
- [basic_json_view::operator==](../basic_json_view/operator_eq.md) - the same comparison on a zero-copy view, without
building a `basic_json` value for it
## Version history
@@ -95,8 +95,6 @@ Linear.
- [operator==](operator_eq.md) comparison: equal
- [operator<=>](operator_spaceship.md) comparison: 3-way (C++20)
- [basic_json_view::operator!=](../basic_json_view/operator_ne.md) - the same comparison on a zero-copy view, without
building a `basic_json` value for it
## Version history
-19
View File
@@ -112,16 +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 "Performance"
Contiguous inputs (strings, string views, vectors, arrays, pointer ranges) are the fastest to parse. A
`#!cpp std::istream` comes close: the parser scans the characters its stream buffer holds in bulk, without reading
ahead, so the stream is left exactly where it would be after reading one character at a time. A `#!cpp FILE*` is
read one character at a time, but the file is locked only once, so other threads that use the same `FILE` object
wait until parsing is done. See [input sources and performance](../../features/parsing/index.md#input-sources-and-performance),
[`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md), and
[`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md).
## Examples
??? example "Example: (1) parse from a character array"
@@ -257,10 +247,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
- [operator>>](../operator_gtgt.md) - deserialize from stream
- [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
instead of treating it as end of input
- [`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) - read a `std::istream` one character
at a time
- [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) - read a `FILE*` with the locking stdio
functions
## Version history
@@ -275,11 +261,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
it as end of input; planned to become the default in version 4.0.0.
- Extended empty-input detection to also cover an `std::istream` without a stream buffer, and fixed a crash
(`std::terminate`) when parsing from an `std::istream` with `eofbit` in its exception mask, in version 3.13.0.
- Parsing from an `std::istream` scans the characters in its stream buffer in bulk in version 3.13.0
([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) restores reading one character at a
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`).
!!! warning "Deprecation"
@@ -116,10 +116,6 @@ consumer `sax` has a super-linear complexity.
A UTF-8 byte order mark is silently ignored.
When reading from a `#!c FILE*`, the file is locked while it is parsed. The lock is recursive, so the SAX handler may
use the same file with stdio functions, but it must not wait for another thread that uses the same `FILE` object; see
[`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md).
## Examples
??? example
@@ -141,10 +137,6 @@ use the same file with stdio functions, but it must not wait for another thread
- [parse](parse.md) - deserialize from a compatible input
- [accept](accept.md) - check if the input is valid JSON
- [`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) - read a `std::istream` one character
at a time
- [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) - read a `FILE*` with the locking stdio
functions
## Version history
@@ -156,10 +148,6 @@ use the same file with stdio functions, but it must not wait for another thread
- Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
- `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave a `#!cpp std::istream` positioned right
after the parsed value when `strict` is `#!cpp false`.
- Parsing from an `std::istream` scans the characters in its stream buffer in bulk in version 3.13.0
([`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)).
!!! warning "Deprecation"
+1 -1
View File
@@ -32,7 +32,7 @@ JSON class into byte-sized characters during deserialization.
### Default type
With the default values for `StringType` (`std::string`), the default type for `string_t` is `#!cpp std::string`.
With the default values for `StringType` (`std::string`), the default value for `string_t` is `#!cpp std::string`.
### Encoding
+1 -3
View File
@@ -123,6 +123,4 @@ Linear in the size of the JSON value `j`.
that is not valid UTF-8 unchanged, as before; `strict` (the default if
[`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.
array or object was silently skipped, producing invalid BJData.
+2 -3
View File
@@ -37,9 +37,8 @@ With (2), the bytes written before the exception remain in the output adapter.
## Exceptions
- Throws [out_of_range.407](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an integer outside
the range of int64 (an unsigned integer above 9223372036854775807, or, with a number type wider than 64 bits, any
integer beyond int64), which BON8 cannot represent
- Throws [out_of_range.407](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an unsigned integer
above 9223372036854775807, which BON8 cannot represent
- Throws [type_error.316](../../home/exceptions.md#jsonexceptiontype_error316) if `j` contains a string that is not
valid UTF-8
- Throws [type_error.321](../../home/exceptions.md#jsonexceptiontype_error321) if `j` or a value nested in it is
@@ -47,10 +47,6 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
- Throws [`type_error.317`](../../home/exceptions.md#jsonexceptiontype_error317) if the top-level type of the JSON value
is not an object; example: `"to serialize to BSON, top-level type must be object, but is string"`
- Throws [`out_of_range.407`](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains a signed integer
outside the range of int64 or an unsigned integer outside the range of uint64, which is only possible with a number
type wider than 64 bits; example:
`"integer number 9223372036854775808 cannot be represented by BSON as it does not fit int64"`
- Throws [`out_of_range.409`](../../home/exceptions.md#jsonexceptionout_of_range409) if a key in the JSON object contains
a null byte (code point U+0000); example: `"BSON key cannot contain code point U+0000 (at byte 2)"`
- Throws [`out_of_range.412`](../../home/exceptions.md#jsonexceptionout_of_range412) if the length of a document, array,
@@ -123,5 +119,3 @@ pass before anything is written.
that is not valid UTF-8 unchanged, as before; `strict` (the default if
[`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled) throws `type_error.316` before anything
is written.
- Throws `out_of_range.407` for integers that do not fit 64 bits since version 3.13.0; previously, integers of a
number type wider than 64 bits were silently truncated.
@@ -46,9 +46,6 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
## Exceptions
- Throws [`out_of_range.407`](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an integer
outside [-2^64, 2^64-1], which is only possible with a number type wider than 64 bits; example:
`"integer number 18446744073709551616 cannot be represented by CBOR as it does not fit [-2^64, 2^64-1]"`
- Throws [type_error.316](../../home/exceptions.md#jsonexceptiontype_error316) if a string or object key in `j` is
not valid UTF-8 and `error_handler` is `strict` (the default only if
[`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled)
@@ -93,5 +90,3 @@ 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 CBOR.
- Throws `out_of_range.407` for integers that do not fit 64 bits since version 3.13.0; previously, integers of a
number type wider than 64 bits were silently truncated.
@@ -46,9 +46,6 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
## Exceptions
- Throws [`out_of_range.407`](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an integer
outside [-2^63, 2^64-1], which is only possible with a number type wider than 64 bits; example:
`"integer number 18446744073709551616 cannot be represented by MessagePack as it does not fit [-2^63, 2^64-1]"`
- Throws [`out_of_range.412`](../../home/exceptions.md#jsonexceptionout_of_range412) if the length of a string, binary
value, array, or object exceeds 4294967295, the maximum MessagePack can store; example:
`"MessagePack length 4294967296 exceeds maximum of 4294967295"`
@@ -115,5 +112,3 @@ Linear in the size of the JSON value `j`.
`number_unsigned_t`.
- 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 MessagePack.
- Throws `out_of_range.407` for integers that do not fit 64 bits since version 3.13.0; previously, integers of a
number type wider than 64 bits were silently truncated.
@@ -56,7 +56,6 @@ Constant.
- [type](type.md) returns the type of the JSON value
- [value_t](value_t.md) the enumeration of JSON types
- [basic_json_view::type_name](../basic_json_view/type_name.md) - the same function on a zero-copy view
## Version history
-1
View File
@@ -224,7 +224,6 @@ changes to any JSON value.
- see [`at`](at.md) for access by reference with range checking
- see [`operator[]`](operator%5B%5D.md) for unchecked access by reference
- [basic_json_view::value](../basic_json_view/value.md) - the same access on a zero-copy view
## Version history
@@ -12,11 +12,6 @@ Checks whether the input is valid JSON, accepting and rejecting exactly what
function never throws an exception for invalid input, and the returned `#!cpp bool` is the only result -- no document
is returned.
The result is the same as that of `BasicJsonType::accept()` by design; the difference is how the check is made. This
function runs the document's index builder (and discards the index), while `BasicJsonType::accept()` runs the SAX
parser with a handler that ignores every event. Use this one if you go on to parse the same input with
[`parse()`](parse.md) anyway, so that both use the same code; either is fine for a plain yes/no answer.
## Template parameters
`InputType`
@@ -16,8 +16,8 @@ basic_json_document(const basic_json_document&) = delete;
2. Move constructor. Takes over `other`'s index and, if owned, its text; `other` is left as an empty document. Views
taken from `other` before the move remain valid, because the index is heap-allocated independently of the
`basic_json_document` object.
3. `basic_json_document` is move-only. Copying is disabled because of its cost: a copy would duplicate the whole
index, the decoded-string buffer, and the owned text, while a move is enough in every use we know of.
3. `basic_json_document` is move-only. Copying is disabled because it would either duplicate a potentially large index
and text, or leave two documents claiming to borrow the same buffer.
## Parameters
@@ -30,7 +30,7 @@ No-throw guarantee: the default and move constructors never throw exceptions.
## Complexity
Constant.
Constant, for the default and move constructors.
## Examples
@@ -1,129 +0,0 @@
# <small>nlohmann::basic_json_document::</small>erase
```cpp
// (1)
std::size_t erase(view_type object, string_view_t key);
// (2)
template<typename I>
void erase(view_type array, I idx);
// (3)
std::size_t erase(const json_pointer& ptr);
```
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
were removed; `#!cpp 0` if `object` has no member with this key.
2. Removes the element at index `idx` of `array`, which must already exist (`#!cpp idx < array.size()`).
3. Removes the value the JSON pointer `ptr` refers to, relative to [`root()`](root.md). `ptr` must not be empty
([`root()`](root.md) itself cannot be erased), and the *parent* of the target must already exist. The target is
removed as in 1. if the parent is an object (returns the number of removed members, `#!cpp 0` or more) and as in 2.
if it is an array (always returns `#!cpp 1`).
## Template parameters
`I`
: an integral type other than `#!cpp bool`, deduced (overloads taking a `#!cpp bool` or a non-integral type for
`idx` do not participate in overload resolution).
## Parameters
`object` (in)
: the object to remove a member of
`array` (in)
: the array to remove an element of
`key` (in)
: the key of the member(s) to remove
`idx` (in)
: the index of the element to remove; a negative value throws (see [Exceptions](#exceptions))
`ptr` (in)
: a JSON pointer to the value to remove, relative to `root()`
## Return value
1. the number of removed members (`#!cpp 0` if `object` had none with this `key`)
2. (nothing)
3. the number of removed values (`#!cpp 0` or more for an object member, always `#!cpp 1` for an array element)
## Exceptions
1. Throws [`type_error.307`](../../home/exceptions.md#jsonexceptiontype_error307) if `object` is not an object -- the
same message [`BasicJsonType::erase`](../basic_json/erase.md) throws for the same type.
2. Throws `type_error.307` if `array` is not an array. Throws
[`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if `idx` is negative, or if
`#!cpp idx >= array.size()`.
3. Throws [`out_of_range.405`](../../home/exceptions.md#jsonexceptionout_of_range405) ("JSON pointer has no parent")
if `ptr` is empty. Throws what [`at`](../basic_json_view/at.md) throws (overload 3) for resolving `ptr`'s parent.
For the last reference token itself: if the parent is an array, throws what 2. throws for an index that is out of
range, or, for a token that is not a valid array index,
[`parse_error.106`](../../home/exceptions.md#jsonexceptionparse_error106) (a leading `#!cpp '0'`),
[`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) (not a number),
[`out_of_range.410`](../../home/exceptions.md#jsonexceptionout_of_range410) (too large for `size_type`), or
[`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) (an empty token); otherwise (an
object, or a primitive value the pointer's parent resolves to) throws what 1. throws.
Overloads 1. and 2. also throw [`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202)
("view does not belong to this document") if `object`/`array` is a [discarded](../basic_json_view/is_discarded.md)
view or a view of a *different* document. Overload 3. never throws `invalid_iterator.202`: it takes no view, and it
always starts from this document's own [`root()`](root.md).
## Complexity
1. Linear in the number of members of `object`.
2. Linear in the number of elements of `array` at or after `idx` (they move one slot over).
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 or the index into the array (as [`at`](../basic_json_view/at.md)), plus the complexity of 1. or 2. for
the last token.
## Notes
!!! info "Duplicate keys"
Overload 1. removes *every* member with `key`, not just the first -- unlike [`set`](set.md), which assigns the
first occurrence and drops the rest. This is why it returns a count rather than a single view: there may be
more than one member removed, or none.
Like [`set`](set.md) and [`push_back`](push_back.md), `erase` never moves an element's *value*: a view still
referring to a removed member or element keeps showing what it last held (see [Edits](index.md#edits)) -- it just no
longer appears when `array`/`object` is read, dumped, or iterated. What does change is the container's sequence of
*links* to its elements: removing an element of `array` (2.) shifts the links to the elements after it by one, as
[`insert`](insert.md) does in the other direction. *Every* iterator already taken over `array`/`object` is invalidated
by an erase, not only those at or after the removed element, since the container may now use a different sequence.
## Examples
??? example
The example below drops a deprecated field and a decommissioned entry from a configuration document -- using all
three overloads -- and shows what stays intact that would not with a plain `json`/`ordered_json` value: the order
of the fields around the ones removed, and the exact spelling of a number that was never touched.
```cpp
--8<-- "examples/basic_json_document__erase.cpp"
```
Output:
```json
--8<-- "examples/basic_json_document__erase.output"
```
## See also
- [insert](insert.md) - insert an element into an array
- [set](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers to
- [push_back](push_back.md) - append to an array
- [root](root.md) - the view of the root value, the starting point of overload 3
- [`BasicJsonType::erase`](../basic_json/erase.md) - the corresponding function of `basic_json`
- [Edits](index.md#edits) - what an edit guarantees, for every overload
## Version history
- Added in version 3.13.0.
@@ -3,7 +3,7 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
template<typename BasicJsonType, bool Editable = false>
template<typename BasicJsonType>
class basic_json_document;
```
@@ -11,19 +11,13 @@ 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 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
`basic_json_document`; [`materialize()`](../basic_json_view/materialize.md) turns a subtree back into the
`BasicJsonType` value that [`BasicJsonType::parse()`](../basic_json/parse.md) would have produced for it.
A document may **borrow** the text it was parsed from (the caller's buffer must then outlive the document) or **own**
it (a copy, or an rvalue `#!cpp std::string` that was moved in); see [`owns_source`](owns_source.md). `basic_json_document`
is move-only: a copy would duplicate the whole index, the decoded-string buffer, and the owned text, and a move is
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 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 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`).
is move-only: copying a document would either duplicate a potentially large index and text, or leave two documents
claiming to borrow the same buffer, so it is disabled.
## Template parameters
@@ -32,38 +26,23 @@ 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`.
`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
- [**json_document**](../json_document.md) - read-only documents of the default specialization [`json`](../json.md)
- [**ordered_json_document**](../ordered_json_document.md) - read-only documents of
[`ordered_json`](../ordered_json.md)
- [**json_editable_document**](../json_editable_document.md) - editable documents of [`json`](../json.md)
- [**ordered_json_editable_document**](../ordered_json_editable_document.md) - editable documents of
[`ordered_json`](../ordered_json.md)
- [**json_document**](../json_document.md) - documents of the default specialization [`json`](../json.md)
- [**ordered_json_document**](../ordered_json_document.md) - documents of [`ordered_json`](../ordered_json.md)
## Member types
- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType, Editable>`)
- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType>`)
- **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)
## Member functions
- [(constructor)](basic_json_document.md)
### Parsing
- [**parse**](parse.md) (_static_) - deserialize from a compatible input, borrowing or owning it as appropriate
- [**parse_copy**](parse_copy.md) (_static_) - deserialize a copy of a compatible input
- [**accept**](accept.md) (_static_) - check whether the input is valid JSON
- [**read**](read.md) - (re-)parse into this document, reusing its memory
### Access
- [**root**](root.md) - the view of the root value
- [**is_discarded**](is_discarded.md) - return whether the last parse failed
- [**source**](source.md) - the parsed text
@@ -72,49 +51,6 @@ bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp
- [**memory_usage**](memory_usage.md) - the number of bytes held by the document
- [**shrink_to_fit**](shrink_to_fit.md) - release unused index capacity
### Images
- [**save**](save.md) - the document as an image that `load()` reads without parsing
- [**load**](load.md) (_static_) - read an image written by `save()`
### Edits
- [**set**](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers
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
(`#!cpp Editable` documents only)
## Edits
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
points apply to every edit:
- **The source text is never written**, and the parsed index never moves: every value keeps the node it was parsed
into, so [views](../basic_json_view/index.md) taken before an edit stay valid, including
[`root()`](root.md). New values (and the element sequences of an edited array/object) go to storage owned by the
document, allocated on demand.
- **A view keeps referring to the same value.** After [`set`](set.md) replaces the value a view refers to, that view
sees the new value; a view of a value that a later edit replaces or drops keeps showing what it last held. An edit
of an array or object, however, **invalidates the iterators taken over it** (its members may now live in a
different sequence), and a string obtained with [`get_string()`](../basic_json_view/get_string.md) stays valid even
as further edits happen (earlier buffers of edited text are kept alive, not overwritten).
- **Values are accepted three ways:** a [`basic_json_view`](../basic_json_view/index.md) of *any* document
(read-only or editable; it is copied, nothing is shared with the source document), a `BasicJsonType` value, or
anything `BasicJsonType` can be constructed from (numbers, strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
- [`dump()`](../basic_json_view/dump.md) writes an edited document with members in document order, new members at
the end, and, with [`number_format::source`](../basic_json_view/number_format.md), keeps the spelling of every
number that was not itself edited -- see [Editing a document](../../features/json_view.md#editing-a-document) for
why this matters.
- [`read()`](read.md) discards all edits, [`shrink_to_fit()`](shrink_to_fit.md) does not move the node index once
there are edits, and [`memory_usage()`](memory_usage.md) includes the memory edits use.
[`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.
## Version history
- Added in version 3.13.0.
@@ -1,114 +0,0 @@
# <small>nlohmann::basic_json_document::</small>insert
```cpp
template<typename I, typename V>
view_type insert(view_type array, I idx, V&& value);
```
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
(`#!cpp idx <= array.size()`; `#!cpp idx == array.size()` appends, like [`push_back`](push_back.md)). Unlike
[`push_back`](push_back.md), a [null](../basic_json_view/is_null.md) `array` does *not* first become an empty array:
`array` must already be an array.
`value` is accepted three ways: a [`basic_json_view`](../basic_json_view/index.md) of *any* document -- read-only or
editable, and it does not have to be `array`'s own document -- which is copied so that nothing is shared with the
source document afterward; a `BasicJsonType` value; or anything `BasicJsonType` can be constructed from (numbers,
strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
## Template parameters
`I`
: an integral type other than `#!cpp bool`, deduced (overloads taking a `#!cpp bool` or a non-integral type for
`idx` do not participate in overload resolution).
`V`
: the type of `value`, deduced; see above for what is accepted.
## Parameters
`array` (in)
: the array to insert into
`idx` (in)
: the position to insert `value` before; a negative value throws (see [Exceptions](#exceptions))
`value` (in)
: the value to insert
## Return value
a view of the new element, now holding `value`
## Exception safety
Basic exception safety: `value` is fully encoded -- including the checks below -- into storage owned by the document
before anything already reachable from [`root()`](root.md) is touched, so a failure while encoding `value` (an
invalid argument, or `#!cpp std::bad_alloc`) leaves the document completely unchanged, other than memory allocated
for the encoding that is not reclaimed. A failure of a later allocation -- while `array` switches from its parsed
layout to a growable block, or while that block grows, see [Notes](#notes) -- can still leave `array` already
switched to that layout even though `value` itself was not inserted.
## Exceptions
Throws [`type_error.309`](../../home/exceptions.md#jsonexceptiontype_error309) if `array` is not an array -- the same
message [`BasicJsonType::insert`](../basic_json/insert.md) throws for the same type; a null `array` throws this too
(see above). Throws [`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if `idx` is negative,
or if `#!cpp idx > array.size()`. Throws
[`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202) ("view does not belong to this
document") if `array` is a [discarded](../basic_json_view/is_discarded.md) view or a view of a *different* document.
Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if `value` is a
[discarded](../basic_json_view/is_discarded.md) view or a [discarded](../basic_json/is_discarded.md) `BasicJsonType`
value, and [`type_error.319`](../../home/exceptions.md#jsonexceptiontype_error319) if `value` is (or contains) a
binary value -- `BasicJsonType` can hold one, but a `json_document` cannot. Throws
[`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) if `value` is (or contains) a string that is
not valid UTF-8, with the same message [`BasicJsonType::dump()`](../basic_json/dump.md) gives for that string.
## Complexity
Linear in the number of elements of `array` at or after `idx` (they move one slot over), plus time linear in the
size of `value` to encode it into the document's storage (constant for a scalar, linear in the number of nested
values for an array or object): like [`push_back`](push_back.md), the elements of `array` move to a growable block
of links the first time it is inserted into (or [`set`](set.md)/[`push_back`](push_back.md) on), and that block
grows in amortized constant time; inserting before the end within that block still shifts every later element.
## Notes
Like [`set`](set.md) on a member or an element, `insert` never moves an existing *element's value* -- only where
`array`'s *links* to its elements live -- so a view of an existing element of `array` stays valid across an
`insert`, and keeps referring to the same element even though its index shifts. Any iterator already taken over
`array` is invalidated, since it was walking the old layout. See [Edits](index.md#edits) for what stays valid across
an edit in general.
## Examples
??? example
The example below inserts a step into the middle of a deployment plan, without touching the steps that come
after it, and shows that a view taken before the insert keeps referring to the same element even though its
index shifts -- something a plain `json`/`ordered_json` array, or its `std::vector`-based storage, has no
equivalent for.
```cpp
--8<-- "examples/basic_json_document__insert.cpp"
```
Output:
```json
--8<-- "examples/basic_json_document__insert.output"
```
## See also
- [push_back](push_back.md) - append to an array
- [erase](erase.md) - remove an object member, an array element, or the value a JSON pointer refers to
- [set](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers to
- [`BasicJsonType::insert`](../basic_json/insert.md) - the corresponding function of `basic_json`
- [Edits](index.md#edits) - what an edit guarantees, for every overload
## Version history
- Added in version 3.13.0.
@@ -1,179 +0,0 @@
# <small>nlohmann::basic_json_document::</small>load
```cpp
// (1)
static basic_json_document load(const std::uint8_t* image, std::size_t size,
const image_check check = image_check::full);
// (2)
static basic_json_document load(const std::vector<std::uint8_t>& image,
const image_check check = image_check::full);
// (3)
static basic_json_document load(std::vector<std::uint8_t>&& image,
const image_check check = image_check::full);
```
1. Reads an image [`save()`](save.md) wrote, from a pointer and a byte count. The image is **borrowed**: `image`
must stay alive and unchanged for as long as the returned document, and any view taken from it, is used.
2. Reads an image from a `#!cpp std::vector`. Also **borrowed** -- equivalent to overload 1 called with
`#!cpp image.data()` and `#!cpp image.size()`.
3. Reads an image, keeping the vector instead of copying it: `image` is moved into the document (no copy), which
then owns it for as long as it needs the text and the decoded strings. [`owns_source()`](owns_source.md) is
`#!cpp true` afterward.
In every overload, the node index is copied into storage the document itself owns -- so that it is properly aligned,
and, for an [editable](index.md#edits) document, can be edited -- while the text and the decoded strings stay in
`image`. The hash indexes [large objects](../../features/json_view.md) use for lookup are rebuilt, exactly as after
parsing.
## Parameters
`image` (in)
: the image [`save()`](save.md) wrote (overloads 1 and 2), or one to take ownership of (overload 3)
`size` (in)
: the number of bytes at `image` (overload 1)
`check` (in)
: how thoroughly to validate `image` before trusting it; see [`image_check`](#image_check) below (optional,
`#!cpp image_check::full` by default)
## Return value
The document read from the image.
## Exception safety
Overloads 1 and 2 give the strong guarantee: `image` is only read, never written, so a thrown exception leaves the
caller's buffer untouched.
Overload 3 moves `image` into the document *before* validating it, so that a good image is kept without a copy. If
loading then fails, the partially built document -- and the vector now inside it -- is discarded along with the
exception, and `image` itself is left **empty**, not restored to what was passed in. Move a copy in instead, or
validate with overload 2 first, if the original vector must survive a failed load.
## Exceptions
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 |
|------------------------|------------------------------------------------------------------------------------------------------|
| `too short` | `image` is `#!cpp nullptr`, or `size` is smaller than the 64-byte header |
| `unknown format` | the header's magic bytes or version do not match, or a reserved header field is not zero |
| `sizes out of range` | the node count, text size, or decoded-string size the header describes does not fit `size`, or the `#!cpp '\0'` after the text or after the decoded strings is missing |
| `the check failed` | `check` is not `#!cpp image_check::none`, and the image fails it -- see [`image_check`](#image_check) |
!!! failure "Example messages"
```
[json.exception.parse_error.116] parse error: invalid json_document image: too short
```
```
[json.exception.parse_error.116] parse error: invalid json_document image: unknown format
```
```
[json.exception.parse_error.116] parse error: invalid json_document image: sizes out of range
```
```
[json.exception.parse_error.116] parse error: invalid json_document image: the check failed
```
## Complexity
Linear in the number of nodes, which are always copied into the document. `#!cpp image_check::none` does not read
the text or the decoded strings. `#!cpp image_check::bounds` reads one byte of the text for each float token (its sign,
to check the recorded digits against the token's length), and nothing else of the text or the decoded strings.
With `#!cpp image_check::full`, linear in the size of the image (the nodes, the text, and the decoded strings), plus
sorting the ranges of the strings and of the float tokens (at most one per node): the contents of each distinct range
are checked once, however many nodes refer to it.
## Notes
### `image_check` { #image_check }
```cpp
using image_check = detail::view::image_check;
enum class image_check
{
full,
bounds,
none
};
```
How thoroughly `load()` validates `image` before trusting it.
`full` (the default)
: Checks everything the parser itself guarantees: structure and bounds; that every string is valid UTF-8 (and, for a
string still in the source text, that it contains no quote, backslash, or control character); and that every number
token is well-formed and matches the value stored for it. Strings and float tokens may share a range only if the
ranges are identical (as nodes that share a value do), and never overlap otherwise. Reading and serializing a
checked image is safe and always produces valid JSON, exactly as for a parsed document. This is the right choice for
an image from anything you do not fully control -- a file, a cache shared with other processes, a peer on the
network.
`bounds`
: Checks structure and bounds only: that every offset and count in the node index stays inside the image. So
`load()`, [`root()`](root.md), element access, and [`materialize()`](../basic_json_view/materialize.md) can never
read outside the image, even on a damaged one. It does *not* guarantee that the image describes valid JSON: a
string that a `full` check would have rejected can make [`dump()`](../basic_json_view/dump.md) write invalid UTF-8
or invalid JSON, or throw [`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316), and a number can
read back with a value that does not match how it is spelled. An [editable document](../json_editable_document.md)
does not take such a string over: [`set`](set.md), [`push_back`](push_back.md) and [`insert`](insert.md) throw
`type_error.316` when they copy it from a view of the loaded document, and leave the editable document unchanged.
`bounds` skips scanning the text and the decoded strings, so it fits a cache your own process just wrote and reads
straight back, where damage would mean a bug or a hardware fault rather than adversarial input.
`none`
: Checks nothing. Reading a damaged image is undefined behavior, so use it only for an image you trust as much as
your own memory.
**Lifetime.** Overloads 1 and 2 borrow `image`: it must stay alive and byte-for-byte unchanged for as long as the
returned document, and any [view](../basic_json_view/index.md) taken from it, is used -- exactly like a document
[`parse()`](parse.md) borrowed its input for. Overload 3 avoids this by keeping the vector itself; see
[`owns_source`](owns_source.md).
!!! warning "Experimental"
The image format is versioned but not yet stable, and may change in an incompatible way before it is declared
stable; `load()` already rejects an image written by a different format version with `parse_error.116`
("unknown format"). Use images to cache a document within one build of the library, or to hand one to another
process running the *same* build on the *same* (little-endian) machine -- not as a long-term storage format.
## Examples
??? example "Caching a document, ownership, and a rejected image"
The example below saves a parsed document as an image, checks that `load()` reproduces the original
[`dump()`](../basic_json_view/dump.md) without parsing, and shows the difference between
`load(std::move(image))` (owned) and `load(image)` (borrowed). It then damages one byte of the image and shows
`image_check::full` rejecting it with `parse_error.116`, while `image_check::bounds` -- meant for a cache the
process already trusts -- still reads it without going out of bounds.
```cpp
--8<-- "examples/basic_json_document__load.cpp"
```
Output:
```json
--8<-- "examples/basic_json_document__load.output"
```
## See also
- [save](save.md) - write the document as an image
- [owns_source](owns_source.md) - return whether the document holds its own copy of the text
- [parse](parse.md) - deserialize from JSON text instead of an image
- [Images](../../features/json_view.md#images) - why and when to use images
## Version history
- Added in version 3.13.0.
@@ -4,7 +4,7 @@
bool owns_source() const noexcept;
```
Returns whether the document holds its own copy of the parsed text or is borrowing the caller's buffer.
Returns whether the document holds its own copy of the parsed text, as opposed to borrowing the caller's buffer.
## Return value
@@ -21,15 +21,13 @@ 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 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.
the input) instead of a tree of `BasicJsonType` values. The input must be byte-oriented (see the template parameters
below): not every input type of `BasicJsonType::parse()` is supported.
## Template parameters
`InputType`
: A compatible input, for instance:
: A byte-oriented input, one of:
- 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`,
@@ -37,10 +35,12 @@ owned copy of a borrowable input as well.
- a container for which `#!cpp obj.data()` and `#!cpp obj.size()` give contiguous single-byte access, e.g.
`#!cpp std::vector<char>` or `#!cpp std::vector<std::uint8_t>`
- an `#!cpp std::istream` object
- a `#!cpp FILE*` pointer
- wide characters (`#!cpp wchar_t`, `#!cpp char16_t`, `#!cpp char32_t`), which are converted to UTF-8: a wide
string object (`#!cpp std::wstring`, `#!cpp std::u16string`, `#!cpp std::u32string`), an array (e.g. a wide
string literal), or a pointer to a null-terminated wide string
- a wide string object (`#!cpp std::wstring`, `#!cpp std::u16string`, `#!cpp std::u32string`), which is converted
to UTF-8
Other inputs are not supported: a `#!cpp FILE*`, and pointers to or arrays of wide characters (`#!cpp wchar_t`,
`#!cpp char16_t`, `#!cpp char32_t`) are rejected at compile time by a `#!cpp static_assert`. (Use
[`BasicJsonType::parse()`](../basic_json/parse.md) for these.)
`IteratorType`
: an input iterator type, for instance a pair of pointers such as `ptr` and `ptr + len`, or a pair of
@@ -78,9 +78,7 @@ discarded; see [`is_discarded`](is_discarded.md).
Throws the same exception [`BasicJsonType::parse()`](../basic_json/parse.md) throws for the same input and options --
the same exception id, message, and position -- because on a failing input the library's own parser is run on the
same bytes to produce the diagnostic. This replay runs only for a failing input, and costs about a lexing pass up to
the error (its SAX handler builds no values); with `allow_exceptions` set to `#!cpp false`, it is skipped and a
discarded document is returned instead. Additionally throws
same bytes to produce the diagnostic. Additionally throws
[`out_of_range.416`](../../home/exceptions.md#jsonexceptionout_of_range416) if the input is 4294967280 bytes (4 GiB
minus 16 bytes) or larger, a size [`BasicJsonType::parse()`](../basic_json/parse.md) does not reject.
@@ -97,7 +95,7 @@ Linear in the length of the input.
| lvalue byte container (`std::string`, `std::vector<char>`, ...), `std::string_view`, C string, character array | **borrowed** -- `input` must outlive the document |
| non-const rvalue `#!cpp std::string` | **owned**, moved in without a copy |
| other rvalue byte container (including a `#!cpp const` rvalue `#!cpp std::string`) | **owned**, copied |
| stream, `#!cpp FILE*`, wide characters, or anything else read through the general input adapter | **owned**, read into a buffer (a stream is read to its end) |
| stream, wide string, or anything else read through the general input adapter | **owned**, read into a buffer (a stream is read to its end) |
For overload (2), a pair of pointers to single-byte integers (e.g. `#!cpp const char*`, `#!cpp std::uint8_t*`) is
borrowed. From C++20 on, so is any other contiguous iterator over single bytes, such as
@@ -149,7 +147,6 @@ buffer of a given length, pass a pair of pointers: `#!cpp parse(ptr, ptr + len)`
- [accept](accept.md) - check whether the input is valid JSON
- [read](read.md) - (re-)parse into this document, reusing its memory
- [owns_source](owns_source.md) - return whether the document holds its own copy of the text
- [load](load.md) - read a document from an image instead of parsing JSON text
- [`BasicJsonType::parse`](../basic_json/parse.md) - the corresponding function of `basic_json`
## Version history
@@ -1,102 +0,0 @@
# <small>nlohmann::basic_json_document::</small>push_back
```cpp
template<typename V>
view_type push_back(view_type array, V&& value);
```
Appends `value` as a new last element of `array`. A [null](../basic_json_view/is_null.md) `array` first becomes an
empty array, the same way [`set`](set.md) turns a null `object` into an empty object.
`value` is accepted three ways: a [`basic_json_view`](../basic_json_view/index.md) of *any* document -- read-only or
editable, and it does not have to be `array`'s own document -- which is copied so that nothing is shared with the
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 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
`V`
: the type of `value`, deduced; see above for what is accepted.
## Parameters
`array` (in)
: the array (or null value) to append to
`value` (in)
: the value to append
## Return value
a view of the new last element of `array`, now holding `value`
## Exception safety
Basic exception safety: `value` is fully encoded -- including the checks below -- into storage owned by the document
before anything already reachable from [`root()`](root.md) is touched, so a failure while encoding `value` (an
invalid argument, or `#!cpp std::bad_alloc`) leaves the document completely unchanged, other than memory allocated
for the encoding that is not reclaimed. A failure of a later allocation -- while `array` switches from its parsed
layout to a growable block, or while that block grows, see [Notes](#notes) -- can still leave a partial effect, such
as a null `array` argument already turned into an empty array even though `value` itself was not appended.
## Exceptions
Throws [`type_error.308`](../../home/exceptions.md#jsonexceptiontype_error308) if `array` is neither an array nor
null -- the same message [`BasicJsonType::push_back`](../basic_json/push_back.md) throws for the same type. Throws
[`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202) ("view does not belong to this
document") if `array` is a [discarded](../basic_json_view/is_discarded.md) view or a view of a *different* document.
Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if `value` is a
[discarded](../basic_json_view/is_discarded.md) view or a [discarded](../basic_json/is_discarded.md) `BasicJsonType`
value, and [`type_error.319`](../../home/exceptions.md#jsonexceptiontype_error319) if `value` is (or contains) a
binary value -- `BasicJsonType` can hold one, but a `json_document` cannot. Throws
[`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) if `value` is (or contains) a string that is
not valid UTF-8, with the same message [`BasicJsonType::dump()`](../basic_json/dump.md) gives for that string.
## Complexity
Amortized constant, plus time linear in the size of `value` to encode it into the document's storage (constant for
a scalar, linear in the number of nested values for an array or object): the elements of `array` move to a growable
block of links the first time it is appended to (or [`set`](set.md) on), and that block itself grows -- doubling its
capacity, so the cost of growing it amortizes to constant per element -- only once it runs out of room. See
[Notes](#notes).
## Notes
Like [`set`](set.md) on a member or an element, `push_back` never moves an existing element itself -- only where
`array`'s *links* to its elements live -- so a view of an existing element of `array` stays valid across a
`push_back`, but any iterator already taken over `array` is invalidated, since it was walking the old layout. See
[Edits](index.md#edits) for what stays valid across an edit in general.
## Examples
??? example
The example below appends records to an array one at a time, as they might arrive from a stream of events,
without ever building a `BasicJsonType` value for the array or for the records already in it, and shows that a
view taken from an earlier `push_back` still refers to the same element once later ones have run.
```cpp
--8<-- "examples/basic_json_document__push_back.cpp"
```
Output:
```json
--8<-- "examples/basic_json_document__push_back.output"
```
## See also
- [set](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers to
- [insert](insert.md) - insert an element into an array before a given position
- [erase](erase.md) - remove an object member, an array element, or the value a JSON pointer refers to
- [root](root.md) - the view of the root value
- [`BasicJsonType::push_back`](../basic_json/push_back.md) - the corresponding function of `basic_json`
- [Edits](index.md#edits) - what an edit guarantees, for every overload
## Version history
- Added in version 3.13.0.
@@ -47,14 +47,7 @@ Every view taken from `#!cpp *this` before the call -- including the previous [`
whether or not the new parse succeeds; take fresh views from [`root()`](root.md) afterward.
`input` is borrowed or owned by the same rules as [`parse()`](parse.md#notes); a document can borrow on one call and
own on the next, since ownership is decided freshly each time. An input that is copied (see the table in
[`parse()`](parse.md#notes)) is written into the document's previous owned copy, reusing its memory; a moved-in
`#!cpp std::string` replaces it.
Reusing a document matters most for large inputs: the operating system provides the memory of a fresh node index one
page at a time, and every page costs a page fault the first time it is written. On x86-64 Linux (4 KiB pages), parsing
a 55 MB document into a reused document took about 40 % less time than parsing it into a fresh one. Programs that parse
many documents of similar size should therefore keep one document and call `read()`.
own on the next, since ownership is decided freshly each time.
An integer argument that is not a `#!cpp bool` where the flags are expected, such as `#!cpp read(ptr, len)`, does not
compile; see [`parse`](parse.md#notes).
@@ -80,7 +73,6 @@ compile; see [`parse`](parse.md#notes).
- [parse](parse.md) - deserialize from a compatible input
- [root](root.md) - the view of the root value
- [load](load.md) - read a document from an image instead of parsing JSON text
## Version history
@@ -39,8 +39,7 @@ auto v = doc.root();
`root()` is a cheap handle into the document's index, not a copy of anything; call it as often as needed. The
returned view is valid under the same conditions as any other view of the document -- see
[Object inspection](../basic_json_view/index.md) -- in particular, it is invalidated by the next
[`read()`](read.md) or [`shrink_to_fit()`](shrink_to_fit.md) on this document. A view can dangle, like a
`#!cpp std::string_view`; see [Ownership and lifetime](../../features/json_view.md#ownership-and-lifetime).
[`read()`](read.md) or [`shrink_to_fit()`](shrink_to_fit.md) on this document.
## Examples
@@ -1,104 +0,0 @@
# <small>nlohmann::basic_json_document::</small>save
```cpp
std::vector<std::uint8_t> save() const;
```
Writes the document as an *image*: a byte buffer that [`load`](load.md) reads back without parsing. The image holds
the node index, the source text (plus, for an edited document, the number tokens edits wrote), and the decoded
strings (plus the strings edits wrote) -- everything [`root()`](root.md) needs, with nothing left to parse.
An edited document is written in its *current* state, with its values in document order, the way the library's own
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 `#!cpp Editable`, since the image reflects document order and
values only, not which specialization produced them.
## Return value
The image, as a `#!cpp std::vector<std::uint8_t>`. Pass it, or a pointer to its data together with its size, to
[`load`](load.md) to read the document back.
## Exception safety
Strong guarantee: `save()` does not modify `#!cpp *this` (it is `#!cpp const`), so if it throws, the document is left
exactly as it was, and the partially built image is discarded with the exception.
## Exceptions
Throws [`type_error.320`](../../home/exceptions.md#jsonexceptiontype_error320) if the document is
[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.
!!! failure "Example messages"
```
[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
```
## Complexity
Linear in the size of the document: the number of nodes, plus the length of the text and the decoded strings that end
up in the image.
## Notes
**Format.** The image begins with a 64-byte header (the magic bytes `#!cpp "NJVI"`, a version number, the node count,
and the sizes of the text and the decoded strings, all little-endian), followed by the nodes
([16 bytes each](../../home/architecture.md#node-index-of-json-views)), the text and a `#!cpp '\0'`, and the decoded
strings and a `#!cpp '\0'`. [`load`](load.md) checks the header, and the sizes it describes, before reading anything
else -- see [`load`'s Exceptions](load.md#exceptions).
!!! warning "Experimental"
The image format is versioned but not yet stable: it may change in an incompatible way before it is declared
stable. Use images to cache a document within one build of the library, or to hand one to another process running
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 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
??? example "Caching a parsed document as an image"
The example below saves a parsed configuration as an image -- the way a service might cache one to answer later
requests without parsing the text again -- and confirms that loading it back gives exactly the same result as
parsing did, and that saving is deterministic.
```cpp
--8<-- "examples/basic_json_document__save.cpp"
```
Output:
```json
--8<-- "examples/basic_json_document__save.output"
```
## See also
- [load](load.md) - read an image written by `save()`
- [owns_source](owns_source.md) - return whether the document holds its own copy of the text
- [`basic_json_view::dump`](../basic_json_view/dump.md) - serialize the document to JSON text instead of an image
- [Images](../../features/json_view.md#images) - why and when to use images
## Version history
- Added in version 3.13.0.
@@ -1,203 +0,0 @@
# <small>nlohmann::basic_json_document::</small>set
```cpp
// (1)
template<typename V>
view_type set(view_type target, V&& value);
// (2)
template<typename V>
view_type set(view_type object, string_view_t key, V&& value);
// (3)
template<typename I, typename V>
view_type set(view_type array, I idx, V&& value);
// (4)
template<typename V>
view_type set(const json_pointer& ptr, V&& value);
```
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`.
2. Sets the member `key` of the object `object` to `value`: assigns it if `object` already has a member with this
key -- the first one, should the key occur more than once, and the later duplicates are then dropped (see the
[Notes](#notes) below) -- or appends a new member at the end otherwise. A [null](../basic_json_view/is_null.md)
`object` first becomes an empty object.
3. Assigns `value` to the element at index `idx` of the array `array`, which must already exist (`#!cpp idx <
array.size()`).
4. Sets the value the JSON pointer `ptr` refers to, relative to [`root()`](root.md), to `value`. The *parent* of the
target must already exist: an object member is set as in 2. (added if it does not exist yet), an array element is
assigned as in 3., and a last reference token of `#!cpp "-"`, or equal to the size of the array, appends `value`
instead, exactly as [`push_back`](push_back.md) would. A [null](../basic_json_view/is_null.md) parent becomes what
[`basic_json::operator[]`](../basic_json/operator%5B%5D.md) with a JSON pointer makes of it: an array if the last
reference token is `#!cpp "-"` or consists of digits only (for an index beyond 0, the array is first filled with
null values up to that index), an object otherwise. An empty `ptr` sets [`root()`](root.md) itself, as in 1.
In every overload, `value` is accepted three ways: a [`basic_json_view`](../basic_json_view/index.md) of *any*
document -- read-only or editable, and it does not have to be `target`'s/`object`'s/`array`'s own document -- which
is copied so that nothing is shared with the source document afterward; a `BasicJsonType` value; or anything
`BasicJsonType` can be constructed from (numbers, strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
## Template parameters
`V`
: the type of `value`, deduced; see above for what is accepted.
`I`
: an integral type other than `#!cpp bool`, deduced (overloads taking a `#!cpp bool` or a non-integral type for
`idx` do not participate in overload resolution).
## Parameters
`target` (in)
: the value to replace
`object` (in)
: the object (or null value) whose member to set
`array` (in)
: the array whose element to assign
`key` (in)
: the key of the member to set
`idx` (in)
: the index of the element to assign; a negative value throws (see [Exceptions](#exceptions))
`ptr` (in)
: a JSON pointer to the value to set, relative to `root()`
`value` (in)
: the new value
## Return value
1. a view of `target`, now holding `value`
2. a view of the member `key` of `object`, now holding `value`
3. a view of the element `idx` of `array`, now holding `value`
4. a view of the value `ptr` refers to, now holding `value`
## Exception safety
Basic exception safety: `value` is fully encoded -- including the checks below -- into storage owned by the document
before anything already reachable from [`root()`](root.md) is touched, so a failure while encoding `value` (an
invalid argument, or `#!cpp std::bad_alloc`) leaves the document completely unchanged, other than memory allocated
for the encoding that is not reclaimed. A failure of a later allocation -- while an edited array or object switches
from its parsed layout to a growable block, see [Notes](#notes) -- can still leave a partial effect, such as a
[null](../basic_json_view/is_null.md) `object`/`array` argument already turned into an empty object/array even
though `value` itself was not linked in. Likewise, a failure of `value` in 4. leaves a null parent that is set with an
index beyond 0 already filled with the null values before the index.
## Exceptions
1. Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if `value` is a
[discarded](../basic_json_view/is_discarded.md) view, or a [discarded](../basic_json/is_discarded.md)
`BasicJsonType` value (e.g. `#!cpp BasicJsonType(value_t::discarded)`) -- an object or array `value`, of either
kind, is fine and is encoded as a whole subtree.
2. Throws [`type_error.305`](../../home/exceptions.md#jsonexceptiontype_error305) if `object` is neither an object
nor null -- the same message [`operator[]`](../basic_json_view/operator%5B%5D.md) throws for a string argument on
such a value. Throws [`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) if `key` is not
valid UTF-8, with the same message [`BasicJsonType::dump()`](../basic_json/dump.md) gives for that string.
Also throws what 1. throws for `value`.
3. Throws `type_error.305` if `array` is not an array -- the same message `operator[]` throws for a numeric argument
on such a value. Throws [`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if `idx` is
negative, or if `#!cpp idx >= array.size()`. Also throws what 1. throws for `value`.
4. Throws what [`at`](../basic_json_view/at.md) throws (overload 3) for resolving `ptr`'s parent, except that a
missing object member or an array index equal to the array's size at the very last reference token is not an
error there (it becomes a new member or an appended element) instead of
[`out_of_range.403`](../../home/exceptions.md#jsonexceptionout_of_range403)/[`out_of_range.402`](../../home/exceptions.md#jsonexceptionout_of_range402).
For the last reference token itself: if the parent is an object (or a primitive value, where it throws
`type_error.305`), throws what 2. throws; if the parent is an array, throws what 3. throws for an index that is
out of range, or, for a token that is not a valid array index,
[`parse_error.106`](../../home/exceptions.md#jsonexceptionparse_error106) (a leading `#!cpp '0'`),
[`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) (not a number),
[`out_of_range.410`](../../home/exceptions.md#jsonexceptionout_of_range410) (too large for `size_type`), or
[`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) (an empty token); the same errors are
thrown for a null parent and a token of digits (the parent is not changed then), and
[`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if the index is 4294967295 or more.
Also throws what 1. throws for `value`.
Every overload also throws [`type_error.319`](../../home/exceptions.md#jsonexceptiontype_error319) if `value` is (or
contains) a binary value -- `BasicJsonType` can hold one, but a `json_document` cannot -- and
[`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202) ("view does not belong to this
document") if `target`/`object`/`array` is a [discarded](../basic_json_view/is_discarded.md) view or a view of a
*different* document (overloads 1-3 only; overload 4 always starts from this document's own [`root()`](root.md)).
## Complexity
1. Linear in the size of `value` (encoding it into the document's storage): constant for a scalar, linear in the
number of nested values for an array or object. If `target` is itself an array or object that spans more than one
node in its parent's original, unedited layout, and `value` is a scalar, replacing it additionally costs time
linear in the size of the document, the *first* time (the parent of `target` is looked up from
[`root()`](root.md), and then switches to links) -- see [Notes](#notes). Once the parent has links, `target` is
replaced in constant time: setting every element of a large array one after the other is linear overall. To avoid
the lookup altogether, use 3. (or 2. for an object), which know the parent.
2. Linear in the number of members of `object`, to find an existing member with `key`, plus the complexity of 1. for
`value`.
3. Constant, plus the complexity of 1. for `value`.
4. Linear in the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
that level or the index into the array (as [`at`](../basic_json_view/at.md)), plus the complexity of 2. or 3. for
the last token; for a null parent and an index, linear in the index.
## Notes
!!! info "Duplicate keys"
If `object` already has more than one member with `key` (2.), the *first* one is assigned `value` and every
later member with the same key is removed -- so that a lookup, an iteration, and
[`materialize()`](../basic_json_view/materialize.md) of `object` afterward all agree on a single value for
`key`, the same way [`operator[]`](../basic_json_view/operator%5B%5D.md) already picks the first occurrence of a
duplicate key for reading. See the [Notes on duplicate keys](../basic_json_view/operator%5B%5D.md#notes) of
`operator[]`.
Setting a member (2.) or an element (3., through 4.) of an array or object whose elements have not been edited
before switches it from its parsed layout to a growable block holding links to its elements; a later
[`push_back`](push_back.md) or `set` on the same container reuses that block, growing it (amortized constant time)
only once it runs out of room. This never moves an element itself -- only where the container's *links* to its
elements live -- so a view of an element stays valid, but any iterator already taken over the container is
invalidated, since it was walking the old layout. See [Edits](index.md#edits) for what stays valid across an edit in
general.
The same switch happens, for the same reason, when overload 1. replaces a multi-node array/object value with a
scalar: the *parent's* element sequence is what has to switch to links, not `target` itself, because the parent
originally stepped over `target`'s whole subtree by its node count, which no longer applies once `target` is a
one-node scalar.
## Examples
??? example "Example: (1)/(2)/(3)/(4) replace a value, set a member, assign an element, set via a JSON pointer"
The example below edits a small configuration document -- replacing a value, adding an object member, assigning
an array element, and reaching a field through a JSON pointer -- and shows what
[`dump()`](../basic_json_view/dump.md) preserves that is lost once the same edits are made on a `BasicJsonType`
value instead: the order object members were written in, and the exact spelling of a number that was never
touched.
```cpp
--8<-- "examples/basic_json_document__set.cpp"
```
Output:
```json
--8<-- "examples/basic_json_document__set.output"
```
## See also
- [push_back](push_back.md) - append to an array
- [insert](insert.md) - insert an element into an array
- [erase](erase.md) - remove an object member, an array element, or the value a JSON pointer refers to
- [root](root.md) - the view of the root value, the starting point of overload 4
- [`basic_json_view::dump`](../basic_json_view/dump.md) - serialize the document, keeping an untouched number's
spelling with `#!cpp number_format::source`
- [Edits](index.md#edits) - what an edit guarantees, for every overload
- [Editing a document](../../features/json_view.md#editing-a-document) - why editable documents keep the source
text's order and number spelling
## Version history
- Added in version 3.13.0.
-144
View File
@@ -1,144 +0,0 @@
# <small>nlohmann::basic_json_view::</small>at
```cpp
// (1)
basic_json_view at(string_view_t key) const;
basic_json_view at(const char* key) const;
basic_json_view at(const string_t& key) const;
// (2)
basic_json_view at(size_type idx) const;
template<typename IntegerType>
basic_json_view at(IntegerType idx) const;
// (3)
basic_json_view at(const json_pointer& ptr) const;
```
1. Returns the value of the object member with key `key` -- the first one, should the key occur more than once (see
[Notes on duplicate keys](operator[].md#notes)).
2. Returns the array element at index `idx`. The template accepts every integer type except `#!cpp bool` and
`#!cpp std::size_t` and forwards to the `size_type` overload, as for [`operator[]`](operator[].md); a negative
`idx` is out of range.
3. Returns the value a JSON pointer `ptr` refers to, starting at this value.
## Parameters
`key` (in)
: object key of the element to access
`idx` (in)
: index of the element to access
`ptr` (in)
: JSON pointer to the element to access
## Return value
1. the value of the first member with key `key`
2. the element at index `idx`
3. the value `ptr` resolves to, starting at this value
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
1. The function can throw the following exceptions, both with the same message as the corresponding call to
[`BasicJsonType::at`](../basic_json/at.md):
- Throws [`type_error.304`](../../home/exceptions.md#jsonexceptiontype_error304) if the value is not an object.
- Throws [`out_of_range.403`](../../home/exceptions.md#jsonexceptionout_of_range403) if no member has key `key`.
2. The function can throw the following exceptions, both with the same message as the corresponding call to
[`BasicJsonType::at`](../basic_json/at.md):
- Throws [`type_error.304`](../../home/exceptions.md#jsonexceptiontype_error304) if the value is not an array.
- Throws [`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if `#!cpp idx >= size()`.
3. The function can throw the following exceptions, all with the same message as the corresponding call to
[`BasicJsonType::at`](../basic_json/at.md):
- Throws [`parse_error.106`](../../home/exceptions.md#jsonexceptionparse_error106) if an array index in `ptr`
begins with `#!cpp '0'`.
- Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) if an array index in `ptr` is
not a number.
- Throws [`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if an array index in `ptr`
is out of range.
- Throws [`out_of_range.402`](../../home/exceptions.md#jsonexceptionout_of_range402) if a reference token is
`#!cpp "-"` at an array -- `at` never inserts an element, so `#!cpp "-"` is always invalid.
- Throws [`out_of_range.403`](../../home/exceptions.md#jsonexceptionout_of_range403) if a reference token names
an object member that does not exist.
- Throws [`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) if `ptr` cannot be resolved
because a reference token is used on a primitive value.
None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) path: the view has no
`BasicJsonType` value to point at, so the exception is created without one, even if `BasicJsonType` was built with
`JSON_DIAGNOSTICS` enabled.
## Complexity
1. Linear in the number of members: as for [`ordered_json`](../ordered_json.md), members are compared one after
another, in document order, stopping at the first match. Each comparison first checks the
key's length -- already known from the index, without reading the key bytes -- before comparing its content.
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).
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.).
## Notes
!!! warning "Duplicate keys: the first member wins"
If the source text repeats a key, this resolves to the *first* member with it, not to the last one that
[`materialize()`](materialize.md) and `parse()` keep. See the [Notes on duplicate keys](operator[].md#notes) of
`operator[]` and [Duplicate keys](../../features/json_view.md#duplicate-keys) for the reasons and for how to get
the last value.
Unlike [`operator[]`](operator[].md), which returns a [discarded](is_discarded.md) view for a missing key or an
out-of-range index, `at` always throws -- exactly as `BasicJsonType::at` does, and with the same messages, so
existing error handling written against `BasicJsonType::at` keeps working unchanged when switched to a view. This
also holds for overload 3: unlike [`operator[]`](operator[].md) with a JSON pointer, which returns a discarded view
for a missing key or an out-of-range index, `at` throws for those too (`out_of_range.403`/`out_of_range.401`).
## Examples
??? example "Example: (1)/(2) access specified element with bounds checking"
The example below reads required fields out of a service configuration with `at`, and shows that the exceptions
it throws -- for a wrong type and for a missing key -- carry the same messages
[`BasicJsonType::at`](../basic_json/at.md) would produce for the same JSON text.
```cpp
--8<-- "examples/basic_json_view__at.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__at.output"
```
??? example "Example: (3) access specified element via JSON pointer with bounds checking"
The example below shows that `at` with a JSON pointer throws exactly the exceptions, with exactly the messages,
that [`BasicJsonType::at`](../basic_json/at.md) throws for the same pointer and the same document.
```cpp
--8<-- "examples/basic_json_view__at_json_pointer.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__at_json_pointer.output"
```
## See also
- [operator[]](operator[].md) - access specified element (returns a discarded view instead of throwing)
- [front](front.md), [back](back.md) - access the first or last element
- [`BasicJsonType::at`](../basic_json/at.md) - the corresponding function of `basic_json`
- [`json_pointer`](../json_pointer/index.md) - JSON pointer type used by overload 3
## Version history
- Added in version 3.13.0.
@@ -1,63 +0,0 @@
# <small>nlohmann::basic_json_view::</small>back
```cpp
basic_json_view back() const;
```
Returns the last element of an array, the last member value of an object, or the value itself if it is primitive
(as for [`BasicJsonType::back()`](../basic_json/back.md), a primitive value is a range of one element).
## Return value
The last element or member value. For a primitive value (number, string, boolean), the value itself.
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
Throws [`invalid_iterator.214`](../../home/exceptions.md#jsonexceptioninvalid_iterator214) if the view is
[null](is_null.md) or [discarded](is_discarded.md), or if it is an empty array or object.
This exception does not carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) path: the view has no
`BasicJsonType` value to point at, so the exception is created without one, even if `BasicJsonType` was built with
`JSON_DIAGNOSTICS` enabled.
## Complexity
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.
## Notes
Unlike [`BasicJsonType::back()`](../basic_json/back.md), which has undefined behavior for an empty array or object,
`back()` throws `invalid_iterator.214` for an empty array, an empty object, a null value, or a discarded view.
## Examples
??? example
The example below reads only the final status of a build log with `back()`. Even though `back()` is linear in
the number of events (unlike [`front()`](front.md), which is constant), it still avoids building a
`BasicJsonType` value for the events that are not needed.
```cpp
--8<-- "examples/basic_json_view__back.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__back.output"
```
## See also
- [front](front.md) - access the first element
- [`BasicJsonType::back`](../basic_json/back.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -8,9 +8,8 @@ Creates an invalid (discarded) view: [`type()`](type.md) is `#!cpp value_t::disc
[`is_discarded()`](is_discarded.md) is `#!cpp true`.
This is the only constructor a caller can use directly. Every other view is obtained from a
[`basic_json_document`](../basic_json_document/index.md), via [`root()`](../basic_json_document/root.md) or by
navigating into a container with [`operator[]`](operator[].md), [`at`](at.md), [`front`](front.md), [`back`](back.md),
[`find`](find.md), or iteration.
[`basic_json_document`](../basic_json_document/index.md), via [`root()`](../basic_json_document/root.md) or (once
element access is added) from navigating into a container.
## Exception safety
@@ -1,65 +0,0 @@
# <small>nlohmann::basic_json_view::</small>begin
```cpp
iterator begin() const noexcept;
```
Returns an iterator to the first element of an array, or the first member value of an object, in **document order**
-- the order the values appear in the source text, not sorted by key. A primitive value iterates as a range of one
element (itself), and a `#!json null` value or a [discarded](is_discarded.md) view iterates as an empty range.
## Return value
Iterator to the first element.
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Constant.
## Notes
For an object, iteration visits **every** member, including all occurrences of a duplicate key -- unlike
[`operator[]`](operator[].md), [`at`](at.md), [`find`](find.md), and [`contains`](contains.md),
which all resolve to the *first* member with a given key. See the
[Notes on duplicate keys](operator[].md#notes) of `operator[]`.
Because objects are iterated in document order rather than sorted by key, the order seen here can differ from what
iterating the [`materialize()`](materialize.md)d `BasicJsonType` value would produce: a `#!cpp basic_json` object
(`std::map`-backed by default) sorts its keys, while a view does not.
An `ordered_json` value also keeps document order, but it keeps only one entry per key: as `parse()` does, it keeps the
*last* value, at the position of the key's *first* occurrence. The view, in contrast, visits every member, including
the duplicates.
## Examples
??? example
The example below iterates a log record's members with `begin()`/[`end()`](end.md) and prints them in the order
they were written. Materializing the record into a `BasicJsonType` object and iterating that would instead print
the members sorted by key.
```cpp
--8<-- "examples/basic_json_view__begin.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__begin.output"
```
## See also
- [end](end.md) - returns an iterator to one past the last element
- [cbegin](cbegin.md) - returns a const iterator to the first element
- [items](items.md) - access iterator member functions in range-based for
- [`BasicJsonType::begin`](../basic_json/begin.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,49 +0,0 @@
# <small>nlohmann::basic_json_view::</small>cbegin
```cpp
iterator cbegin() const noexcept;
```
Returns an iterator to the first element, in [document order](begin.md). Equivalent to [`begin()`](begin.md): a view
is always read-only, so `#!cpp const_iterator` and `#!cpp iterator` are the same type, and `cbegin()` exists only so
that generic code that expects a `cbegin()`/`cend()` pair works with a view too.
## Return value
Iterator to the first element; identical to what [`begin()`](begin.md) returns.
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Constant.
## Examples
??? example
The example below sums many measurements with `std::accumulate`, using `cbegin()`/[`cend()`](cend.md) as the
range -- the same way it would for any standard container -- without ever materializing the whole array into a
`BasicJsonType` value.
```cpp
--8<-- "examples/basic_json_view__cbegin.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__cbegin.output"
```
## See also
- [begin](begin.md) - returns an iterator to the first element
- [cend](cend.md) - returns a const iterator to one past the last element
- [`BasicJsonType::cbegin`](../basic_json/cbegin.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,49 +0,0 @@
# <small>nlohmann::basic_json_view::</small>cend
```cpp
iterator cend() const noexcept;
```
Returns an iterator to one past the last element, in [document order](begin.md). Equivalent to [`end()`](end.md): a
view is always read-only, so `#!cpp const_iterator` and `#!cpp iterator` are the same type, and `cend()` exists only
so that generic code that expects a `cbegin()`/`cend()` pair works with a view too.
## Return value
Iterator one past the last element; identical to what [`end()`](end.md) returns.
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Constant.
## Examples
??? example
The example below checks that every record of a batch is an object with `std::all_of`, using
[`cbegin()`](cbegin.md)/`cend()` as the range -- the same way it would for any standard container -- before
materializing any record of the batch.
```cpp
--8<-- "examples/basic_json_view__cend.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__cend.output"
```
## See also
- [end](end.md) - returns an iterator to one past the last element
- [cbegin](cbegin.md) - returns a const iterator to the first element
- [`BasicJsonType::cend`](../basic_json/cend.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,111 +0,0 @@
# <small>nlohmann::basic_json_view::</small>contains
```cpp
// (1)
bool contains(string_view_t key) const;
bool contains(const char* key) const;
bool contains(const string_t& key) const;
// (2)
bool contains(const json_pointer& ptr) const;
```
1. Checks whether the value is an object with a member with key `key`.
2. Checks whether a JSON pointer `ptr` can be resolved, starting at this value.
## Parameters
`key` (in)
: key value to check its existence
`ptr` (in)
: JSON pointer to check its existence
## Return value
1. `#!cpp true` if the value is an object and has a member with key `key`, `#!cpp false` otherwise
2. `#!cpp true` if `ptr` can be resolved to a value starting at this view, `#!cpp false` otherwise
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
1. Linear in the number of members: as for [`ordered_json`](../ordered_json.md), members are compared one after
another, in document order, stopping at the first match. Each comparison first checks the
key's length -- already known from the index, without reading the key bytes -- before comparing its content.
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 the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
that level or the index into the array -- as for [`operator[]`](operator[].md#complexity) and
[`at`](at.md#complexity) with a JSON pointer.
## Notes
!!! warning "Duplicate keys: the first member wins"
If the source text repeats a key, this resolves to the *first* member with it, not to the last one that
[`materialize()`](materialize.md) and `parse()` keep. See the [Notes on duplicate keys](operator[].md#notes) of
`operator[]` and [Duplicate keys](../../features/json_view.md#duplicate-keys) for the reasons and for how to get
the last value.
Overload 1 always returns `#!cpp false` when the value is not an object -- including a [discarded](is_discarded.md)
view.
!!! info "Postconditions"
If `#!cpp v.contains(key)` returns `#!cpp true`, then `#!cpp v[key]` is not [discarded](is_discarded.md) and
`#!cpp v.at(key)` does not throw. If
`#!cpp v.contains(ptr)` returns `#!cpp true`, then `#!cpp v[ptr]` is not discarded and `#!cpp v.at(ptr)` does not
throw.
!!! info "Overload 2 never throws"
Unlike [`BasicJsonType::contains(const json_pointer&)`](../basic_json/contains.md), which can throw for certain
malformed pointers (for instance an empty array-index reference token), overload 2 never throws: a missing key,
an out-of-range or malformed array index, a `#!cpp "-"` index, or a reference token used on a primitive all
simply make it return `#!cpp false`.
## Examples
??? example "Example: (1) check with key"
The example below counts how many of a batch of records carry an optional `retry_of` field, using `contains()`
to check without ever materializing a single record of the batch.
```cpp
--8<-- "examples/basic_json_view__contains.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__contains.output"
```
??? example "Example: (2) check with JSON pointer"
The example below checks an optional, nested field with a JSON pointer, and shows two pointers that
`#!cpp contains()` resolves to `#!cpp false` without throwing.
```cpp
--8<-- "examples/basic_json_view__contains_json_pointer.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__contains_json_pointer.output"
```
## See also
- [find](find.md) - find a value in an object
- [count](count.md) - returns the number of occurrences of a key
- [at](at.md), [operator[]](operator[].md) - resolve a JSON pointer and throw, or return a discarded view
- [`BasicJsonType::contains`](../basic_json/contains.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,71 +0,0 @@
# <small>nlohmann::basic_json_view::</small>count
```cpp
size_type count(string_view_t key) const;
size_type count(const char* key) const;
size_type count(const string_t& key) const;
```
Returns the number of members with key `key` if the value is an object, `#!cpp 0` otherwise. Members with a repeated
key are all counted.
## Parameters
`key` (in)
: key value of the element to count
## Return value
the number of members of the object with key `key` (duplicates included), or `#!cpp 0` if the value is not an object
or has no such member.
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Linear in the number of members: unlike the lookup functions, `count()` does not stop at the first match, because it
has to count every member with the key. Members are compared one after another, in document order. Each comparison
first checks the key's length -- already known from the index, without reading the key bytes -- before comparing its
content. The hash index of the keys of objects with 128 or more members does not help here, since every member
is visited.
## Notes
This method always returns `#!cpp 0` when the value is not an object -- including a [discarded](is_discarded.md)
view.
If the source text repeats a key, `count()` returns more than `#!cpp 1` for it, even though the
[materialized](materialize.md) value (like the result of `parse()`) would have only one member with that key. Hence
`#!cpp count(key) > 1` detects duplicate keys. This is unlike the lookup functions
([`operator[]`](operator[].md), [`at`](at.md), [`find`](find.md), [`contains`](contains.md)), which resolve to the
*first* member; see the [Notes on duplicate keys](operator[].md#notes) of `operator[]`.
## Examples
??? example
The example below validates that every transaction of a batch carries exactly one `amount` field, using
`count()` before deciding whether to materialize a transaction at all. It reports a transaction with no `amount`
field and one with a duplicated `amount` field.
```cpp
--8<-- "examples/basic_json_view__count.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__count.output"
```
## See also
- [find](find.md) - find a value in an object
- [contains](contains.md) - checks whether a key exists
- [`BasicJsonType::count`](../basic_json/count.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,104 +0,0 @@
# <small>nlohmann::basic_json_view::</small>dump
```cpp
string_t dump(const int indent = -1,
const char indent_char = ' ',
const bool ensure_ascii = false,
const number_format numbers = number_format::shortest) const;
```
Serializes this value (and its subtree) directly from the flat index, without ever building a `BasicJsonType` value
first. With the default `#!cpp numbers == number_format::shortest`, the result is the same string
[`BasicJsonType::dump`](../basic_json/dump.md) would produce for the value
[`BasicJsonType::parse()`](../basic_json/parse.md) builds from the same source text, called with the same `indent`,
`indent_char`, and `ensure_ascii` -- except that members of an object appear in document order rather than sorted by
key, and *every* occurrence of a repeated key is written rather than only the last one (see
[Notes on duplicate keys](operator[].md#notes)). For a `json_view` (whose `BasicJsonType` is not ordered), this means
`dump()` can print an object's members in a different order than [`materialize()`](materialize.md)`.dump()` of the
same subtree.
## Parameters
`indent` (in)
: If `indent` is nonnegative, array elements and object members are pretty-printed with that indent level. An
indent level of `0` only inserts newlines. `-1` (the default) selects the most compact representation.
`indent_char` (in)
: The character used for indentation if `indent` is greater than `0`. The default is ` ` (space).
`ensure_ascii` (in)
: If `ensure_ascii` is `#!cpp true`, all non-ASCII characters in the output are escaped with `\uXXXX` sequences, and
the result consists of ASCII characters only.
`numbers` (in)
: how to write numbers, see [`number_format`](number_format.md): `shortest` (the default) writes them the way
[`BasicJsonType::dump`](../basic_json/dump.md) would; `source` copies every number exactly as it appears in the
source text.
## Return value
string containing the serialization of this value, or `#!cpp "<discarded>"` if the view is
[discarded](is_discarded.md).
## Exception safety
Strong exception safety: if an exception is thrown, there are no changes to the view or the document it refers to.
## Exceptions
May throw `#!cpp std::bad_alloc` if allocating the output string fails. Unlike
[`BasicJsonType::dump`](../basic_json/dump.md), there is no `error_handler` parameter and no
[`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316): the view only ever holds text the parser
already validated as UTF-8, so there is nothing to replace or ignore.
## Complexity
Linear in the size of the output text.
## Notes
The walk over the subtree is iterative, so the nesting depth it can write is limited by available memory only, not by
the call stack -- as for [`materialize()`](materialize.md).
Strings are escaped by the same rules as [`BasicJsonType::dump`](../basic_json/dump.md).
With `#!cpp numbers == number_format::shortest`, floats are written with the library's shortest round-trip conversion,
exactly as [`BasicJsonType::dump`](../basic_json/dump.md) would (e.g. `#!cpp 1.5`, `#!cpp 100.0`, `#!cpp 1e+100`), and
integers are copied from the source text -- already canonical in JSON, so this matches their shortest form too --
except that `#!cpp -0` is written as `#!cpp 0`, the way [`BasicJsonType::parse()`](../basic_json/parse.md) reads it.
`#!cpp number_format::source` copies every number exactly as written in the source text instead, with no exception
for `#!cpp -0` -- `#!cpp 1.50`, `#!cpp 1E2`, `#!cpp -0.0`, `#!cpp -0`, or all digits of an integer literal with more
digits than any number type holds (such a literal is itself classified as a float, see
[What is different](../../features/json_view.md#what-is-different)) -- something `BasicJsonType` cannot do, since
parsing already reduces every number to its parsed value.
## Examples
??? example
The example below forwards a single record out of a larger batch, and re-serializes a configuration file, both
without ever building a `BasicJsonType` value for the surrounding array or for the parts of it that were not
needed. It also shows that [`materialize()`](materialize.md)`.dump()` of the configuration sorts its keys, where
`dump()` on the view keeps the order they appear in the source text.
```cpp
--8<-- "examples/basic_json_view__dump.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__dump.output"
```
## See also
- [`number_format`](number_format.md) - how `dump()` writes numbers
- [operator<<](operator_ltlt.md) - serialize this value to a stream
- [materialize](materialize.md) - build a `BasicJsonType` value, e.g. to use `BasicJsonType::dump`'s `error_handler`
- [`BasicJsonType::dump`](../basic_json/dump.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,53 +0,0 @@
# <small>nlohmann::basic_json_view::</small>end
```cpp
iterator end() const noexcept;
```
Returns an iterator to one past the last element of an array, one past the last member value of an object, in
**document order** -- see [`begin()`](begin.md). A primitive value iterates as a range of one element (itself), and a
`#!json null` value or a [discarded](is_discarded.md) view iterates as an empty range (`#!cpp begin() == end()`).
## Return value
Iterator one past the last element.
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Constant.
## Notes
`#!cpp iterator` is a forward iterator: unlike `BasicJsonType::iterator`, it cannot be decremented, so there is no
way to reach the last element by stepping back from `end()`. Use [`back()`](back.md) instead.
## Examples
??? example
The example below scans a (possibly large) array of readings for the first one over a threshold, stopping the
loop at `end()` as soon as one is found. Only the matching reading, if any, is ever materialized.
```cpp
--8<-- "examples/basic_json_view__end.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__end.output"
```
## See also
- [begin](begin.md) - returns an iterator to the first element
- [cend](cend.md) - returns a const iterator to one past the last element
- [`BasicJsonType::end`](../basic_json/end.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,72 +0,0 @@
# <small>nlohmann::basic_json_view::</small>find
```cpp
iterator find(string_view_t key) const;
iterator find(const char* key) const;
iterator find(const string_t& key) const;
```
Finds a member with key `key` -- the first one, should the key occur more than once (see
[Notes on duplicate keys](operator[].md#notes)). If the value is not an object, or no member has this key,
[`end()`](end.md) is returned.
## Parameters
`key` (in)
: key value of the element to search for
## Return value
An iterator to the member with key `key`, or [`end()`](end.md) if there is none or the value is not an object.
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Linear in the number of members: as for [`ordered_json`](../ordered_json.md), members are compared one after another,
in document order, stopping at the first match. Each comparison first checks the key's length
-- already known from the index, without reading the key bytes -- before comparing its content.
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.
## Notes
!!! warning "Duplicate keys: the first member wins"
If the source text repeats a key, this resolves to the *first* member with it, not to the last one that
[`materialize()`](materialize.md) and `parse()` keep. See the [Notes on duplicate keys](operator[].md#notes) of
`operator[]` and [Duplicate keys](../../features/json_view.md#duplicate-keys) for the reasons and for how to get
the last value.
Unlike [`BasicJsonType::find`](../basic_json/find.md), which always returns `#!cpp end()` for a non-object type, this
also does so for a [discarded](is_discarded.md) view -- there is no separate "invalid" iterator to return.
## Examples
??? example
The example below scans a batch of events for those that carry an optional `user_id` field, using `find()`
instead of [`operator[]`](operator[].md) (which would throw for the events that are not objects at all) or
[`contains()`](contains.md) followed by a second lookup. Events without a match are never materialized.
```cpp
--8<-- "examples/basic_json_view__find.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__find.output"
```
## See also
- [count](count.md) - returns the number of occurrences of a key
- [contains](contains.md) - checks whether a key exists
- [`BasicJsonType::find`](../basic_json/find.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,61 +0,0 @@
# <small>nlohmann::basic_json_view::</small>front
```cpp
basic_json_view front() const;
```
Returns the first element of an array, the first member value of an object, or the value itself if it is primitive
(as for [`BasicJsonType::front()`](../basic_json/front.md), a primitive value is a range of one element).
## Return value
The first element or member value. For a primitive value (number, string, boolean), the value itself.
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
Throws [`invalid_iterator.214`](../../home/exceptions.md#jsonexceptioninvalid_iterator214) if the view is
[null](is_null.md) or [discarded](is_discarded.md), or if it is an empty array or object.
This exception does not carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) path: the view has no
`BasicJsonType` value to point at, so the exception is created without one, even if `BasicJsonType` was built with
`JSON_DIAGNOSTICS` enabled.
## Complexity
Constant.
## Notes
Unlike [`BasicJsonType::front()`](../basic_json/front.md), which has undefined behavior for an empty array or
object, `front()` throws `invalid_iterator.214` for an empty array, an empty object, a null value, or a discarded
view.
## Examples
??? example
The example below reads only the earliest entry of a build log with `front()`, without materializing the rest
of the (possibly long) log.
```cpp
--8<-- "examples/basic_json_view__front.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__front.output"
```
## See also
- [back](back.md) - access the last element
- [`BasicJsonType::front`](../basic_json/front.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
-133
View File
@@ -1,133 +0,0 @@
# <small>nlohmann::basic_json_view::</small>get
```cpp
template<typename T>
T get() const;
```
Converts the value to `T`.
For the types below, the conversion works directly on the flat index -- no `BasicJsonType` value is built for it:
- `#!cpp bool`
- arithmetic types other than `#!cpp bool` (for a boolean, `#!cpp 0`/`#!cpp 1`, exactly as for
[`BasicJsonType::get<T>()`](../basic_json/get.md))
- `#!cpp std::nullptr_t`
- `#!cpp std::basic_string<char, Traits, Alloc>` (including `string_t`) -- a copy of the string
- [`string_view_t`](index.md#member-types) -- **no copy**: the returned view points into the document's
[`source()`](../basic_json_document/source.md) text, or, for a string that contains escape sequences, into the
document's own buffer of decoded strings (see [`get_string()`](get_string.md))
- `BasicJsonType` -- equivalent to [`materialize()`](materialize.md)
- `basic_json_view` -- returns `#!cpp *this`
- `#!cpp std::vector<U, A>` -- from an array, element by element, each converted with `#!cpp get<U>()`; `#!cpp
std::vector<basic_json_view>` keeps a view of every element instead of a value
- `#!cpp std::map<K, V, C, A>` and `#!cpp std::unordered_map<K, V, H, E, A>`, if `K` is constructible from a `#!cpp
(const char*, std::size_t)` pair -- from an object, member by member, each value converted with `#!cpp get<V>()`; with a repeated
key, the *last* value is kept, as [`BasicJsonType::parse()`](../basic_json/parse.md) (and
[`materialize()`](materialize.md)) does; `#!cpp std::map<std::string, basic_json_view>` keeps views of the members
instead of values
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.
## Template parameters
`T`
: the type to convert the value to
## Return value
the value, converted to `T`
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
- For the directly-converted types listed above (other than `BasicJsonType` and `basic_json_view`, which never
throw): throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if the value's type does not
match `T` -- the same exception, with the same message, that [`BasicJsonType::get<T>()`](../basic_json/get.md)
throws for the same JSON type and `T`.
- For `#!cpp std::vector<U, A>`: throws `type_error.302` if the value is not an array; otherwise, whatever converting
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 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 (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.
That path is relative to the root of the view's subtree, because `materialize()` builds only the subtree (with parent
pointers): it is empty if the failing value is the subtree's root itself, and it never is the path within the whole
document.
## Complexity
- `#!cpp bool`, arithmetic types, `#!cpp std::nullptr_t`, [`string_view_t`](index.md#member-types), `basic_json_view`:
constant.
- `#!cpp std::basic_string<char, Traits, Alloc>`: constant, plus one allocation and a copy of the string's bytes.
- `BasicJsonType`: linear in the size of the subtree, see [`materialize()`](materialize.md).
- `#!cpp std::vector<U, A>`: linear in the number of elements, times the complexity of converting one element to `U`.
- `#!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.
- 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).
## Notes
!!! info "Floating-point values"
A floating-point `T` is converted from the same digits the lexer would see during `#!cpp BasicJsonType::parse()`,
using the same conversion, so the result is bit-for-bit identical to `#!cpp BasicJsonType::parse(text).get<T>()`
for the same source text.
!!! info "Duplicate keys"
`#!cpp std::map`/`#!cpp std::unordered_map` conversions keep the *last* value of a repeated key, like
[`materialize()`](materialize.md) and [`BasicJsonType::parse()`](../basic_json/parse.md) do. This is the opposite
of [`operator[]`](operator[].md)/[`at`](at.md)/[`find`](find.md)/[`contains`](contains.md), which resolve to the
*first* occurrence (see the [Notes on duplicate keys](operator[].md#notes)).
!!! info "No pointers, references, or implicit conversion"
Unlike `BasicJsonType`, `basic_json_view` has no stored value anywhere to hand out a pointer or a reference to, so
it provides neither `#!cpp get_ptr()`, `#!cpp get_ref()`, nor `#!cpp operator ValueType()`.
[`get_string()`](get_string.md) (equivalently, `#!cpp get<string_view_t>()`) is the zero-copy alternative for
strings.
## Examples
??? example
The example below reads typed fields straight into C++ variables, collects a view of every array element with
`#!cpp get<std::vector<basic_json_view>>()` instead of a value, and converts a nested object into a user type
through its `from_json()` -- which runs on a `BasicJsonType` value `materialize()` builds for just that one
member.
```cpp
--8<-- "examples/basic_json_view__get.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__get.output"
```
## See also
- [get_to](get_to.md) - convert and write into a passed value
- [get_string](get_string.md) - the string, without a copy
- [number_token](number_token.md) - a number's token text, without a copy
- [materialize](materialize.md) - build the `BasicJsonType` value of this subtree
- [`BasicJsonType::get`](../basic_json/get.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,76 +0,0 @@
# <small>nlohmann::basic_json_view::</small>get_string
```cpp
string_view_t get_string() const;
```
Returns the string value as a [`string_view_t`](index.md#member-types), without copying it.
## Return value
The string, as a [`string_view_t`](index.md#member-types) that points either into the document's
[`source()`](../basic_json_document/source.md) text (a string with no escape sequences), or into the document's own
buffer of decoded strings (a string that contains escape sequences, such as `#!json "\n"` or `#!json "\u00e9"`, which
had to be decoded once when the document was parsed).
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if the value is not a string; example:
`"type must be string, but is array"`.
This exception does not carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) path: the view has no
`BasicJsonType` value to point at, so the exception is created without one, even if `BasicJsonType` was built with
`JSON_DIAGNOSTICS` enabled.
## Complexity
Constant.
## Notes
`basic_json_view` has no `BasicJsonType` value stored anywhere, so unlike `BasicJsonType`, it has no `get_ref()` to
hand out a reference to a stored `string_t`. `get_string()` (equivalently, [`get<string_view_t>()`](get.md)) is the
zero-copy alternative: [`BasicJsonType::get_ref<const string_t&>()`](../basic_json/get_ref.md) is its closest
counterpart, except that it returns a view instead of a reference to a value that must already exist.
`get_string()` borrows the string: nothing is copied, whereas [`get<std::string>()`](get.md) copies it. For a borrowed
document, the returned [`string_view_t`](index.md#member-types) is valid as long as the caller's buffer; for an owned
one, as long as the document.
The returned [`string_view_t`](index.md#member-types) is valid exactly as long as the view that produced it -- see the
[validity rules](index.md) of `basic_json_view` -- and, for a string with no escapes, for as long as the document's
source text, which for a borrowed document must remain valid **and unmodified** for as long as the document exists,
since floating-point values and unescaped strings are read from the source lazily.
## Examples
??? example
The example below pulls one field out of a JSON text that stands in for a large API response, and shows that no
`#!cpp std::string` was allocated for it: the returned view still points inside the original buffer. A field that
contains an escape sequence cannot point into the original text -- it was decoded once into the document's own
buffer instead -- but still avoids a per-field allocation.
```cpp
--8<-- "examples/basic_json_view__get_string.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__get_string.output"
```
## See also
- [get](get.md) - convert the value to a given type (`#!cpp get<string_view_t>()` is equivalent to this function)
- [number_token](number_token.md) - a number's token text, without a copy
- [`BasicJsonType::get_ref`](../basic_json/get_ref.md) - the closest counterpart of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -1,80 +0,0 @@
# <small>nlohmann::basic_json_view::</small>get_to
```cpp
template<typename T>
T& get_to(T& v) const;
```
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 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.
## Template parameters
`T`
: the type to convert the value to
## Parameters
`v` (out)
: the variable to store the converted value in
## Return value
`v`, allowing calls to chain
## Exception safety
- For the directly converted types: strong exception safety. If an exception is thrown, `v` is not modified.
- For every other type: as for [`BasicJsonType::get_to()`](../basic_json/get_to.md). `materialize()` throws before `v`
is touched, but a `from_json()` that throws may leave `v` partly modified.
## Exceptions
- For the directly converted types: whatever [`get<T>()`](get.md) throws for the same value and `T`.
- For every other type: whatever [`materialize()`](materialize.md) and
[`BasicJsonType::get_to()`](../basic_json/get_to.md) throw.
## Complexity
- For the directly converted types: whatever [`get<T>()`](get.md) has for the same `T`.
- For every other type: that of [`materialize()`](materialize.md), plus that of
[`BasicJsonType::get_to()`](../basic_json/get_to.md).
## Notes
The difference between the two ways matters for a `from_json()` that sets only the fields present in the JSON: since
it runs on the existing `v`, the other fields of `v` keep their values, whereas assigning `get<T>()` would replace
them with those of a default-constructed `T`.
## Examples
??? example
The example below reads several fields of a service configuration directly into existing variables, then uses
the returned reference to fold the `#!cpp host`/`#!cpp port` pair into a single string in the same expression.
```cpp
--8<-- "examples/basic_json_view__get_to.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__get_to.output"
```
## See also
- [get](get.md) - convert the value to a given type
- [`BasicJsonType::get_to`](../basic_json/get_to.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
+5 -72
View File
@@ -3,7 +3,7 @@
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
```cpp
template<typename BasicJsonType, bool Editable = false>
template<typename BasicJsonType>
class basic_json_view;
```
@@ -14,34 +14,14 @@ to the document and a pointer into its index), trivially copyable. A view is val
- the document has not been re-parsed with [`read()`](../basic_json_document/read.md) (or
[`parse()`](../basic_json_document/parse.md) into it) or shrunk with
[`shrink_to_fit()`](../basic_json_document/shrink_to_fit.md) since the view was taken, and
- if the document borrows its source text, that text is still alive and unmodified (floating-point values and
unescaped strings are read from it lazily).
- if the document borrows its source text, that text is still alive.
Moving the document itself does not invalidate its views: the index is heap-allocated independently of the
`basic_json_document` object.
`basic_json_view` provides the read-only part of the `BasicJsonType` interface:
- the type-inspection functions
- element access
- lookup
- iteration
- conversion: [`get<T>()`](get.md), [`get_string()`](get_string.md), [`number_token()`](number_token.md), and
[`materialize()`](materialize.md) to build the `BasicJsonType` value of a subtree on demand
- comparison: [`operator==`](operator_eq.md) and [`operator!=`](operator_ne.md) compare two views, or a view and a
`BasicJsonType` value, without ever building a `BasicJsonType` value for a view; no ordering comparison
(`#!cpp operator<`) is provided
[`operator[]`](operator%5B%5D.md), [`at`](at.md), [`contains`](contains.md), and [`value`](value.md) also accept a
[`json_pointer`](../json_pointer/index.md). Unlike `basic_json`, there are no implicit conversion operators (no
`#!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 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
[Edits](../basic_json_document/index.md#edits).
`basic_json_view` provides the read-only part of the `BasicJsonType` interface: the type-inspection functions, and
[`materialize()`](materialize.md) to build the `BasicJsonType` value of a subtree on demand. It does not (yet) provide
element access, iteration, `get<T>()`, JSON Pointer support, `dump()`, or comparison.
## Template parameters
@@ -49,17 +29,10 @@ 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.
`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
- [**json_view**](../json_view.md) - views of a [`json_document`](../json_document.md)
- [**ordered_json_view**](../ordered_json_view.md) - views of an [`ordered_json_document`](../ordered_json_document.md)
- [**json_editable_view**](../json_editable_view.md) - views of a [`json_editable_document`](../json_editable_document.md)
- [**ordered_json_editable_view**](../ordered_json_editable_view.md) - views of an
[`ordered_json_editable_document`](../ordered_json_editable_document.md)
## Member types
@@ -68,9 +41,6 @@ still refers to it -- including ones taken before the change -- reads the new va
member types of `BasicJsonType`
- **size_type** - `#!cpp std::size_t`
- **string_view_t** - `#!cpp std::string_view` on C++17 and newer, a minimal internal substitute otherwise
- **iterator**, **const_iterator** - a forward iterator over the elements of an array or the member values of an
object, in document order; both names refer to the same type, since a view is always read-only
- [**number_format**](number_format.md) - how [`dump()`](dump.md) writes numbers
## Member functions
@@ -79,7 +49,6 @@ still refers to it -- including ones taken before the change -- reads the new va
### Object inspection
- [**type**](type.md) - return the type of the value
- [**type_name**](type_name.md) - return the type as string
- [**is_null**](is_null.md) - return whether the value is null
- [**is_boolean**](is_boolean.md) - return whether the value is a boolean
- [**is_number**](is_number.md) - return whether the value is a number
@@ -94,28 +63,6 @@ still refers to it -- including ones taken before the change -- reads the new va
- [**is_structured**](is_structured.md) - return whether the type is structured
- [**is_discarded**](is_discarded.md) - return whether the view is invalid
### Element access
- [**at**](at.md) - access specified element with bounds checking
- [**operator[]**](operator[].md) - access specified element
- [**value**](value.md) - access specified element with default value
- [**front**](front.md) - access the first element
- [**back**](back.md) - access the last element
### Lookup
- [**find**](find.md) - find an element in an object
- [**count**](count.md) - returns the number of occurrences of a key in an object
- [**contains**](contains.md) - check the existence of an element in an object
### Iterators
- [**begin**](begin.md) - returns an iterator to the first element
- [**cbegin**](cbegin.md) - returns a const iterator to the first element
- [**end**](end.md) - returns an iterator to one past the last element
- [**cend**](cend.md) - returns a const iterator to one past the last element
- [**items**](items.md) - wrapper to access iterator member functions in range-based for
### Capacity
- [**size**](size.md) - return the number of elements
@@ -123,22 +70,8 @@ still refers to it -- including ones taken before the change -- reads the new va
### Conversion
- [**get**](get.md) - get a value
- [**get_to**](get_to.md) - get a value and write it to a destination
- [**get_string**](get_string.md) - get a string value without a copy
- [**number_token**](number_token.md) - get a number's token text without a copy
- [**materialize**](materialize.md) - build the `BasicJsonType` value of this subtree
### Comparison
- [**operator==**](operator_eq.md) - comparison: equal
- [**operator!=**](operator_ne.md) - comparison: not equal
### Serialization
- [**dump**](dump.md) - serialize to a JSON-formatted string
- [**operator<<**](operator_ltlt.md) - serialize to stream
### Source access
- [**source_offset**](source_offset.md) - byte offset of this value in the document's source text
@@ -38,8 +38,7 @@ Constant.
## See also
- [is_structured](is_structured.md) - return whether the type is structured
- [size](size.md) - the number of elements
- [empty](empty.md) - whether there are no elements
- [size](size.md), [empty](empty.md) - the number of elements, and whether there are none
- [`BasicJsonType::is_array`](../basic_json/is_array.md) - the corresponding function of `basic_json`
## Version history
@@ -4,9 +4,8 @@
bool is_binary() const noexcept;
```
This function always returns `#!cpp false`: a document is only ever parsed from JSON text, never from CBOR or the other
binary formats, and a JSON text has no binary values, so a view can never refer to one. The function exists for
interface parity with [`BasicJsonType::is_binary`](../basic_json/is_binary.md).
This function always returns `#!cpp false`: a JSON text has no binary values, so a view can never refer to one. The
function exists for interface parity with [`BasicJsonType::is_binary`](../basic_json/is_binary.md).
## Return value
@@ -9,13 +9,9 @@ view (see [(constructor)](basic_json_view.md)), and for [`root()`](../basic_json
that is itself [discarded](../basic_json_document/is_discarded.md) -- in particular, the root of a failed
[`parse()`](../basic_json_document/parse.md) with `allow_exceptions` set to `#!cpp false`.
A discarded view is also what [`operator[]`](operator[].md) returns for a missing key, an index out of range, or a
JSON pointer that cannot be resolved, and for any access on a view that is itself discarded (so a chain such as
`#!cpp v["a"]["b"]` is safe). [`at`](at.md) throws instead.
## Return value
`#!cpp true` if the view or its document is discarded, `#!cpp false` otherwise.
`#!cpp true` if the view is discarded, `#!cpp false` otherwise.
## Exception safety
@@ -50,7 +46,6 @@ A `basic_json_view` is not convertible to `#!cpp bool`: such a conversion would
## See also
- [operator[]](operator[].md) - access specified element; yields a discarded view where an element is missing
- [(constructor)](basic_json_view.md) - the default constructor creates a discarded view
- [is_discarded (basic_json_document)](../basic_json_document/is_discarded.md) - return whether the last parse failed
- [`BasicJsonType::is_discarded`](../basic_json/is_discarded.md) - the corresponding function of `basic_json`
@@ -38,8 +38,7 @@ Constant.
## See also
- [is_structured](is_structured.md) - return whether the type is structured
- [size](size.md) - the number of elements
- [empty](empty.md) - whether there are no elements
- [size](size.md), [empty](empty.md) - the number of elements, and whether there are none
- [`BasicJsonType::is_object`](../basic_json/is_object.md) - the corresponding function of `basic_json`
## Version history
@@ -37,8 +37,7 @@ Constant.
## See also
- [source_offset](source_offset.md) - byte offset of this value in the source text, which differs for strings: an
escaped string has none
- [source_offset](source_offset.md) - byte offset of this value in the document's source text
- [`BasicJsonType::is_string`](../basic_json/is_string.md) - the corresponding function of `basic_json`
## Version history
@@ -1,86 +0,0 @@
# <small>nlohmann::basic_json_view::</small>items
```cpp
/* unspecified */ items() const noexcept;
```
Returns a range of items -- (key, value) pairs -- for use in range-based for loops. An item's `#!cpp key()` is a
`#!cpp string_view_t` (for an array element, its index converted to a string, as for
[`BasicJsonType::items()`](../basic_json/items.md)), and its `#!cpp value()` is a `basic_json_view` of the element.
The returned type is not part of the public API and may change between versions; use a range-based for loop (see the
example), or `#!cpp decltype(v.items())` if you need to name it.
```cpp
for (const auto& item : v.items())
{
std::cout << "key: " << item.key() << ", value: " << item.value() << '\n';
}
```
On C++17, `item` also supports [structured bindings](https://en.cppreference.com/w/cpp/language/structured_binding):
```cpp
for (const auto [key, value] : v.items())
{
std::cout << "key: " << key << ", value: " << value << '\n';
}
```
Note the `#!cpp const auto` (by value), not `#!cpp const auto&`: unlike `BasicJsonType::items()`, whose elements are
references into an existing object, a view's `item` is produced on the fly for each step of the iteration, so there
is nothing for a reference to bind to.
## Return value
A range whose iterators dereference to an item (with `#!cpp key()` and `#!cpp value()`, see above) and whose
`#!cpp begin()`/`#!cpp end()` are equivalent to [`basic_json_view::begin()`](begin.md)/[`end()`](end.md), in document order.
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Constant.
## Notes
As for [`begin()`](begin.md)/[`end()`](end.md), `items()` visits **every** member of an object, including all
occurrences of a duplicate key -- unlike [`operator[]`](operator[].md), [`at`](at.md), [`find`](find.md),
and [`contains`](contains.md), which resolve to the *first* member with a given key. See the
[Notes on duplicate keys](operator[].md#notes) of `operator[]`.
!!! danger "Lifetime issues"
Unlike `BasicJsonType::items()` (see [#2040](https://github.com/nlohmann/json/issues/2040)), calling `items()` on
a temporary view is safe, for instance `#!cpp for (auto item : v["a"].items())`: the returned range holds a copy
of the view. What must outlive the loop is the document and, for a borrowed document, the source buffer.
## Examples
??? example
The example below shows a settings object whose source text records every update to a key as a duplicate
member, in the order they happened. `items()` walks all of them, so the update history is visible, while
[`operator[]`](operator[].md) only ever sees the *first* one and [`materialize()`](materialize.md) -- like
[`BasicJsonType::parse()`](../basic_json/parse.md) -- keeps only the *last*.
```cpp
--8<-- "examples/basic_json_view__items.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__items.output"
```
## See also
- [begin](begin.md), [end](end.md) - the iterators `items()` is built on
- [`BasicJsonType::items`](../basic_json/items.md) - the corresponding function of `basic_json`
## Version history
- Added in version 3.13.0.
@@ -14,8 +14,8 @@ if the view is [discarded](is_discarded.md).
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to (nothing about either is mutated by
this function).
Strong guarantee: if an exception is thrown, there are no changes to the view or the document it refers to (nothing
about either is mutated by this function).
## Exceptions
@@ -28,13 +28,12 @@ Linear in the size of the subtree.
## Notes
`materialize()` replays the subtree through the same SAX builder [`BasicJsonType::parse()`](../basic_json/parse.md)
uses, so the result matches it exactly -- including, for an object, that a repeated key keeps only its
uses internally, so the result matches it exactly -- including, for an object, that a repeated key keeps only its
last value. The replay is iterative, so it is not limited by the call stack the way a naive recursive conversion
would be; the JSON nesting depth is limited only by available memory, as for `BasicJsonType::parse()` itself.
Unlike parsing with [`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) enabled, the values
produced by `materialize()` do not carry source positions. The index has the start offset of every value, but not the
end of arrays, objects, and escaped strings, which the positions also need.
produced by `materialize()` do not carry source positions: there is no lexer run during the replay to record them.
Calling `materialize()` on the same view repeatedly builds a new, independent `BasicJsonType` value each time; it
never caches the result.
@@ -1,51 +0,0 @@
# <small>nlohmann::basic_json_view::</small>number_format
```cpp
enum class number_format {
shortest,
source
};
```
This enumeration is used in [`dump`](dump.md) to choose how numbers are written. Two values are differentiated:
shortest
: integers are copied from the source text -- already canonical in JSON -- except that `#!cpp -0` becomes
`#!cpp 0`, the way [`BasicJsonType::parse()`](../basic_json/parse.md) reads it; floats are written with the
library's shortest round-trip conversion, exactly as [`BasicJsonType::dump()`](../basic_json/dump.md) would (e.g.
`#!cpp 1.5`, `#!cpp 100.0`, `#!cpp 1e+100`)
source
: every number is copied exactly as it appears in the source text -- `#!cpp 1.50`, `#!cpp 1E2`, `#!cpp -0`, all
digits of an integer literal with more digits than any number type holds -- something `BasicJsonType` cannot do,
since parsing already reduces every number to its parsed value
## Examples
??? example
The example below writes back a price list received from a supplier: with `number_format::shortest` (the
default), a trailing zero and scientific notation are normalized away and a long account number that overflows
every number type is rounded, the same way `#!cpp materialize().dump()` (or `basic_json::dump()`) would;
`number_format::source` keeps every number exactly as it was written in the source text instead.
```cpp
--8<-- "examples/basic_json_view__number_format.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__number_format.output"
```
## See also
- [dump](dump.md) - serialize to a JSON-formatted string
- [number_token](number_token.md) - get a single number's token text without dumping the whole value
- [`BasicJsonType::error_handler_t`](../basic_json/error_handler_t.md) - the analogous enumeration for
`BasicJsonType::dump`'s decoding-error behavior
## Version history
- Added in version 3.13.0.
@@ -1,74 +0,0 @@
# <small>nlohmann::basic_json_view::</small>number_token
```cpp
string_view_t number_token() const;
```
Returns the number exactly as it appears in the source text, without parsing or rounding it.
## Return value
The number's token text, as a [`string_view_t`](index.md#member-types) into the document's
[`source()`](../basic_json_document/source.md) text -- for example `#!cpp "1.50"`, `#!cpp "1E2"`, `#!cpp "-0"`, or an
integer literal with more digits than any number type holds (such as a 30-digit integer, which [`get<T>()`](get.md)
and [`materialize()`](materialize.md) can only represent approximately, as a `number_float_t`).
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if the value is not a number; example:
`"type must be number, but is string"`.
This exception does not carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) path: the view has no
`BasicJsonType` value to point at, so the exception is created without one, even if `BasicJsonType` was built with
`JSON_DIAGNOSTICS` enabled.
## Complexity
Constant.
## Notes
`BasicJsonType` has no counterpart to this function: once a number is parsed into `number_integer_t`,
`number_unsigned_t`, or `number_float_t`, its original textual form (leading zeros aside, which are already rejected
by the grammar; trailing zeros in the fraction; the case and sign of the exponent; ...) is gone. `number_token()` is
useful precisely where that form must survive -- a price or an identifier that must be reproduced exactly, or a
number too large for any of `BasicJsonType`'s number types to hold without loss.
The returned [`string_view_t`](index.md#member-types) always points into the document's
[`source()`](../basic_json_document/source.md) text -- numbers are never decoded into the document's separate string
buffer -- and is valid exactly as long as that text is, see the [validity rules](index.md) of `basic_json_view`.
## Examples
??? example
The example below keeps a price and an order ID exactly as they were written in an incoming order, where
converting them with [`get<T>()`](get.md) would lose information: the price picks up floating-point rounding, and
the order ID -- more digits than a 64-bit integer holds -- can only be approximated as a `#!cpp double` once
`#!cpp materialize()`d.
```cpp
--8<-- "examples/basic_json_view__number_token.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__number_token.output"
```
## See also
- [get](get.md) - convert the value to a given type
- [get_string](get_string.md) - the string, without a copy
- [`BasicJsonType::number_integer_t`](../basic_json/number_integer_t.md),
[`number_unsigned_t`](../basic_json/number_unsigned_t.md), [`number_float_t`](../basic_json/number_float_t.md) - the
number types `#!cpp get<T>()` and `materialize()` convert into
## Version history
- Added in version 3.13.0.
@@ -1,178 +0,0 @@
# <small>nlohmann::basic_json_view::</small>operator[]
```cpp
// (1)
basic_json_view operator[](string_view_t key) const;
basic_json_view operator[](const char* key) const;
basic_json_view operator[](const string_t& key) const;
// (2)
basic_json_view operator[](size_type idx) const;
template<typename IntegerType>
basic_json_view operator[](IntegerType idx) const;
// (3)
basic_json_view operator[](const json_pointer& ptr) const;
```
1. Returns the value of the object member with key `key` -- the first one, should the key occur more than once (see
the [Notes](#notes) below) -- or a [discarded](is_discarded.md) view if there is no such member.
2. Returns the array element at index `idx`, or a [discarded](is_discarded.md) view if `idx` is out of range. The
template accepts every integer type except `#!cpp bool` and `#!cpp std::size_t` (`#!cpp int`, `#!cpp unsigned`,
`#!cpp long`, `#!cpp std::int64_t`, ...) and forwards to the `size_type` overload, so that an integer argument is
not ambiguous between that overload and 1; a negative `idx` is out of range.
3. Returns the value a JSON pointer `ptr` refers to, starting at this value, or a [discarded](is_discarded.md) view
wherever resolving it further is not possible without inserting into or extending the document (see
[Return value](#return-value) and [Exceptions](#exceptions) below).
## Parameters
`key` (in)
: object key of the element to access
`idx` (in)
: index of the element to access
`ptr` (in)
: JSON pointer to the element to access
## Return value
1. the value of the first member with key `key`, or a discarded view if no member has this key (or if this view is
[discarded](is_discarded.md))
2. the element at index `idx`, or a discarded view if `#!cpp idx >= size()` or `idx` is negative (or if this view is
[discarded](is_discarded.md))
3. the value `ptr` resolves to, starting at this value, or a discarded view (also if this view is
[discarded](is_discarded.md)) for exactly the reference tokens where the
**const** overload of [`BasicJsonType::operator[]`](../basic_json/operator%5B%5D.md) invokes undefined behavior for
the same pointer and the same document: an object member that does not exist, or an array index that is out of
range
## Exception safety
Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
1. Throws [`type_error.305`](../../home/exceptions.md#jsonexceptiontype_error305) if the value is not an object and
not [discarded](is_discarded.md) --
the same exception, with the same message, that the **const** overload of
[`BasicJsonType::operator[]`](../basic_json/operator%5B%5D.md) throws for a string argument on a non-object value.
2. Throws [`type_error.305`](../../home/exceptions.md#jsonexceptiontype_error305) if the value is not an array and
not [discarded](is_discarded.md) --
the same exception, with the same message, that the **const** overload of
[`BasicJsonType::operator[]`](../basic_json/operator%5B%5D.md) throws for a numeric argument on a non-array value.
3. Throws the same exceptions, with the same messages, that the **const** overload of
[`BasicJsonType::operator[]`](../basic_json/operator%5B%5D.md) throws for the same pointer and the same document:
- [`out_of_range.402`](../../home/exceptions.md#jsonexceptionout_of_range402) if a reference token is `#!cpp "-"`
at an array.
- [`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) if a reference token cannot be
resolved because it is used on a primitive value.
- [`parse_error.106`](../../home/exceptions.md#jsonexceptionparse_error106) if an array index in `ptr` begins
with `#!cpp '0'`.
- [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) if an array index in `ptr` is not a
number.
None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) path: the view has no
`BasicJsonType` value to point at, so the exception is created without one, even if `BasicJsonType` was built with
`JSON_DIAGNOSTICS` enabled.
## Complexity
1. Linear in the number of members: as for [`ordered_json`](../ordered_json.md), members are compared one after
another, in document order, stopping at the first match. Each comparison first checks the
key's length -- already known from the index, without reading the key bytes -- before comparing its content, so a
key of a different length than `key` is rejected without touching the source text.
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).
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.).
## Notes
Unlike `BasicJsonType::operator[]`, which is undefined behavior (guarded by a
[runtime assertion](../../features/assertions.md)) for a missing key on a **const** value, this operator returns a
safe, testable result for a missing key or an index out of range: a [discarded](is_discarded.md) view, which is
tested with [`is_discarded`](is_discarded.md).
There is also no non-const overload that inserts a missing key or extends an array -- a view never modifies the
document.
!!! info "Chained access"
`#!cpp operator[]` on a [discarded](is_discarded.md) view returns a discarded view and does not throw, so a chain
like `#!cpp v["a"]["b"][0]` is safe even if `"a"` or `"b"` is missing: the first missing step makes the whole
result discarded, which is tested once at the end. Type errors on values that are *not* discarded still throw: a
key on an array or a primitive, or an index on an object or a primitive, is `type_error.305` as for
`BasicJsonType`. [`at`](at.md) still throws for a discarded view, as it does for a missing key.
!!! warning "Duplicate keys: the first member wins"
If the source text has an object with a duplicate key, `#!cpp operator[]` (and [`at`](at.md), [`find`](find.md),
[`contains`](contains.md), [`value`](value.md), and JSON pointer resolution) all resolve to
the *first* member with that key, because a lookup can stop as soon as it finds a match. This is different from
[`materialize()`](materialize.md) (and [`BasicJsonType::parse()`](../basic_json/parse.md)), which replay every
member in order and so keep the *last* value for a repeated key, so `#!cpp v["a"]` and
`#!cpp v.materialize()["a"]` can differ. To get the value `parse()` would give, use
[`materialize()`](materialize.md) or iterate the members with [`items()`](items.md) and keep the last match.
The key hash index of a larger object (128 members or more) leads to the first member of a key as well.
[`begin()`](begin.md)/[`end()`](end.md) and [`items()`](items.md) iterate over *all* members, including
duplicates, in document order. See [Duplicate keys](../../features/json_view.md#duplicate-keys) and
[`size()`](size.md#notes).
!!! info "JSON pointer resolution"
Overload 3 walks `ptr` one reference token at a time, starting at this value, the same way [`at`](at.md) and
[`contains`](contains.md) do. It only ever returns a discarded view where the **const** overload of
`BasicJsonType::operator[]` would be undefined behavior for the same pointer -- a missing object member or an
out-of-range array index -- and still throws for every other way `ptr` can fail to resolve. See
[`at`](at.md#exceptions) for the checked version, which throws in every case instead, and
[`contains`](contains.md) for a version that never throws.
## Examples
??? example "Example: (1)/(2) access specified element"
The example below reads a couple of fields out of a batch of user records without ever materializing a full
`BasicJsonType` value for the batch. `operator[]` is used both to look up an optional object member and to index
into an array -- in both cases, a missing value comes back as a discarded view that can be tested with a plain
`#!cpp if`, instead of relying on undefined behavior.
```cpp
--8<-- "examples/basic_json_view__operator[].cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__operator[].output"
```
??? example "Example: (3) access specified element via JSON pointer"
The example below reaches straight into one deeply nested field of a large document with a single JSON pointer,
without ever building a tree for the rest of it, and shows the discarded-view and throwing outcomes of a pointer
that cannot be fully resolved.
```cpp
--8<-- "examples/basic_json_view__operator[]_json_pointer.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__operator[]_json_pointer.output"
```
## See also
- [at](at.md) - access specified element with bounds checking (throws instead of returning a discarded view)
- [front](front.md), [back](back.md) - access the first or last element
- [find](find.md), [contains](contains.md) - look up a member without throwing
- [`BasicJsonType::operator[]`](../basic_json/operator%5B%5D.md) - the corresponding function of `basic_json`
- [`json_pointer`](../json_pointer/index.md) - JSON pointer type used by overload 3
## Version history
- Added in version 3.13.0.
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