Niels Lohmann
a47170346a
* docs: new design for the documentation site Apply the brand to the Material for MkDocs site: Inter and JetBrains Mono served by the site (upright and real italic), brand colours, blue header band with the syntax pattern, wordmark in the header, new home page (hero, cards, animated feature tour), 404 page, polish for tabs, search, footer, focus rings, tables and code blocks, and theme features (code copy, previous/next footer, TOC follow, search suggestions). Draw the number railroad diagram, the parser callback events and the iterator illustrations as inline SVGs that follow the light and dark scheme. The generator scripts are in docs/mkdocs/scripts/figures; the feature slideshow (json-light.svg, json-dark.svg, replacing json.gif on the home page) is built by docs/mkdocs/scripts/slideshow. Decision nodes in five flowcharts become hexagons, which need far less room. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: add figures, table captions and a macro chooser - Figures with numbered captions: SAX stepper, json_view layout and edit stepper, exception map, JSON pointer and patch walkers, QA pipeline, scaling and binary size charts, roadmap lanes, release timeline, integration decision tree and namespace builder - Table captions (nj-table-caption) on 9 pages - Compile times: modules and PCH charts, filesystem section, re-measured Figure 1, links between features/modules.md and compile_times.md - Interactive macro chooser for features/arbitrary_types.md - Link check: exclude URLs that answer the plugin with 400/401/419 or are dead (customers.md) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: macro chooser generates adl_serializer for non-default-constructible types Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: cross-link concept pages and API pages in See also sections Add See also links in both directions between the concept pages (features, home, integration) and the API pages, write API links in code font, give every entry a comment after a dash, and show the callback event figure on the parser callbacks page. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: address review comments on the new design - Home: add a "Latest release" button - Sponsors: update the list and group it by tier - Features: list all feature pages on the index page - Releases: add highlights per release, link the 4.0 roadmap, add the first commit to the timeline - Exceptions: prefix all example messages with the exception name - API: no code font for format names in the See also links of the to_/from_ pages - Merge Patch: show the document before, the patch, and the result - Replace "--" with typographic dashes, mark external links with an icon, center Mermaid diagrams Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
3.5 KiB
JSON_USE_SIMDUTF
#define JSON_USE_SIMDUTF
When defined, the parser validates the UTF-8 content of JSON strings that come from a contiguous byte input
(std::string, std::vector<char>/<std::uint8_t>, string literals, const char* ranges, …) using the
simdutf library instead of the built-in validator (which uses SSSE3 or NEON where
available, see JSON_NO_SIMD). On text with many non-ASCII characters (e.g. CJK or emoji) this can
validate faster, depending on the CPU.
This is an opt-in external dependency. The library itself remains header-only and its behavior is unchanged: the
same input is accepted or rejected either way, and every parse error is reported at the same position with the same
message (simdutf is only used to fast-path valid runs; anything it flags falls back to the scalar path so the exact
diagnostic is preserved). A std::istream uses simdutf for the characters its stream buffer holds (see
JSON_DISABLE_STREAM_BULK_SCAN); other streaming inputs (FILE*, wide strings,
user-defined adapters) always use the scalar path.
When JSON_USE_SIMDUTF is defined you must make the simdutf.h header available on the include path and link the
simdutf library. When it is not defined, no simdutf header is included and there is no dependency.
!!! note "Requires C++17"
simdutf requires C++17 and its header rejects older standards with an `#!cpp #error`. The backend is therefore only
compiled in from C++17 on. In C++11 and C++14 the macro has no effect and the scalar validator is used, which
accepts and rejects exactly the same input — only throughput differs. Setting the macro project-wide is therefore
safe even when some translation units are built with an older standard.
!!! warning "Define consistently"
The macro selects between two definitions of the same inline validation function. It must therefore be defined
identically for **every** translation unit that includes the library; mixing translation units that define it with
ones that do not is an ODR violation. Prefer setting it as a compile definition on the target rather than with
`#!cpp #define` in individual source files.
Default definition
By default, #!cpp JSON_USE_SIMDUTF is not defined and the portable C++11 scalar validator is used.
#undef JSON_USE_SIMDUTF
Examples
??? example
The code below enables the simdutf backend for UTF-8 validation.
```cpp
#define JSON_USE_SIMDUTF 1
#include <nlohmann/json.hpp>
...
```
The project must also link against simdutf, e.g. with CMake:
```cmake
target_compile_definitions(your_target PRIVATE JSON_USE_SIMDUTF)
target_link_libraries(your_target PRIVATE simdutf::simdutf)
```
!!! hint "Testing this configuration"
The unit tests can be built against the simdutf backend with the CMake option
[`JSON_TestSimdutf`](../../integration/cmake.md#json_testsimdutf) (`OFF` by default), which fetches simdutf and
defines `JSON_USE_SIMDUTF` for every test target. The `ci_test_simdutf` target runs the whole test suite in that
configuration.
See also
- :simple-cmake: JSON_TestSimdutf - CMake option to build the unit tests against the simdutf backend
- Parsing - overview of the parsing functions
- Serialization - pretty-printing, UTF-8 handling, and number output
Version history
- Added in version 3.13.0.