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>
2.6 KiB
2.6 KiB
JSON_NO_AUTOMATIC_UDLS
#define JSON_NO_AUTOMATIC_UDLS
When defined, <nlohmann/json.hpp> does not include <nlohmann/json_literals.hpp>, so the user-defined string
literals operator""_json and
operator""_json_pointer are not declared. Include
<nlohmann/json_literals.hpp> in the files that use them.
The literals are ordinary inline functions whose bodies call the parser, so every translation unit that includes them
instantiates the parser — even if it never parses anything itself. Defining JSON_NO_AUTOMATIC_UDLS for a whole project
avoids this cost in translation units that do not parse (e.g., ones that only define types and conversions or pass
json values around) and reduces their compile time.
Default definition
By default, #!cpp JSON_NO_AUTOMATIC_UDLS is not defined, and <nlohmann/json.hpp> includes
<nlohmann/json_literals.hpp>.
#undef JSON_NO_AUTOMATIC_UDLS
Notes
!!! info "Header <nlohmann/json_literals.hpp>"
The header includes `<nlohmann/json.hpp>` itself and places the literals according to
[`JSON_USE_GLOBAL_UDLS`](json_use_global_udls.md). It is part of the multi-header sources (`include/nlohmann`)
and of the single-header sources (`single_include/nlohmann`), next to `json.hpp`.
!!! info "C++ modules"
The `nlohmann.json` [module](../../features/modules.md) always exports the literals, regardless of this macro.
Examples
??? example
The code below includes the library without the literals and adds them in a single translation unit.
```cpp
// compiled with -DJSON_NO_AUTOMATIC_UDLS for the whole project
// this file uses the literals, so it includes them explicitly
// (the header includes <nlohmann/json.hpp> itself)
#include <nlohmann/json_literals.hpp>
int main()
{
auto j = R"({"foo": 42})"_json;
return j.at("/foo"_json_pointer) == 42 ? 0 : 1;
}
```
Without the include of `<nlohmann/json_literals.hpp>`, the code would fail to compile.
See also
operator""_json- user-defined string literal for JSON valuesoperator""_json_pointer- user-defined string literal for JSON pointersJSON_USE_GLOBAL_UDLS- place user-defined string literals (UDLs) into the global namespace- Compile times - options to reduce compile times
- Creating JSON values - the article on creating JSON values
Version history
- Added in version 3.13.0.