mirror of https://github.com/nlohmann/json.git synced 2026-10-02 20:50:32 +00:00

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Niels Lohmann 526b6d3fd6 Review and extend the documentation, and check it in CI

A review of all documentation pages found factual errors, dead links,
missing cross-references, and gaps in examples. This fixes them and adds
checks so the same problems are caught automatically.

Fixes:
- wrong signatures and version histories (operator!= C++20 member,
  binary() subtype type, get<PointerType>(), JSON_NO_THREAD_LOCAL, ...)
- stale descriptions (number parsing since #5283, UBJSON table, SAX
  example that no longer compiled, tsl::ordered_map advice)
- dead internal and external links; repology.org badges (the domain is
  suspended) replaced by badges that query the registries directly
- deprecation notes link the migration guide; the guide itself fixed

Additions:
- "See also" sections, cross-references, 25 runnable examples, 12
  Mermaid diagrams, new API pages for json_pointer::operator<=> and
  byte_container_with_subtype::operator==/!=
- landing page, guides for untrusted input and performance
- "unreleased" badge after versions newer than the latest release

Checks:
- strict documentation build (broken links/anchors fail it); CI and
  the publish workflow fetch the full history the build needs
- weekly external link check, Mermaid syntax check in CI
- check_structure.py: example titles, heading levels, alt texts,
  header links, docset index coverage; its unused-example check works
  again
- all examples produce the same output on every platform

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

2026-09-29 17:05:35 +02:00

2.1 KiB

Raw Blame History

JSON_HAS_RANGES

#define JSON_HAS_RANGES /* value */

This macro indicates whether the standard library has any support for ranges. Implies support for concepts. Possible values are 1 when supported or 0 when unsupported.

Default definition

The default value is detected based on the preprocessor macro #!cpp __cpp_lib_ranges.

When the macro is not defined, the library will define it to its default value.

!!! info "Known compiler/stdlib exclusions"

Even when the feature-test macro `__cpp_lib_ranges` indicates ranges support is available, the library disables it on
the following incomplete or broken toolchains:

- **GCC 11.1.0** — disabled (the shipped `<ranges>` header has a syntax error; [issue #4440](https://github.com/nlohmann/json/issues/4440))
- **libstdc++ < 11** — disabled (incomplete C++20 ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
- **Clang < 16 with libstdc++** — disabled (incomplete ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
- **libc++ < 160000** — disabled (incomplete C++20 ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
- **nvcc (CUDA) 12.0.x and 12.1.x** — disabled (the `enable_borrowed_range` variable-template syntax triggers a parse error
  under these two toolkit versions; fixed in CUDA 12.2; [issue #3907](https://github.com/nlohmann/json/issues/3907))

If `JSON_HAS_RANGES` is `0` despite `__cpp_lib_ranges` being defined, one of the exclusions above likely applies to your toolchain.

Examples

??? example

The code below forces the library to enable support for ranges:

```cpp
#define JSON_HAS_RANGES 1
#include <nlohmann/json.hpp>

...
```

Version history

Added in version 3.11.0.

2.1 KiB Raw Blame History

JSON_HAS_RANGES

Default definition

Examples

See also

Version history

2.1 KiB

Raw Blame History