63c10a51fc
* 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> * Keep the customer links that could not be fixed A dead link on the customers page is still the evidence of where the use of the library was documented. Keep the original URLs of the entries without a working replacement (Marne, Cisco Webex Desk Camera, Philips Hue, CyberArk) and exclude exactly these URLs from the link check. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Correct the duplicate-key recipe's claim about SAX positions The SAX interface's key() receives no position either; only parse_error() does. Also note that the recipe does not report the path to the repeated key (see discussion #5085). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Say the library is available as a single header and mention json_fwd.hpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Correct documentation errors found while hunting for bugs - patch/patch_inplace: list the JSON pointer errors parse_error.106-109 and out_of_range.402/404, and quote the actual parse_error.105 message. - unflatten: list parse_error.106/107/108 and out_of_range.404. - to_bson: list out_of_range.415 (binary subtype above 255) and note that 412 and 415 are new in 3.13.0. - to_string: state that string_t must be convertible to std::string, also in the StringType requirements table. - JSON Lines: a `while (input >> j)` loop also throws after the last value for concatenated JSON values; show a loop that works for both. - BON8: a string gets 0xFF only if nothing follows it in the message; a string at the end of an array or object is ended by 0xFE. - custom_string_type.hpp: add operator+=(char), which the "Always required" list asks for (json_pointer::to_string, flatten, unflatten, and diff did not compile), and an ADL int_to_string for diff and items. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Cache the release headers with functools.lru_cache Codacy (Pylint) flagged the mutable default argument that header() used as its cache. functools.lru_cache keeps the same memoization without it. The script's output is unchanged. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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JSON_NO_THREAD_LOCAL
#define JSON_NO_THREAD_LOCAL
When defined, the library does not use #!cpp thread_local storage. This is relevant for the few environments whose
toolchain does not support it.
Copying a value and comparing two values both descend into the first levels by letting the containers copy or compare
themselves, and finish whatever is nested deeper than that without the call stack, so that neither can exhaust the stack
however deeply the values are nested. Each counts the levels it has descended into in a #!cpp thread_local variable, as
a counter shared between threads would be raced.
Without those counters, no descent can be bounded safely, so objects and arrays are copied and compared without the call
stack right away. Both keep working exactly as they do otherwise - the same values come out, the same comparisons hold,
and deeply nested values are handled just as safely - but both are slower, because the containers no longer copy or
compare themselves. Copying the benchmark documents takes 9% (canada.json) to 34% (twitter.json) longer, and
comparing two equal ones 10% (citm_catalog.json) to 90% (canada.json) longer.
Default definition
By default, #!cpp JSON_NO_THREAD_LOCAL is not defined.
#undef JSON_NO_THREAD_LOCAL
The library defines it by itself for Clang targeting MinGW, which does not survive the #!cpp thread_local storage:
copying a value segfaults there, with both old and current Clang versions, while GCC targeting MinGW is unaffected.
Copying and comparing fall back to working without the call stack there, as they do whenever the macro is defined.
Examples
??? example
The code below forces the library not to use `#!cpp thread_local` storage.
```cpp
#define JSON_NO_THREAD_LOCAL 1
#include <nlohmann/json.hpp>
...
```
See also
Version history
- Added in version 3.13.0.