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Niels Lohmann
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_DIAGNOSTICS
#define JSON_DIAGNOSTICS /* value */
This macro enables extended diagnostics for exception messages.
Possible values are 1 to enable or 0 to disable (default).
When enabled, exception messages contain a JSON Pointer to the JSON value that triggered the exception. Note that enabling this macro increases the size of every JSON value by one pointer and adds some runtime overhead.
Default definition
The default value is 0 (extended diagnostics are switched off).
#define JSON_DIAGNOSTICS 0
When the macro is not defined, the library will define it to its default value.
Notes
!!! note "ABI compatibility"
As of version 3.11.0, this macro is no longer required to be defined consistently throughout a codebase to avoid
One Definition Rule (ODR) violations, as the value of this macro is encoded in the namespace, resulting in distinct
symbol names.
This allows different parts of a codebase to use different versions or configurations of this library without
causing improper behavior.
Where possible, it is still recommended that all code define this the same way for maximum interoperability.
!!! hint "CMake option"
Diagnostic messages can also be controlled with the CMake option
[`JSON_Diagnostics`](../../integration/cmake.md#json_diagnostics) (`OFF` by default)
which defines `JSON_DIAGNOSTICS` accordingly. Note this only applies when building the
library from source — see the pre-installed-package caveat on that page.
Examples
??? example "Example: default behavior"
```cpp
--8<-- "examples/diagnostics_standard.cpp"
```
Output:
```
--8<-- "examples/diagnostics_standard.output"
```
This exception can be hard to debug if storing the value `#!c "12"` and accessing it is further apart.
??? example "Example: extended diagnostic messages"
```cpp
--8<-- "examples/diagnostics_extended.cpp"
```
Output:
```
--8<-- "examples/diagnostics_extended.output"
```
Now the exception message contains a JSON Pointer `/address/housenumber` that indicates which value has the wrong type.
??? example "Example: using only diagnostic positions in exceptions"
```cpp
--8<-- "examples/diagnostic_positions_exception.cpp"
```
Output:
```
--8<-- "examples/diagnostic_positions_exception.output"
```
The output shows the exception with start/end positions only.
See also
- :simple-cmake: JSON_Diagnostics - CMake option to control the macro
- JSON_DIAGNOSTIC_POSITIONS - macro to access positions of elements
Version history
- Added in version 3.10.0.
- As of version 3.11.0, the definition is allowed to vary between translation units.