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Niels Lohmann
526b6d3fd6
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>
1.6 KiB
1.6 KiB
nlohmann::basic_json::flatten
basic_json flatten() const;
The function creates a JSON object whose keys are JSON pointers (see RFC 6901)
and whose values are all primitive (see is_primitive() for more information). The original JSON
value can be restored using the unflatten() function.
Return value
an object that maps JSON pointers to primitive values
Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
Complexity
Linear in the size of the JSON value.
Notes
Empty objects and arrays are flattened to #!json null and will not be reconstructed correctly by the
unflatten() function.
Examples
??? example "Example: flatten a JSON object"
The following code shows how a JSON object is flattened to an object whose keys consist of JSON pointers.
```cpp
--8<-- "examples/flatten.cpp"
```
Output:
```json
--8<-- "examples/flatten.output"
```
??? example "Example: empty objects and arrays are flattened to #!json null"
The following code shows that an empty object and an empty array are both flattened to `#!json null`, and that
`unflatten()` restores them as `#!json null` rather than as empty containers.
```cpp
--8<-- "examples/flatten__empty.cpp"
```
Output:
```json
--8<-- "examples/flatten__empty.output"
```
See also
- unflatten the reverse function
Version history
- Added in version 2.0.0.