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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>
3.2 KiB
3.2 KiB
nlohmann::json_pointer
template<typename RefStringType>
class json_pointer;
A JSON pointer defines a string syntax for identifying a specific value within a JSON document. It can be used with
functions at and operator[]. Furthermore, JSON pointers
are the base for JSON patches.
Template parameters
RefStringType- the string type used for the reference tokens making up the JSON pointer
!!! warning "Deprecation"
For backwards compatibility `RefStringType` may also be a specialization of [`basic_json`](../basic_json/index.md)
in which case `string_t` will be deduced as [`basic_json::string_t`](../basic_json/string_t.md). This feature is
deprecated and may be removed in a future major version.
See the [migration guide](../../integration/migration_guide.md#json-pointers) for how to update existing code.
A JSON pointer is internally a sequence of reference tokens. front, pop_front, and
push_front act on the first reference token, whereas back, pop_back,
and push_back act on the last one. parent_pointer returns a new JSON pointer
with the last reference token removed (like a non-mutating pop_back):
flowchart LR
A["a"] --> B["b"] --> C["c"]
front["front() / pop_front() / push_front()"] -.-> A
back["back() / pop_back() / push_back()"] -.-> C
parent["parent_pointer() returns /a/b"] -.-> B
The diagram shows the reference tokens of the JSON pointer /a/b/c.
Member types
- string_t - the string type used for the reference tokens
Member functions
- (constructor)
- to_string - return a string representation of the JSON pointer
- operator string_t - return a string representation of the JSON pointer (deprecated)
- operator== - compare: equal
- operator!= - compare: not equal
- operator<=> - compare: 3-way (C++20)
- operator/= - append to the end of the JSON pointer
- operator/ - create JSON Pointer by appending
- parent_pointer - returns the parent of this JSON pointer
- pop_back - remove the last reference token
- back - return last reference token
- push_back - append an unescaped token at the end of the pointer
- pop_front - remove the first reference token
- front - return first reference token
- push_front - append an unescaped token at the start of the pointer
- empty - return whether the pointer points to the root document
Literals
- operator""_json_pointer - user-defined string literal for JSON pointers
See also
Version history
- Added in version 2.0.0.
- Changed template parameter from
basic_jsonto string type in version 3.11.0.