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>
96 lines
3.1 KiB
Markdown
96 lines
3.1 KiB
Markdown
# <small>nlohmann::</small>operator<<(basic_json), <small>nlohmann::</small>operator<<(json_pointer)
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```cpp
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std::ostream& operator<<(std::ostream& o, const basic_json& j); // (1)
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std::ostream& operator<<(std::ostream& o, const json_pointer& ptr); // (2)
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```
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1. Serialize the given JSON value `j` to the output stream `o`. The JSON value will be serialized using the
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[`dump`](basic_json/dump.md) member function.
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- The indentation of the output can be controlled with the member variable `width` of the output stream `o`. For
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instance, using the manipulator `std::setw(4)` on `o` sets the indentation level to `4` and the serialization
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result is the same as calling `dump(4)`.
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- The indentation character can be controlled with the member variable `fill` of the output stream `o`.
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For instance, the manipulator `std::setfill('\\t')` sets indentation to use a tab character rather than the
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default space character.
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2. Write a string representation of the given JSON pointer `ptr` to the output stream `o`. The string representation is
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obtained using the [`to_string`](json_pointer/to_string.md) member function.
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## Parameters
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`o` (in, out)
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: stream to write to
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`j` (in)
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: JSON value to serialize
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`ptr` (in)
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: JSON pointer to write
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## Return value
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the stream `o`
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## Exceptions
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1. Throws [`type_error.316`](../home/exceptions.md#jsonexceptiontype_error316) if a string stored inside the JSON
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value is not UTF-8 encoded. Note that unlike the [`dump`](basic_json/dump.md) member functions, no `error_handler`
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can be set.
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2. None.
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## Complexity
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Linear.
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## Notes
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!!! warning "Deprecation"
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Function `#!cpp std::ostream& operator<<(std::ostream& o, const basic_json& j)` replaces function
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`#!cpp std::ostream& operator>>(const basic_json& j, std::ostream& o)` which has been deprecated in version 3.0.0.
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It will be removed in version 4.0.0. Please replace calls like `#!cpp j >> o;` with `#!cpp o << j;`.
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See the [migration guide](../integration/migration_guide.md#miscellaneous-functions) for how to update existing code.
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## Examples
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??? example "Example: (1) serialize JSON value to stream"
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The example below shows the serialization with different parameters to `width` to adjust the indentation level.
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```cpp
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--8<-- "examples/operator_ltlt__basic_json.cpp"
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```
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Output:
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```json
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--8<-- "examples/operator_ltlt__basic_json.output"
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```
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??? example "Example: (2) write JSON pointer to stream"
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The example below shows how to write a JSON pointer to a stream.
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```cpp
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--8<-- "examples/operator_ltlt__json_pointer.cpp"
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```
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Output:
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```json
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--8<-- "examples/operator_ltlt__json_pointer.output"
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```
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## See also
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- [dump](basic_json/dump.md) - serialize to a JSON-formatted string
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- [Serialization](../features/serialization.md) - the serialization article
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## Version history
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1. Added in version 1.0.0. Added support for indentation character and deprecated
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`#!cpp std::ostream& operator>>(const basic_json& j, std::ostream& o)` in version 3.0.0.
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2. Added in version 3.11.0.
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