Niels Lohmann
a47170346a
* docs: new design for the documentation site Apply the brand to the Material for MkDocs site: Inter and JetBrains Mono served by the site (upright and real italic), brand colours, blue header band with the syntax pattern, wordmark in the header, new home page (hero, cards, animated feature tour), 404 page, polish for tabs, search, footer, focus rings, tables and code blocks, and theme features (code copy, previous/next footer, TOC follow, search suggestions). Draw the number railroad diagram, the parser callback events and the iterator illustrations as inline SVGs that follow the light and dark scheme. The generator scripts are in docs/mkdocs/scripts/figures; the feature slideshow (json-light.svg, json-dark.svg, replacing json.gif on the home page) is built by docs/mkdocs/scripts/slideshow. Decision nodes in five flowcharts become hexagons, which need far less room. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: add figures, table captions and a macro chooser - Figures with numbered captions: SAX stepper, json_view layout and edit stepper, exception map, JSON pointer and patch walkers, QA pipeline, scaling and binary size charts, roadmap lanes, release timeline, integration decision tree and namespace builder - Table captions (nj-table-caption) on 9 pages - Compile times: modules and PCH charts, filesystem section, re-measured Figure 1, links between features/modules.md and compile_times.md - Interactive macro chooser for features/arbitrary_types.md - Link check: exclude URLs that answer the plugin with 400/401/419 or are dead (customers.md) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: macro chooser generates adl_serializer for non-default-constructible types Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: cross-link concept pages and API pages in See also sections Add See also links in both directions between the concept pages (features, home, integration) and the API pages, write API links in code font, give every entry a comment after a dash, and show the callback event figure on the parser callbacks page. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: address review comments on the new design - Home: add a "Latest release" button - Sponsors: update the list and group it by tier - Features: list all feature pages on the index page - Releases: add highlights per release, link the 4.0 roadmap, add the first commit to the timeline - Exceptions: prefix all example messages with the exception name - API: no code font for format names in the See also links of the to_/from_ pages - Merge Patch: show the document before, the patch, and the result - Replace "--" with typographic dashes, mark external links with an icon, center Mermaid diagrams Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
100 lines
3.4 KiB
Markdown
100 lines
3.4 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. Throws no library exceptions. As the string representation is built with [`to_string`](json_pointer/to_string.md),
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`#!cpp std::bad_alloc` is possible.
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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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- [`basic_json_view::operator<<`](basic_json_view/operator_ltlt.md) - the corresponding operator for
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`basic_json_view`
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- [Serialization](../features/serialization.md) - the serialization article
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- [`JSON_NO_IO`](macros/json_no_io.md) - remove stream and file I/O
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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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