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>
2.6 KiB
2.6 KiB
nlohmann::basic_json::get_to
template<typename ValueType>
ValueType& get_to(ValueType& v) const noexcept(
noexcept(JSONSerializer<ValueType>::from_json(
std::declval<const basic_json_t&>(), v)));
Explicit type conversion between the JSON value and a compatible value. The value is filled into the input parameter by
calling the json_serializer<ValueType> from_json() method.
The function is equivalent to executing
ValueType v;
JSONSerializer<ValueType>::from_json(*this, v);
This overload is chosen if:
ValueTypeis notbasic_json,json_serializer<ValueType>has afrom_json()method of the formvoid from_json(const basic_json&, ValueType&)
v must not be const. Passing a const object is a compile-time error. For types such as arithmetic types, enums,
and C arrays, the error is a static_assert that names the problem. For other types, the overload is not viable, and
the compiler reports that no matching get_to was found.
Template parameters
ValueType- the value type to return
Return value
the input parameter, allowing chaining calls
Exception safety
Depends on what json_serializer<ValueType> from_json() method throws; the JSON value itself is never modified,
since get_to() is a #!cpp const member function.
Exceptions
Depends on what json_serializer<ValueType> from_json() method throws
Complexity
Depends on the json_serializer<ValueType>::from_json() implementation.
Examples
??? example
The example below shows several conversions from JSON values to other types. There a few things to note: (1)
Floating-point numbers can be converted to integers, (2) A JSON array can be converted to a standard
`#!cpp std::vector<short>`, (3) A JSON object can be converted to C++ associative containers such as
`#!cpp std::map<std::string, json>`.
```cpp
--8<-- "examples/get_to.cpp"
```
Output:
```json
--8<-- "examples/get_to.output"
```
See also
get- get a value (explicit conversion)get_ref- get a reference to the stored valueget_ptr- get a pointer to the stored value- Converting values - the type conversions article
basic_json_view::get_to- the same conversion on a zero-copy view- Arbitrary Type Conversions - make your own types usable with
get_to
Version history
- Added in version 3.3.0.
- Added a
static_assertwith a clear message forconstarguments in version 3.13.0.