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>
95 lines
3.0 KiB
Markdown
95 lines
3.0 KiB
Markdown
# <small>nlohmann::basic_json::</small>exception
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```cpp
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class exception : public std::exception;
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```
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This class is an extension of [`std::exception`](https://en.cppreference.com/w/cpp/error/exception) objects with a
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member `id` for exception ids. It is used as the base class for all exceptions thrown by the `basic_json` class. This
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class can hence be used as "wildcard" to catch exceptions, see example below.
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```mermaid
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classDiagram
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direction LR
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class std_exception ["std::exception"] {
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<<interface>>
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}
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class json_exception ["basic_json::exception"] {
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+const int id
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+const char* what() const
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}
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class json_parse_error ["basic_json::parse_error"] {
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+const std::size_t byte
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}
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class json_invalid_iterator ["basic_json::invalid_iterator"]
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class json_type_error ["basic_json::type_error"]
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class json_out_of_range ["basic_json::out_of_range"]
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class json_other_error ["basic_json::other_error"]
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std_exception <|-- json_exception
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json_exception <|-- json_parse_error
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json_exception <|-- json_invalid_iterator
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json_exception <|-- json_type_error
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json_exception <|-- json_out_of_range
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json_exception <|-- json_other_error
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style json_exception fill:#CCCCFF
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```
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<p class="nj-caption" markdown>Class hierarchy of the library's exceptions; arrows point from a derived class to its
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base class, and the highlighted box is `basic_json::exception`.</p>
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Subclasses:
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- [`parse_error`](parse_error.md) for exceptions indicating a parse error
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- [`invalid_iterator`](invalid_iterator.md) for exceptions indicating errors with iterators
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- [`type_error`](type_error.md) for exceptions indicating executing a member function with a wrong type
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- [`out_of_range`](out_of_range.md) for exceptions indicating access out of the defined range
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- [`other_error`](other_error.md) for exceptions indicating other library errors
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## Member functions
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- **what** - returns explanatory string
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## Member variables
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- **id** - the id of the exception
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## Notes
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To have nothrow-copy-constructible exceptions, we internally use `std::runtime_error` which can cope with
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arbitrary-length error messages. Intermediate strings are built with static functions and then passed to the actual
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constructor.
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## Examples
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??? example
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The following code shows how arbitrary library exceptions can be caught.
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```cpp
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--8<-- "examples/exception.cpp"
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```
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Output:
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```json
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--8<-- "examples/exception.output"
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```
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## See also
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- [List of exceptions](../../home/exceptions.md) - overview of all exceptions thrown by the library
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- [Working Without Exceptions](../../features/no_exceptions.md) - using the library without exceptions
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- [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) - extended exception messages with the path of the failing value
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- [Parsing and Exceptions](../../features/parsing/parse_exceptions.md) - parsing alternatives that do not throw
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- [Debugging](../../home/debugging.md) - debugging aids
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## Version history
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- Added in version 3.0.0.
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