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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>
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2.4 KiB
nlohmann::basic_json::array_t
using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
The type used to store JSON arrays.
RFC 8259 describes JSON arrays as follows:
An array is an ordered sequence of zero or more values.
To store objects in C++, a type is defined by the template parameters explained below.
Template parameters
ArrayType- container type to store arrays. It must be a vector-like container: the library uses
operator[],at(), andresize(), and requires random-access iterators.#!cpp std::vectorand#!cpp std::dequequalify;#!cpp std::listdoes not. See Template Parameter Requirements for the full list of requirements. AllocatorType- the allocator to use for objects (e.g.,
std::allocator)
Notes
Default type
With the default values for ArrayType (std::vector) and AllocatorType (std::allocator), the default value for
array_t is:
std::vector<
basic_json, // value_type
std::allocator<basic_json> // allocator_type
>
Limits
RFC 8259 specifies:
An implementation may set limits on the maximum depth of nesting.
In this class, the array's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be
introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the
max_size function of a JSON array.
Storage
Arrays are stored as pointers in a basic_json type. That is, for any access to array values, a pointer of type
#!cpp array_t* must be dereferenced.
Examples
??? example
The following code shows that `array_t` is by default, a typedef to `#!cpp std::vector<nlohmann::json>`.
```cpp
--8<-- "examples/array_t.cpp"
```
Output:
```json
--8<-- "examples/array_t.output"
```
See also
- object_t the type used to store JSON objects
- binary_t the type used to store binary values
- is_array checks whether the JSON value is an array
- max_size returns the maximum possible number of elements
Version history
- Added in version 1.0.0.
- Made
capacity()optional, so that array types such as#!cpp std::dequecan be used, in version 3.13.0.