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Niels Lohmann
0adb7783a4
Give basic_json_view the read-only access functions of basic_json: operator[] and at() with keys and indices, front()/back(), find(), contains(), count(), begin()/end() and cbegin()/cend(), items() with structured bindings from C++17 on, and type_name(). Exceptions have the ids and messages of the const functions of basic_json. Where basic_json has undefined behavior the view answers safely: operator[] with a missing key or an out-of-range index returns a discarded view, and front()/back() of an empty container throw invalid_iterator.214. Objects are iterated in document order, and all members are visited; duplicate-key lookups find the first member (as yyjson and simdjson do), while parse(), materialize(), and the map conversions keep the last value, as parse() does. Keys of up to 16 bytes are compared with two overlapping loads. Add value conversions: get<T>()/get_to() for arithmetic types, bool, nullptr_t, strings (std::basic_string copied, string_view_t without a copy), BasicJsonType, views, std::vector, and maps with string keys; get_string() for the string without a copy; number_token() for the number exactly as written in the source; value() with keys and JSON pointers; and operator[]/at()/ contains() with JSON pointers. Everything else, including types with from_json(), goes through materialize() of that subtree. get<T>() of arithmetic types is inlined down to the conversion, so reading an integer needs no call. detail::json_pointer_access exposes a pointer's reference tokens to code outside basic_json. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
1.5 KiB
1.5 KiB
nlohmann::basic_json_view::end
iterator end() const noexcept;
Returns an iterator to one past the last element of an array, one past the last member value of an object, in
document order -- see begin(). A primitive value iterates as a range of one element (itself);
#!json null and a discarded view iterate as an empty range, so #!cpp begin() == end() for
them.
Return value
Iterator one past the last element.
Exception safety
No-throw guarantee: this function never throws exceptions.
Complexity
Constant.
Notes
#!cpp iterator is a forward iterator: unlike BasicJsonType::iterator, it cannot be decremented, so there is no
way to reach the last element by stepping back from end(). Use back() instead.
Examples
??? example
The example below scans a (possibly large) array of readings for the first one over a threshold, stopping the
loop at `end()` as soon as one is found. Only the matching reading, if any, is ever materialized.
```cpp
--8<-- "examples/basic_json_view__end.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__end.output"
```
See also
- begin - returns an iterator to the first element
- cend - returns a const iterator to one past the last element
BasicJsonType::end- the corresponding function ofbasic_json
Version history
- Added in version 3.13.0.