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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>
1.3 KiB
1.3 KiB
nlohmann::basic_json_view::cend
iterator cend() const noexcept;
Returns an iterator to one past the last element, in document order. Equivalent to end(): a
view is always read-only, so #!cpp const_iterator and #!cpp iterator are the same type, and cend() exists only
so that generic code that expects a cbegin()/cend() pair works with a view too.
Return value
Iterator one past the last element; identical to what end() returns.
Exception safety
No-throw guarantee: this function never throws exceptions.
Complexity
Constant.
Examples
??? example
The example below checks that every record of a batch is an object with `std::all_of`, using
[`cbegin()`](cbegin.md)/`cend()` as the range -- the same way it would for any standard container -- before
materializing any record of the batch.
```cpp
--8<-- "examples/basic_json_view__cend.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__cend.output"
```
See also
- end - returns an iterator to one past the last element
- cbegin - returns a const iterator to the first element
BasicJsonType::cend- the corresponding function ofbasic_json
Version history
- Added in version 3.13.0.