1.6 KiB
1.6 KiB
nlohmann::ordered_map
template<class Key, class T, class IgnoredLess = std::less<Key>,
class Allocator = std::allocator<std::pair<const Key, T>>>
struct ordered_map : std::vector<std::pair<const Key, T>, Allocator>;
A minimal map-like container that preserves insertion order for use within nlohmann::ordered_json
(nlohmann::basic_json<ordered_map>).
Template parameters
Key- key type
T- mapped type
IgnoredLess- comparison function (ignored and only added to ensure compatibility with
#!cpp std::map) Allocator- allocator type
Member types
- key_type - key type (
Key) - mapped_type - mapped type (
T) - Container - base container type (
#!cpp std::vector<std::pair<const Key, T>, Allocator>) - iterator
- const_iterator
- size_type
- value_type
- key_compare - key comparison function
std::equal_to<Key> // until C++14
std::equal_to<> // since C++14
Member functions
- (constructor)
- (destructor)
- emplace
- operator[]
- at
- erase
- count
- find
- insert
Examples
??? example
The example shows the different behavior of `std::map` and `nlohmann::ordered_map`.
```cpp
--8<-- "examples/ordered_map.cpp"
```
Output:
```json
--8<-- "examples/ordered_map.output"
```
See also
Version history
- Added in version 3.9.0 to implement
nlohmann::ordered_json. - Added key_compare member in version 3.11.0.