ceph/src/jaegertracing/opentelemetry-cpp/third_party/nlohmann-json/doc/mkdocs/docs/api/ordered_map.md

   1 # <small>nlohmann::</small>ordered_map
   2
   3 ```cpp
   4 template<class Key, class T, class IgnoredLess = std::less<Key>,
   5          class Allocator = std::allocator<std::pair<const Key, T>>>
   6 struct ordered_map : std::vector<std::pair<const Key, T>, Allocator>;
   7 ```
   8
   9 A minimal map-like container that preserves insertion order for use within [`nlohmann::ordered_json`](ordered_json.md)
  10 (`nlohmann::basic_json<ordered_map>`).
  11
  12 ## Template parameters
  13
  14 `Key`
  15 :   key type
  16
  17 `T`
  18 :   mapped type
  19
  20 `IgnoredLess`
  21 :   comparison function (ignored and only added to ensure compatibility with `#!cpp std::map`)
  22
  23 `Allocator`
  24 :   allocator type
  25
  26 ## Member types
  27
  28 - **key_type** - key type (`Key`)
  29 - **mapped_type** - mapped type (`T`)
  30 - **Container** - base container type (`#!cpp std::vector<std::pair<const Key, T>, Allocator>`)
  31 - **iterator**
  32 - **const_iterator**
  33 - **size_type**
  34 - **value_type**
  35
  36 ## Member functions
  37
  38 - (constructor)
  39 - (destructor)
  40 - **emplace**
  41 - **operator\[\]**
  42 - **at**
  43 - **erase**
  44 - **count**
  45 - **find**
  46 - **insert**
  47
  48 ## Examples
  49
  50 ??? example
  51
  52     The example shows the different behavior of `std::map` and `nlohmann::ordered_map`.
  53
  54     ```cpp
  55     --8<-- "examples/ordered_map.cpp"
  56     ```
  57
  58     Output:
  59
  60     ```json
  61     --8<-- "examples/ordered_map.output"
  62     ```
  63
  64 ## See also
  65
  66 - [ordered_json](ordered_json.md)
  67
  68 ## Version history
  69
  70 - Added in version 3.9.0 to implement [`nlohmann::ordered_json`](ordered_json.md).