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Defined in header <fkYAML/node.hpp>

fkyaml::basic_node::mapping_type

using mapping_type = MappingType<StringType, basic_node>;

The type used to store mapping node values.

To store mapping objects in basic_node class, the container type is defined by the template parameter MappingType which chooses the type to use for integer objects.
If not explicitly specified, the default type std::map will be chosen.
With the decided container type, the type of mapping objects will then be decided in the form of MappingType<StringType, basic_node> with which mapping objects are stored inside a basic_node.
Note that mapping objects are stored as pointers in a basic_node so that the internal storage size will at most be 8 bytes.

Preserve the insertion order of key-value pairs

The YAML specification describes as a mapping node as "an unordered association of unique keys to values".
Which means that the insertion order of key-value pairs are not guranteed by the YAML specification.
To follow the specification, the fkYAML library uses std::map as the mapping container type by default with the intention of better integration with other C++ programs.
If your YAML documents really needs to be dependent on the insertion order (the YAML specification discourages that though), you can force preserving the insertion order by specifying fkyaml::ordered_map as the MappingType template parameter as follows:

#include <fkYAML/node.hpp>
using ordered_node = basic_node<std::vector, fkyaml::ordered_map>;

Template Paramters

MappingType
The container to store key-value pairs. Defaults to std::map.
StringType
The type of keys and string scalar values. Defaults to std::string.
Example 
#include <cstdint>
#include <iomanip>
#include <iostream>
#include <type_traits>
#include <fkYAML/node.hpp>

int main() {
    std::cout << std::boolalpha << std::is_same<std::map<std::string, fkyaml::node>, fkyaml::node::mapping_type>::value
              << std::endl;
    return 0;
}

output: 

false

See Also