Description

map is an Associative Sequence of heteregenous typed data elements. Each element is a key/data pair (see fusion::pair) where the key has no data (type only). Type identity is used to impose an equivalence relation on keys. A map may contain at most one element for each key. Membership testing and element key lookup has constant runtime complexity (see Overloaded Functions).

Header

#include <boost/fusion/sequence/container/map.hpp>

Synopsis

template <
    typename T0 = unspecified
  , typename T1 = unspecified
  , typename T2 = unspecified
    ...
  , typename TN = unspecified
>
struct map;

The variadic class interface accepts 0 to FUSION_MAX_MAP_SIZE elements, where FUSION_MAX_MAP_SIZE is a user definable predefined maximum that defaults to 10. Example:

map<pair<int, char>, pair<char, char>, pair<double, char> >

You may define the preprocessor constant FUSION_MAX_MAP_SIZE before including any Fusion header to change the default. Example:

#define FUSION_MAX_MAP_SIZE 20

Template parameters

Model of

Expression Semantics

Semantics of an expression is defined only where it differs from, or is not defined in Random Access Sequence and Associative Sequence.

Example

typedef map<
    pair<int, char>
  , pair<double, std::string> > 
map_type;

map_type m(
    make_pair<int>('X')
  , make_pair<double>("Men"));

std::cout << at<int>(m) << std::endl;
std::cout << at<double>(m) << std::endl;