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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).
<<<<<<< .working#include <boost/fusion/container/map.hpp> #include <boost/fusion/include/map.hpp> #include <boost/fusion/container/map_fwd.hpp> #include <boost/fusion/include/map_fwd.hpp><<<<<<< .working
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<<<<<<< .working
Parameter |
Description |
Default |
|---|---|---|
T0...TN |
Element types |
unspecified-type |
Notation
A map type
An instance of map
Heterogeneous key/value pairs (see fusion::pair)
Semantics of an expression is defined only where it differs from, or is not defined in Random Access Sequence and Associative Sequence.
Expression |
Semantics |
|---|---|
M() |
Creates a map with default constructed elements. |
M(e0, e1,... en) |
Creates a map with element pairs e0...en. |
M(s) |
Copy constructs a map from a Forward Sequence s. |
m = s |
Assigns to a map, m, from a Forward Sequence s. |
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_key<int>(m) << std::endl; std::cout << at_key<double>(m) << std::endl;