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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).
#include <boost/fusion/sequence/container/map.hpp>
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
Parameter | Description | Default |
---|---|---|
T0...TN | Element types | unspecified-type |
Notation
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<int>(m) << std::endl; std::cout << at<double>(m) << std::endl;
Copyright © 2001-2005 Joel de Guzman, Dan Marsden |