map

Description

map is a variadic, associative, extensible sequence of type pairs that supports constant-time insertion and removal of elements, and testing for membership. A map may contain at most one element for each key.

Header

Sequence form	Header
Variadic	`#include <boost/mpl/map.hpp>`
Numbered	`#include <boost/mpl/map/map`n`.hpp>`

Model of

Expression semantics

In the following table and subsequent specifications, m is an instance of map, pos is an iterator into m, x and p₁,p₂,... p_n are pairs, and k is an arbitrary type.

Expression	Semantics
map<p₁,p₂,... p_n> mapn<p₁,p₂,... p_n>	`map` of elements p₁,p₂,... p_n; see Variadic Sequence.
map<p₁,p₂,... p_n>::type mapn<p₁,p₂,... p_n>::type	Identical to `map`n`<`p₁,p₂,... p_n`>`; see Variadic Sequence.
`begin<m>::type`	An iterator pointing to the beginning of `m`; see Associative Sequence.
`end<m>::type`	An iterator pointing to the end of `m`; see Associative Sequence.
`size<m>::type`	The size of `m`; see Associative Sequence.
`empty<m>::type`	A boolean Integral Constant `c` such that `c::value == true` if and only if `m` is empty; see Associative Sequence.
`front<m>::type`	The first element in `m`; see Associative Sequence.
`has_key<m,k>::type`	Queries the presence of elements with the key `k` in `m`; see Associative Sequence.
`count<m,k>::type`	The number of elements with the key `k` in `m`; see Associative Sequence.
`order<m,k>::type`	A unique unsigned Integral Constant associated with the key `k` in `m`; see Associative Sequence.
at<m,k>::type at<m,k,default>::type	The element associated with the key `k` in `m`; see Associative Sequence.
`key_type<m,x>::type`	Identical to `x::first`; see Associative Sequence.
`value_type<m,x>::type`	Identical to `x::second`; see Associative Sequence.
`insert<m,x>::type`	A new `map`, `t`, equivalent to `m` except that at< t, key_type<m,x>::type >::type is identical to `value_type<m,x>::type`.
`insert<m,pos,x>::type`	Equivalent to `insert<m,x>::type`; `pos` is ignored.
`erase_key<m,k>::type`	A new `map`, `t`, equivalent to `m` except that `has_key<t, k>::value == false`.
`erase<m,pos>::type`	Equivalent to `erase<m, deref<pos>::type >::type`.
`clear<m>::type`	An empty `map`; see clear.

Example

typedef map<
      pair<int,unsigned>
    , pair<char,unsigned char>
    , pair<long_<5>,char[17]>
    , pair<int[42],bool>
    > m;

BOOST_MPL_ASSERT_RELATION( size<m>::value, ==, 4 );
BOOST_MPL_ASSERT_NOT(( empty<m> ));

BOOST_MPL_ASSERT(( is_same< at<m,int>::type, unsigned > ));
BOOST_MPL_ASSERT(( is_same< at<m,long_<5> >::type, char[17] > ));
BOOST_MPL_ASSERT(( is_same< at<m,int[42]>::type, bool > ));
BOOST_MPL_ASSERT(( is_same< at<m,long>::type, void_ > ));

Boost C++ Libraries

map

Description

Header

Model of

Expression semantics

Example

See also