set

Description

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

Header

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

Model of

Expression semantics

In the following table, s is an instance of set, pos is an iterator into s, and x, k, and t₁,t₂,... t_n is a set of unique arbitrary types. [Note: See below for an example of how to construct a set from a list of potentially non-unique types — end note]

Expression	Semantics
set<t₁,t₂,... t_n> setn<t₁,t₂,... t_n>	`set` of elements t₁,t₂,... t_n; see Variadic Sequence.
set<t₁,t₂,... t_n>::type setn<t₁,t₂,... t_n>::type	Identical to `set`n`<`t₁,t₂,... t_n`>`; see Variadic Sequence.
`begin<s>::type`	An iterator pointing to the beginning of `s`; see Associative Sequence.
`end<s>::type`	An iterator pointing to the end of `s`; see Associative Sequence.
`size<s>::type`	The size of `s`; see Associative Sequence.
`empty<s>::type`	A boolean Integral Constant `c` such that `c::value == true` if and only if `s` is empty; see Associative Sequence.
`front<s>::type`	The first element in `s`; see Associative Sequence.
`has_key<s,k>::type`	A boolean Integral Constant `c` such that `c::value == true` if and only if there is one or more elements with the key `k` in `s`; see Associative Sequence.
`count<s,k>::type`	The number of elements with the key `k` in `s`; see Associative Sequence.
`order<s,k>::type`	A unique unsigned Integral Constant associated with the key `k` in `s`; see Associative Sequence.
at<s,k>::type at<s,k,def>::type	The element associated with the key `k` in `s`; see Associative Sequence.
`key_type<s,x>::type`	Identical to `x`; see Associative Sequence.
`value_type<s,x>::type`	Identical to `x`; see Associative Sequence.
`insert<s,x>::type`	A new `set` equivalent to `s` except that at< t, key_type<s,x>::type >::type is identical to `value_type<s,x>::type`.
`insert<s,pos,x>::type`	Equivalent to `insert<s,x>::type`; `pos` is ignored.
`erase_key<s,k>::type`	A new `set` equivalent to `s` except that `has_key<t, k>::value == false`.
`erase<s,pos>::type`	Equivalent to `erase<s, deref<pos>::type >::type`.
`clear<s>::type`	An empty `set`; see clear.

Example

Basic set invariants:

typedef set< int,long,double,int_<5> > s;

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

BOOST_MPL_ASSERT(( is_same< at<s,int>::type, int > ));
BOOST_MPL_ASSERT(( is_same< at<s,long>::type, long > ));
BOOST_MPL_ASSERT(( is_same< at<s,int_<5> >::type, int_<5> > ));
BOOST_MPL_ASSERT(( is_same< at<s,char>::type, void_ > ));

Constructing a set from a list of potentially non-unique types:

typedef fold<
      vector<int,int,long,long>
    , set0<>
    , insert<_1,_2>
    >::type s;

BOOST_MPL_ASSERT_RELATION( size<s>::value, ==, 2 );

Boost C++ Libraries

set

Description

Header

Model of

Expression semantics

Example

See also