.. Sequences/Classes//set |40

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.

__ Associative Sequence_ __ Extensible Associative Sequence_

Header

+-------------------+-------------------------------------------------------+ | Sequence form | Header | +===================+=======================================================+ | Variadic | #include <boost/mpl/set.hpp> | +-------------------+-------------------------------------------------------+ | Numbered | #include <boost/mpl/set/set\ n\ .hpp> | +-------------------+-------------------------------------------------------+

Model of

• |Variadic Sequence|
• |Associative Sequence|
• |Extensible Associative Sequence|

Expression semantics

In the following table, s is an instance of set, pos is an iterator into s, and x, k, and |t1...tn| 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]

__ nonunique-set-example_

+---------------------------------------+-----------------------------------------------------------+ | Expression | Semantics | +=======================================+===========================================================+ | .. parsed-literal:: | set of elements |t1...tn|; see | | | |Variadic Sequence|. | | set<|t1...tn|> | | | set\ n\ <|t1...tn|> | | +---------------------------------------+-----------------------------------------------------------+ | .. parsed-literal:: | Identical to set\ n\ <\ |t1...tn|\ >; | | | see |Variadic Sequence|. | | set<|t1...tn|>::type | | | set\ n\ <|t1...tn|>::type | | +---------------------------------------+-----------------------------------------------------------+ | 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 | |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 | |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|. | +---------------------------------------+-----------------------------------------------------------+ | .. parsed-literal:: | The element associated with the key k in | | | s; see |Associative Sequence|. | | at<s,k>::type | | | at<s,k,def>::type | | +---------------------------------------+-----------------------------------------------------------+ | 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:

.. parsed-literal::

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\_ > ));

.. _nonunique-set-example:

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

.. parsed-literal::

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

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

See also

|Sequences|, |Variadic Sequence|, |Associative Sequence|, |Extensible Associative Sequence|, |set_c|, |map|, |vector|

.. copyright:: Copyright 2001-2011 Aleksey Gurtovoy and David Abrahams Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)