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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.
| Sequence form | Header |
|---|---|
| Variadic | #include <boost/mpl/set.hpp> |
| Numbered | #include <boost/mpl/set/setn.hpp> |
In the following table, s is an instance of set, pos is an iterator into s, and x, k, and t1,t2,... 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]
| Expression | Semantics |
|---|---|
set<t1,t2,... tn> setn<t1,t2,... tn> |
set of elements t1,t2,... tn; see Variadic Sequence. |
set<t1,t2,... tn>::type setn<t1,t2,... tn>::type |
Identical to setn<t1,t2,... tn>; 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. |
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 );