Synopsis

template<
      typename Seq
    , typename Pred
    , typename In = |unspecified|
    >
struct unique
{
    typedef |unspecified| type;
};

Description

Returns a sequence of the initial elements of every subrange of the original sequence Seq whose elements are all the same.

|transformation algorithm disclaimer|

Header

#include <boost/mpl/unique.hpp>

Model of

|Reversible Algorithm|

Parameters

Expression semantics

|Semantics disclaimer...| |Reversible Algorithm|.

For any |Forward Sequence| s, a binary |Lambda Expression| pred, and an |Inserter| in:

typedef unique<s,pred,in>::type r;

typedef copy<s,in>::type r;

typedef lambda<pred>::type p;
typedef lambda<in::operation>::type in_op;
typedef apply_wrap2<
      in_op
    , in::state
    , front<types>::type
    >::type in_state;
typedef fold<
      s
    , pair< in_state, front<s>::type >
    , eval_if<
          apply_wrap2<p, second<_1>, _2>
        , identity< first<_1> >
        , apply_wrap2<in_op, first<_1>, _2>
        >
    >::type::first r;

Complexity

Linear. Performs exactly size<s>::value - 1 applications of pred, and at most size<s>::value insertions.

Example

typedef vector<int,float,float,char,int,int,int,double> types;
typedef vector<int,float,char,int,double> expected;
typedef unique< types, is_same<_1,_2> >::type result;
BOOST_MPL_ASSERT(( equal< result,expected > ));

See also

|Transformation Algorithms|, |Reversible Algorithm|, |reverse_unique|, |remove|, |copy_if|, |replace_if|