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boost_mpl/include/boost/mpl/unique.hpp
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2002-09-15 22:13:24 +00:00

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//-----------------------------------------------------------------------------
// boost mpl/unique.hpp header file
// See http://www.boost.org for updates, documentation, and revision history.
//-----------------------------------------------------------------------------
//
// Copyright (c) 2000-02
// Aleksey Gurtovoy and John R. Bandela
//
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appears in all copies and
// that both the copyright notice and this permission notice appear in
// supporting documentation. No representations are made about the
// suitability of this software for any purpose. It is provided "as is"
// without express or implied warranty.
#ifndef BOOST_MPL_UNIQUE_HPP_INCLUDED
#define BOOST_MPL_UNIQUE_HPP_INCLUDED
#include "boost/mpl/fold_backward.hpp"
#include "boost/mpl/push_front.hpp"
#include "boost/mpl/clear.hpp"
#include "boost/mpl/front.hpp"
#include "boost/mpl/identity.hpp"
#include "boost/mpl/pair.hpp"
#include "boost/mpl/select1st.hpp"
#include "boost/mpl/lambda.hpp"
#include "boost/mpl/apply_if.hpp"
#include "boost/mpl/apply.hpp"
#include "boost/mpl/void.hpp"
#include "boost/mpl/aux_/void_spec.hpp"
#include "boost/mpl/aux_/lambda_spec.hpp"
#include "boost/type_traits/is_same.hpp"
namespace boost {
namespace mpl {
namespace aux {
template< typename Predicate >
struct unique_op
{
template< typename Pair, typename T > struct apply
{
typedef typename Pair::first seq_;
typedef typename Pair::second prior_;
typedef typename apply_if<
typename apply2<Predicate,prior_,T>::type
, identity<seq_>
, push_front<seq_,T>
>::type new_seq_;
typedef pair<new_seq_,T> type;
};
};
} // namespace aux
BOOST_MPL_AUX_PASS_THROUGH_LAMBDA_SPEC(1,aux::unique_op)
template<
typename BOOST_MPL_AUX_VOID_SPEC_PARAM(Sequence)
, typename Predicate = is_same<_,_>
>
struct unique
{
private:
struct none_;
typedef typename lambda<Predicate>::type pred_;
typedef typename clear<Sequence>::type result_;
typedef typename fold_backward<
Sequence
, pair<result_,none_>
, aux::unique_op<pred_>
>::type fold_result_;
public:
// MSVC6.5 forces us to use 'select1st<fold_result_>::type' instead of
// simple 'fold_result_::first' here
typedef typename select1st<fold_result_>::type type;
};
BOOST_MPL_AUX_VOID_SPEC(1, unique)
} // namespace mpl
} // namespace boost
#endif // BOOST_MPL_UNIQUE_HPP_INCLUDED