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+/*
+ Copyright (c) Marshall Clow 2014.
+
+ 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)
+*/
+
+/// \file is_permutation.hpp
+/// \brief Is a sequence a permutation of another sequence (four iterator versions)
+/// \author Marshall Clow
+
+#ifndef BOOST_ALGORITHM_IS_PERMUTATION14_HPP
+#define BOOST_ALGORITHM_IS_PERMUTATION14_HPP
+
+#include <algorithm> // for std::less, tie, mismatch and is_permutation (if available)
+#include <utility> // for std::make_pair
+#include <functional> // for std::equal_to
+#include <iterator>
+
+#include <boost/algorithm/cxx11/is_permutation.hpp>
+#include <boost/algorithm/cxx14/mismatch.hpp>
+
+namespace boost { namespace algorithm {
+
+#if __cplusplus <= 201103L
+/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last,
+/// ForwardIterator2 first2, ForwardIterator2 last2 )
+/// \brief Tests to see if the sequence [first,last) is a permutation of the sequence starting at first2
+///
+/// \param first1 The start of the input sequence
+/// \param last2 One past the end of the input sequence
+/// \param first2 The start of the second sequence
+/// \param last1 One past the end of the second sequence
+/// \note This function is part of the C++2014 standard library.
+/// We will use the standard one if it is available,
+/// otherwise we have our own implementation.
+template< class ForwardIterator1, class ForwardIterator2 >
+bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1,
+ ForwardIterator2 first2, ForwardIterator2 last2 )
+{
+// How should I deal with the idea that ForwardIterator1::value_type
+// and ForwardIterator2::value_type could be different? Define my own comparison predicate?
+ std::pair<ForwardIterator1, ForwardIterator2> eq = boost::algorithm::mismatch
+ ( first1, last1, first2, last2 );
+ if ( eq.first == last1 && eq.second == last2)
+ return true;
+ return boost::algorithm::detail::is_permutation_tag (
+ eq.first, last1, eq.second, last2,
+ std::equal_to<typename std::iterator_traits<ForwardIterator1>::value_type> (),
+ typename std::iterator_traits<ForwardIterator1>::iterator_category (),
+ typename std::iterator_traits<ForwardIterator2>::iterator_category ());
+}
+
+/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last,
+/// ForwardIterator2 first2, ForwardIterator2 last2,
+/// BinaryPredicate p )
+/// \brief Tests to see if the sequence [first,last) is a permutation of the sequence starting at first2
+///
+/// \param first1 The start of the input sequence
+/// \param last1 One past the end of the input sequence
+/// \param first2 The start of the second sequence
+/// \param last2 One past the end of the second sequence
+/// \param pred The predicate to compare elements with
+///
+/// \note This function is part of the C++2014 standard library.
+/// We will use the standard one if it is available,
+/// otherwise we have our own implementation.
+template< class ForwardIterator1, class ForwardIterator2, class BinaryPredicate >
+bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1,
+ ForwardIterator2 first2, ForwardIterator2 last2,
+ BinaryPredicate pred )
+{
+ std::pair<ForwardIterator1, ForwardIterator2> eq = boost::algorithm::mismatch
+ ( first1, last1, first2, last2, pred );
+ if ( eq.first == last1 && eq.second == last2)
+ return true;
+ return boost::algorithm::detail::is_permutation_tag (
+ first1, last1, first2, last2, pred,
+ typename std::iterator_traits<ForwardIterator1>::iterator_category (),
+ typename std::iterator_traits<ForwardIterator2>::iterator_category ());
+}
+#endif
+
+}}
+
+#endif // BOOST_ALGORITHM_IS_PERMUTATION14_HPP