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/*
Copyright (c) Marshall Clow 2011-2012.
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
/// \author Marshall Clow
#ifndef BOOST_ALGORITHM_IS_PERMUTATION_HPP
#define BOOST_ALGORITHM_IS_PERMUTATION_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/range/begin.hpp>
#include <boost/range/end.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/tr1/tr1/tuple> // for tie
namespace boost { namespace algorithm {
#if __cplusplus >= 201103L
// Use the C++11 versions of is_permutation if it is available
using std::is_permutation; // Section 25.2.12
#else
/// \cond DOXYGEN_HIDE
namespace detail {
template <typename Predicate, typename Iterator>
struct value_predicate {
value_predicate ( Predicate p, Iterator it ) : p_ ( p ), it_ ( it ) {}
template <typename T1>
bool operator () ( const T1 &t1 ) const { return p_ ( *it_, t1 ); }
private:
Predicate &p_;
Iterator it_;
};
}
/// \endcond
/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 first2, BinaryPredicate p )
/// \brief Tests to see if a the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param first The start of the input sequence
/// \param last One past the end of the input sequence
/// \param first2 The start of the second sequence
/// \param p The predicate to compare elements with
///
/// \note This function is part of the C++2011 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, BinaryPredicate p )
{
// Skip the common prefix (if any)
// std::tie (first1, first2) = std::mismatch (first1, last1, first2, p);
std::pair<ForwardIterator1, ForwardIterator2> eq = std::mismatch (first1, last1, first2, p);
first1 = eq.first;
first2 = eq.second;
if ( first1 != last1 ) {
// Create last2
ForwardIterator2 last2 = first2;
std::advance ( last2, std::distance (first1, last1));
// for each unique value in the sequence [first1,last1), count how many times
// it occurs, and make sure it occurs the same number of times in [first2, last2)
for ( ForwardIterator1 iter = first1; iter != last1; ++iter ) {
detail::value_predicate<BinaryPredicate, ForwardIterator1> pred ( p, iter );
/* For each value we haven't seen yet... */
if ( std::find_if ( first1, iter, pred ) == iter ) {
std::size_t dest_count = std::count_if ( first2, last2, pred );
if ( dest_count == 0 || dest_count != (std::size_t) std::count_if ( iter, last1, pred ))
return false;
}
}
}
return true;
}
/// \fn is_permutation ( ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 first2 )
/// \brief Tests to see if a the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param first The start of the input sequence
/// \param last One past the end of the input sequence
/// \param first2 The start of the second sequence
/// \note This function is part of the C++2011 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 first, ForwardIterator1 last, ForwardIterator2 first2 )
{
// How should I deal with the idea that ForwardIterator1::value_type
// and ForwardIterator2::value_type could be different? Define my own comparison predicate?
return boost::algorithm::is_permutation ( first, last, first2,
std::equal_to<typename std::iterator_traits<ForwardIterator1>::value_type> ());
}
#endif
/// \fn is_permutation ( const Range &r, ForwardIterator first2 )
/// \brief Tests to see if a the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param r The input range
/// \param first2 The start of the second sequence
template <typename Range, typename ForwardIterator>
bool is_permutation ( const Range &r, ForwardIterator first2 )
{
return boost::algorithm::is_permutation (boost::begin (r), boost::end (r), first2 );
}
/// \fn is_permutation ( const Range &r, ForwardIterator first2, BinaryPredicate pred )
/// \brief Tests to see if a the sequence [first,last) is a permutation of the sequence starting at first2
///
/// \param r The input range
/// \param first2 The start of the second sequence
/// \param pred The predicate to compare elements with
///
// Disable this template when the first two parameters are the same type
// That way the non-range version will be chosen.
template <typename Range, typename ForwardIterator, typename BinaryPredicate>
typename boost::disable_if_c<boost::is_same<Range, ForwardIterator>::value, bool>::type
is_permutation ( const Range &r, ForwardIterator first2, BinaryPredicate pred )
{
return boost::algorithm::is_permutation (boost::begin (r), boost::end (r), first2, pred );
}
}}
#endif // BOOST_ALGORITHM_IS_PERMUTATION_HPP
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