equal.hpp

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// clang-format off
/*
   Copyright (c) Marshall Clow 2008-2012.
 
   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)
*/
 
 
#pragma once
 
#include <algorithm>    // for std::equal
#include <iterator>
 
namespace boost { namespace algorithm {
 
namespace detail {
 
    template <class T1, class T2>
    struct eq {
        bool operator () ( const T1& v1, const T2& v2 ) const { return v1 == v2 ;}
        };
 
    template <class RandomAccessIterator1, class RandomAccessIterator2, class BinaryPredicate>
    bool equal ( RandomAccessIterator1 first1, RandomAccessIterator1 last1,
                 RandomAccessIterator2 first2, RandomAccessIterator2 last2, BinaryPredicate pred,
                 std::random_access_iterator_tag /*unused*/, std::random_access_iterator_tag  /*unused*/)
    {
    //  Random-access iterators let is check the sizes in constant time
        if ( std::distance ( first1, last1 ) != std::distance ( first2, last2 ))
            return false;
    // If we know that the sequences are the same size, the original version is fine
        return std::equal ( first1, last1, first2, pred );
    }
 
    template <class InputIterator1, class InputIterator2, class BinaryPredicate>
    bool equal ( InputIterator1 first1, InputIterator1 last1,
                 InputIterator2 first2, InputIterator2 last2, BinaryPredicate pred,
                 std::input_iterator_tag /*unused*/, std::input_iterator_tag  /*unused*/)
    {
    for (; first1 != last1 && first2 != last2; ++first1, ++first2 )
        if ( !pred(*first1, *first2 ))
            return false;
 
    return first1 == last1 && first2 == last2;
    }
}
 
template <class InputIterator1, class InputIterator2, class BinaryPredicate>
bool equal ( InputIterator1 first1, InputIterator1 last1,
             InputIterator2 first2, InputIterator2 last2, BinaryPredicate pred )
{
    return boost::algorithm::detail::equal (
        first1, last1, first2, last2, pred,
        typename std::iterator_traits<InputIterator1>::iterator_category (),
        typename std::iterator_traits<InputIterator2>::iterator_category ());
}
 
template <class InputIterator1, class InputIterator2>
bool equal ( InputIterator1 first1, InputIterator1 last1,
             InputIterator2 first2, InputIterator2 last2 )
{
    return boost::algorithm::detail::equal (
        first1, last1, first2, last2,
        boost::algorithm::detail::eq<
            typename std::iterator_traits<InputIterator1>::value_type,
            typename std::iterator_traits<InputIterator2>::value_type> (),
        typename std::iterator_traits<InputIterator1>::iterator_category (),
        typename std::iterator_traits<InputIterator2>::iterator_category ());
}
 
//  There are already range-based versions of these.
 
}} // namespace boost and algorithm
// clang-format on