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/*
Copyright (c) Alexander Zaitsev <zamazan4ik@gmail.com>, 2016
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)
See http://www.boost.org/ for latest version.
*/
/// \file is_palindrome.hpp
/// \brief Checks the input sequence on palindrome.
/// \author Alexander Zaitsev
#ifndef BOOST_ALGORITHM_IS_PALINDROME_HPP
#define BOOST_ALGORITHM_IS_PALINDROME_HPP
#include <iterator>
#include <functional>
#include <cstring>
#include <boost/range/begin.hpp>
#include <boost/range/end.hpp>
namespace boost { namespace algorithm {
/// \fn is_palindrome ( BidirectionalIterator begin, BidirectionalIterator end, Predicate p )
/// \return true if the entire sequence is palindrome
///
/// \param begin The start of the input sequence
/// \param end One past the end of the input sequence
/// \param p A predicate used to compare the values.
///
/// \note This function will return true for empty sequences and for palindromes.
/// For other sequences function will return false.
/// Complexity: O(N).
template <typename BidirectionalIterator, typename Predicate>
bool is_palindrome(BidirectionalIterator begin, BidirectionalIterator end, Predicate p )
{
if(begin == end)
{
return true;
}
--end;
while(begin != end)
{
if(!p(*begin, *end))
{
return false;
}
++begin;
if(begin == end)
{
break;
}
--end;
}
return true;
}
/// \fn is_palindrome ( BidirectionalIterator begin, BidirectionalIterator end )
/// \return true if the entire sequence is palindrome
///
/// \param begin The start of the input sequence
/// \param end One past the end of the input sequence
///
/// \note This function will return true for empty sequences and for palindromes.
/// For other sequences function will return false.
/// Complexity: O(N).
template <typename BidirectionalIterator>
bool is_palindrome(BidirectionalIterator begin, BidirectionalIterator end)
{
if(begin == end)
{
return true;
}
--end;
while(begin != end)
{
if(!(*begin == *end))
{
return false;
}
++begin;
if(begin == end)
{
break;
}
--end;
}
return true;
}
/// \fn is_palindrome ( const R& range )
/// \return true if the entire sequence is palindrome
///
/// \param range The range to be tested.
///
/// \note This function will return true for empty sequences and for palindromes.
/// For other sequences function will return false.
/// Complexity: O(N).
template <typename R>
bool is_palindrome(const R& range)
{
return is_palindrome(boost::begin(range), boost::end(range));
}
/// \fn is_palindrome ( const R& range, Predicate p )
/// \return true if the entire sequence is palindrome
///
/// \param range The range to be tested.
/// \param p A predicate used to compare the values.
///
/// \note This function will return true for empty sequences and for palindromes.
/// For other sequences function will return false.
/// Complexity: O(N).
template <typename R, typename Predicate>
bool is_palindrome(const R& range, Predicate p)
{
return is_palindrome(boost::begin(range), boost::end(range), p);
}
/// \fn is_palindrome ( const char* str )
/// \return true if the entire sequence is palindrome
///
/// \param str C-string to be tested.
///
/// \note This function will return true for empty sequences and for palindromes.
/// For other sequences function will return false.
/// Complexity: O(N).
bool is_palindrome(const char* str)
{
if(!str)
return true;
return is_palindrome(str, str + strlen(str));
}
/// \fn is_palindrome ( const char* str, Predicate p )
/// \return true if the entire sequence is palindrome
///
/// \param str C-string to be tested.
/// \param p A predicate used to compare the values.
///
/// \note This function will return true for empty sequences and for palindromes.
/// For other sequences function will return false.
/// Complexity: O(N).
template<typename Predicate>
bool is_palindrome(const char* str, Predicate p)
{
if(!str)
return true;
return is_palindrome(str, str + strlen(str), p);
}
}}
#endif // BOOST_ALGORITHM_IS_PALINDROME_HPP
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