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+/*
+ 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)
+*/
+
+/// \file one_of.hpp
+/// \brief Test ranges to see if only one element matches a value or predicate.
+/// \author Marshall Clow
+
+#ifndef BOOST_ALGORITHM_ONE_OF_HPP
+#define BOOST_ALGORITHM_ONE_OF_HPP
+
+#include <algorithm> // for std::find and std::find_if
+#include <boost/algorithm/cxx11/none_of.hpp>
+
+#include <boost/range/begin.hpp>
+#include <boost/range/end.hpp>
+
+namespace boost { namespace algorithm {
+
+/// \fn one_of ( InputIterator first, InputIterator last, Predicate p )
+/// \return true if the predicate 'p' is true for exactly one item in [first, last).
+///
+/// \param first The start of the input sequence
+/// \param last One past the end of the input sequence
+/// \param p A predicate for testing the elements of the sequence
+///
+template<typename InputIterator, typename Predicate>
+bool one_of ( InputIterator first, InputIterator last, Predicate p )
+{
+ InputIterator i = std::find_if (first, last, p);
+ if (i == last)
+ return false; // Didn't occur at all
+ return boost::algorithm::none_of (++i, last, p);
+}
+
+/// \fn one_of ( const Range &r, Predicate p )
+/// \return true if the predicate 'p' is true for exactly one item in the range.
+///
+/// \param r The input range
+/// \param p A predicate for testing the elements of the range
+///
+template<typename Range, typename Predicate>
+bool one_of ( const Range &r, Predicate p )
+{
+ return boost::algorithm::one_of ( boost::begin (r), boost::end (r), p );
+}
+
+
+/// \fn one_of_equal ( InputIterator first, InputIterator last, const V &val )
+/// \return true if the value 'val' exists only once in [first, last).
+///
+/// \param first The start of the input sequence
+/// \param last One past the end of the input sequence
+/// \param val A value to compare against
+///
+template<typename InputIterator, typename V>
+bool one_of_equal ( InputIterator first, InputIterator last, const V &val )
+{
+ InputIterator i = std::find (first, last, val); // find first occurrence of 'val'
+ if (i == last)
+ return false; // Didn't occur at all
+ return boost::algorithm::none_of_equal (++i, last, val);
+}
+
+/// \fn one_of_equal ( const Range &r, const V &val )
+/// \return true if the value 'val' exists only once in the range.
+///
+/// \param r The input range
+/// \param val A value to compare against
+///
+template<typename Range, typename V>
+bool one_of_equal ( const Range &r, const V &val )
+{
+ return boost::algorithm::one_of_equal ( boost::begin (r), boost::end (r), val );
+}
+
+}} // namespace boost and algorithm
+
+#endif // BOOST_ALGORITHM_ALL_HPP