Chris@16: /* 
Chris@16:    Copyright (c) Marshall Clow 2011-2012.
Chris@16: 
Chris@16:    Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16:    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: */
Chris@16: 
Chris@16: /// \file  partition_point.hpp
Chris@16: /// \brief Find the partition point in a sequence
Chris@16: /// \author Marshall Clow
Chris@16: 
Chris@16: #ifndef BOOST_ALGORITHM_PARTITION_POINT_HPP
Chris@16: #define BOOST_ALGORITHM_PARTITION_POINT_HPP
Chris@16: 
Chris@16: #include <algorithm>    // for std::partition_point, if available
Chris@16: 
Chris@16: #include <boost/range/begin.hpp>
Chris@16: #include <boost/range/end.hpp>
Chris@16: 
Chris@16: namespace boost { namespace algorithm {
Chris@16: 
Chris@16: /// \fn partition_point ( ForwardIterator first, ForwardIterator last, Predicate p )
Chris@16: /// \brief Given a partitioned range, returns the partition point, i.e, the first element 
Chris@16: ///     that does not satisfy p
Chris@16: /// 
Chris@16: /// \param first    The start of the input sequence
Chris@16: /// \param last     One past the end of the input sequence
Chris@16: /// \param p        The predicate to test the values with
Chris@16: /// \note           This function is part of the C++2011 standard library.
Chris@16: ///  We will use the standard one if it is available, 
Chris@16: ///  otherwise we have our own implementation.
Chris@16: template <typename ForwardIterator, typename Predicate>
Chris@16: ForwardIterator partition_point ( ForwardIterator first, ForwardIterator last, Predicate p )
Chris@16: {
Chris@16:     std::size_t dist = std::distance ( first, last );
Chris@16:     while ( first != last ) {
Chris@16:         std::size_t d2 = dist / 2;
Chris@16:         ForwardIterator ret_val = first;
Chris@16:         std::advance (ret_val, d2);
Chris@16:         if (p (*ret_val)) {
Chris@16:             first = ++ret_val;
Chris@16:             dist -= d2 + 1;
Chris@16:             }
Chris@16:         else {
Chris@16:             last = ret_val;
Chris@16:             dist = d2;
Chris@16:             }
Chris@16:         }
Chris@16:     return first;
Chris@16: }
Chris@16: 
Chris@16: /// \fn partition_point ( Range &r, Predicate p )
Chris@16: /// \brief Given a partitioned range, returns the partition point
Chris@16: /// 
Chris@16: /// \param r        The input range
Chris@16: /// \param p        The predicate to test the values with
Chris@16: ///
Chris@16: template <typename Range, typename Predicate>
Chris@101: typename boost::range_iterator<Range>::type partition_point ( Range &r, Predicate p )
Chris@16: {
Chris@16:     return boost::algorithm::partition_point (boost::begin(r), boost::end(r), p);
Chris@16: }
Chris@16: 
Chris@16: 
Chris@16: }}
Chris@16: 
Chris@16: #endif  // BOOST_ALGORITHM_PARTITION_POINT_HPP