Boost C++ Libraries

boost/move/algo/adaptive_merge.hpp

//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2015-2016.
// 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/libs/move for documentation.
//
//////////////////////////////////////////////////////////////////////////////

#ifndef BOOST_MOVE_ADAPTIVE_MERGE_HPP
#define BOOST_MOVE_ADAPTIVE_MERGE_HPP

#include <boost/move/detail/config_begin.hpp>
#include <boost/move/algo/detail/adaptive_sort_merge.hpp>

namespace boost {
namespace movelib {

//! <b>Effects</b>: Merges two consecutive sorted ranges [first, middle) and [middle, last)
//!   into one sorted range [first, last) according to the given comparison function comp.
//!   The algorithm is stable (if there are equivalent elements in the original two ranges,
//!   the elements from the first range (preserving their original order) precede the elements
//!   from the second range (preserving their original order).
//!
//! <b>Requires</b>:
//!   - RandIt must meet the requirements of ValueSwappable and RandomAccessIterator.
//!   - The type of dereferenced RandIt must meet the requirements of MoveAssignable and MoveConstructible.
//!
//! <b>Parameters</b>:
//!   - first: the beginning of the first sorted range. 
//!   - middle: the end of the first sorted range and the beginning of the second
//!   - last: the end of the second sorted range
//!   - comp: comparison function object which returns true if the first argument is is ordered before the second.
//!   - uninitialized, uninitialized_len: raw storage starting on "uninitialized", able to hold "uninitialized_len"
//!      elements of type iterator_traits<RandIt>::value_type. Maximum performance is achieved when uninitialized_len
//!      is min(std::distance(first, middle), std::distance(middle, last)).
//!
//! <b>Throws</b>: If comp throws or the move constructor, move assignment or swap of the type
//!   of dereferenced RandIt throws.
//!
//! <b>Complexity</b>: Always K x O(N) comparisons and move assignments/constructors/swaps.
//!   Constant factor for comparisons and data movement is minimized when uninitialized_len
//!   is min(std::distance(first, middle), std::distance(middle, last)).
//!   Pretty good enough performance is achieved when uninitialized_len is
//!   ceil(sqrt(std::distance(first, last)))*2.
//!
//! <b>Caution</b>: Experimental implementation, not production-ready.
template<class RandIt, class Compare>
void adaptive_merge( RandIt first, RandIt middle, RandIt last, Compare comp
                , typename iterator_traits<RandIt>::value_type* uninitialized = 0
                , std::size_t uninitialized_len = 0)
{
   typedef typename iterator_traits<RandIt>::size_type  size_type;
   typedef typename iterator_traits<RandIt>::value_type value_type;

   ::boost::movelib::detail_adaptive::adaptive_xbuf<value_type> xbuf(uninitialized, uninitialized_len);
   ::boost::movelib::detail_adaptive::adaptive_merge_impl(first, size_type(middle - first), size_type(last - middle), comp, xbuf);
}

}  //namespace movelib {
}  //namespace boost {

#include <boost/move/detail/config_end.hpp>

#endif   //#define BOOST_MOVE_ADAPTIVE_MERGE_HPP