//////////////////////////////////////////////////////////////////////////////
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//
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// (C) Copyright Ion Gaztanaga 2015-2016.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/move for documentation.
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//
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//////////////////////////////////////////////////////////////////////////////
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#ifndef BOOST_MOVE_ADAPTIVE_SORT_HPP
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#define BOOST_MOVE_ADAPTIVE_SORT_HPP
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#include <boost/move/detail/config_begin.hpp>
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#include <boost/move/algo/detail/adaptive_sort_merge.hpp>
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#include <boost/core/ignore_unused.hpp>
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namespace boost {
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namespace movelib {
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///@cond
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namespace detail_adaptive {
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template<class RandIt>
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void move_data_backward( RandIt cur_pos
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, typename iterator_traits<RandIt>::size_type const l_data
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, RandIt new_pos
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, bool const xbuf_used)
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{
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//Move buffer to the total combination right
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if(xbuf_used){
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boost::move_backward(cur_pos, cur_pos+l_data, new_pos+l_data);
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}
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else{
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boost::adl_move_swap_ranges_backward(cur_pos, cur_pos+l_data, new_pos+l_data);
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//Rotate does less moves but it seems slower due to cache issues
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//rotate_gcd(first-l_block, first+len-l_block, first+len);
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}
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}
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template<class RandIt>
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void move_data_forward( RandIt cur_pos
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, typename iterator_traits<RandIt>::size_type const l_data
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, RandIt new_pos
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, bool const xbuf_used)
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{
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//Move buffer to the total combination right
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if(xbuf_used){
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boost::move(cur_pos, cur_pos+l_data, new_pos);
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}
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else{
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boost::adl_move_swap_ranges(cur_pos, cur_pos+l_data, new_pos);
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//Rotate does less moves but it seems slower due to cache issues
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//rotate_gcd(first-l_block, first+len-l_block, first+len);
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}
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}
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// build blocks of length 2*l_build_buf. l_build_buf is power of two
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// input: [0, l_build_buf) elements are buffer, rest unsorted elements
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// output: [0, l_build_buf) elements are buffer, blocks 2*l_build_buf and last subblock sorted
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//
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// First elements are merged from right to left until elements start
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// at first. All old elements [first, first + l_build_buf) are placed at the end
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// [first+len-l_build_buf, first+len). To achieve this:
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// - If we have external memory to merge, we save elements from the buffer
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// so that a non-swapping merge is used. Buffer elements are restored
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// at the end of the buffer from the external memory.
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//
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// - When the external memory is not available or it is insufficient
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// for a merge operation, left swap merging is used.
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//
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// Once elements are merged left to right in blocks of l_build_buf, then a single left
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// to right merge step is performed to achieve merged blocks of size 2K.
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// If external memory is available, usual merge is used, swap merging otherwise.
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//
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// As a last step, if auxiliary memory is available in-place merge is performed.
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// until all is merged or auxiliary memory is not large enough.
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template<class RandIt, class Compare, class XBuf>
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typename iterator_traits<RandIt>::size_type
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adaptive_sort_build_blocks
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( RandIt const first
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, typename iterator_traits<RandIt>::size_type const len
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, typename iterator_traits<RandIt>::size_type const l_base
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, typename iterator_traits<RandIt>::size_type const l_build_buf
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, XBuf & xbuf
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, Compare comp)
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{
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typedef typename iterator_traits<RandIt>::size_type size_type;
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BOOST_ASSERT(l_build_buf <= len);
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BOOST_ASSERT(0 == ((l_build_buf / l_base)&(l_build_buf/l_base-1)));
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//Place the start pointer after the buffer
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RandIt first_block = first + l_build_buf;
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size_type const elements_in_blocks = len - l_build_buf;
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//////////////////////////////////
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// Start of merge to left step
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//////////////////////////////////
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size_type l_merged = 0u;
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BOOST_ASSERT(l_build_buf);
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//If there is no enough buffer for the insertion sort step, just avoid the external buffer
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size_type kbuf = min_value<size_type>(l_build_buf, size_type(xbuf.capacity()));
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kbuf = kbuf < l_base ? 0 : kbuf;
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if(kbuf){
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//Backup internal buffer values in external buffer so they can be overwritten
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xbuf.move_assign(first+l_build_buf-kbuf, kbuf);
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l_merged = op_insertion_sort_step_left(first_block, elements_in_blocks, l_base, comp, move_op());
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//Now combine them using the buffer. Elements from buffer can be
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//overwritten since they've been saved to xbuf
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l_merged = op_merge_left_step_multiple
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( first_block - l_merged, elements_in_blocks, l_merged, l_build_buf, kbuf - l_merged, comp, move_op());
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//Restore internal buffer from external buffer unless kbuf was l_build_buf,
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//in that case restoration will happen later
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if(kbuf != l_build_buf){
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boost::move(xbuf.data()+kbuf-l_merged, xbuf.data() + kbuf, first_block-l_merged+elements_in_blocks);
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}
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}
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else{
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l_merged = insertion_sort_step(first_block, elements_in_blocks, l_base, comp);
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rotate_gcd(first_block - l_merged, first_block, first_block+elements_in_blocks);
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}
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//Now combine elements using the buffer. Elements from buffer can't be
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//overwritten since xbuf was not big enough, so merge swapping elements.
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l_merged = op_merge_left_step_multiple
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(first_block - l_merged, elements_in_blocks, l_merged, l_build_buf, l_build_buf - l_merged, comp, swap_op());
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BOOST_ASSERT(l_merged == l_build_buf);
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//////////////////////////////////
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// Start of merge to right step
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//////////////////////////////////
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//If kbuf is l_build_buf then we can merge right without swapping
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//Saved data is still in xbuf
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if(kbuf && kbuf == l_build_buf){
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op_merge_right_step_once(first, elements_in_blocks, l_build_buf, comp, move_op());
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//Restore internal buffer from external buffer if kbuf was l_build_buf.
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//as this operation was previously delayed.
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boost::move(xbuf.data(), xbuf.data() + kbuf, first);
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}
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else{
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op_merge_right_step_once(first, elements_in_blocks, l_build_buf, comp, swap_op());
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}
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xbuf.clear();
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//2*l_build_buf or total already merged
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return min_value<size_type>(elements_in_blocks, 2*l_build_buf);
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}
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template<class RandItKeys, class KeyCompare, class RandIt, class Compare, class XBuf>
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void adaptive_sort_combine_blocks
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( RandItKeys const keys
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, KeyCompare key_comp
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, RandIt const first
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, typename iterator_traits<RandIt>::size_type const len
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, typename iterator_traits<RandIt>::size_type const l_prev_merged
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, typename iterator_traits<RandIt>::size_type const l_block
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, bool const use_buf
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, bool const xbuf_used
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, XBuf & xbuf
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, Compare comp
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, bool merge_left)
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{
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boost::ignore_unused(xbuf);
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typedef typename iterator_traits<RandIt>::size_type size_type;
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size_type const l_reg_combined = 2*l_prev_merged;
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size_type l_irreg_combined = 0;
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size_type const l_total_combined = calculate_total_combined(len, l_prev_merged, &l_irreg_combined);
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size_type const n_reg_combined = len/l_reg_combined;
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RandIt combined_first = first;
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boost::ignore_unused(l_total_combined);
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BOOST_ASSERT(l_total_combined <= len);
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size_type const max_i = n_reg_combined + (l_irreg_combined != 0);
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if(merge_left || !use_buf) {
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for( size_type combined_i = 0; combined_i != max_i; ) {
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//Now merge blocks
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bool const is_last = combined_i==n_reg_combined;
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size_type const l_cur_combined = is_last ? l_irreg_combined : l_reg_combined;
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range_xbuf<RandIt, size_type, move_op> rbuf( (use_buf && xbuf_used) ? (combined_first-l_block) : combined_first, combined_first);
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size_type n_block_a, n_block_b, l_irreg1, l_irreg2;
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combine_params( keys, key_comp, l_cur_combined
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, l_prev_merged, l_block, rbuf
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, n_block_a, n_block_b, l_irreg1, l_irreg2); //Outputs
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BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A combpar: ", len + l_block);
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BOOST_MOVE_ADAPTIVE_SORT_INVARIANT(boost::movelib::is_sorted(combined_first, combined_first + n_block_a*l_block+l_irreg1, comp));
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BOOST_MOVE_ADAPTIVE_SORT_INVARIANT(boost::movelib::is_sorted(combined_first + n_block_a*l_block+l_irreg1, combined_first + n_block_a*l_block+l_irreg1+n_block_b*l_block+l_irreg2, comp));
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if(!use_buf){
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merge_blocks_bufferless
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(keys, key_comp, combined_first, l_block, 0u, n_block_a, n_block_b, l_irreg2, comp);
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}
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else{
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merge_blocks_left
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(keys, key_comp, combined_first, l_block, 0u, n_block_a, n_block_b, l_irreg2, comp, xbuf_used);
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}
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BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" After merge_blocks_L: ", len + l_block);
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++combined_i;
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if(combined_i != max_i)
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combined_first += l_reg_combined;
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}
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}
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else{
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combined_first += l_reg_combined*(max_i-1);
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for( size_type combined_i = max_i; combined_i; ) {
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--combined_i;
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bool const is_last = combined_i==n_reg_combined;
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size_type const l_cur_combined = is_last ? l_irreg_combined : l_reg_combined;
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RandIt const combined_last(combined_first+l_cur_combined);
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range_xbuf<RandIt, size_type, move_op> rbuf(combined_last, xbuf_used ? (combined_last+l_block) : combined_last);
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size_type n_block_a, n_block_b, l_irreg1, l_irreg2;
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combine_params( keys, key_comp, l_cur_combined
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, l_prev_merged, l_block, rbuf
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, n_block_a, n_block_b, l_irreg1, l_irreg2); //Outputs
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BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A combpar: ", len + l_block);
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BOOST_MOVE_ADAPTIVE_SORT_INVARIANT(boost::movelib::is_sorted(combined_first, combined_first + n_block_a*l_block+l_irreg1, comp));
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BOOST_MOVE_ADAPTIVE_SORT_INVARIANT(boost::movelib::is_sorted(combined_first + n_block_a*l_block+l_irreg1, combined_first + n_block_a*l_block+l_irreg1+n_block_b*l_block+l_irreg2, comp));
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merge_blocks_right
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(keys, key_comp, combined_first, l_block, n_block_a, n_block_b, l_irreg2, comp, xbuf_used);
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BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" After merge_blocks_R: ", len + l_block);
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if(combined_i)
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combined_first -= l_reg_combined;
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}
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}
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}
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//Returns true if buffer is placed in
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//[buffer+len-l_intbuf, buffer+len). Otherwise, buffer is
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//[buffer,buffer+l_intbuf)
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template<class RandIt, class Compare, class XBuf>
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bool adaptive_sort_combine_all_blocks
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( RandIt keys
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, typename iterator_traits<RandIt>::size_type &n_keys
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, RandIt const buffer
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, typename iterator_traits<RandIt>::size_type const l_buf_plus_data
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, typename iterator_traits<RandIt>::size_type l_merged
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, typename iterator_traits<RandIt>::size_type &l_intbuf
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, XBuf & xbuf
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, Compare comp)
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{
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typedef typename iterator_traits<RandIt>::size_type size_type;
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RandIt const first = buffer + l_intbuf;
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size_type const l_data = l_buf_plus_data - l_intbuf;
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size_type const l_unique = l_intbuf+n_keys;
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//Backup data to external buffer once if possible
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bool const common_xbuf = l_data > l_merged && l_intbuf && l_intbuf <= xbuf.capacity();
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if(common_xbuf){
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xbuf.move_assign(buffer, l_intbuf);
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}
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bool prev_merge_left = true;
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size_type l_prev_total_combined = l_merged, l_prev_block = 0;
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bool prev_use_internal_buf = true;
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for( size_type n = 0; l_data > l_merged
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; l_merged*=2
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, ++n){
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//If l_intbuf is non-zero, use that internal buffer.
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// Implies l_block == l_intbuf && use_internal_buf == true
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//If l_intbuf is zero, see if half keys can be reused as a reduced emergency buffer,
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// Implies l_block == n_keys/2 && use_internal_buf == true
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//Otherwise, just give up and and use all keys to merge using rotations (use_internal_buf = false)
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bool use_internal_buf = false;
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size_type const l_block = lblock_for_combine(l_intbuf, n_keys, size_type(2*l_merged), use_internal_buf);
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BOOST_ASSERT(!l_intbuf || (l_block == l_intbuf));
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BOOST_ASSERT(n == 0 || (!use_internal_buf || prev_use_internal_buf) );
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BOOST_ASSERT(n == 0 || (!use_internal_buf || l_prev_block == l_block) );
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bool const is_merge_left = (n&1) == 0;
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size_type const l_total_combined = calculate_total_combined(l_data, l_merged);
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if(n && prev_use_internal_buf && prev_merge_left){
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if(is_merge_left || !use_internal_buf){
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move_data_backward(first-l_prev_block, l_prev_total_combined, first, common_xbuf);
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}
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else{
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//Put the buffer just after l_total_combined
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RandIt const buf_end = first+l_prev_total_combined;
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RandIt const buf_beg = buf_end-l_block;
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if(l_prev_total_combined > l_total_combined){
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size_type const l_diff = l_prev_total_combined - l_total_combined;
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move_data_backward(buf_beg-l_diff, l_diff, buf_end-l_diff, common_xbuf);
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}
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else if(l_prev_total_combined < l_total_combined){
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size_type const l_diff = l_total_combined - l_prev_total_combined;
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move_data_forward(buf_end, l_diff, buf_beg, common_xbuf);
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}
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}
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BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" After move_data : ", l_data + l_intbuf);
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}
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//Combine to form l_merged*2 segments
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if(n_keys){
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size_type upper_n_keys_this_iter = 2*l_merged/l_block;
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if(upper_n_keys_this_iter > 256){
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adaptive_sort_combine_blocks
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( keys, comp, !use_internal_buf || is_merge_left ? first : first-l_block
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, l_data, l_merged, l_block, use_internal_buf, common_xbuf, xbuf, comp, is_merge_left);
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}
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else{
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unsigned char uint_keys[256];
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adaptive_sort_combine_blocks
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( uint_keys, less(), !use_internal_buf || is_merge_left ? first : first-l_block
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, l_data, l_merged, l_block, use_internal_buf, common_xbuf, xbuf, comp, is_merge_left);
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}
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}
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else{
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size_type *const uint_keys = xbuf.template aligned_trailing<size_type>();
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adaptive_sort_combine_blocks
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( uint_keys, less(), !use_internal_buf || is_merge_left ? first : first-l_block
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, l_data, l_merged, l_block, use_internal_buf, common_xbuf, xbuf, comp, is_merge_left);
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}
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BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1(is_merge_left ? " After comb blocks L: " : " After comb blocks R: ", l_data + l_intbuf);
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prev_merge_left = is_merge_left;
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l_prev_total_combined = l_total_combined;
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l_prev_block = l_block;
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prev_use_internal_buf = use_internal_buf;
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}
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BOOST_ASSERT(l_prev_total_combined == l_data);
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bool const buffer_right = prev_use_internal_buf && prev_merge_left;
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l_intbuf = prev_use_internal_buf ? l_prev_block : 0u;
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n_keys = l_unique - l_intbuf;
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//Restore data from to external common buffer if used
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if(common_xbuf){
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if(buffer_right){
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boost::move(xbuf.data(), xbuf.data() + l_intbuf, buffer+l_data);
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}
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else{
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boost::move(xbuf.data(), xbuf.data() + l_intbuf, buffer);
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}
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}
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return buffer_right;
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}
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template<class RandIt, class Compare, class XBuf>
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void adaptive_sort_final_merge( bool buffer_right
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, RandIt const first
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, typename iterator_traits<RandIt>::size_type const l_intbuf
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, typename iterator_traits<RandIt>::size_type const n_keys
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, typename iterator_traits<RandIt>::size_type const len
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, XBuf & xbuf
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, Compare comp)
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{
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//BOOST_ASSERT(n_keys || xbuf.size() == l_intbuf);
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xbuf.clear();
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typedef typename iterator_traits<RandIt>::size_type size_type;
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size_type const n_key_plus_buf = l_intbuf+n_keys;
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if(buffer_right){
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//Use stable sort as some buffer elements might not be unique (see non_unique_buf)
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stable_sort(first+len-l_intbuf, first+len, comp, xbuf);
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stable_merge(first+n_keys, first+len-l_intbuf, first+len, antistable<Compare>(comp), xbuf);
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unstable_sort(first, first+n_keys, comp, xbuf);
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stable_merge(first, first+n_keys, first+len, comp, xbuf);
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}
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else{
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//Use stable sort as some buffer elements might not be unique (see non_unique_buf)
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stable_sort(first, first+n_key_plus_buf, comp, xbuf);
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if(xbuf.capacity() >= n_key_plus_buf){
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buffered_merge(first, first+n_key_plus_buf, first+len, comp, xbuf);
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}
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else if(xbuf.capacity() >= min_value<size_type>(l_intbuf, n_keys)){
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stable_merge(first+n_keys, first+n_key_plus_buf, first+len, comp, xbuf);
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stable_merge(first, first+n_keys, first+len, comp, xbuf);
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}
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else{
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stable_merge(first, first+n_key_plus_buf, first+len, comp, xbuf);
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}
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}
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BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1(" After final_merge : ", len);
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}
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template<class RandIt, class Compare, class Unsigned, class XBuf>
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bool adaptive_sort_build_params
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(RandIt first, Unsigned const len, Compare comp
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, Unsigned &n_keys, Unsigned &l_intbuf, Unsigned &l_base, Unsigned &l_build_buf
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, XBuf & xbuf
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)
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{
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typedef Unsigned size_type;
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//Calculate ideal parameters and try to collect needed unique keys
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l_base = 0u;
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//Try to find a value near sqrt(len) that is 2^N*l_base where
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//l_base <= AdaptiveSortInsertionSortThreshold. This property is important
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//as build_blocks merges to the left iteratively duplicating the
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//merged size and all the buffer must be used just before the final
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//merge to right step. This guarantees "build_blocks" produces
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//segments of size l_build_buf*2, maximizing the classic merge phase.
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l_intbuf = size_type(ceil_sqrt_multiple(len, &l_base));
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//The internal buffer can be expanded if there is enough external memory
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while(xbuf.capacity() >= l_intbuf*2){
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l_intbuf *= 2;
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}
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//This is the minimum number of keys to implement the ideal algorithm
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//
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//l_intbuf is used as buffer plus the key count
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size_type n_min_ideal_keys = l_intbuf-1;
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while(n_min_ideal_keys >= (len-l_intbuf-n_min_ideal_keys)/l_intbuf){
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--n_min_ideal_keys;
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}
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n_min_ideal_keys += 1;
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BOOST_ASSERT(n_min_ideal_keys <= l_intbuf);
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if(xbuf.template supports_aligned_trailing<size_type>(l_intbuf, (len-l_intbuf-1)/l_intbuf+1)){
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n_keys = 0u;
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l_build_buf = l_intbuf;
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}
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else{
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//Try to achieve a l_build_buf of length l_intbuf*2, so that we can merge with that
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//l_intbuf*2 buffer in "build_blocks" and use half of them as buffer and the other half
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//as keys in combine_all_blocks. In that case n_keys >= n_min_ideal_keys but by a small margin.
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//
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//If available memory is 2*sqrt(l), then only sqrt(l) unique keys are needed,
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//(to be used for keys in combine_all_blocks) as the whole l_build_buf
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//will be backuped in the buffer during build_blocks.
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bool const non_unique_buf = xbuf.capacity() >= l_intbuf;
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size_type const to_collect = non_unique_buf ? n_min_ideal_keys : l_intbuf*2;
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size_type collected = collect_unique(first, first+len, to_collect, comp, xbuf);
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//If available memory is 2*sqrt(l), then for "build_params"
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//the situation is the same as if 2*l_intbuf were collected.
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if(non_unique_buf && collected == n_min_ideal_keys){
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l_build_buf = l_intbuf;
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n_keys = n_min_ideal_keys;
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}
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else if(collected == 2*l_intbuf){
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//l_intbuf*2 elements found. Use all of them in the build phase
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l_build_buf = l_intbuf*2;
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n_keys = l_intbuf;
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}
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else if(collected == (n_min_ideal_keys+l_intbuf)){
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l_build_buf = l_intbuf;
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n_keys = n_min_ideal_keys;
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}
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//If collected keys are not enough, try to fix n_keys and l_intbuf. If no fix
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//is possible (due to very low unique keys), then go to a slow sort based on rotations.
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else{
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BOOST_ASSERT(collected < (n_min_ideal_keys+l_intbuf));
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if(collected < 4){ //No combination possible with less that 4 keys
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return false;
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}
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n_keys = l_intbuf;
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while(n_keys&(n_keys-1)){
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n_keys &= n_keys-1; // make it power or 2
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}
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while(n_keys > collected){
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n_keys/=2;
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}
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//AdaptiveSortInsertionSortThreshold is always power of two so the minimum is power of two
|
l_base = min_value<Unsigned>(n_keys, AdaptiveSortInsertionSortThreshold);
|
l_intbuf = 0;
|
l_build_buf = n_keys;
|
}
|
BOOST_ASSERT((n_keys+l_intbuf) >= l_build_buf);
|
}
|
|
return true;
|
}
|
|
// Main explanation of the sort algorithm.
|
//
|
// csqrtlen = ceil(sqrt(len));
|
//
|
// * First, 2*csqrtlen unique elements elements are extracted from elements to be
|
// sorted and placed in the beginning of the range.
|
//
|
// * Step "build_blocks": In this nearly-classic merge step, 2*csqrtlen unique elements
|
// will be used as auxiliary memory, so trailing len-2*csqrtlen elements are
|
// are grouped in blocks of sorted 4*csqrtlen elements. At the end of the step
|
// 2*csqrtlen unique elements are again the leading elements of the whole range.
|
//
|
// * Step "combine_blocks": pairs of previously formed blocks are merged with a different
|
// ("smart") algorithm to form blocks of 8*csqrtlen elements. This step is slower than the
|
// "build_blocks" step and repeated iteratively (forming blocks of 16*csqrtlen, 32*csqrtlen
|
// elements, etc) of until all trailing (len-2*csqrtlen) elements are merged.
|
//
|
// In "combine_blocks" len/csqrtlen elements used are as "keys" (markers) to
|
// know if elements belong to the first or second block to be merged and another
|
// leading csqrtlen elements are used as buffer. Explanation of the "combine_blocks" step:
|
//
|
// Iteratively until all trailing (len-2*csqrtlen) elements are merged:
|
// Iteratively for each pair of previously merged block:
|
// * Blocks are divided groups of csqrtlen elements and
|
// 2*merged_block/csqrtlen keys are sorted to be used as markers
|
// * Groups are selection-sorted by first or last element (depending whether they are going
|
// to be merged to left or right) and keys are reordered accordingly as an imitation-buffer.
|
// * Elements of each block pair are merged using the csqrtlen buffer taking into account
|
// if they belong to the first half or second half (marked by the key).
|
//
|
// * In the final merge step leading elements (2*csqrtlen) are sorted and merged with
|
// rotations with the rest of sorted elements in the "combine_blocks" step.
|
//
|
// Corner cases:
|
//
|
// * If no 2*csqrtlen elements can be extracted:
|
//
|
// * If csqrtlen+len/csqrtlen are extracted, then only csqrtlen elements are used
|
// as buffer in the "build_blocks" step forming blocks of 2*csqrtlen elements. This
|
// means that an additional "combine_blocks" step will be needed to merge all elements.
|
//
|
// * If no csqrtlen+len/csqrtlen elements can be extracted, but still more than a minimum,
|
// then reduces the number of elements used as buffer and keys in the "build_blocks"
|
// and "combine_blocks" steps. If "combine_blocks" has no enough keys due to this reduction
|
// then uses a rotation based smart merge.
|
//
|
// * If the minimum number of keys can't be extracted, a rotation-based sorting is performed.
|
//
|
// * If auxiliary memory is more or equal than ceil(len/2), half-copying mergesort is used.
|
//
|
// * If auxiliary memory is more than csqrtlen+n_keys*sizeof(std::size_t),
|
// then only csqrtlen elements need to be extracted and "combine_blocks" will use integral
|
// keys to combine blocks.
|
//
|
// * If auxiliary memory is available, the "build_blocks" will be extended to build bigger blocks
|
// using classic merge and "combine_blocks" will use bigger blocks when merging.
|
template<class RandIt, class Compare, class XBuf>
|
void adaptive_sort_impl
|
( RandIt first
|
, typename iterator_traits<RandIt>::size_type const len
|
, Compare comp
|
, XBuf & xbuf
|
)
|
{
|
typedef typename iterator_traits<RandIt>::size_type size_type;
|
|
//Small sorts go directly to insertion sort
|
if(len <= size_type(AdaptiveSortInsertionSortThreshold)){
|
insertion_sort(first, first + len, comp);
|
}
|
else if((len-len/2) <= xbuf.capacity()){
|
merge_sort(first, first+len, comp, xbuf.data());
|
}
|
else{
|
//Make sure it is at least four
|
BOOST_STATIC_ASSERT(AdaptiveSortInsertionSortThreshold >= 4);
|
|
size_type l_base = 0;
|
size_type l_intbuf = 0;
|
size_type n_keys = 0;
|
size_type l_build_buf = 0;
|
|
//Calculate and extract needed unique elements. If a minimum is not achieved
|
//fallback to a slow stable sort
|
if(!adaptive_sort_build_params(first, len, comp, n_keys, l_intbuf, l_base, l_build_buf, xbuf)){
|
stable_sort(first, first+len, comp, xbuf);
|
}
|
else{
|
BOOST_ASSERT(l_build_buf);
|
//Otherwise, continue the adaptive_sort
|
BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1("\n After collect_unique: ", len);
|
size_type const n_key_plus_buf = l_intbuf+n_keys;
|
//l_build_buf is always power of two if l_intbuf is zero
|
BOOST_ASSERT(l_intbuf || (0 == (l_build_buf & (l_build_buf-1))));
|
|
//Classic merge sort until internal buffer and xbuf are exhausted
|
size_type const l_merged = adaptive_sort_build_blocks
|
(first+n_key_plus_buf-l_build_buf, len-n_key_plus_buf+l_build_buf, l_base, l_build_buf, xbuf, comp);
|
BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1(" After build_blocks: ", len);
|
|
//Non-trivial merge
|
bool const buffer_right = adaptive_sort_combine_all_blocks
|
(first, n_keys, first+n_keys, len-n_keys, l_merged, l_intbuf, xbuf, comp);
|
|
//Sort keys and buffer and merge the whole sequence
|
adaptive_sort_final_merge(buffer_right, first, l_intbuf, n_keys, len, xbuf, comp);
|
}
|
}
|
}
|
|
} //namespace detail_adaptive {
|
|
///@endcond
|
|
//! <b>Effects</b>: Sorts the elements in the range [first, last) in ascending order according
|
//! to comparison functor "comp". The sort is stable (order of equal elements
|
//! is guaranteed to be preserved). Performance is improved if additional raw storage is
|
//! provided.
|
//!
|
//! <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, last: the range of elements to sort
|
//! - 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 ceil(std::distance(first, last)/2).
|
//!
|
//! <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(Nxlog(N)) comparisons and move assignments/constructors/swaps.
|
//! Comparisons are close to minimum even with no additional memory. Constant factor for data movement is minimized
|
//! when uninitialized_len is ceil(std::distance(first, last)/2). Pretty good enough performance is achieved when
|
//! ceil(sqrt(std::distance(first, last)))*2.
|
//!
|
//! <b>Caution</b>: Experimental implementation, not production-ready.
|
template<class RandIt, class RandRawIt, class Compare>
|
void adaptive_sort( RandIt first, RandIt last, Compare comp
|
, RandRawIt uninitialized
|
, typename iterator_traits<RandIt>::size_type uninitialized_len)
|
{
|
typedef typename iterator_traits<RandIt>::size_type size_type;
|
typedef typename iterator_traits<RandIt>::value_type value_type;
|
|
::boost::movelib::adaptive_xbuf<value_type, RandRawIt, size_type> xbuf(uninitialized, uninitialized_len);
|
::boost::movelib::detail_adaptive::adaptive_sort_impl(first, size_type(last - first), comp, xbuf);
|
}
|
|
template<class RandIt, class Compare>
|
void adaptive_sort( RandIt first, RandIt last, Compare comp)
|
{
|
typedef typename iterator_traits<RandIt>::value_type value_type;
|
adaptive_sort(first, last, comp, (value_type*)0, 0u);
|
}
|
|
} //namespace movelib {
|
} //namespace boost {
|
|
#include <boost/move/detail/config_end.hpp>
|
|
#endif //#define BOOST_MOVE_ADAPTIVE_SORT_HPP
|
