namespace boost {
namespace movelib {
+///@cond
+namespace detail_adaptive {
+
+template<class RandIt, class Compare, class XBuf>
+inline void adaptive_merge_combine_blocks( RandIt first
+ , typename iterator_traits<RandIt>::size_type len1
+ , typename iterator_traits<RandIt>::size_type len2
+ , typename iterator_traits<RandIt>::size_type collected
+ , typename iterator_traits<RandIt>::size_type n_keys
+ , typename iterator_traits<RandIt>::size_type l_block
+ , bool use_internal_buf
+ , bool xbuf_used
+ , Compare comp
+ , XBuf & xbuf
+ )
+{
+ typedef typename iterator_traits<RandIt>::size_type size_type;
+ size_type const len = len1+len2;
+ size_type const l_combine = len-collected;
+ size_type const l_combine1 = len1-collected;
+
+ if(n_keys){
+ RandIt const first_data = first+collected;
+ RandIt const keys = first;
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A combine: ", len);
+ if(xbuf_used){
+ if(xbuf.size() < l_block){
+ xbuf.initialize_until(l_block, *first);
+ }
+ BOOST_ASSERT(xbuf.size() >= l_block);
+ size_type n_block_a, n_block_b, l_irreg1, l_irreg2;
+ combine_params( keys, comp, l_combine
+ , l_combine1, l_block, xbuf
+ , n_block_a, n_block_b, l_irreg1, l_irreg2); //Outputs
+ op_merge_blocks_with_buf
+ (keys, comp, first_data, l_block, l_irreg1, n_block_a, n_block_b, l_irreg2, comp, move_op(), xbuf.data());
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1(" A mrg xbf: ", len);
+ }
+ else{
+ size_type n_block_a, n_block_b, l_irreg1, l_irreg2;
+ combine_params( keys, comp, l_combine
+ , l_combine1, l_block, xbuf
+ , n_block_a, n_block_b, l_irreg1, l_irreg2); //Outputs
+ if(use_internal_buf){
+ op_merge_blocks_with_buf
+ (keys, comp, first_data, l_block, l_irreg1, n_block_a, n_block_b, l_irreg2, comp, swap_op(), first_data-l_block);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A mrg buf: ", len);
+ }
+ else{
+ merge_blocks_bufferless
+ (keys, comp, first_data, l_block, l_irreg1, n_block_a, n_block_b, l_irreg2, comp);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1(" A mrg nbf: ", len);
+ }
+ }
+ }
+ else{
+ xbuf.shrink_to_fit(l_block);
+ if(xbuf.size() < l_block){
+ xbuf.initialize_until(l_block, *first);
+ }
+ size_type *const uint_keys = xbuf.template aligned_trailing<size_type>(l_block);
+ size_type n_block_a, n_block_b, l_irreg1, l_irreg2;
+ combine_params( uint_keys, less(), l_combine
+ , l_combine1, l_block, xbuf
+ , n_block_a, n_block_b, l_irreg1, l_irreg2, true); //Outputs
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A combine: ", len);
+ BOOST_ASSERT(xbuf.size() >= l_block);
+ op_merge_blocks_with_buf
+ (uint_keys, less(), first, l_block, l_irreg1, n_block_a, n_block_b, l_irreg2, comp, move_op(), xbuf.data());
+ xbuf.clear();
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1(" A mrg buf: ", len);
+ }
+}
+
+template<class RandIt, class Compare, class XBuf>
+inline void adaptive_merge_final_merge( RandIt first
+ , typename iterator_traits<RandIt>::size_type len1
+ , typename iterator_traits<RandIt>::size_type len2
+ , typename iterator_traits<RandIt>::size_type collected
+ , typename iterator_traits<RandIt>::size_type l_intbuf
+ , typename iterator_traits<RandIt>::size_type l_block
+ , bool use_internal_buf
+ , bool xbuf_used
+ , Compare comp
+ , XBuf & xbuf
+ )
+{
+ typedef typename iterator_traits<RandIt>::size_type size_type;
+ (void)l_block;
+ size_type n_keys = collected-l_intbuf;
+ size_type len = len1+len2;
+ if(use_internal_buf){
+ if(xbuf_used){
+ xbuf.clear();
+ //Nothing to do
+ if(n_keys){
+ unstable_sort(first, first+n_keys, comp, xbuf);
+ stable_merge(first, first+n_keys, first+len, comp, xbuf);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A key mrg: ", len);
+ }
+ }
+ else{
+ xbuf.clear();
+ unstable_sort(first, first+collected, comp, xbuf);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A k/b srt: ", len);
+ stable_merge(first, first+collected, first+len, comp, xbuf);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A k/b mrg: ", len);
+ }
+ }
+ else{
+ xbuf.clear();
+ unstable_sort(first, first+collected, comp, xbuf);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A k/b srt: ", len);
+ stable_merge(first, first+collected, first+len1+len2, comp, xbuf);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L2(" A k/b mrg: ", len);
+ }
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1(" A fin mrg: ", len);
+}
+
+template<class SizeType, class Xbuf>
+inline SizeType adaptive_merge_n_keys_intbuf(SizeType &rl_block, SizeType len1, SizeType len2, Xbuf & xbuf, SizeType &l_intbuf_inout)
+{
+ typedef SizeType size_type;
+ size_type l_block = rl_block;
+ size_type l_intbuf = xbuf.capacity() >= l_block ? 0u : l_block;
+
+ while(xbuf.capacity() >= l_block*2){
+ l_block *= 2;
+ }
+
+ //This is the minimum number of keys to implement the ideal algorithm
+ size_type n_keys = len1/l_block+len2/l_block;
+ while(n_keys >= ((len1-l_intbuf-n_keys)/l_block + len2/l_block)){
+ --n_keys;
+ }
+ ++n_keys;
+ BOOST_ASSERT(n_keys >= ((len1-l_intbuf-n_keys)/l_block + len2/l_block));
+
+ if(xbuf.template supports_aligned_trailing<size_type>(l_block, n_keys)){
+ n_keys = 0u;
+ }
+ l_intbuf_inout = l_intbuf;
+ rl_block = l_block;
+ return n_keys;
+}
+
+// Main explanation of the merge algorithm.
+//
+// csqrtlen = ceil(sqrt(len));
+//
+// * First, csqrtlen [to be used as buffer] + (len/csqrtlen - 1) [to be used as keys] => to_collect
+// unique elements are extracted from elements to be sorted and placed in the beginning of the range.
+//
+// * Step "combine_blocks": the leading (len1-to_collect) elements plus trailing len2 elements
+// are merged with a non-trivial ("smart") algorithm to form an ordered range trailing "len-to_collect" elements.
+//
+// Explanation of the "combine_blocks" step:
+//
+// * Trailing [first+to_collect, first+len1) elements are divided in groups of cqrtlen elements.
+// Remaining elements that can't form a group are grouped in front of those elements.
+// * Trailing [first+len1, first+len1+len2) elements are divided in groups of cqrtlen elements.
+// Remaining elements that can't form a group are grouped in the back of those elements.
+// * In parallel the following two steps are performed:
+// * 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 "to_collect" elements are merged with rotations
+// with the rest of merged elements in the "combine_blocks" step.
+//
+// Corner cases:
+//
+// * If no "to_collect" elements can be extracted:
+//
+// * If more than a minimum number of elements is extracted
+// then reduces the number of elements used as buffer and keys in the
+// 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 merge is performed.
+//
+// * If auxiliary memory is more or equal than min(len1, len2), a buffered merge is performed.
+//
+// * If the len1 or len2 are less than 2*csqrtlen then a rotation-based merge is performed.
+//
+// * If auxiliary memory is more than csqrtlen+n_keys*sizeof(std::size_t),
+// then no csqrtlen need to be extracted and "combine_blocks" will use integral
+// keys to combine blocks.
+template<class RandIt, class Compare, class XBuf>
+void adaptive_merge_impl
+ ( RandIt first
+ , typename iterator_traits<RandIt>::size_type len1
+ , typename iterator_traits<RandIt>::size_type len2
+ , Compare comp
+ , XBuf & xbuf
+ )
+{
+ typedef typename iterator_traits<RandIt>::size_type size_type;
+
+ if(xbuf.capacity() >= min_value<size_type>(len1, len2)){
+ buffered_merge(first, first+len1, first+(len1+len2), comp, xbuf);
+ }
+ else{
+ const size_type len = len1+len2;
+ //Calculate ideal parameters and try to collect needed unique keys
+ size_type l_block = size_type(ceil_sqrt(len));
+
+ //One range is not big enough to extract keys and the internal buffer so a
+ //rotation-based based merge will do just fine
+ if(len1 <= l_block*2 || len2 <= l_block*2){
+ merge_bufferless(first, first+len1, first+len1+len2, comp);
+ return;
+ }
+
+ //Detail the number of keys and internal buffer. If xbuf has enough memory, no
+ //internal buffer is needed so l_intbuf will remain 0.
+ size_type l_intbuf = 0;
+ size_type n_keys = adaptive_merge_n_keys_intbuf(l_block, len1, len2, xbuf, l_intbuf);
+ size_type const to_collect = l_intbuf+n_keys;
+ //Try to extract needed unique values from the first range
+ size_type const collected = collect_unique(first, first+len1, to_collect, comp, xbuf);
+ BOOST_MOVE_ADAPTIVE_SORT_PRINT_L1("\n A collect: ", len);
+
+ //Not the minimum number of keys is not available on the first range, so fallback to rotations
+ if(collected != to_collect && collected < 4){
+ merge_bufferless(first, first+collected, first+len1, comp);
+ merge_bufferless(first, first + len1, first + len1 + len2, comp);
+ return;
+ }
+
+ //If not enough keys but more than minimum, adjust the internal buffer and key count
+ bool use_internal_buf = collected == to_collect;
+ if (!use_internal_buf){
+ l_intbuf = 0u;
+ n_keys = collected;
+ l_block = lblock_for_combine(l_intbuf, n_keys, len, use_internal_buf);
+ //If use_internal_buf is false, then then internal buffer will be zero and rotation-based combination will be used
+ l_intbuf = use_internal_buf ? l_block : 0u;
+ }
+
+ bool const xbuf_used = collected == to_collect && xbuf.capacity() >= l_block;
+ //Merge trailing elements using smart merges
+ adaptive_merge_combine_blocks(first, len1, len2, collected, n_keys, l_block, use_internal_buf, xbuf_used, comp, xbuf);
+ //Merge buffer and keys with the rest of the values
+ adaptive_merge_final_merge (first, len1, len2, collected, l_intbuf, l_block, use_internal_buf, xbuf_used, comp, xbuf);
+ }
+}
+
+} //namespace detail_adaptive {
+
+///@endcond
+
//! <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,
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