--- /dev/null
+// -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file parallel/multiway_merge.h
+* @brief Implementation of sequential and parallel multiway merge.
+*
+* Explanations on the high-speed merging routines in the appendix of
+*
+* P. Sanders.
+* Fast priority queues for cached memory.
+* ACM Journal of Experimental Algorithmics, 5, 2000.
+*
+* This file is a GNU parallel extension to the Standard C++ Library.
+*/
+
+// Written by Johannes Singler and Manuel Holtgrewe.
+
+#ifndef _GLIBCXX_PARALLEL_MULTIWAY_MERGE_H
+#define _GLIBCXX_PARALLEL_MULTIWAY_MERGE_H
+
+#include <vector>
+
+#include <bits/stl_algo.h>
+#include <parallel/features.h>
+#include <parallel/parallel.h>
+#include <parallel/losertree.h>
+#include <parallel/multiseq_selection.h>
+#if _GLIBCXX_ASSERTIONS
+#include <parallel/checkers.h>
+#endif
+
+/** @brief Length of a sequence described by a pair of iterators. */
+#define _GLIBCXX_PARALLEL_LENGTH(__s) ((__s).second - (__s).first)
+
+namespace __gnu_parallel
+{
+ template<typename _RAIter1, typename _RAIter2, typename _OutputIterator,
+ typename _DifferenceTp, typename _Compare>
+ _OutputIterator
+ __merge_advance(_RAIter1&, _RAIter1, _RAIter2&, _RAIter2,
+ _OutputIterator, _DifferenceTp, _Compare);
+
+ /** @brief _Iterator wrapper supporting an implicit supremum at the end
+ * of the sequence, dominating all comparisons.
+ *
+ * The implicit supremum comes with a performance cost.
+ *
+ * Deriving from _RAIter is not possible since
+ * _RAIter need not be a class.
+ */
+ template<typename _RAIter, typename _Compare>
+ class _GuardedIterator
+ {
+ private:
+ /** @brief Current iterator __position. */
+ _RAIter _M_current;
+
+ /** @brief End iterator of the sequence. */
+ _RAIter _M_end;
+
+ /** @brief _Compare. */
+ _Compare& __comp;
+
+ public:
+ /** @brief Constructor. Sets iterator to beginning of sequence.
+ * @param __begin Begin iterator of sequence.
+ * @param __end End iterator of sequence.
+ * @param __comp Comparator provided for associated overloaded
+ * compare operators. */
+ _GuardedIterator(_RAIter __begin, _RAIter __end, _Compare& __comp)
+ : _M_current(__begin), _M_end(__end), __comp(__comp)
+ { }
+
+ /** @brief Pre-increment operator.
+ * @return This. */
+ _GuardedIterator<_RAIter, _Compare>&
+ operator++()
+ {
+ ++_M_current;
+ return *this;
+ }
+
+ /** @brief Dereference operator.
+ * @return Referenced element. */
+ typename std::iterator_traits<_RAIter>::value_type&
+ operator*()
+ { return *_M_current; }
+
+ /** @brief Convert to wrapped iterator.
+ * @return Wrapped iterator. */
+ operator _RAIter()
+ { return _M_current; }
+
+ /** @brief Compare two elements referenced by guarded iterators.
+ * @param __bi1 First iterator.
+ * @param __bi2 Second iterator.
+ * @return @c true if less. */
+ friend bool
+ operator<(_GuardedIterator<_RAIter, _Compare>& __bi1,
+ _GuardedIterator<_RAIter, _Compare>& __bi2)
+ {
+ if (__bi1._M_current == __bi1._M_end) // __bi1 is sup
+ return __bi2._M_current == __bi2._M_end; // __bi2 is not sup
+ if (__bi2._M_current == __bi2._M_end) // __bi2 is sup
+ return true;
+ return (__bi1.__comp)(*__bi1, *__bi2); // normal compare
+ }
+
+ /** @brief Compare two elements referenced by guarded iterators.
+ * @param __bi1 First iterator.
+ * @param __bi2 Second iterator.
+ * @return @c True if less equal. */
+ friend bool
+ operator<=(_GuardedIterator<_RAIter, _Compare>& __bi1,
+ _GuardedIterator<_RAIter, _Compare>& __bi2)
+ {
+ if (__bi2._M_current == __bi2._M_end) // __bi1 is sup
+ return __bi1._M_current != __bi1._M_end; // __bi2 is not sup
+ if (__bi1._M_current == __bi1._M_end) // __bi2 is sup
+ return false;
+ return !(__bi1.__comp)(*__bi2, *__bi1); // normal compare
+ }
+ };
+
+ template<typename _RAIter, typename _Compare>
+ class _UnguardedIterator
+ {
+ private:
+ /** @brief Current iterator __position. */
+ _RAIter _M_current;
+ /** @brief _Compare. */
+ _Compare& __comp;
+
+ public:
+ /** @brief Constructor. Sets iterator to beginning of sequence.
+ * @param __begin Begin iterator of sequence.
+ * @param __end Unused, only for compatibility.
+ * @param __comp Unused, only for compatibility. */
+ _UnguardedIterator(_RAIter __begin,
+ _RAIter /* __end */, _Compare& __comp)
+ : _M_current(__begin), __comp(__comp)
+ { }
+
+ /** @brief Pre-increment operator.
+ * @return This. */
+ _UnguardedIterator<_RAIter, _Compare>&
+ operator++()
+ {
+ ++_M_current;
+ return *this;
+ }
+
+ /** @brief Dereference operator.
+ * @return Referenced element. */
+ typename std::iterator_traits<_RAIter>::value_type&
+ operator*()
+ { return *_M_current; }
+
+ /** @brief Convert to wrapped iterator.
+ * @return Wrapped iterator. */
+ operator _RAIter()
+ { return _M_current; }
+
+ /** @brief Compare two elements referenced by unguarded iterators.
+ * @param __bi1 First iterator.
+ * @param __bi2 Second iterator.
+ * @return @c true if less. */
+ friend bool
+ operator<(_UnguardedIterator<_RAIter, _Compare>& __bi1,
+ _UnguardedIterator<_RAIter, _Compare>& __bi2)
+ {
+ // Normal compare.
+ return (__bi1.__comp)(*__bi1, *__bi2);
+ }
+
+ /** @brief Compare two elements referenced by unguarded iterators.
+ * @param __bi1 First iterator.
+ * @param __bi2 Second iterator.
+ * @return @c True if less equal. */
+ friend bool
+ operator<=(_UnguardedIterator<_RAIter, _Compare>& __bi1,
+ _UnguardedIterator<_RAIter, _Compare>& __bi2)
+ {
+ // Normal compare.
+ return !(__bi1.__comp)(*__bi2, *__bi1);
+ }
+ };
+
+ /** @brief Highly efficient 3-way merging procedure.
+ *
+ * Merging is done with the algorithm implementation described by Peter
+ * Sanders. Basically, the idea is to minimize the number of necessary
+ * comparison after merging an element. The implementation trick
+ * that makes this fast is that the order of the sequences is stored
+ * in the instruction pointer (translated into labels in C++).
+ *
+ * This works well for merging up to 4 sequences.
+ *
+ * Note that making the merging stable does @a not come at a
+ * performance hit.
+ *
+ * Whether the merging is done guarded or unguarded is selected by the
+ * used iterator class.
+ *
+ * @param __seqs_begin Begin iterator of iterator pair input sequence.
+ * @param __seqs_end End iterator of iterator pair input sequence.
+ * @param __target Begin iterator of output sequence.
+ * @param __comp Comparator.
+ * @param __length Maximum length to merge, less equal than the
+ * total number of elements available.
+ *
+ * @return End iterator of output sequence.
+ */
+ template<template<typename RAI, typename C> class iterator,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIter3
+ multiway_merge_3_variant(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _DifferenceTp __length, _Compare __comp)
+ {
+ _GLIBCXX_CALL(__length);
+
+ typedef _DifferenceTp _DifferenceType;
+
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ if (__length == 0)
+ return __target;
+
+#if _GLIBCXX_ASSERTIONS
+ _DifferenceTp __orig_length = __length;
+#endif
+
+ iterator<_RAIter1, _Compare>
+ __seq0(__seqs_begin[0].first, __seqs_begin[0].second, __comp),
+ __seq1(__seqs_begin[1].first, __seqs_begin[1].second, __comp),
+ __seq2(__seqs_begin[2].first, __seqs_begin[2].second, __comp);
+
+ if (__seq0 <= __seq1)
+ {
+ if (__seq1 <= __seq2)
+ goto __s012;
+ else
+ if (__seq2 < __seq0)
+ goto __s201;
+ else
+ goto __s021;
+ }
+ else
+ {
+ if (__seq1 <= __seq2)
+ {
+ if (__seq0 <= __seq2)
+ goto __s102;
+ else
+ goto __s120;
+ }
+ else
+ goto __s210;
+ }
+#define _GLIBCXX_PARALLEL_MERGE_3_CASE(__a, __b, __c, __c0, __c1) \
+ __s ## __a ## __b ## __c : \
+ *__target = *__seq ## __a; \
+ ++__target; \
+ --__length; \
+ ++__seq ## __a; \
+ if (__length == 0) goto __finish; \
+ if (__seq ## __a __c0 __seq ## __b) goto __s ## __a ## __b ## __c; \
+ if (__seq ## __a __c1 __seq ## __c) goto __s ## __b ## __a ## __c; \
+ goto __s ## __b ## __c ## __a;
+
+ _GLIBCXX_PARALLEL_MERGE_3_CASE(0, 1, 2, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_3_CASE(1, 2, 0, <=, < );
+ _GLIBCXX_PARALLEL_MERGE_3_CASE(2, 0, 1, < , < );
+ _GLIBCXX_PARALLEL_MERGE_3_CASE(1, 0, 2, < , <=);
+ _GLIBCXX_PARALLEL_MERGE_3_CASE(0, 2, 1, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_3_CASE(2, 1, 0, < , < );
+
+#undef _GLIBCXX_PARALLEL_MERGE_3_CASE
+
+ __finish:
+ ;
+
+#if _GLIBCXX_ASSERTIONS
+ _GLIBCXX_PARALLEL_ASSERT(
+ ((_RAIter1)__seq0 - __seqs_begin[0].first) +
+ ((_RAIter1)__seq1 - __seqs_begin[1].first) +
+ ((_RAIter1)__seq2 - __seqs_begin[2].first)
+ == __orig_length);
+#endif
+
+ __seqs_begin[0].first = __seq0;
+ __seqs_begin[1].first = __seq1;
+ __seqs_begin[2].first = __seq2;
+
+ return __target;
+ }
+
+ /**
+ * @brief Highly efficient 4-way merging procedure.
+ *
+ * Merging is done with the algorithm implementation described by Peter
+ * Sanders. Basically, the idea is to minimize the number of necessary
+ * comparison after merging an element. The implementation trick
+ * that makes this fast is that the order of the sequences is stored
+ * in the instruction pointer (translated into goto labels in C++).
+ *
+ * This works well for merging up to 4 sequences.
+ *
+ * Note that making the merging stable does @a not come at a
+ * performance hit.
+ *
+ * Whether the merging is done guarded or unguarded is selected by the
+ * used iterator class.
+ *
+ * @param __seqs_begin Begin iterator of iterator pair input sequence.
+ * @param __seqs_end End iterator of iterator pair input sequence.
+ * @param __target Begin iterator of output sequence.
+ * @param __comp Comparator.
+ * @param __length Maximum length to merge, less equal than the
+ * total number of elements available.
+ *
+ * @return End iterator of output sequence.
+ */
+ template<template<typename RAI, typename C> class iterator,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIter3
+ multiway_merge_4_variant(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _DifferenceTp __length, _Compare __comp)
+ {
+ _GLIBCXX_CALL(__length);
+ typedef _DifferenceTp _DifferenceType;
+
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ iterator<_RAIter1, _Compare>
+ __seq0(__seqs_begin[0].first, __seqs_begin[0].second, __comp),
+ __seq1(__seqs_begin[1].first, __seqs_begin[1].second, __comp),
+ __seq2(__seqs_begin[2].first, __seqs_begin[2].second, __comp),
+ __seq3(__seqs_begin[3].first, __seqs_begin[3].second, __comp);
+
+#define _GLIBCXX_PARALLEL_DECISION(__a, __b, __c, __d) { \
+ if (__seq ## __d < __seq ## __a) \
+ goto __s ## __d ## __a ## __b ## __c; \
+ if (__seq ## __d < __seq ## __b) \
+ goto __s ## __a ## __d ## __b ## __c; \
+ if (__seq ## __d < __seq ## __c) \
+ goto __s ## __a ## __b ## __d ## __c; \
+ goto __s ## __a ## __b ## __c ## __d; }
+
+ if (__seq0 <= __seq1)
+ {
+ if (__seq1 <= __seq2)
+ _GLIBCXX_PARALLEL_DECISION(0,1,2,3)
+ else
+ if (__seq2 < __seq0)
+ _GLIBCXX_PARALLEL_DECISION(2,0,1,3)
+ else
+ _GLIBCXX_PARALLEL_DECISION(0,2,1,3)
+ }
+ else
+ {
+ if (__seq1 <= __seq2)
+ {
+ if (__seq0 <= __seq2)
+ _GLIBCXX_PARALLEL_DECISION(1,0,2,3)
+ else
+ _GLIBCXX_PARALLEL_DECISION(1,2,0,3)
+ }
+ else
+ _GLIBCXX_PARALLEL_DECISION(2,1,0,3)
+ }
+
+#define _GLIBCXX_PARALLEL_MERGE_4_CASE(__a, __b, __c, __d, \
+ __c0, __c1, __c2) \
+ __s ## __a ## __b ## __c ## __d: \
+ if (__length == 0) goto __finish; \
+ *__target = *__seq ## __a; \
+ ++__target; \
+ --__length; \
+ ++__seq ## __a; \
+ if (__seq ## __a __c0 __seq ## __b) \
+ goto __s ## __a ## __b ## __c ## __d; \
+ if (__seq ## __a __c1 __seq ## __c) \
+ goto __s ## __b ## __a ## __c ## __d; \
+ if (__seq ## __a __c2 __seq ## __d) \
+ goto __s ## __b ## __c ## __a ## __d; \
+ goto __s ## __b ## __c ## __d ## __a;
+
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(0, 1, 2, 3, <=, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(0, 1, 3, 2, <=, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(0, 2, 1, 3, <=, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(0, 2, 3, 1, <=, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(0, 3, 1, 2, <=, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(0, 3, 2, 1, <=, <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(1, 0, 2, 3, < , <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(1, 0, 3, 2, < , <=, <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(1, 2, 0, 3, <=, < , <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(1, 2, 3, 0, <=, <=, < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(1, 3, 0, 2, <=, < , <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(1, 3, 2, 0, <=, <=, < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(2, 0, 1, 3, < , < , <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(2, 0, 3, 1, < , <=, < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(2, 1, 0, 3, < , < , <=);
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(2, 1, 3, 0, < , <=, < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(2, 3, 0, 1, <=, < , < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(2, 3, 1, 0, <=, < , < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(3, 0, 1, 2, < , < , < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(3, 0, 2, 1, < , < , < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(3, 1, 0, 2, < , < , < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(3, 1, 2, 0, < , < , < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(3, 2, 0, 1, < , < , < );
+ _GLIBCXX_PARALLEL_MERGE_4_CASE(3, 2, 1, 0, < , < , < );
+
+#undef _GLIBCXX_PARALLEL_MERGE_4_CASE
+#undef _GLIBCXX_PARALLEL_DECISION
+
+ __finish:
+ ;
+
+ __seqs_begin[0].first = __seq0;
+ __seqs_begin[1].first = __seq1;
+ __seqs_begin[2].first = __seq2;
+ __seqs_begin[3].first = __seq3;
+
+ return __target;
+ }
+
+ /** @brief Multi-way merging procedure for a high branching factor,
+ * guarded case.
+ *
+ * This merging variant uses a LoserTree class as selected by <tt>_LT</tt>.
+ *
+ * Stability is selected through the used LoserTree class <tt>_LT</tt>.
+ *
+ * At least one non-empty sequence is required.
+ *
+ * @param __seqs_begin Begin iterator of iterator pair input sequence.
+ * @param __seqs_end End iterator of iterator pair input sequence.
+ * @param __target Begin iterator of output sequence.
+ * @param __comp Comparator.
+ * @param __length Maximum length to merge, less equal than the
+ * total number of elements available.
+ *
+ * @return End iterator of output sequence.
+ */
+ template<typename _LT,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIter3
+ multiway_merge_loser_tree(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _DifferenceTp __length, _Compare __comp)
+ {
+ _GLIBCXX_CALL(__length)
+
+ typedef _DifferenceTp _DifferenceType;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::difference_type _SeqNumber;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ _SeqNumber __k = static_cast<_SeqNumber>(__seqs_end - __seqs_begin);
+
+ _LT __lt(__k, __comp);
+
+ // Default value for potentially non-default-constructible types.
+ _ValueType* __arbitrary_element = 0;
+
+ for (_SeqNumber __t = 0; __t < __k; ++__t)
+ {
+ if(!__arbitrary_element
+ && _GLIBCXX_PARALLEL_LENGTH(__seqs_begin[__t]) > 0)
+ __arbitrary_element = &(*__seqs_begin[__t].first);
+ }
+
+ for (_SeqNumber __t = 0; __t < __k; ++__t)
+ {
+ if (__seqs_begin[__t].first == __seqs_begin[__t].second)
+ __lt.__insert_start(*__arbitrary_element, __t, true);
+ else
+ __lt.__insert_start(*__seqs_begin[__t].first, __t, false);
+ }
+
+ __lt.__init();
+
+ _SeqNumber __source;
+
+ for (_DifferenceType __i = 0; __i < __length; ++__i)
+ {
+ //take out
+ __source = __lt.__get_min_source();
+
+ *(__target++) = *(__seqs_begin[__source].first++);
+
+ // Feed.
+ if (__seqs_begin[__source].first == __seqs_begin[__source].second)
+ __lt.__delete_min_insert(*__arbitrary_element, true);
+ else
+ // Replace from same __source.
+ __lt.__delete_min_insert(*__seqs_begin[__source].first, false);
+ }
+
+ return __target;
+ }
+
+ /** @brief Multi-way merging procedure for a high branching factor,
+ * unguarded case.
+ *
+ * Merging is done using the LoserTree class <tt>_LT</tt>.
+ *
+ * Stability is selected by the used LoserTrees.
+ *
+ * @pre No input will run out of elements during the merge.
+ *
+ * @param __seqs_begin Begin iterator of iterator pair input sequence.
+ * @param __seqs_end End iterator of iterator pair input sequence.
+ * @param __target Begin iterator of output sequence.
+ * @param __comp Comparator.
+ * @param __length Maximum length to merge, less equal than the
+ * total number of elements available.
+ *
+ * @return End iterator of output sequence.
+ */
+ template<typename _LT,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp, typename _Compare>
+ _RAIter3
+ multiway_merge_loser_tree_unguarded(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ const typename std::iterator_traits<typename std::iterator_traits<
+ _RAIterIterator>::value_type::first_type>::value_type&
+ __sentinel,
+ _DifferenceTp __length,
+ _Compare __comp)
+ {
+ _GLIBCXX_CALL(__length)
+ typedef _DifferenceTp _DifferenceType;
+
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::difference_type _SeqNumber;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ _SeqNumber __k = __seqs_end - __seqs_begin;
+
+ _LT __lt(__k, __sentinel, __comp);
+
+ for (_SeqNumber __t = 0; __t < __k; ++__t)
+ {
+#if _GLIBCXX_ASSERTIONS
+ _GLIBCXX_PARALLEL_ASSERT(__seqs_begin[__t].first
+ != __seqs_begin[__t].second);
+#endif
+ __lt.__insert_start(*__seqs_begin[__t].first, __t, false);
+ }
+
+ __lt.__init();
+
+ _SeqNumber __source;
+
+#if _GLIBCXX_ASSERTIONS
+ _DifferenceType __i = 0;
+#endif
+
+ _RAIter3 __target_end = __target + __length;
+ while (__target < __target_end)
+ {
+ // Take out.
+ __source = __lt.__get_min_source();
+
+#if _GLIBCXX_ASSERTIONS
+ _GLIBCXX_PARALLEL_ASSERT(0 <= __source && __source < __k);
+ _GLIBCXX_PARALLEL_ASSERT(__i == 0
+ || !__comp(*(__seqs_begin[__source].first), *(__target - 1)));
+#endif
+
+ // Feed.
+ *(__target++) = *(__seqs_begin[__source].first++);
+
+#if _GLIBCXX_ASSERTIONS
+ ++__i;
+#endif
+ // Replace from same __source.
+ __lt.__delete_min_insert(*__seqs_begin[__source].first, false);
+ }
+
+ return __target;
+ }
+
+
+ /** @brief Multi-way merging procedure for a high branching factor,
+ * requiring sentinels to exist.
+ *
+ * @tparam UnguardedLoserTree _Loser Tree variant to use for the unguarded
+ * merging.
+ *
+ * @param __seqs_begin Begin iterator of iterator pair input sequence.
+ * @param __seqs_end End iterator of iterator pair input sequence.
+ * @param __target Begin iterator of output sequence.
+ * @param __comp Comparator.
+ * @param __length Maximum length to merge, less equal than the
+ * total number of elements available.
+ *
+ * @return End iterator of output sequence.
+ */
+ template<typename UnguardedLoserTree,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIter3
+ multiway_merge_loser_tree_sentinel(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ const typename std::iterator_traits<typename std::iterator_traits<
+ _RAIterIterator>::value_type::first_type>::value_type&
+ __sentinel,
+ _DifferenceTp __length,
+ _Compare __comp)
+ {
+ _GLIBCXX_CALL(__length)
+
+ typedef _DifferenceTp _DifferenceType;
+ typedef std::iterator_traits<_RAIterIterator> _TraitsType;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ _RAIter3 __target_end;
+
+ for (_RAIterIterator __s = __seqs_begin; __s != __seqs_end; ++__s)
+ // Move the sequence ends to the sentinel. This has the
+ // effect that the sentinel appears to be within the sequence. Then,
+ // we can use the unguarded variant if we merge out as many
+ // non-sentinel elements as we have.
+ ++((*__s).second);
+
+ __target_end = multiway_merge_loser_tree_unguarded<UnguardedLoserTree>
+ (__seqs_begin, __seqs_end, __target, __sentinel, __length, __comp);
+
+#if _GLIBCXX_ASSERTIONS
+ _GLIBCXX_PARALLEL_ASSERT(__target_end == __target + __length);
+ _GLIBCXX_PARALLEL_ASSERT(__is_sorted(__target, __target_end, __comp));
+#endif
+
+ // Restore the sequence ends so the sentinels are not contained in the
+ // sequence any more (see comment in loop above).
+ for (_RAIterIterator __s = __seqs_begin; __s != __seqs_end; ++__s)
+ --((*__s).second);
+
+ return __target_end;
+ }
+
+ /**
+ * @brief Traits for determining whether the loser tree should
+ * use pointers or copies.
+ *
+ * The field "_M_use_pointer" is used to determine whether to use pointers
+ * in he loser trees or whether to copy the values into the loser tree.
+ *
+ * The default behavior is to use pointers if the data type is 4 times as
+ * big as the pointer to it.
+ *
+ * Specialize for your data type to customize the behavior.
+ *
+ * Example:
+ *
+ * template<>
+ * struct _LoserTreeTraits<int>
+ * { static const bool _M_use_pointer = false; };
+ *
+ * template<>
+ * struct _LoserTreeTraits<heavyweight_type>
+ * { static const bool _M_use_pointer = true; };
+ *
+ * @param _Tp type to give the loser tree traits for.
+ */
+ template <typename _Tp>
+ struct _LoserTreeTraits
+ {
+ /**
+ * @brief True iff to use pointers instead of values in loser trees.
+ *
+ * The default behavior is to use pointers if the data type is four
+ * times as big as the pointer to it.
+ */
+ static const bool _M_use_pointer = (sizeof(_Tp) > 4 * sizeof(_Tp*));
+ };
+
+ /**
+ * @brief Switch for 3-way merging with __sentinels turned off.
+ *
+ * Note that 3-way merging is always stable!
+ */
+ template<bool __sentinels /*default == false*/,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ struct __multiway_merge_3_variant_sentinel_switch
+ {
+ _RAIter3
+ operator()(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _DifferenceTp __length, _Compare __comp)
+ { return multiway_merge_3_variant<_GuardedIterator>
+ (__seqs_begin, __seqs_end, __target, __length, __comp); }
+ };
+
+ /**
+ * @brief Switch for 3-way merging with __sentinels turned on.
+ *
+ * Note that 3-way merging is always stable!
+ */
+ template<typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ struct __multiway_merge_3_variant_sentinel_switch<true, _RAIterIterator,
+ _RAIter3, _DifferenceTp,
+ _Compare>
+ {
+ _RAIter3
+ operator()(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _DifferenceTp __length, _Compare __comp)
+ { return multiway_merge_3_variant<_UnguardedIterator>
+ (__seqs_begin, __seqs_end, __target, __length, __comp); }
+ };
+
+ /**
+ * @brief Switch for 4-way merging with __sentinels turned off.
+ *
+ * Note that 4-way merging is always stable!
+ */
+ template<bool __sentinels /*default == false*/,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ struct __multiway_merge_4_variant_sentinel_switch
+ {
+ _RAIter3
+ operator()(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _DifferenceTp __length, _Compare __comp)
+ { return multiway_merge_4_variant<_GuardedIterator>
+ (__seqs_begin, __seqs_end, __target, __length, __comp); }
+ };
+
+ /**
+ * @brief Switch for 4-way merging with __sentinels turned on.
+ *
+ * Note that 4-way merging is always stable!
+ */
+ template<typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ struct __multiway_merge_4_variant_sentinel_switch<true, _RAIterIterator,
+ _RAIter3, _DifferenceTp,
+ _Compare>
+ {
+ _RAIter3
+ operator()(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _DifferenceTp __length, _Compare __comp)
+ { return multiway_merge_4_variant<_UnguardedIterator>
+ (__seqs_begin, __seqs_end, __target, __length, __comp); }
+ };
+
+ /**
+ * @brief Switch for k-way merging with __sentinels turned on.
+ */
+ template<bool __sentinels,
+ bool __stable,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ struct __multiway_merge_k_variant_sentinel_switch
+ {
+ _RAIter3
+ operator()(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ const typename std::iterator_traits<typename std::iterator_traits<
+ _RAIterIterator>::value_type::first_type>::value_type&
+ __sentinel,
+ _DifferenceTp __length, _Compare __comp)
+ {
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ return multiway_merge_loser_tree_sentinel<
+ typename __gnu_cxx::__conditional_type<
+ _LoserTreeTraits<_ValueType>::_M_use_pointer,
+ _LoserTreePointerUnguarded<__stable, _ValueType, _Compare>,
+ _LoserTreeUnguarded<__stable, _ValueType, _Compare>
+ >::__type>
+ (__seqs_begin, __seqs_end, __target, __sentinel, __length, __comp);
+ }
+ };
+
+ /**
+ * @brief Switch for k-way merging with __sentinels turned off.
+ */
+ template<bool __stable,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ struct __multiway_merge_k_variant_sentinel_switch<false, __stable,
+ _RAIterIterator,
+ _RAIter3, _DifferenceTp,
+ _Compare>
+ {
+ _RAIter3
+ operator()(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ const typename std::iterator_traits<typename std::iterator_traits<
+ _RAIterIterator>::value_type::first_type>::value_type&
+ __sentinel,
+ _DifferenceTp __length, _Compare __comp)
+ {
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ return multiway_merge_loser_tree<
+ typename __gnu_cxx::__conditional_type<
+ _LoserTreeTraits<_ValueType>::_M_use_pointer,
+ _LoserTreePointer<__stable, _ValueType, _Compare>,
+ _LoserTree<__stable, _ValueType, _Compare>
+ >::__type >(__seqs_begin, __seqs_end, __target, __length, __comp);
+ }
+ };
+
+ /** @brief Sequential multi-way merging switch.
+ *
+ * The _GLIBCXX_PARALLEL_DECISION is based on the branching factor and
+ * runtime settings.
+ * @param __seqs_begin Begin iterator of iterator pair input sequence.
+ * @param __seqs_end End iterator of iterator pair input sequence.
+ * @param __target Begin iterator of output sequence.
+ * @param __comp Comparator.
+ * @param __length Maximum length to merge, possibly larger than the
+ * number of elements available.
+ * @param __sentinel The sequences have __a __sentinel element.
+ * @return End iterator of output sequence. */
+ template<bool __stable,
+ bool __sentinels,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIter3
+ __sequential_multiway_merge(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ const typename std::iterator_traits<typename std::iterator_traits<
+ _RAIterIterator>::value_type::first_type>::value_type&
+ __sentinel,
+ _DifferenceTp __length, _Compare __comp)
+ {
+ _GLIBCXX_CALL(__length)
+
+ typedef _DifferenceTp _DifferenceType;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::difference_type _SeqNumber;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+#if _GLIBCXX_ASSERTIONS
+ for (_RAIterIterator __s = __seqs_begin; __s != __seqs_end; ++__s)
+ {
+ _GLIBCXX_PARALLEL_ASSERT(__is_sorted((*__s).first,
+ (*__s).second, __comp));
+ }
+#endif
+
+ _DifferenceTp __total_length = 0;
+ for (_RAIterIterator __s = __seqs_begin; __s != __seqs_end; ++__s)
+ __total_length += _GLIBCXX_PARALLEL_LENGTH(*__s);
+
+ __length = std::min<_DifferenceTp>(__length, __total_length);
+
+ if(__length == 0)
+ return __target;
+
+ _RAIter3 __return_target = __target;
+ _SeqNumber __k = static_cast<_SeqNumber>(__seqs_end - __seqs_begin);
+
+ switch (__k)
+ {
+ case 0:
+ break;
+ case 1:
+ __return_target = std::copy(__seqs_begin[0].first,
+ __seqs_begin[0].first + __length,
+ __target);
+ __seqs_begin[0].first += __length;
+ break;
+ case 2:
+ __return_target = __merge_advance(__seqs_begin[0].first,
+ __seqs_begin[0].second,
+ __seqs_begin[1].first,
+ __seqs_begin[1].second,
+ __target, __length, __comp);
+ break;
+ case 3:
+ __return_target = __multiway_merge_3_variant_sentinel_switch
+ <__sentinels, _RAIterIterator, _RAIter3, _DifferenceTp, _Compare>()
+ (__seqs_begin, __seqs_end, __target, __length, __comp);
+ break;
+ case 4:
+ __return_target = __multiway_merge_4_variant_sentinel_switch
+ <__sentinels, _RAIterIterator, _RAIter3, _DifferenceTp, _Compare>()
+ (__seqs_begin, __seqs_end, __target, __length, __comp);
+ break;
+ default:
+ __return_target = __multiway_merge_k_variant_sentinel_switch
+ <__sentinels, __stable, _RAIterIterator, _RAIter3, _DifferenceTp,
+ _Compare>()
+ (__seqs_begin, __seqs_end, __target, __sentinel, __length, __comp);
+ break;
+ }
+#if _GLIBCXX_ASSERTIONS
+ _GLIBCXX_PARALLEL_ASSERT(
+ __is_sorted(__target, __target + __length, __comp));
+#endif
+
+ return __return_target;
+ }
+
+ /**
+ * @brief Stable sorting functor.
+ *
+ * Used to reduce code instanciation in multiway_merge_sampling_splitting.
+ */
+ template<bool __stable, class _RAIter, class _StrictWeakOrdering>
+ struct _SamplingSorter
+ {
+ void
+ operator()(_RAIter __first, _RAIter __last, _StrictWeakOrdering __comp)
+ { __gnu_sequential::stable_sort(__first, __last, __comp); }
+ };
+
+ /**
+ * @brief Non-__stable sorting functor.
+ *
+ * Used to reduce code instantiation in multiway_merge_sampling_splitting.
+ */
+ template<class _RAIter, class _StrictWeakOrdering>
+ struct _SamplingSorter<false, _RAIter, _StrictWeakOrdering>
+ {
+ void
+ operator()(_RAIter __first, _RAIter __last, _StrictWeakOrdering __comp)
+ { __gnu_sequential::sort(__first, __last, __comp); }
+ };
+
+ /**
+ * @brief Sampling based splitting for parallel multiway-merge routine.
+ */
+ template<bool __stable,
+ typename _RAIterIterator,
+ typename _Compare,
+ typename _DifferenceType>
+ void
+ multiway_merge_sampling_splitting(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _DifferenceType __length,
+ _DifferenceType __total_length,
+ _Compare __comp,
+ std::vector<std::pair<_DifferenceType, _DifferenceType> > *__pieces)
+ {
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::difference_type _SeqNumber;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
+
+ // __k sequences.
+ const _SeqNumber __k
+ = static_cast<_SeqNumber>(__seqs_end - __seqs_begin);
+
+ const _ThreadIndex __num_threads = omp_get_num_threads();
+
+ const _DifferenceType __num_samples =
+ __gnu_parallel::_Settings::get().merge_oversampling * __num_threads;
+
+ _ValueType* __samples = static_cast<_ValueType*>
+ (::operator new(sizeof(_ValueType) * __k * __num_samples));
+ // Sample.
+ for (_SeqNumber __s = 0; __s < __k; ++__s)
+ for (_DifferenceType __i = 0; __i < __num_samples; ++__i)
+ {
+ _DifferenceType sample_index = static_cast<_DifferenceType>
+ (_GLIBCXX_PARALLEL_LENGTH(__seqs_begin[__s])
+ * (double(__i + 1) / (__num_samples + 1))
+ * (double(__length) / __total_length));
+ new(&(__samples[__s * __num_samples + __i]))
+ _ValueType(__seqs_begin[__s].first[sample_index]);
+ }
+
+ // Sort stable or non-stable, depending on value of template parameter
+ // "__stable".
+ _SamplingSorter<__stable, _ValueType*, _Compare>()
+ (__samples, __samples + (__num_samples * __k), __comp);
+
+ for (_ThreadIndex __slab = 0; __slab < __num_threads; ++__slab)
+ // For each slab / processor.
+ for (_SeqNumber __seq = 0; __seq < __k; ++__seq)
+ {
+ // For each sequence.
+ if (__slab > 0)
+ __pieces[__slab][__seq].first = std::upper_bound
+ (__seqs_begin[__seq].first, __seqs_begin[__seq].second,
+ __samples[__num_samples * __k * __slab / __num_threads],
+ __comp)
+ - __seqs_begin[__seq].first;
+ else
+ // Absolute beginning.
+ __pieces[__slab][__seq].first = 0;
+ if ((__slab + 1) < __num_threads)
+ __pieces[__slab][__seq].second = std::upper_bound
+ (__seqs_begin[__seq].first, __seqs_begin[__seq].second,
+ __samples[__num_samples * __k * (__slab + 1) / __num_threads],
+ __comp)
+ - __seqs_begin[__seq].first;
+ else
+ // Absolute end.
+ __pieces[__slab][__seq].second =
+ _GLIBCXX_PARALLEL_LENGTH(__seqs_begin[__seq]);
+ }
+
+ for (_SeqNumber __s = 0; __s < __k; ++__s)
+ for (_DifferenceType __i = 0; __i < __num_samples; ++__i)
+ __samples[__s * __num_samples + __i].~_ValueType();
+ ::operator delete(__samples);
+ }
+
+ /**
+ * @brief Exact splitting for parallel multiway-merge routine.
+ *
+ * None of the passed sequences may be empty.
+ */
+ template<bool __stable,
+ typename _RAIterIterator,
+ typename _Compare,
+ typename _DifferenceType>
+ void
+ multiway_merge_exact_splitting(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _DifferenceType __length,
+ _DifferenceType __total_length,
+ _Compare __comp,
+ std::vector<std::pair<_DifferenceType, _DifferenceType> > *__pieces)
+ {
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::difference_type _SeqNumber;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+
+ const bool __tight = (__total_length == __length);
+
+ // __k sequences.
+ const _SeqNumber __k = __seqs_end - __seqs_begin;
+
+ const _ThreadIndex __num_threads = omp_get_num_threads();
+
+ // (Settings::multiway_merge_splitting
+ // == __gnu_parallel::_Settings::EXACT).
+ std::vector<_RAIter1>* __offsets =
+ new std::vector<_RAIter1>[__num_threads];
+ std::vector<std::pair<_RAIter1, _RAIter1> > __se(__k);
+
+ copy(__seqs_begin, __seqs_end, __se.begin());
+
+ _DifferenceType* __borders =
+ new _DifferenceType[__num_threads + 1];
+ __equally_split(__length, __num_threads, __borders);
+
+ for (_ThreadIndex __s = 0; __s < (__num_threads - 1); ++__s)
+ {
+ __offsets[__s].resize(__k);
+ multiseq_partition(__se.begin(), __se.end(), __borders[__s + 1],
+ __offsets[__s].begin(), __comp);
+
+ // Last one also needed and available.
+ if (!__tight)
+ {
+ __offsets[__num_threads - 1].resize(__k);
+ multiseq_partition(__se.begin(), __se.end(),
+ _DifferenceType(__length),
+ __offsets[__num_threads - 1].begin(),
+ __comp);
+ }
+ }
+ delete[] __borders;
+
+ for (_ThreadIndex __slab = 0; __slab < __num_threads; ++__slab)
+ {
+ // For each slab / processor.
+ for (_SeqNumber __seq = 0; __seq < __k; ++__seq)
+ {
+ // For each sequence.
+ if (__slab == 0)
+ {
+ // Absolute beginning.
+ __pieces[__slab][__seq].first = 0;
+ }
+ else
+ __pieces[__slab][__seq].first =
+ __pieces[__slab - 1][__seq].second;
+ if (!__tight || __slab < (__num_threads - 1))
+ __pieces[__slab][__seq].second =
+ __offsets[__slab][__seq] - __seqs_begin[__seq].first;
+ else
+ {
+ // __slab == __num_threads - 1
+ __pieces[__slab][__seq].second =
+ _GLIBCXX_PARALLEL_LENGTH(__seqs_begin[__seq]);
+ }
+ }
+ }
+ delete[] __offsets;
+ }
+
+ /** @brief Parallel multi-way merge routine.
+ *
+ * The _GLIBCXX_PARALLEL_DECISION is based on the branching factor
+ * and runtime settings.
+ *
+ * Must not be called if the number of sequences is 1.
+ *
+ * @tparam _Splitter functor to split input (either __exact or sampling based)
+ * @tparam __stable Stable merging incurs a performance penalty.
+ * @tparam __sentinel Ignored.
+ *
+ * @param __seqs_begin Begin iterator of iterator pair input sequence.
+ * @param __seqs_end End iterator of iterator pair input sequence.
+ * @param __target Begin iterator of output sequence.
+ * @param __comp Comparator.
+ * @param __length Maximum length to merge, possibly larger than the
+ * number of elements available.
+ * @return End iterator of output sequence.
+ */
+ template<bool __stable,
+ bool __sentinels,
+ typename _RAIterIterator,
+ typename _RAIter3,
+ typename _DifferenceTp,
+ typename _Splitter,
+ typename _Compare>
+ _RAIter3
+ parallel_multiway_merge(_RAIterIterator __seqs_begin,
+ _RAIterIterator __seqs_end,
+ _RAIter3 __target,
+ _Splitter __splitter,
+ _DifferenceTp __length,
+ _Compare __comp,
+ _ThreadIndex __num_threads)
+ {
+#if _GLIBCXX_ASSERTIONS
+ _GLIBCXX_PARALLEL_ASSERT(__seqs_end - __seqs_begin > 1);
+#endif
+
+ _GLIBCXX_CALL(__length)
+
+ typedef _DifferenceTp _DifferenceType;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::difference_type _SeqNumber;
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename
+ std::iterator_traits<_RAIter1>::value_type _ValueType;
+
+ // Leave only non-empty sequences.
+ typedef std::pair<_RAIter1, _RAIter1> seq_type;
+ seq_type* __ne_seqs = new seq_type[__seqs_end - __seqs_begin];
+ _SeqNumber __k = 0;
+ _DifferenceType __total_length = 0;
+ for (_RAIterIterator __raii = __seqs_begin;
+ __raii != __seqs_end; ++__raii)
+ {
+ _DifferenceTp __seq_length = _GLIBCXX_PARALLEL_LENGTH(*__raii);
+ if(__seq_length > 0)
+ {
+ __total_length += __seq_length;
+ __ne_seqs[__k++] = *__raii;
+ }
+ }
+
+ _GLIBCXX_CALL(__total_length)
+
+ __length = std::min<_DifferenceTp>(__length, __total_length);
+
+ if (__total_length == 0 || __k == 0)
+ {
+ delete[] __ne_seqs;
+ return __target;
+ }
+
+ std::vector<std::pair<_DifferenceType, _DifferenceType> >* __pieces;
+
+ __num_threads = static_cast<_ThreadIndex>
+ (std::min<_DifferenceType>(__num_threads, __total_length));
+
+# pragma omp parallel num_threads (__num_threads)
+ {
+# pragma omp single
+ {
+ __num_threads = omp_get_num_threads();
+ // Thread __t will have to merge pieces[__iam][0..__k - 1]
+ __pieces = new std::vector<
+ std::pair<_DifferenceType, _DifferenceType> >[__num_threads];
+ for (_ThreadIndex __s = 0; __s < __num_threads; ++__s)
+ __pieces[__s].resize(__k);
+
+ _DifferenceType __num_samples =
+ __gnu_parallel::_Settings::get().merge_oversampling
+ * __num_threads;
+
+ __splitter(__ne_seqs, __ne_seqs + __k, __length, __total_length,
+ __comp, __pieces);
+ } //single
+
+ _ThreadIndex __iam = omp_get_thread_num();
+
+ _DifferenceType __target_position = 0;
+
+ for (_SeqNumber __c = 0; __c < __k; ++__c)
+ __target_position += __pieces[__iam][__c].first;
+
+ seq_type* __chunks = new seq_type[__k];
+
+ for (_SeqNumber __s = 0; __s < __k; ++__s)
+ __chunks[__s] = std::make_pair(__ne_seqs[__s].first
+ + __pieces[__iam][__s].first,
+ __ne_seqs[__s].first
+ + __pieces[__iam][__s].second);
+
+ if(__length > __target_position)
+ __sequential_multiway_merge<__stable, __sentinels>
+ (__chunks, __chunks + __k, __target + __target_position,
+ *(__seqs_begin->second), __length - __target_position, __comp);
+
+ delete[] __chunks;
+ } // parallel
+
+#if _GLIBCXX_ASSERTIONS
+ _GLIBCXX_PARALLEL_ASSERT(
+ __is_sorted(__target, __target + __length, __comp));
+#endif
+
+ __k = 0;
+ // Update ends of sequences.
+ for (_RAIterIterator __raii = __seqs_begin;
+ __raii != __seqs_end; ++__raii)
+ {
+ _DifferenceTp __length = _GLIBCXX_PARALLEL_LENGTH(*__raii);
+ if(__length > 0)
+ (*__raii).first += __pieces[__num_threads - 1][__k++].second;
+ }
+
+ delete[] __pieces;
+ delete[] __ne_seqs;
+
+ return __target + __length;
+ }
+
+ /**
+ * @brief Multiway Merge Frontend.
+ *
+ * Merge the sequences specified by seqs_begin and __seqs_end into
+ * __target. __seqs_begin and __seqs_end must point to a sequence of
+ * pairs. These pairs must contain an iterator to the beginning
+ * of a sequence in their first entry and an iterator the _M_end of
+ * the same sequence in their second entry.
+ *
+ * Ties are broken arbitrarily. See stable_multiway_merge for a variant
+ * that breaks ties by sequence number but is slower.
+ *
+ * The first entries of the pairs (i.e. the begin iterators) will be moved
+ * forward.
+ *
+ * The output sequence has to provide enough space for all elements
+ * that are written to it.
+ *
+ * This function will merge the input sequences:
+ *
+ * - not stable
+ * - parallel, depending on the input size and Settings
+ * - using sampling for splitting
+ * - not using sentinels
+ *
+ * Example:
+ *
+ * <pre>
+ * int sequences[10][10];
+ * for (int __i = 0; __i < 10; ++__i)
+ * for (int __j = 0; __i < 10; ++__j)
+ * sequences[__i][__j] = __j;
+ *
+ * int __out[33];
+ * std::vector<std::pair<int*> > seqs;
+ * for (int __i = 0; __i < 10; ++__i)
+ * { seqs.push(std::make_pair<int*>(sequences[__i],
+ * sequences[__i] + 10)) }
+ *
+ * multiway_merge(seqs.begin(), seqs.end(), __target, std::less<int>(), 33);
+ * </pre>
+ *
+ * @see stable_multiway_merge
+ *
+ * @pre All input sequences must be sorted.
+ * @pre Target must provide enough space to merge out length elements or
+ * the number of elements in all sequences, whichever is smaller.
+ *
+ * @post [__target, return __value) contains merged __elements from the
+ * input sequences.
+ * @post return __value - __target = min(__length, number of elements in all
+ * sequences).
+ *
+ * @tparam _RAIterPairIterator iterator over sequence
+ * of pairs of iterators
+ * @tparam _RAIterOut iterator over target sequence
+ * @tparam _DifferenceTp difference type for the sequence
+ * @tparam _Compare strict weak ordering type to compare elements
+ * in sequences
+ *
+ * @param __seqs_begin __begin of sequence __sequence
+ * @param __seqs_end _M_end of sequence __sequence
+ * @param __target target sequence to merge to.
+ * @param __comp strict weak ordering to use for element comparison.
+ * @param __length Maximum length to merge, possibly larger than the
+ * number of elements available.
+ *
+ * @return _M_end iterator of output sequence
+ */
+ // multiway_merge
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::sequential_tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute multiway merge *sequentially*.
+ return __sequential_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::exact_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_exact_splitting</* __stable = */ false,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::sampling_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_exact_splitting</* __stable = */ false,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ parallel_tag __tag = parallel_tag(0))
+ { return multiway_merge(__seqs_begin, __seqs_end, __target, __length,
+ __comp, exact_tag(__tag.__get_num_threads())); }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ default_parallel_tag __tag)
+ { return multiway_merge(__seqs_begin, __seqs_end, __target, __length,
+ __comp, exact_tag(__tag.__get_num_threads())); }
+
+ // stable_multiway_merge
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::sequential_tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute multiway merge *sequentially*.
+ return __sequential_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::exact_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_exact_splitting</* __stable = */ true,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ sampling_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_sampling_splitting</* __stable = */ true,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ false>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ parallel_tag __tag = parallel_tag(0))
+ {
+ return stable_multiway_merge
+ (__seqs_begin, __seqs_end, __target, __length, __comp,
+ exact_tag(__tag.__get_num_threads()));
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ default_parallel_tag __tag)
+ {
+ return stable_multiway_merge
+ (__seqs_begin, __seqs_end, __target, __length, __comp,
+ exact_tag(__tag.__get_num_threads()));
+ }
+
+ /**
+ * @brief Multiway Merge Frontend.
+ *
+ * Merge the sequences specified by seqs_begin and __seqs_end into
+ * __target. __seqs_begin and __seqs_end must point to a sequence of
+ * pairs. These pairs must contain an iterator to the beginning
+ * of a sequence in their first entry and an iterator the _M_end of
+ * the same sequence in their second entry.
+ *
+ * Ties are broken arbitrarily. See stable_multiway_merge for a variant
+ * that breaks ties by sequence number but is slower.
+ *
+ * The first entries of the pairs (i.e. the begin iterators) will be moved
+ * forward accordingly.
+ *
+ * The output sequence has to provide enough space for all elements
+ * that are written to it.
+ *
+ * This function will merge the input sequences:
+ *
+ * - not stable
+ * - parallel, depending on the input size and Settings
+ * - using sampling for splitting
+ * - using sentinels
+ *
+ * You have to take care that the element the _M_end iterator points to is
+ * readable and contains a value that is greater than any other non-sentinel
+ * value in all sequences.
+ *
+ * Example:
+ *
+ * <pre>
+ * int sequences[10][11];
+ * for (int __i = 0; __i < 10; ++__i)
+ * for (int __j = 0; __i < 11; ++__j)
+ * sequences[__i][__j] = __j; // __last one is sentinel!
+ *
+ * int __out[33];
+ * std::vector<std::pair<int*> > seqs;
+ * for (int __i = 0; __i < 10; ++__i)
+ * { seqs.push(std::make_pair<int*>(sequences[__i],
+ * sequences[__i] + 10)) }
+ *
+ * multiway_merge(seqs.begin(), seqs.end(), __target, std::less<int>(), 33);
+ * </pre>
+ *
+ * @pre All input sequences must be sorted.
+ * @pre Target must provide enough space to merge out length elements or
+ * the number of elements in all sequences, whichever is smaller.
+ * @pre For each @c __i, @c __seqs_begin[__i].second must be the end
+ * marker of the sequence, but also reference the one more __sentinel
+ * element.
+ *
+ * @post [__target, return __value) contains merged __elements from the
+ * input sequences.
+ * @post return __value - __target = min(__length, number of elements in all
+ * sequences).
+ *
+ * @see stable_multiway_merge_sentinels
+ *
+ * @tparam _RAIterPairIterator iterator over sequence
+ * of pairs of iterators
+ * @tparam _RAIterOut iterator over target sequence
+ * @tparam _DifferenceTp difference type for the sequence
+ * @tparam _Compare strict weak ordering type to compare elements
+ * in sequences
+ *
+ * @param __seqs_begin __begin of sequence __sequence
+ * @param __seqs_end _M_end of sequence __sequence
+ * @param __target target sequence to merge to.
+ * @param __comp strict weak ordering to use for element comparison.
+ * @param __length Maximum length to merge, possibly larger than the
+ * number of elements available.
+ *
+ * @return _M_end iterator of output sequence
+ */
+ // multiway_merge_sentinels
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::sequential_tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute multiway merge *sequentially*.
+ return __sequential_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end,
+ __target, *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::exact_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_exact_splitting</* __stable = */ false,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ sampling_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ false, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_sampling_splitting</* __stable = */ false,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */false, /* __sentinels = */ true>(
+ __seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ parallel_tag __tag = parallel_tag(0))
+ {
+ return multiway_merge_sentinels
+ (__seqs_begin, __seqs_end, __target, __length, __comp,
+ exact_tag(__tag.__get_num_threads()));
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ default_parallel_tag __tag)
+ {
+ return multiway_merge_sentinels
+ (__seqs_begin, __seqs_end, __target, __length, __comp,
+ exact_tag(__tag.__get_num_threads()));
+ }
+
+ // stable_multiway_merge_sentinels
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::sequential_tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute multiway merge *sequentially*.
+ return __sequential_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ __gnu_parallel::exact_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_exact_splitting</* __stable = */ true,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length,
+ _Compare __comp,
+ sampling_tag __tag)
+ {
+ typedef _DifferenceTp _DifferenceType;
+ _GLIBCXX_CALL(__seqs_end - __seqs_begin)
+
+ // catch special case: no sequences
+ if (__seqs_begin == __seqs_end)
+ return __target;
+
+ // Execute merge; maybe parallel, depending on the number of merged
+ // elements and the number of sequences and global thresholds in
+ // Settings.
+ if ((__seqs_end - __seqs_begin > 1)
+ && _GLIBCXX_PARALLEL_CONDITION(
+ ((__seqs_end - __seqs_begin) >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_k)
+ && ((_SequenceIndex)__length >=
+ __gnu_parallel::_Settings::get().multiway_merge_minimal_n)))
+ return parallel_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ multiway_merge_sampling_splitting</* __stable = */ true,
+ typename std::iterator_traits<_RAIterPairIterator>
+ ::value_type*, _Compare, _DifferenceTp>,
+ static_cast<_DifferenceType>(__length), __comp,
+ __tag.__get_num_threads());
+ else
+ return __sequential_multiway_merge
+ </* __stable = */ true, /* __sentinels = */ true>
+ (__seqs_begin, __seqs_end, __target,
+ *(__seqs_begin->second), __length, __comp);
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length,
+ _Compare __comp,
+ parallel_tag __tag = parallel_tag(0))
+ {
+ return stable_multiway_merge_sentinels
+ (__seqs_begin, __seqs_end, __target, __length, __comp,
+ exact_tag(__tag.__get_num_threads()));
+ }
+
+ // public interface
+ template<typename _RAIterPairIterator,
+ typename _RAIterOut,
+ typename _DifferenceTp,
+ typename _Compare>
+ _RAIterOut
+ stable_multiway_merge_sentinels(_RAIterPairIterator __seqs_begin,
+ _RAIterPairIterator __seqs_end,
+ _RAIterOut __target,
+ _DifferenceTp __length, _Compare __comp,
+ default_parallel_tag __tag)
+ {
+ return stable_multiway_merge_sentinels
+ (__seqs_begin, __seqs_end, __target, __length, __comp,
+ exact_tag(__tag.__get_num_threads()));
+ }
+}; // namespace __gnu_parallel
+
+#endif /* _GLIBCXX_PARALLEL_MULTIWAY_MERGE_H */
projects / cross.git / blobdiff