// -*- C++ -*-
-// Copyright (C) 2007 Free Software Foundation, Inc.
+// 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 2, or (at your option) any later
+// Foundation; either version 3, or (at your option) any later
// version.
// This library is distributed in the hope that it will be useful, but
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
-// You should have received a copy of the GNU General Public License
-// along with this library; see the file COPYING. If not, write to
-// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
-// MA 02111-1307, USA.
-
-// As a special exception, you may use this file as part of a free
-// software library without restriction. Specifically, if other files
-// instantiate templates or use macros or inline functions from this
-// file, or you compile this file and link it with other files to
-// produce an executable, this file does not by itself cause the
-// resulting executable to be covered by the GNU General Public
-// License. This exception does not however invalidate any other
-// reasons why the executable file might be covered by the GNU General
-// Public License.
+// 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.
-/** @file parallel/multiway_merge.h
- * @brief Implementation of sequential and parallel multiway merge.
- * This file is a GNU parallel extension to the Standard C++ Library.
- */
+// 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/>.
-// Written by Johannes Singler.
+/** @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 <bits/stl_algo.h>
#include <parallel/features.h>
#include <parallel/parallel.h>
-#include <parallel/merge.h>
#include <parallel/losertree.h>
-#include <parallel/timing.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 LENGTH(s) ((s).second - (s).first)
+#define _GLIBCXX_PARALLEL_LENGTH(__s) ((__s).second - (__s).first)
-// XXX need iterator typedefs
namespace __gnu_parallel
{
- template<typename RandomAccessIterator, typename Comparator>
- class guarded_iterator;
-
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<(guarded_iterator<RandomAccessIterator, Comparator>& bi1,
- guarded_iterator<RandomAccessIterator, Comparator>& bi2);
-
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<=(guarded_iterator<RandomAccessIterator, Comparator>& bi1,
- guarded_iterator<RandomAccessIterator, Comparator>& bi2);
-
- /** @brief Iterator wrapper supporting an implicit supremum at the end
- of the sequence, dominating all comparisons.
- * Deriving from RandomAccessIterator is not possible since
- * RandomAccessIterator need not be a class.
- */
- template<typename RandomAccessIterator, typename Comparator>
- class guarded_iterator
- {
- private:
- /** @brief Current iterator position. */
- RandomAccessIterator current;
-
- /** @brief End iterator of the sequence. */
- RandomAccessIterator end;
-
- /** @brief Comparator. */
- Comparator& 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. */
- inline guarded_iterator(RandomAccessIterator begin,
- RandomAccessIterator end, Comparator& comp)
- : current(begin), end(end), comp(comp)
- { }
-
- /** @brief Pre-increment operator.
- * @return This. */
- inline guarded_iterator<RandomAccessIterator, Comparator>&
- operator++()
- {
- ++current;
- return *this;
- }
-
- /** @brief Dereference operator.
- * @return Referenced element. */
- inline typename std::iterator_traits<RandomAccessIterator>::value_type
- operator*()
- { return *current; }
-
- /** @brief Convert to wrapped iterator.
- * @return Wrapped iterator. */
- inline operator RandomAccessIterator()
- { return current; }
-
- friend bool
- operator< <RandomAccessIterator, Comparator>(guarded_iterator<RandomAccessIterator, Comparator>& bi1, guarded_iterator<RandomAccessIterator, Comparator>& bi2);
-
- friend bool
- operator<= <RandomAccessIterator, Comparator>(guarded_iterator<RandomAccessIterator, Comparator>& bi1, guarded_iterator<RandomAccessIterator, Comparator>& bi2);
- };
-
- /** @brief Compare two elements referenced by guarded iterators.
- * @param bi1 First iterator.
- * @param bi2 Second iterator.
- * @return @c True if less. */
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<(guarded_iterator<RandomAccessIterator, Comparator>& bi1,
- guarded_iterator<RandomAccessIterator, Comparator>& bi2)
- {
- if (bi1.current == bi1.end) //bi1 is sup
- return bi2.current == bi2.end; //bi2 is not sup
- if (bi2.current == bi2.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. */
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<=(guarded_iterator<RandomAccessIterator, Comparator>& bi1,
- guarded_iterator<RandomAccessIterator, Comparator>& bi2)
- {
- if (bi2.current == bi2.end) //bi1 is sup
- return bi1.current != bi1.end; //bi2 is not sup
- if (bi1.current == bi1.end) //bi2 is sup
- return false;
- return !(bi1.comp)(*bi2, *bi1); //normal compare
- }
-
- template<typename RandomAccessIterator, typename Comparator>
- class unguarded_iterator;
-
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<(unguarded_iterator<RandomAccessIterator, Comparator>& bi1,
- unguarded_iterator<RandomAccessIterator, Comparator>& bi2);
-
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<=(unguarded_iterator<RandomAccessIterator, Comparator>& bi1,
- unguarded_iterator<RandomAccessIterator, Comparator>& bi2);
-
- template<typename RandomAccessIterator, typename Comparator>
- class unguarded_iterator
- {
- private:
- /** @brief Current iterator position. */
- RandomAccessIterator& current;
- /** @brief Comparator. */
- mutable Comparator& 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. */
- inline unguarded_iterator(RandomAccessIterator begin,
- RandomAccessIterator end, Comparator& comp)
- : current(begin), comp(comp)
- { }
-
- /** @brief Pre-increment operator.
- * @return This. */
- inline unguarded_iterator<RandomAccessIterator, Comparator>&
- operator++()
+ 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
{
- current++;
- return *this;
- }
-
- /** @brief Dereference operator.
- * @return Referenced element. */
- inline typename std::iterator_traits<RandomAccessIterator>::value_type
- operator*()
- { return *current; }
-
- /** @brief Convert to wrapped iterator.
- * @return Wrapped iterator. */
- inline
- operator RandomAccessIterator()
- { return current; }
-
- friend bool
- operator< <RandomAccessIterator, Comparator>(unguarded_iterator<RandomAccessIterator, Comparator>& bi1, unguarded_iterator<RandomAccessIterator, Comparator>& bi2);
-
- friend bool
- operator<= <RandomAccessIterator, Comparator>(unguarded_iterator<RandomAccessIterator, Comparator>& bi1, unguarded_iterator<RandomAccessIterator, Comparator>& bi2);
- };
-
- /** @brief Compare two elements referenced by unguarded iterators.
- * @param bi1 First iterator.
- * @param bi2 Second iterator.
- * @return @c True if less. */
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<(unguarded_iterator<RandomAccessIterator, Comparator>& bi1,
- unguarded_iterator<RandomAccessIterator, Comparator>& 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. */
- template<typename RandomAccessIterator, typename Comparator>
- inline bool
- operator<=(unguarded_iterator<RandomAccessIterator, Comparator>& bi1,
- unguarded_iterator<RandomAccessIterator, Comparator>& bi2)
- {
- // Normal compare.
- return !(bi1.comp)(*bi2, *bi1);
- }
-
- /** Prepare a set of sequences to be merged without a (end) guard
- * @param seqs_begin
- * @param seqs_end
- * @param comp
- * @param min_sequence
- * @param stable
- * @pre (seqs_end - seqs_begin > 0) */
- template<typename RandomAccessIteratorIterator, typename Comparator>
- typename std::iterator_traits<typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type>::difference_type
- prepare_unguarded(RandomAccessIteratorIterator seqs_begin,
- RandomAccessIteratorIterator seqs_end, Comparator comp,
- int& min_sequence, bool stable)
- {
- _GLIBCXX_CALL(seqs_end - seqs_begin)
-
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
- typedef typename std::iterator_traits<RandomAccessIterator1>::difference_type
- difference_type;
-
- if ((*seqs_begin).first == (*seqs_begin).second)
+ 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++()
{
- // Empty sequence found, it's the first one.
- min_sequence = 0;
- return -1;
+ ++_M_current;
+ return *this;
}
- // Last element in sequence.
- value_type min = *((*seqs_begin).second - 1);
- min_sequence = 0;
- for (RandomAccessIteratorIterator s = seqs_begin + 1; s != seqs_end; s++)
+ /** @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 ((*s).first == (*s).second)
- {
- // Empty sequence found.
- min_sequence = static_cast<int>(s - seqs_begin);
- return -1;
- }
-
- // Last element in sequence.
- const value_type& v = *((*s).second - 1);
- if (comp(v, min)) //strictly smaller
- {
- min = v;
- min_sequence = static_cast<int>(s - seqs_begin);
- }
+ 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
}
- difference_type overhang_size = 0;
-
- int s = 0;
- for (s = 0; s <= min_sequence; s++)
+ /** @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)
{
- RandomAccessIterator1 split;
- if (stable)
- split = std::upper_bound(seqs_begin[s].first, seqs_begin[s].second,
- min, comp);
- else
- split = std::lower_bound(seqs_begin[s].first, seqs_begin[s].second,
- min, comp);
-
- overhang_size += seqs_begin[s].second - split;
- }
-
- for (; s < (seqs_end - seqs_begin); s++)
+ 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++()
{
- RandomAccessIterator1 split = std::lower_bound(seqs_begin[s].first, seqs_begin[s].second, min, comp);
- overhang_size += seqs_begin[s].second - split;
+ ++_M_current;
+ return *this;
}
- // So many elements will be left over afterwards.
- return overhang_size;
- }
-
- /** Prepare a set of sequences to be merged with a (end) guard (sentinel)
- * @param seqs_begin
- * @param seqs_end
- * @param comp */
- template<typename RandomAccessIteratorIterator, typename Comparator>
- typename std::iterator_traits<typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type>::difference_type
- prepare_unguarded_sentinel(RandomAccessIteratorIterator seqs_begin,
- RandomAccessIteratorIterator seqs_end,
- Comparator comp)
- {
- _GLIBCXX_CALL(seqs_end - seqs_begin)
-
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
- typedef typename std::iterator_traits<RandomAccessIterator1>::difference_type
- difference_type;
-
- // Last element in sequence.
- value_type max;
- bool max_found = false;
- for (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end; s++)
+ /** @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)
{
- if ((*s).first == (*s).second)
- continue;
-
- // Last element in sequence.
- value_type& v = *((*s).second - 1);
-
- // Strictly greater.
- if (!max_found || comp(max, v))
- max = v;
- max_found = true;
+ // Normal compare.
+ return (__bi1.__comp)(*__bi1, *__bi2);
}
- difference_type overhang_size = 0;
-
- for (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end; s++)
+ /** @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)
{
- RandomAccessIterator1 split = std::lower_bound((*s).first, (*s).second, max, comp);
- overhang_size += (*s).second - split;
-
- // Set sentinel.
- *((*s).second) = max;
+ // Normal compare.
+ return !(__bi1.__comp)(*__bi2, *__bi1);
}
-
- // So many elements will be left over afterwards.
- return overhang_size;
- }
+ };
/** @brief Highly efficient 3-way merging procedure.
- * @param seqs_begin Begin iterator of iterator pair input sequence.
- * @param seqs_end End iterator of iterator pair input sequence.
- * @param target Begin iterator out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Unused, stable anyway.
- * @return End iterator of output sequence. */
- template<template<typename RAI, typename C> class iterator, typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_3_variant(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length);
-
- typedef _DifferenceTp difference_type;
-
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
-
- if (length == 0)
- return target;
-
- iterator<RandomAccessIterator1, Comparator>
- 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;
- }
+ *
+ * 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);
-#define Merge3Case(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;
-
- Merge3Case(0, 1, 2, <=, <=);
- Merge3Case(1, 2, 0, <=, < );
- Merge3Case(2, 0, 1, < , < );
- Merge3Case(1, 0, 2, < , <=);
- Merge3Case(0, 2, 1, <=, <=);
- Merge3Case(2, 1, 0, < , < );
-
-#undef Merge3Case
-
- finish:
- ;
-
- seqs_begin[0].first = seq0;
- seqs_begin[1].first = seq1;
- seqs_begin[2].first = seq2;
-
- return target;
- }
-
- template<typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_3_combined(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length);
-
- typedef _DifferenceTp difference_type;
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
-
- int min_seq;
- RandomAccessIterator3 target_end;
-
- // Stable anyway.
- difference_type overhang = prepare_unguarded(seqs_begin, seqs_end, comp, min_seq, true);
-
- difference_type total_length = 0;
- for (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end; ++s)
- total_length += LENGTH(*s);
-
- if (overhang != -1)
- {
- difference_type unguarded_length = std::min(length, total_length - overhang);
- target_end = multiway_merge_3_variant<unguarded_iterator>
- (seqs_begin, seqs_end, target, comp, unguarded_length, stable);
- overhang = length - unguarded_length;
- }
- else
- {
- // Empty sequence found.
- overhang = length;
- target_end = target;
- }
+ typedef _DifferenceTp _DifferenceType;
-#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(target_end == target + length - overhang);
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target_end, comp));
-#endif
+ typedef typename std::iterator_traits<_RAIterIterator>
+ ::value_type::first_type
+ _RAIter1;
+ typedef typename std::iterator_traits<_RAIter1>::value_type
+ _ValueType;
- switch (min_seq)
- {
- case 0:
- // Iterators will be advanced accordingly.
- target_end = merge_advance(seqs_begin[1].first, seqs_begin[1].second,
- seqs_begin[2].first, seqs_begin[2].second,
- target_end, overhang, comp);
- break;
- case 1:
- target_end = merge_advance(seqs_begin[0].first, seqs_begin[0].second,
- seqs_begin[2].first, seqs_begin[2].second,
- target_end, overhang, comp);
- break;
- case 2:
- target_end = merge_advance(seqs_begin[0].first, seqs_begin[0].second,
- seqs_begin[1].first, seqs_begin[1].second,
- target_end, overhang, comp);
- break;
- default:
- _GLIBCXX_PARALLEL_ASSERT(false);
- }
+ if (__length == 0)
+ return __target;
#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(target_end == target + length);
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target_end, comp));
+ _DifferenceTp __orig_length = __length;
#endif
- return target_end;
- }
-
- /** @brief Highly efficient 4-way merging procedure.
- * @param seqs_begin Begin iterator of iterator pair input sequence.
- * @param seqs_end End iterator of iterator pair input sequence.
- * @param target Begin iterator out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Unused, stable anyway.
- * @return End iterator of output sequence. */
- template<template<typename RAI, typename C> class iterator, typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_4_variant(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length);
- typedef _DifferenceTp difference_type;
-
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
-
- iterator<RandomAccessIterator1, Comparator>
- 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 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)
- Decision(0,1,2,3)
- else
- if (seq2 < seq0)
- Decision(2,0,1,3)
- else
- Decision(0,2,1,3)
- }
- else
- {
- if (seq1 <= seq2)
- {
- if (seq0 <= seq2)
- Decision(1,0,2,3)
- else
- Decision(1,2,0,3)
- }
- else
- Decision(2,1,0,3)
- }
+ 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);
-#define Merge4Case(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;
-
- Merge4Case(0, 1, 2, 3, <=, <=, <=);
- Merge4Case(0, 1, 3, 2, <=, <=, <=);
- Merge4Case(0, 2, 1, 3, <=, <=, <=);
- Merge4Case(0, 2, 3, 1, <=, <=, <=);
- Merge4Case(0, 3, 1, 2, <=, <=, <=);
- Merge4Case(0, 3, 2, 1, <=, <=, <=);
- Merge4Case(1, 0, 2, 3, < , <=, <=);
- Merge4Case(1, 0, 3, 2, < , <=, <=);
- Merge4Case(1, 2, 0, 3, <=, < , <=);
- Merge4Case(1, 2, 3, 0, <=, <=, < );
- Merge4Case(1, 3, 0, 2, <=, < , <=);
- Merge4Case(1, 3, 2, 0, <=, <=, < );
- Merge4Case(2, 0, 1, 3, < , < , <=);
- Merge4Case(2, 0, 3, 1, < , <=, < );
- Merge4Case(2, 1, 0, 3, < , < , <=);
- Merge4Case(2, 1, 3, 0, < , <=, < );
- Merge4Case(2, 3, 0, 1, <=, < , < );
- Merge4Case(2, 3, 1, 0, <=, < , < );
- Merge4Case(3, 0, 1, 2, < , < , < );
- Merge4Case(3, 0, 2, 1, < , < , < );
- Merge4Case(3, 1, 0, 2, < , < , < );
- Merge4Case(3, 1, 2, 0, < , < , < );
- Merge4Case(3, 2, 0, 1, < , < , < );
- Merge4Case(3, 2, 1, 0, < , < , < );
-
-#undef Merge4Case
-#undef Decision
-
- finish:
- ;
-
- seqs_begin[0].first = seq0;
- seqs_begin[1].first = seq1;
- seqs_begin[2].first = seq2;
- seqs_begin[3].first = seq3;
-
- return target;
- }
-
- template<typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_4_combined(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length);
- typedef _DifferenceTp difference_type;
-
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
-
- int min_seq;
- RandomAccessIterator3 target_end;
-
- // Stable anyway.
- difference_type overhang = prepare_unguarded(seqs_begin, seqs_end, comp, min_seq, true);
-
- difference_type total_length = 0;
- for (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end; ++s)
- total_length += LENGTH(*s);
-
- if (overhang != -1)
- {
- difference_type unguarded_length = std::min(length, total_length - overhang);
- target_end = multiway_merge_4_variant<unguarded_iterator>
- (seqs_begin, seqs_end, target, comp, unguarded_length, stable);
- overhang = length - unguarded_length;
- }
- else
- {
- // Empty sequence found.
- overhang = length;
- target_end = target;
- }
+ 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(target_end == target + length - overhang);
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target_end, comp));
+ _GLIBCXX_PARALLEL_ASSERT(
+ ((_RAIter1)__seq0 - __seqs_begin[0].first) +
+ ((_RAIter1)__seq1 - __seqs_begin[1].first) +
+ ((_RAIter1)__seq2 - __seqs_begin[2].first)
+ == __orig_length);
#endif
- std::vector<std::pair<RandomAccessIterator1, RandomAccessIterator1> > one_missing(seqs_begin, seqs_end);
- one_missing.erase(one_missing.begin() + min_seq); //remove
-
- target_end = multiway_merge_3_variant<guarded_iterator>(one_missing.begin(), one_missing.end(), target_end, comp, overhang, stable);
+ __seqs_begin[0].first = __seq0;
+ __seqs_begin[1].first = __seq1;
+ __seqs_begin[2].first = __seq2;
- // Insert back again.
- one_missing.insert(one_missing.begin() + min_seq, seqs_begin[min_seq]);
- // Write back modified iterators.
- copy(one_missing.begin(), one_missing.end(), seqs_begin);
-
-#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(target_end == target + length);
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target_end, comp));
-#endif
-
- return target_end;
- }
+ return __target;
+ }
- /** @brief Basic multi-way merging procedure.
+ /**
+ * @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++).
*
- * The head elements are kept in a sorted array, new heads are
- * inserted linearly.
- * @param seqs_begin Begin iterator of iterator pair input sequence.
- * @param seqs_end End iterator of iterator pair input sequence.
- * @param target Begin iterator out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Stable merging incurs a performance penalty.
- * @return End iterator of output sequence.
+ * 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<typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_bubble(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length)
-
- typedef _DifferenceTp difference_type;
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
-
- // Num remaining pieces.
- int k = static_cast<int>(seqs_end - seqs_begin), nrp;
-
- value_type* pl = new value_type[k];
- int* source = new int[k];
- difference_type total_length = 0;
-
-#define POS(i) seqs_begin[(i)].first
-#define STOPS(i) seqs_begin[(i)].second
-
- // Write entries into queue.
- nrp = 0;
- for (int pi = 0; pi < k; pi++)
- {
- if (STOPS(pi) != POS(pi))
- {
- pl[nrp] = *(POS(pi));
- source[nrp] = pi;
- nrp++;
- total_length += LENGTH(seqs_begin[pi]);
- }
- }
-
- if (stable)
- {
- for (int k = 0; k < nrp - 1; k++)
- for (int pi = nrp - 1; pi > k; pi--)
- if (comp(pl[pi], pl[pi - 1]) ||
- (!comp(pl[pi - 1], pl[pi]) && source[pi] < source[pi - 1]))
- {
- std::swap(pl[pi - 1], pl[pi]);
- std::swap(source[pi - 1], source[pi]);
- }
- }
- else
- {
- for (int k = 0; k < nrp - 1; k++)
- for (int pi = nrp - 1; pi > k; pi--)
- if (comp(pl[pi], pl[pi-1]))
- {
- std::swap(pl[pi-1], pl[pi]);
- std::swap(source[pi-1], source[pi]);
- }
- }
-
- // Iterate.
- if (stable)
- {
- int j;
- while (nrp > 0 && length > 0)
- {
- if (source[0] < source[1])
- {
- // pl[0] <= pl[1]
- while ((nrp == 1 || !(comp(pl[1], pl[0]))) && length > 0)
- {
- *target = pl[0];
- ++target;
- ++POS(source[0]);
- length--;
- if (POS(source[0]) == STOPS(source[0]))
- {
- // Move everything to the left.
- for (int s = 0; s < nrp - 1; s++)
- {
- pl[s] = pl[s + 1];
- source[s] = source[s + 1];
- }
- nrp--;
- break;
- }
- else
- pl[0] = *(POS(source[0]));
- }
- }
- else
- {
- // pl[0] < pl[1]
- while ((nrp == 1 || comp(pl[0], pl[1])) && length > 0)
- {
- *target = pl[0];
- ++target;
- ++POS(source[0]);
- length--;
- if (POS(source[0]) == STOPS(source[0]))
- {
- for (int s = 0; s < nrp - 1; s++)
- {
- pl[s] = pl[s + 1];
- source[s] = source[s + 1];
- }
- nrp--;
- break;
- }
- else
- pl[0] = *(POS(source[0]));
- }
- }
-
- // Sink down.
- j = 1;
- while ((j < nrp) && (comp(pl[j], pl[j - 1]) ||
- (!comp(pl[j - 1], pl[j]) && (source[j] < source[j - 1]))))
- {
- std::swap(pl[j - 1], pl[j]);
- std::swap(source[j - 1], source[j]);
- j++;
- }
- }
- }
- else
- {
- int j;
- while (nrp > 0 && length > 0)
- {
- // pl[0] <= pl[1]
- while (nrp == 1 || (!comp(pl[1], pl[0])) && length > 0)
- {
- *target = pl[0];
- ++target;
- ++POS(source[0]);
- length--;
- if (POS(source[0]) == STOPS(source[0]))
- {
- for (int s = 0; s < (nrp - 1); s++)
- {
- pl[s] = pl[s + 1];
- source[s] = source[s + 1];
- }
- nrp--;
- break;
- }
- else
- pl[0] = *(POS(source[0]));
- }
-
- // Sink down.
- j = 1;
- while ((j < nrp) && comp(pl[j], pl[j - 1]))
- {
- std::swap(pl[j - 1], pl[j]);
- std::swap(source[j - 1], source[j]);
- j++;
- }
- }
- }
-
- delete[] pl;
- delete[] source;
-
- return target;
- }
+ 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.
- *
- * The head elements are kept in a loser tree.
- * @param seqs_begin Begin iterator of iterator pair input sequence.
- * @param seqs_end End iterator of iterator pair input sequence.
- * @param target Begin iterator out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Stable merging incurs a performance penalty.
- * @return End iterator of output sequence.
+ * 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 RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_loser_tree(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length)
-
- typedef _DifferenceTp difference_type;
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
-
- int k = static_cast<int>(seqs_end - seqs_begin);
-
- LT lt(k, comp);
-
- difference_type total_length = 0;
+ 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)
- for (int t = 0; t < k; t++)
- {
- if (stable)
- {
- if (seqs_begin[t].first == seqs_begin[t].second)
- lt.insert_start_stable(value_type(), t, true);
- else
- lt.insert_start_stable(*seqs_begin[t].first, t, false);
- }
- else
- {
- if (seqs_begin[t].first == seqs_begin[t].second)
- lt.insert_start(value_type(), t, true);
- else
- lt.insert_start(*seqs_begin[t].first, t, false);
- }
+ 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;
- total_length += LENGTH(seqs_begin[t]);
- }
+ _SeqNumber __k = static_cast<_SeqNumber>(__seqs_end - __seqs_begin);
- if (stable)
- lt.init_stable();
- else
- lt.init();
+ _LT __lt(__k, __comp);
- total_length = std::min(total_length, length);
+ // Default value for potentially non-default-constructible types.
+ _ValueType* __arbitrary_element = 0;
- int source;
+ for (_SeqNumber __t = 0; __t < __k; ++__t)
+ {
+ if(!__arbitrary_element
+ && _GLIBCXX_PARALLEL_LENGTH(__seqs_begin[__t]) > 0)
+ __arbitrary_element = &(*__seqs_begin[__t].first);
+ }
- if (stable)
- {
- for (difference_type i = 0; i < total_length; i++)
- {
- // Take out.
- source = lt.get_min_source();
+ 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);
+ }
- *(target++) = *(seqs_begin[source].first++);
+ __lt.__init();
- // Feed.
- if (seqs_begin[source].first == seqs_begin[source].second)
- lt.delete_min_insert_stable(value_type(), true);
- else
- // Replace from same source.
- lt.delete_min_insert_stable(*seqs_begin[source].first, false);
+ _SeqNumber __source;
- }
- }
- else
- {
- for (difference_type i = 0; i < total_length; i++)
- {
- //take out
- source = lt.get_min_source();
+ for (_DifferenceType __i = 0; __i < __length; ++__i)
+ {
+ //take out
+ __source = __lt.__get_min_source();
- *(target++) = *(seqs_begin[source].first++);
+ *(__target++) = *(__seqs_begin[__source].first++);
- // Feed.
- if (seqs_begin[source].first == seqs_begin[source].second)
- lt.delete_min_insert(value_type(), true);
- else
- // Replace from same source.
- lt.delete_min_insert(*seqs_begin[source].first, false);
- }
- }
+ // 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;
- }
+ return __target;
+ }
/** @brief Multi-way merging procedure for a high branching factor,
- * unguarded case.
- *
- * The head elements are kept in a loser tree.
- * @param seqs_begin Begin iterator of iterator pair input sequence.
- * @param seqs_end End iterator of iterator pair input sequence.
- * @param target Begin iterator out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Stable merging incurs a performance penalty.
- * @return End iterator of output sequence.
- * @pre No input will run out of elements during the merge.
+ * 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 RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_loser_tree_unguarded(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length)
- typedef _DifferenceTp difference_type;
-
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
+ 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;
- int k = seqs_end - seqs_begin;
+ 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;
- LT lt(k, comp);
+ _SeqNumber __k = __seqs_end - __seqs_begin;
- difference_type total_length = 0;
+ _LT __lt(__k, __sentinel, __comp);
- for (int t = 0; t < k; t++)
- {
+ for (_SeqNumber __t = 0; __t < __k; ++__t)
+ {
#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(seqs_begin[t].first != seqs_begin[t].second);
+ _GLIBCXX_PARALLEL_ASSERT(__seqs_begin[__t].first
+ != __seqs_begin[__t].second);
#endif
- if (stable)
- lt.insert_start_stable(*seqs_begin[t].first, t, false);
- else
- lt.insert_start(*seqs_begin[t].first, t, false);
-
- total_length += LENGTH(seqs_begin[t]);
- }
-
- if (stable)
- lt.init_stable();
- else
- lt.init();
+ __lt.__insert_start(*__seqs_begin[__t].first, __t, false);
+ }
- // Do not go past end.
- length = std::min(total_length, length);
+ __lt.__init();
- int source;
+ _SeqNumber __source;
#if _GLIBCXX_ASSERTIONS
- difference_type i = 0;
+ _DifferenceType __i = 0;
#endif
- if (stable)
- {
- RandomAccessIterator3 target_end = target + length;
- while (target < target_end)
- {
- // Take out.
- source = lt.get_min_source();
+ _RAIter3 __target_end = __target + __length;
+ while (__target < __target_end)
+ {
+ // Take out.
+ __source = __lt.__get_min_source();
#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(i == 0 || !comp(*(seqs_begin[source].first), *(target - 1)));
+ _GLIBCXX_PARALLEL_ASSERT(0 <= __source && __source < __k);
+ _GLIBCXX_PARALLEL_ASSERT(__i == 0
+ || !__comp(*(__seqs_begin[__source].first), *(__target - 1)));
#endif
- *(target++) = *(seqs_begin[source].first++);
+ // Feed.
+ *(__target++) = *(__seqs_begin[__source].first++);
#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT((seqs_begin[source].first != seqs_begin[source].second) || (i == length - 1));
- i++;
+ ++__i;
#endif
- // Feed.
- // Replace from same source.
- lt.delete_min_insert_stable(*seqs_begin[source].first, false);
+ // Replace from same __source.
+ __lt.__delete_min_insert(*__seqs_begin[__source].first, false);
+ }
- }
- }
- else
- {
- RandomAccessIterator3 target_end = target + length;
- while (target < target_end)
- {
- // Take out.
- source = lt.get_min_source();
+ return __target;
+ }
-#if _GLIBCXX_ASSERTIONS
- if (i > 0 && comp(*(seqs_begin[source].first), *(target - 1)))
- printf(" %i %i %i\n", length, i, source);
- _GLIBCXX_PARALLEL_ASSERT(i == 0 || !comp(*(seqs_begin[source].first), *(target - 1)));
-#endif
- *(target++) = *(seqs_begin[source].first++);
+ /** @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)
-#if _GLIBCXX_ASSERTIONS
- if (!((seqs_begin[source].first != seqs_begin[source].second) || (i >= length - 1)))
- printf(" %i %i %i\n", length, i, source);
- _GLIBCXX_PARALLEL_ASSERT((seqs_begin[source].first != seqs_begin[source].second) || (i >= length - 1));
- i++;
-#endif
- // Feed.
- // Replace from same source.
- lt.delete_min_insert(*seqs_begin[source].first, false);
- }
- }
+ 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;
- return target;
- }
-
- template<typename _ValueTp, class Comparator>
- struct loser_tree_traits
- {
- typedef LoserTree/*Pointer*/<_ValueTp, Comparator> LT;
- };
-
-
- /*#define NO_POINTER(T) \
- template<typename Comparator> \
- struct loser_tree_traits<T, Comparator> \
- { \
- typedef LoserTreePointer<T, Comparator> LT; \
- };*/
- //
- // NO_POINTER(unsigned char)
- // NO_POINTER(char)
- // NO_POINTER(unsigned short)
- // NO_POINTER(short)
- // NO_POINTER(unsigned int)
- // NO_POINTER(int)
- // NO_POINTER(unsigned long)
- // NO_POINTER(long)
- // NO_POINTER(unsigned long long)
- // NO_POINTER(long long)
- //
- // #undef NO_POINTER
-
- template<typename _ValueTp, class Comparator>
- struct loser_tree_traits_unguarded
- {
- typedef LoserTreeUnguarded<_ValueTp, Comparator> LT;
- };
-
- /*#define NO_POINTER_UNGUARDED(T) \
- template<typename Comparator> \
- struct loser_tree_traits_unguarded<T, Comparator> \
- { \
- typedef LoserTreePointerUnguarded<T, Comparator> LT; \
- };*/
- //
- // NO_POINTER_UNGUARDED(unsigned char)
- // NO_POINTER_UNGUARDED(char)
- // NO_POINTER_UNGUARDED(unsigned short)
- // NO_POINTER_UNGUARDED(short)
- // NO_POINTER_UNGUARDED(unsigned int)
- // NO_POINTER_UNGUARDED(int)
- // NO_POINTER_UNGUARDED(unsigned long)
- // NO_POINTER_UNGUARDED(long)
- // NO_POINTER_UNGUARDED(unsigned long long)
- // NO_POINTER_UNGUARDED(long long)
- //
- // #undef NO_POINTER_UNGUARDED
-
- template<typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_loser_tree_combined(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length)
-
- typedef _DifferenceTp difference_type;
-
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
-
- int min_seq;
- RandomAccessIterator3 target_end;
- difference_type overhang = prepare_unguarded(seqs_begin, seqs_end,
- comp, min_seq, stable);
-
- difference_type total_length = 0;
- for (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end; s++)
- total_length += LENGTH(*s);
-
- if (overhang != -1)
- {
- difference_type unguarded_length = std::min(length, total_length - overhang);
- target_end = multiway_merge_loser_tree_unguarded
- <typename loser_tree_traits_unguarded<value_type, Comparator>::LT>
- (seqs_begin, seqs_end, target, comp, unguarded_length, stable);
- overhang = length - unguarded_length;
- }
- else
- {
- // Empty sequence found.
- overhang = length;
- target_end = target;
- }
+ _RAIter3 __target_end;
-#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(target_end == target + length - overhang);
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target_end, comp));
-#endif
+ 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
- <typename loser_tree_traits<value_type, Comparator>::LT>
- (seqs_begin, seqs_end, target_end, comp, overhang, stable);
+ __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));
+ _GLIBCXX_PARALLEL_ASSERT(__target_end == __target + __length);
+ _GLIBCXX_PARALLEL_ASSERT(__is_sorted(__target, __target_end, __comp));
#endif
- return target_end;
- }
-
- template<typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_loser_tree_sentinel(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable)
- {
- _GLIBCXX_CALL(length)
-
- typedef _DifferenceTp difference_type;
- typedef std::iterator_traits<RandomAccessIteratorIterator> traits_type;
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
-
- RandomAccessIterator3 target_end;
- difference_type overhang = prepare_unguarded_sentinel(seqs_begin, seqs_end, comp);
-
- difference_type total_length = 0;
- for (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end; s++)
- {
- total_length += LENGTH(*s);
+ // 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);
- // Sentinel spot.
- (*s).second++;
- }
-
- difference_type unguarded_length = std::min(length, total_length - overhang);
- target_end = multiway_merge_loser_tree_unguarded
- <typename loser_tree_traits_unguarded<value_type, Comparator>::LT>
- (seqs_begin, seqs_end, target, comp, unguarded_length, stable);
- overhang = length - unguarded_length;
-
-#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(target_end == target + length - overhang);
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target_end, comp));
-#endif
+ return __target_end;
+ }
- // Copy rest stable.
- for (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end && overhang > 0; s++)
+ /**
+ * @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)
{
- // Restore.
- (*s).second--;
- difference_type local_length = std::min((difference_type)overhang, (difference_type)LENGTH(*s));
- target_end = std::copy((*s).first, (*s).first + local_length, target_end);
- (*s).first += local_length;
- overhang -= local_length;
+ 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);
}
+ };
-#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(overhang == 0);
- _GLIBCXX_PARALLEL_ASSERT(target_end == target + length);
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target_end, comp));
-#endif
-
- return target_end;
- }
+ /**
+ * @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 decision if 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 out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Stable merging incurs a performance penalty.
- * @param sentinel The sequences have a sentinel element.
+ * 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<typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable, bool sentinel, sequential_tag)
- {
- _GLIBCXX_CALL(length)
-
- typedef _DifferenceTp difference_type;
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
+ 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 (RandomAccessIteratorIterator s = seqs_begin; s != seqs_end; s++)
- _GLIBCXX_PARALLEL_ASSERT(is_sorted((*s).first, (*s).second, comp));
+ for (_RAIterIterator __s = __seqs_begin; __s != __seqs_end; ++__s)
+ {
+ _GLIBCXX_PARALLEL_ASSERT(__is_sorted((*__s).first,
+ (*__s).second, __comp));
+ }
#endif
- RandomAccessIterator3 return_target = target;
- int k = static_cast<int>(seqs_end - seqs_begin);
+ _DifferenceTp __total_length = 0;
+ for (_RAIterIterator __s = __seqs_begin; __s != __seqs_end; ++__s)
+ __total_length += _GLIBCXX_PARALLEL_LENGTH(*__s);
- Settings::MultiwayMergeAlgorithm mwma = Settings::multiway_merge_algorithm;
+ __length = std::min<_DifferenceTp>(__length, __total_length);
- if (!sentinel && mwma == Settings::LOSER_TREE_SENTINEL)
- mwma = Settings::LOSER_TREE_COMBINED;
+ if(__length == 0)
+ return __target;
- 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:
- switch (mwma)
- {
- case Settings::LOSER_TREE_COMBINED:
- return_target = multiway_merge_3_combined(seqs_begin, seqs_end, target, comp, length, stable);
- break;
- case Settings::LOSER_TREE_SENTINEL:
- return_target = multiway_merge_3_variant<unguarded_iterator>(seqs_begin, seqs_end, target, comp, length, stable);
- break;
- default:
- return_target = multiway_merge_3_variant<guarded_iterator>(seqs_begin, seqs_end, target, comp, length, stable);
- break;
- }
- break;
- case 4:
- switch (mwma)
- {
- case Settings::LOSER_TREE_COMBINED:
- return_target = multiway_merge_4_combined(seqs_begin, seqs_end, target, comp, length, stable);
- break;
- case Settings::LOSER_TREE_SENTINEL:
- return_target = multiway_merge_4_variant<unguarded_iterator>(seqs_begin, seqs_end, target, comp, length, stable);
- break;
- default:
- return_target = multiway_merge_4_variant<guarded_iterator>(seqs_begin, seqs_end, target, comp, length, stable);
- break;
- }
- break;
- default:
+ _RAIter3 __return_target = __target;
+ _SeqNumber __k = static_cast<_SeqNumber>(__seqs_end - __seqs_begin);
+
+ switch (__k)
{
- switch (mwma)
- {
- case Settings::BUBBLE:
- return_target = multiway_merge_bubble(seqs_begin, seqs_end, target, comp, length, stable);
- break;
-#if _GLIBCXX_LOSER_TREE_EXPLICIT
- case Settings::LOSER_TREE_EXPLICIT:
- return_target = multiway_merge_loser_tree<LoserTreeExplicit<value_type, Comparator> >(seqs_begin, seqs_end, target, comp, length, stable);
- break;
-#endif
-#if _GLIBCXX_LOSER_TREE
- case Settings::LOSER_TREE:
- return_target = multiway_merge_loser_tree<LoserTree<value_type, Comparator> >(seqs_begin, seqs_end, target, comp, length, stable);
- break;
-#endif
-#if _GLIBCXX_LOSER_TREE_COMBINED
- case Settings::LOSER_TREE_COMBINED:
- return_target = multiway_merge_loser_tree_combined(seqs_begin, seqs_end, target, comp, length, stable);
- break;
-#endif
-#if _GLIBCXX_LOSER_TREE_SENTINEL
- case Settings::LOSER_TREE_SENTINEL:
- return_target = multiway_merge_loser_tree_sentinel(seqs_begin, seqs_end, target, comp, length, stable);
- break;
-#endif
- default:
- // multiway_merge algorithm not implemented.
- _GLIBCXX_PARALLEL_ASSERT(0);
- break;
- }
+ 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));
+ _GLIBCXX_PARALLEL_ASSERT(
+ __is_sorted(__target, __target + __length, __comp));
#endif
- return return_target;
- }
+ return __return_target;
+ }
- /** @brief Parallel multi-way merge routine.
+ /**
+ * @brief Stable sorting functor.
*
- * The decision if 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 out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Stable merging incurs a performance penalty.
- * @param sentinel Ignored.
- * @return End iterator of output sequence.
+ * Used to reduce code instanciation in multiway_merge_sampling_splitting.
*/
- template<typename RandomAccessIteratorIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- parallel_multiway_merge(RandomAccessIteratorIterator seqs_begin, RandomAccessIteratorIterator seqs_end, RandomAccessIterator3 target, Comparator comp, _DifferenceTp length, bool stable, bool sentinel)
- {
- _GLIBCXX_CALL(length)
-
- typedef _DifferenceTp difference_type;
- typedef typename std::iterator_traits<RandomAccessIteratorIterator>::value_type::first_type
- RandomAccessIterator1;
- typedef typename std::iterator_traits<RandomAccessIterator1>::value_type
- value_type;
+ template<bool __stable, class _RAIter, class _StrictWeakOrdering>
+ struct _SamplingSorter
+ {
+ void
+ operator()(_RAIter __first, _RAIter __last, _StrictWeakOrdering __comp)
+ { __gnu_sequential::stable_sort(__first, __last, __comp); }
+ };
-#if _GLIBCXX_ASSERTIONS
- for (RandomAccessIteratorIterator rii = seqs_begin; rii != seqs_end; rii++)
- _GLIBCXX_PARALLEL_ASSERT(is_sorted((*rii).first, (*rii).second, comp));
-#endif
+ /**
+ * @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);
- // k sequences.
- int k = static_cast<int>(seqs_end - seqs_begin);
+ 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]);
+ }
- difference_type total_length = 0;
- for (RandomAccessIteratorIterator raii = seqs_begin; raii != seqs_end; raii++)
- total_length += LENGTH(*raii);
+ for (_SeqNumber __s = 0; __s < __k; ++__s)
+ for (_DifferenceType __i = 0; __i < __num_samples; ++__i)
+ __samples[__s * __num_samples + __i].~_ValueType();
+ ::operator delete(__samples);
+ }
- _GLIBCXX_CALL(total_length)
+ /**
+ * @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;
- if (total_length == 0 || k == 0)
- return target;
+ const bool __tight = (__total_length == __length);
- thread_index_t num_threads = static_cast<thread_index_t>(std::min(static_cast<difference_type>(get_max_threads()), total_length));
+ // __k sequences.
+ const _SeqNumber __k = __seqs_end - __seqs_begin;
- Timing<sequential_tag>* t = new Timing<sequential_tag>[num_threads];
+ const _ThreadIndex __num_threads = omp_get_num_threads();
- for (int pr = 0; pr < num_threads; pr++)
- t[pr].tic();
+ // (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);
- bool tight = (total_length == length);
+ copy(__seqs_begin, __seqs_end, __se.begin());
- // Thread t will have to merge pieces[iam][0..k - 1]
- std::vector<std::pair<difference_type, difference_type> >* pieces = new std::vector<std::pair<difference_type, difference_type> >[num_threads];
- for (int s = 0; s < num_threads; s++)
- pieces[s].resize(k);
+ _DifferenceType* __borders =
+ new _DifferenceType[__num_threads + 1];
+ __equally_split(__length, __num_threads, __borders);
- difference_type num_samples = Settings::merge_oversampling * num_threads;
+ 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);
- if (Settings::multiway_merge_splitting == Settings::SAMPLING)
- {
- value_type* samples = new value_type[k * num_samples];
- // Sample.
- for (int s = 0; s < k; s++)
- for (int i = 0; (difference_type)i < num_samples; i++)
+ // Last one also needed and available.
+ if (!__tight)
{
- difference_type sample_index = static_cast<difference_type>(LENGTH(seqs_begin[s]) * (double(i + 1) / (num_samples + 1)) * (double(length) / total_length));
- samples[s * num_samples + i] = seqs_begin[s].first[sample_index];
+ __offsets[__num_threads - 1].resize(__k);
+ multiseq_partition(__se.begin(), __se.end(),
+ _DifferenceType(__length),
+ __offsets[__num_threads - 1].begin(),
+ __comp);
}
+ }
+ delete[] __borders;
- if (stable)
- __gnu_sequential::stable_sort(samples, samples + (num_samples * k), comp);
- else
- __gnu_sequential::sort(samples, samples + (num_samples * k), comp);
-
- for (int slab = 0; slab < num_threads; slab++)
+ for (_ThreadIndex __slab = 0; __slab < __num_threads; ++__slab)
+ {
// For each slab / processor.
- for (int seq = 0; seq < k; seq++)
+ 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
+ if (__slab == 0)
{
// Absolute beginning.
- pieces[slab][seq].first = 0;
+ __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
- pieces[slab][seq].second = LENGTH(seqs_begin[seq]); //absolute ending
+ __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[] samples;
- }
- else
- {
- // (Settings::multiway_merge_splitting == Settings::EXACT).
- std::vector<RandomAccessIterator1>* offsets = new std::vector<RandomAccessIterator1>[num_threads];
- std::vector<std::pair<RandomAccessIterator1, RandomAccessIterator1> > se(k);
-
- copy(seqs_begin, seqs_end, se.begin());
+ }
+ delete[] __offsets;
+ }
- difference_type borders[num_threads + 1];
- equally_split(length, num_threads, borders);
+ /** @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
- for (int s = 0; s < (num_threads - 1); s++)
+ _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)
{
- 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(), (difference_type)length,
- offsets[num_threads - 1].begin(), comp);
- }
+ delete[] __ne_seqs;
+ return __target;
}
+ std::vector<std::pair<_DifferenceType, _DifferenceType> >* __pieces;
- for (int slab = 0; slab < num_threads; slab++)
+ __num_threads = static_cast<_ThreadIndex>
+ (std::min<_DifferenceType>(__num_threads, __total_length));
+
+# pragma omp parallel num_threads (__num_threads)
+ {
+# pragma omp single
{
- // For each slab / processor.
- for (int 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 = LENGTH(seqs_begin[seq]);
- }
- }
- }
- delete[] offsets;
+ __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;
}
- for (int pr = 0; pr < num_threads; pr++)
- t[pr].tic();
+ /**
+ * @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);
+ }
-# pragma omp parallel num_threads(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,
+ __gnu_parallel::exact_tag __tag)
{
- thread_index_t iam = omp_get_thread_num();
+ 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);
+ }
- t[iam].tic();
+ // 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);
+ }
- difference_type target_position = 0;
+ // 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);
+ }
- for (int c = 0; c < k; c++)
- target_position += pieces[iam][c].first;
+ // 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);
+ }
- if (k > 2)
- {
- std::pair<RandomAccessIterator1, RandomAccessIterator1>* chunks = new std::pair<RandomAccessIterator1, RandomAccessIterator1>[k];
+ // 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);
+ }
- difference_type local_length = 0;
- for (int s = 0; s < k; s++)
- {
- chunks[s] = std::make_pair(seqs_begin[s].first + pieces[iam][s].first, seqs_begin[s].first + pieces[iam][s].second);
- local_length += LENGTH(chunks[s]);
- }
+ // 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()));
+ }
- multiway_merge(chunks, chunks + k, target + target_position, comp,
- std::min(local_length, length - target_position),
- stable, false, sequential_tag());
+ // 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()));
+ }
- delete[] chunks;
- }
- else if (k == 2)
- {
- RandomAccessIterator1 begin0 = seqs_begin[0].first + pieces[iam][0].first, begin1 = seqs_begin[1].first + pieces[iam][1].first;
- merge_advance(begin0,
- seqs_begin[0].first + pieces[iam][0].second,
- begin1,
- seqs_begin[1].first + pieces[iam][1].second,
- target + target_position,
- (pieces[iam][0].second - pieces[iam][0].first) + (pieces[iam][1].second - pieces[iam][1].first),
- comp);
- }
+ /**
+ * @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);
+ }
- t[iam].tic();
+ // 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()));
}
- for (int pr = 0; pr < num_threads; pr++)
- t[pr].tic();
+ // 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()));
+ }
-#if _GLIBCXX_ASSERTIONS
- _GLIBCXX_PARALLEL_ASSERT(is_sorted(target, target + length, comp));
-#endif
+ // 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);
+ }
- // Update ends of sequences.
- for (int s = 0; s < k; s++)
- seqs_begin[s].first += pieces[num_threads - 1][s].second;
-
- delete[] pieces;
-
- for (int pr = 0; pr < num_threads; pr++)
- t[pr].tic();
- for (int pr = 0; pr < num_threads; pr++)
- t[pr].print();
- delete[] t;
-
- return target + length;
- }
-
- /**
- * @brief Multi-way merging front-end.
- * @param seqs_begin Begin iterator of iterator pair input sequence.
- * @param seqs_end End iterator of iterator pair input sequence.
- * @param target Begin iterator out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Stable merging incurs a performance penalty.
- * @return End iterator of output sequence.
- */
- template<typename RandomAccessIteratorPairIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge(RandomAccessIteratorPairIterator seqs_begin,
- RandomAccessIteratorPairIterator seqs_end,
- RandomAccessIterator3 target, Comparator comp,
- _DifferenceTp length, bool stable)
- {
- typedef _DifferenceTp difference_type;
- _GLIBCXX_CALL(seqs_end - seqs_begin)
-
- if (seqs_begin == seqs_end)
- return target;
-
- RandomAccessIterator3 target_end;
- if (_GLIBCXX_PARALLEL_CONDITION(((seqs_end - seqs_begin) >= Settings::multiway_merge_minimal_k) && ((sequence_index_t)length >= Settings::multiway_merge_minimal_n)))
- target_end = parallel_multiway_merge(seqs_begin, seqs_end, target, comp, (difference_type)length, stable, false);
- else
- target_end = multiway_merge(seqs_begin, seqs_end, target, comp, length, stable, false, sequential_tag());
-
- return target_end;
- }
-
- /** @brief Multi-way merging front-end.
- * @param seqs_begin Begin iterator of iterator pair input sequence.
- * @param seqs_end End iterator of iterator pair input sequence.
- * @param target Begin iterator out output sequence.
- * @param comp Comparator.
- * @param length Maximum length to merge.
- * @param stable Stable merging incurs a performance penalty.
- * @return End iterator of output sequence.
- * @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. */
- template<typename RandomAccessIteratorPairIterator, typename RandomAccessIterator3, typename _DifferenceTp, typename Comparator>
- RandomAccessIterator3
- multiway_merge_sentinel(RandomAccessIteratorPairIterator seqs_begin,
- RandomAccessIteratorPairIterator seqs_end,
- RandomAccessIterator3 target,
- Comparator comp,
- _DifferenceTp length,
- bool stable)
- {
- typedef _DifferenceTp difference_type;
-
- if (seqs_begin == seqs_end)
- return target;
-
- _GLIBCXX_CALL(seqs_end - seqs_begin)
-
- if (_GLIBCXX_PARALLEL_CONDITION(((seqs_end - seqs_begin) >= Settings::multiway_merge_minimal_k) && ((sequence_index_t)length >= Settings::multiway_merge_minimal_n)))
- return parallel_multiway_merge(seqs_begin, seqs_end, target, comp, (typename std::iterator_traits<RandomAccessIterator3>::difference_type)length, stable, true);
- else
- return multiway_merge(seqs_begin, seqs_end, target, comp, length, stable, true, sequential_tag());
- }
-}
+ // 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);
+ }
-#endif
+ // 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 */
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