losertree.h
Go to the documentation of this file.
// -*- C++ -*-
// Copyright (C) 2007-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software
// Foundation; either version 3, or (at your option) any later
// version.
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file parallel/losertree.h
* @brief Many generic loser tree variants.
* This file is a GNU parallel extension to the Standard C++ Library.
*/
// Written by Johannes Singler.
#ifndef _GLIBCXX_PARALLEL_LOSERTREE_H
#define _GLIBCXX_PARALLEL_LOSERTREE_H 1
#include <bits/stl_algobase.h>
#include <bits/stl_function.h>
#include <parallel/features.h>
#include <parallel/base.h>
namespace __gnu_parallel
{
/**
* @brief Guarded loser/tournament tree.
*
* The smallest element is at the top.
*
* Guarding is done explicitly through one flag _M_sup per element,
* inf is not needed due to a better initialization routine. This
* is a well-performing variant.
*
* @param _Tp the element type
* @param _Compare the comparator to use, defaults to std::less<_Tp>
*/
template<typename _Tp, typename _Compare>
class _LoserTreeBase
{
protected:
/** @brief Internal representation of a _LoserTree element. */
struct _Loser
{
/** @brief flag, true iff this is a "maximum" __sentinel. */
bool _M_sup;
/** @brief __index of the __source __sequence. */
int _M_source;
/** @brief _M_key of the element in the _LoserTree. */
_Tp _M_key;
};
unsigned int _M_ik, _M_k, _M_offset;
/** log_2{_M_k} */
unsigned int _M_log_k;
/** @brief _LoserTree __elements. */
_Loser* _M_losers;
/** @brief _Compare to use. */
_Compare _M_comp;
/**
* @brief State flag that determines whether the _LoserTree is empty.
*
* Only used for building the _LoserTree.
*/
bool _M_first_insert;
public:
/**
* @brief The constructor.
*
* @param __k The number of sequences to merge.
* @param __comp The comparator to use.
*/
_LoserTreeBase(unsigned int __k, _Compare __comp)
: _M_comp(__comp)
{
_M_ik = __k;
// Compute log_2{_M_k} for the _Loser Tree
_M_log_k = __rd_log2(_M_ik - 1) + 1;
// Next greater power of 2.
_M_k = 1 << _M_log_k;
_M_offset = _M_k;
// Avoid default-constructing _M_losers[]._M_key
_M_losers = static_cast<_Loser*>(::operator new(2 * _M_k
* sizeof(_Loser)));
for (unsigned int __i = _M_ik - 1; __i < _M_k; ++__i)
_M_losers[__i + _M_k]._M_sup = true;
_M_first_insert = true;
}
/**
* @brief The destructor.
*/
~_LoserTreeBase()
{
for (unsigned int __i = 0; __i < (2 * _M_k); ++__i)
_M_losers[__i].~_Loser();
::operator delete(_M_losers);
}
/**
* @brief Initializes the sequence "_M_source" with the element "__key".
*
* @param __key the element to insert
* @param __source __index of the __source __sequence
* @param __sup flag that determines whether the value to insert is an
* explicit __supremum.
*/
void
__insert_start(const _Tp& __key, int __source, bool __sup)
{
unsigned int __pos = _M_k + __source;
if (_M_first_insert)
{
// Construct all keys, so we can easily destruct them.
for (unsigned int __i = 0; __i < (2 * _M_k); ++__i)
::new(&(_M_losers[__i]._M_key)) _Tp(__key);
_M_first_insert = false;
}
else
_M_losers[__pos]._M_key = __key;
_M_losers[__pos]._M_sup = __sup;
_M_losers[__pos]._M_source = __source;
}
/**
* @return the index of the sequence with the smallest element.
*/
int __get_min_source()
{ return _M_losers[0]._M_source; }
};
/**
* @brief Stable _LoserTree variant.
*
* Provides the stable implementations of insert_start, __init_winner,
* __init and __delete_min_insert.
*
* Unstable variant is done using partial specialisation below.
*/
template<bool __stable/* default == true */, typename _Tp,
typename _Compare>
class _LoserTree
: public _LoserTreeBase<_Tp, _Compare>
{
typedef _LoserTreeBase<_Tp, _Compare> _Base;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
using _Base::_M_first_insert;
public:
_LoserTree(unsigned int __k, _Compare __comp)
: _Base::_LoserTreeBase(__k, __comp)
{ }
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
if (_M_losers[__right]._M_sup
|| (!_M_losers[__left]._M_sup
&& !_M_comp(_M_losers[__right]._M_key,
_M_losers[__left]._M_key)))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void __init()
{ _M_losers[0] = _M_losers[__init_winner(1)]; }
/**
* @brief Delete the smallest element and insert a new element from
* the previously smallest element's sequence.
*
* This implementation is stable.
*/
// Do not pass a const reference since __key will be used as
// local variable.
void
__delete_min_insert(_Tp __key, bool __sup)
{
using std::swap;
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted, ties are broken by _M_source.
if ((__sup && (!_M_losers[__pos]._M_sup
|| _M_losers[__pos]._M_source < __source))
|| (!__sup && !_M_losers[__pos]._M_sup
&& ((_M_comp(_M_losers[__pos]._M_key, __key))
|| (!_M_comp(__key, _M_losers[__pos]._M_key)
&& _M_losers[__pos]._M_source < __source))))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_sup, __sup);
std::swap(_M_losers[__pos]._M_source, __source);
swap(_M_losers[__pos]._M_key, __key);
}
}
_M_losers[0]._M_sup = __sup;
_M_losers[0]._M_source = __source;
_M_losers[0]._M_key = __key;
}
};
/**
* @brief Unstable _LoserTree variant.
*
* Stability (non-stable here) is selected with partial specialization.
*/
template<typename _Tp, typename _Compare>
class _LoserTree</* __stable == */false, _Tp, _Compare>
: public _LoserTreeBase<_Tp, _Compare>
{
typedef _LoserTreeBase<_Tp, _Compare> _Base;
using _Base::_M_log_k;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
using _Base::_M_first_insert;
public:
_LoserTree(unsigned int __k, _Compare __comp)
: _Base::_LoserTreeBase(__k, __comp)
{ }
/**
* Computes the winner of the competition at position "__root".
*
* Called recursively (starting at 0) to build the initial tree.
*
* @param __root __index of the "game" to start.
*/
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
if (_M_losers[__right]._M_sup
|| (!_M_losers[__left]._M_sup
&& !_M_comp(_M_losers[__right]._M_key,
_M_losers[__left]._M_key)))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void
__init()
{ _M_losers[0] = _M_losers[__init_winner(1)]; }
/**
* Delete the _M_key smallest element and insert the element __key
* instead.
*
* @param __key the _M_key to insert
* @param __sup true iff __key is an explicitly marked supremum
*/
// Do not pass a const reference since __key will be used as local
// variable.
void
__delete_min_insert(_Tp __key, bool __sup)
{
using std::swap;
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted.
if (__sup || (!_M_losers[__pos]._M_sup
&& _M_comp(_M_losers[__pos]._M_key, __key)))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_sup, __sup);
std::swap(_M_losers[__pos]._M_source, __source);
swap(_M_losers[__pos]._M_key, __key);
}
}
_M_losers[0]._M_sup = __sup;
_M_losers[0]._M_source = __source;
_M_losers[0]._M_key = __key;
}
};
/**
* @brief Base class of _Loser Tree implementation using pointers.
*/
template<typename _Tp, typename _Compare>
class _LoserTreePointerBase
{
protected:
/** @brief Internal representation of _LoserTree __elements. */
struct _Loser
{
bool _M_sup;
int _M_source;
const _Tp* _M_keyp;
};
unsigned int _M_ik, _M_k, _M_offset;
_Loser* _M_losers;
_Compare _M_comp;
public:
_LoserTreePointerBase(unsigned int __k,
_Compare __comp = std::less<_Tp>())
: _M_comp(__comp)
{
_M_ik = __k;
// Next greater power of 2.
_M_k = 1 << (__rd_log2(_M_ik - 1) + 1);
_M_offset = _M_k;
_M_losers = new _Loser[_M_k * 2];
for (unsigned int __i = _M_ik - 1; __i < _M_k; __i++)
_M_losers[__i + _M_k]._M_sup = true;
}
~_LoserTreePointerBase()
{ delete[] _M_losers; }
int __get_min_source()
{ return _M_losers[0]._M_source; }
void __insert_start(const _Tp& __key, int __source, bool __sup)
{
unsigned int __pos = _M_k + __source;
_M_losers[__pos]._M_sup = __sup;
_M_losers[__pos]._M_source = __source;
_M_losers[__pos]._M_keyp = &__key;
}
};
/**
* @brief Stable _LoserTree implementation.
*
* The unstable variant is implemented using partial instantiation below.
*/
template<bool __stable/* default == true */, typename _Tp, typename _Compare>
class _LoserTreePointer
: public _LoserTreePointerBase<_Tp, _Compare>
{
typedef _LoserTreePointerBase<_Tp, _Compare> _Base;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
public:
_LoserTreePointer(unsigned int __k, _Compare __comp = std::less<_Tp>())
: _Base::_LoserTreePointerBase(__k, __comp)
{ }
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
if (_M_losers[__right]._M_sup
|| (!_M_losers[__left]._M_sup
&& !_M_comp(*_M_losers[__right]._M_keyp,
*_M_losers[__left]._M_keyp)))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void __init()
{ _M_losers[0] = _M_losers[__init_winner(1)]; }
void __delete_min_insert(const _Tp& __key, bool __sup)
{
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
const _Tp* __keyp = &__key;
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted, ties are broken by __source.
if ((__sup && (!_M_losers[__pos]._M_sup
|| _M_losers[__pos]._M_source < __source))
|| (!__sup && !_M_losers[__pos]._M_sup &&
((_M_comp(*_M_losers[__pos]._M_keyp, *__keyp))
|| (!_M_comp(*__keyp, *_M_losers[__pos]._M_keyp)
&& _M_losers[__pos]._M_source < __source))))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_sup, __sup);
std::swap(_M_losers[__pos]._M_source, __source);
std::swap(_M_losers[__pos]._M_keyp, __keyp);
}
}
_M_losers[0]._M_sup = __sup;
_M_losers[0]._M_source = __source;
_M_losers[0]._M_keyp = __keyp;
}
};
/**
* @brief Unstable _LoserTree implementation.
*
* The stable variant is above.
*/
template<typename _Tp, typename _Compare>
class _LoserTreePointer</* __stable == */false, _Tp, _Compare>
: public _LoserTreePointerBase<_Tp, _Compare>
{
typedef _LoserTreePointerBase<_Tp, _Compare> _Base;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
public:
_LoserTreePointer(unsigned int __k, _Compare __comp = std::less<_Tp>())
: _Base::_LoserTreePointerBase(__k, __comp)
{ }
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
if (_M_losers[__right]._M_sup
|| (!_M_losers[__left]._M_sup
&& !_M_comp(*_M_losers[__right]._M_keyp,
*_M_losers[__left]._M_keyp)))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void __init()
{ _M_losers[0] = _M_losers[__init_winner(1)]; }
void __delete_min_insert(const _Tp& __key, bool __sup)
{
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
const _Tp* __keyp = &__key;
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted.
if (__sup || (!_M_losers[__pos]._M_sup
&& _M_comp(*_M_losers[__pos]._M_keyp, *__keyp)))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_sup, __sup);
std::swap(_M_losers[__pos]._M_source, __source);
std::swap(_M_losers[__pos]._M_keyp, __keyp);
}
}
_M_losers[0]._M_sup = __sup;
_M_losers[0]._M_source = __source;
_M_losers[0]._M_keyp = __keyp;
}
};
/** @brief Base class for unguarded _LoserTree implementation.
*
* The whole element is copied into the tree structure.
*
* No guarding is done, therefore not a single input sequence must
* run empty. Unused __sequence heads are marked with a sentinel which
* is &gt; all elements that are to be merged.
*
* This is a very fast variant.
*/
template<typename _Tp, typename _Compare>
class _LoserTreeUnguardedBase
{
protected:
struct _Loser
{
int _M_source;
_Tp _M_key;
};
unsigned int _M_ik, _M_k, _M_offset;
_Loser* _M_losers;
_Compare _M_comp;
public:
_LoserTreeUnguardedBase(unsigned int __k, const _Tp& __sentinel,
_Compare __comp = std::less<_Tp>())
: _M_comp(__comp)
{
_M_ik = __k;
// Next greater power of 2.
_M_k = 1 << (__rd_log2(_M_ik - 1) + 1);
_M_offset = _M_k;
// Avoid default-constructing _M_losers[]._M_key
_M_losers = static_cast<_Loser*>(::operator new(2 * _M_k
* sizeof(_Loser)));
for (unsigned int __i = 0; __i < _M_k; ++__i)
{
::new(&(_M_losers[__i]._M_key)) _Tp(__sentinel);
_M_losers[__i]._M_source = -1;
}
for (unsigned int __i = _M_k + _M_ik - 1; __i < (2 * _M_k); ++__i)
{
::new(&(_M_losers[__i]._M_key)) _Tp(__sentinel);
_M_losers[__i]._M_source = -1;
}
}
~_LoserTreeUnguardedBase()
{
for (unsigned int __i = 0; __i < (2 * _M_k); ++__i)
_M_losers[__i].~_Loser();
::operator delete(_M_losers);
}
int
__get_min_source()
{
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
return _M_losers[0]._M_source;
}
void
__insert_start(const _Tp& __key, int __source, bool)
{
unsigned int __pos = _M_k + __source;
::new(&(_M_losers[__pos]._M_key)) _Tp(__key);
_M_losers[__pos]._M_source = __source;
}
};
/**
* @brief Stable implementation of unguarded _LoserTree.
*
* Unstable variant is selected below with partial specialization.
*/
template<bool __stable/* default == true */, typename _Tp, typename _Compare>
class _LoserTreeUnguarded
: public _LoserTreeUnguardedBase<_Tp, _Compare>
{
typedef _LoserTreeUnguardedBase<_Tp, _Compare> _Base;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
public:
_LoserTreeUnguarded(unsigned int __k, const _Tp& __sentinel,
_Compare __comp = std::less<_Tp>())
: _Base::_LoserTreeUnguardedBase(__k, __sentinel, __comp)
{ }
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
if (!_M_comp(_M_losers[__right]._M_key,
_M_losers[__left]._M_key))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void
__init()
{
_M_losers[0] = _M_losers[__init_winner(1)];
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top at the beginning
// (0 sequences!)
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
}
// Do not pass a const reference since __key will be used as
// local variable.
void
__delete_min_insert(_Tp __key, bool)
{
using std::swap;
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted, ties are broken by _M_source.
if (_M_comp(_M_losers[__pos]._M_key, __key)
|| (!_M_comp(__key, _M_losers[__pos]._M_key)
&& _M_losers[__pos]._M_source < __source))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_source, __source);
swap(_M_losers[__pos]._M_key, __key);
}
}
_M_losers[0]._M_source = __source;
_M_losers[0]._M_key = __key;
}
};
/**
* @brief Non-Stable implementation of unguarded _LoserTree.
*
* Stable implementation is above.
*/
template<typename _Tp, typename _Compare>
class _LoserTreeUnguarded</* __stable == */false, _Tp, _Compare>
: public _LoserTreeUnguardedBase<_Tp, _Compare>
{
typedef _LoserTreeUnguardedBase<_Tp, _Compare> _Base;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
public:
_LoserTreeUnguarded(unsigned int __k, const _Tp& __sentinel,
_Compare __comp = std::less<_Tp>())
: _Base::_LoserTreeUnguardedBase(__k, __sentinel, __comp)
{ }
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
#if _GLIBCXX_PARALLEL_ASSERTIONS
// If __left one is sentinel then __right one must be, too.
if (_M_losers[__left]._M_source == -1)
_GLIBCXX_PARALLEL_ASSERT(_M_losers[__right]._M_source == -1);
#endif
if (!_M_comp(_M_losers[__right]._M_key,
_M_losers[__left]._M_key))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void
__init()
{
_M_losers[0] = _M_losers[__init_winner(1)];
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top at the beginning
// (0 sequences!)
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
}
// Do not pass a const reference since __key will be used as
// local variable.
void
__delete_min_insert(_Tp __key, bool)
{
using std::swap;
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted.
if (_M_comp(_M_losers[__pos]._M_key, __key))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_source, __source);
swap(_M_losers[__pos]._M_key, __key);
}
}
_M_losers[0]._M_source = __source;
_M_losers[0]._M_key = __key;
}
};
/** @brief Unguarded loser tree, keeping only pointers to the
* elements in the tree structure.
*
* No guarding is done, therefore not a single input sequence must
* run empty. This is a very fast variant.
*/
template<typename _Tp, typename _Compare>
class _LoserTreePointerUnguardedBase
{
protected:
struct _Loser
{
int _M_source;
const _Tp* _M_keyp;
};
unsigned int _M_ik, _M_k, _M_offset;
_Loser* _M_losers;
_Compare _M_comp;
public:
_LoserTreePointerUnguardedBase(unsigned int __k, const _Tp& __sentinel,
_Compare __comp = std::less<_Tp>())
: _M_comp(__comp)
{
_M_ik = __k;
// Next greater power of 2.
_M_k = 1 << (__rd_log2(_M_ik - 1) + 1);
_M_offset = _M_k;
// Avoid default-constructing _M_losers[]._M_key
_M_losers = new _Loser[2 * _M_k];
for (unsigned int __i = _M_k + _M_ik - 1; __i < (2 * _M_k); ++__i)
{
_M_losers[__i]._M_keyp = &__sentinel;
_M_losers[__i]._M_source = -1;
}
}
~_LoserTreePointerUnguardedBase()
{ delete[] _M_losers; }
int
__get_min_source()
{
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
return _M_losers[0]._M_source;
}
void
__insert_start(const _Tp& __key, int __source, bool)
{
unsigned int __pos = _M_k + __source;
_M_losers[__pos]._M_keyp = &__key;
_M_losers[__pos]._M_source = __source;
}
};
/**
* @brief Stable unguarded _LoserTree variant storing pointers.
*
* Unstable variant is implemented below using partial specialization.
*/
template<bool __stable/* default == true */, typename _Tp, typename _Compare>
class _LoserTreePointerUnguarded
: public _LoserTreePointerUnguardedBase<_Tp, _Compare>
{
typedef _LoserTreePointerUnguardedBase<_Tp, _Compare> _Base;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
public:
_LoserTreePointerUnguarded(unsigned int __k, const _Tp& __sentinel,
_Compare __comp = std::less<_Tp>())
: _Base::_LoserTreePointerUnguardedBase(__k, __sentinel, __comp)
{ }
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
if (!_M_comp(*_M_losers[__right]._M_keyp,
*_M_losers[__left]._M_keyp))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void
__init()
{
_M_losers[0] = _M_losers[__init_winner(1)];
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top at the beginning
// (0 sequences!)
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
}
void
__delete_min_insert(const _Tp& __key, bool __sup)
{
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
const _Tp* __keyp = &__key;
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted, ties are broken by _M_source.
if (_M_comp(*_M_losers[__pos]._M_keyp, *__keyp)
|| (!_M_comp(*__keyp, *_M_losers[__pos]._M_keyp)
&& _M_losers[__pos]._M_source < __source))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_source, __source);
std::swap(_M_losers[__pos]._M_keyp, __keyp);
}
}
_M_losers[0]._M_source = __source;
_M_losers[0]._M_keyp = __keyp;
}
};
/**
* @brief Unstable unguarded _LoserTree variant storing pointers.
*
* Stable variant is above.
*/
template<typename _Tp, typename _Compare>
class _LoserTreePointerUnguarded</* __stable == */false, _Tp, _Compare>
: public _LoserTreePointerUnguardedBase<_Tp, _Compare>
{
typedef _LoserTreePointerUnguardedBase<_Tp, _Compare> _Base;
using _Base::_M_k;
using _Base::_M_comp;
using _Base::_M_losers;
public:
_LoserTreePointerUnguarded(unsigned int __k, const _Tp& __sentinel,
_Compare __comp = std::less<_Tp>())
: _Base::_LoserTreePointerUnguardedBase(__k, __sentinel, __comp)
{ }
unsigned int
__init_winner(unsigned int __root)
{
if (__root >= _M_k)
return __root;
else
{
unsigned int __left = __init_winner(2 * __root);
unsigned int __right = __init_winner(2 * __root + 1);
#if _GLIBCXX_PARALLEL_ASSERTIONS
// If __left one is sentinel then __right one must be, too.
if (_M_losers[__left]._M_source == -1)
_GLIBCXX_PARALLEL_ASSERT(_M_losers[__right]._M_source == -1);
#endif
if (!_M_comp(*_M_losers[__right]._M_keyp,
*_M_losers[__left]._M_keyp))
{
// Left one is less or equal.
_M_losers[__root] = _M_losers[__right];
return __left;
}
else
{
// Right one is less.
_M_losers[__root] = _M_losers[__left];
return __right;
}
}
}
void
__init()
{
_M_losers[0] = _M_losers[__init_winner(1)];
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top at the beginning
// (0 sequences!)
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
}
void
__delete_min_insert(const _Tp& __key, bool __sup)
{
#if _GLIBCXX_PARALLEL_ASSERTIONS
// no dummy sequence can ever be at the top!
_GLIBCXX_PARALLEL_ASSERT(_M_losers[0]._M_source != -1);
#endif
const _Tp* __keyp = &__key;
int __source = _M_losers[0]._M_source;
for (unsigned int __pos = (_M_k + __source) / 2; __pos > 0;
__pos /= 2)
{
// The smaller one gets promoted.
if (_M_comp(*(_M_losers[__pos]._M_keyp), *__keyp))
{
// The other one is smaller.
std::swap(_M_losers[__pos]._M_source, __source);
std::swap(_M_losers[__pos]._M_keyp, __keyp);
}
}
_M_losers[0]._M_source = __source;
_M_losers[0]._M_keyp = __keyp;
}
};
} // namespace __gnu_parallel
#endif /* _GLIBCXX_PARALLEL_LOSERTREE_H */
stl_algobase.h
stl_function.h
base.h
Sequential helper functions. This file is a GNU parallel extension to the Standard C++ Library.
features.h
Defines on whether to include algorithm variants.
std::swap
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:428
__gnu_parallel
GNU parallel code for public use.
Definition: balanced_quicksort.h:62
__gnu_parallel::__rd_log2
_Size __rd_log2(_Size __n)
Calculates the rounded-down logarithm of __n for base 2.
Definition: base.h:102
std::less
One of the comparison functors.
Definition: stl_function.h:396
__gnu_parallel::_LoserTreeBase
Guarded loser/tournament tree.
Definition: losertree.h:56
__gnu_parallel::_LoserTreeBase::_M_losers
_Loser * _M_losers
_LoserTree __elements.
Definition: losertree.h:75
__gnu_parallel::_LoserTreeBase::_M_log_k
unsigned int _M_log_k
Definition: losertree.h:72
__gnu_parallel::_LoserTreeBase::_M_comp
_Compare _M_comp
_Compare to use.
Definition: losertree.h:78
__gnu_parallel::_LoserTreeBase::~_LoserTreeBase
~_LoserTreeBase()
The destructor.
Definition: losertree.h:118
__gnu_parallel::_LoserTreeBase::_LoserTreeBase
_LoserTreeBase(unsigned int __k, _Compare __comp)
The constructor.
Definition: losertree.h:94
__gnu_parallel::_LoserTreeBase::__get_min_source
int __get_min_source()
Definition: losertree.h:155
__gnu_parallel::_LoserTreeBase::__insert_start
void __insert_start(const _Tp &__key, int __source, bool __sup)
Initializes the sequence "_M_source" with the element "__key".
Definition: losertree.h:134
__gnu_parallel::_LoserTreeBase::_M_first_insert
bool _M_first_insert
State flag that determines whether the _LoserTree is empty.
Definition: losertree.h:85
__gnu_parallel::_LoserTreeBase::_Loser
Internal representation of a _LoserTree element.
Definition: losertree.h:60
__gnu_parallel::_LoserTreeBase::_Loser::_M_source
int _M_source
__index of the __source __sequence.
Definition: losertree.h:64
__gnu_parallel::_LoserTreeBase::_Loser::_M_sup
bool _M_sup
flag, true iff this is a "maximum" __sentinel.
Definition: losertree.h:62
__gnu_parallel::_LoserTreeBase::_Loser::_M_key
_Tp _M_key
_M_key of the element in the _LoserTree.
Definition: losertree.h:66
__gnu_parallel::_LoserTree
Stable _LoserTree variant.
Definition: losertree.h:171
__gnu_parallel::_LoserTree::__delete_min_insert
void __delete_min_insert(_Tp __key, bool __sup)
Delete the smallest element and insert a new element from the previously smallest element's sequence.
Definition: losertree.h:222
__gnu_parallel::_LoserTree< false, _Tp, _Compare >::__init_winner
unsigned int __init_winner(unsigned int __root)
Definition: losertree.h:284
__gnu_parallel::_LoserTree< false, _Tp, _Compare >::__delete_min_insert
void __delete_min_insert(_Tp __key, bool __sup)
Definition: losertree.h:324
__gnu_parallel::_LoserTreePointerBase
Base class of _Loser Tree implementation using pointers.
Definition: losertree.h:358
__gnu_parallel::_LoserTreePointerBase::_Loser
Internal representation of _LoserTree __elements.
Definition: losertree.h:362
__gnu_parallel::_LoserTreePointer
Stable _LoserTree implementation.
Definition: losertree.h:411
__gnu_parallel::_LoserTreeUnguardedBase
Base class for unguarded _LoserTree implementation.
Definition: losertree.h:575
__gnu_parallel::_LoserTreeUnguarded
Stable implementation of unguarded _LoserTree.
Definition: losertree.h:648
__gnu_parallel::_LoserTreePointerUnguardedBase
Unguarded loser tree, keeping only pointers to the elements in the tree structure.
Definition: losertree.h:829
__gnu_parallel::_LoserTreePointerUnguarded
Stable unguarded _LoserTree variant storing pointers.
Definition: losertree.h:893