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// -*- C++ -*-
// Copyright (C) 2005, 2006, 2009 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/>.
// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
// Permission to use, copy, modify, sell, and distribute this software
// is hereby granted without fee, provided that the above copyright
// notice appears in all copies, and that both that copyright notice
// and this permission notice appear in supporting documentation. None
// of the above authors, nor IBM Haifa Research Laboratories, make any
// representation about the suitability of this software for any
// purpose. It is provided "as is" without express or implied
// warranty.
/**
* @file resize_policy.hpp
* Contains an implementation class for a binary_heap.
*/
#ifndef PB_DS_BINARY_HEAP_RESIZE_POLICY_HPP
#define PB_DS_BINARY_HEAP_RESIZE_POLICY_HPP
#include <debug/debug.h>
namespace __gnu_pbds
{
namespace detail
{
#define PB_DS_CLASS_T_DEC template<typename Size_Type>
#define PB_DS_CLASS_C_DEC resize_policy<Size_Type>
template<typename Size_Type>
class resize_policy
{
public:
typedef Size_Type size_type;
enum
{
min_size = 16
};
public:
inline
resize_policy();
inline void
swap(PB_DS_CLASS_C_DEC& other);
inline bool
resize_needed_for_grow(size_type size) const;
inline bool
resize_needed_for_shrink(size_type size) const;
inline bool
grow_needed(size_type size) const;
inline bool
shrink_needed(size_type size) const;
inline size_type
get_new_size_for_grow() const;
inline size_type
get_new_size_for_shrink() const;
size_type
get_new_size_for_arbitrary(size_type size) const;
inline void
notify_grow_resize();
inline void
notify_shrink_resize();
void
notify_arbitrary(size_type actual_size);
#ifdef _GLIBCXX_DEBUG
void
assert_valid() const;
#endif
#ifdef PB_DS_BINARY_HEAP_TRACE_
void
trace() const;
#endif
private:
enum
{
ratio = 8,
factor = 2
};
private:
size_type m_next_shrink_size;
size_type m_next_grow_size;
};
PB_DS_CLASS_T_DEC
inline
PB_DS_CLASS_C_DEC::
resize_policy() :
m_next_shrink_size(0),
m_next_grow_size(min_size)
{ _GLIBCXX_DEBUG_ONLY(assert_valid();) }
PB_DS_CLASS_T_DEC
inline void
PB_DS_CLASS_C_DEC::
swap(PB_DS_CLASS_C_DEC& other)
{
std::swap(m_next_shrink_size, other.m_next_shrink_size);
std::swap(m_next_grow_size, other.m_next_grow_size);
}
PB_DS_CLASS_T_DEC
inline bool
PB_DS_CLASS_C_DEC::
resize_needed_for_grow(size_type size) const
{
_GLIBCXX_DEBUG_ASSERT(size <= m_next_grow_size);
return size == m_next_grow_size;
}
PB_DS_CLASS_T_DEC
inline bool
PB_DS_CLASS_C_DEC::
resize_needed_for_shrink(size_type size) const
{
_GLIBCXX_DEBUG_ASSERT(size <= m_next_grow_size);
return size == m_next_shrink_size;
}
PB_DS_CLASS_T_DEC
inline typename PB_DS_CLASS_C_DEC::size_type
PB_DS_CLASS_C_DEC::
get_new_size_for_grow() const
{ return m_next_grow_size* factor; }
PB_DS_CLASS_T_DEC
inline typename PB_DS_CLASS_C_DEC::size_type
PB_DS_CLASS_C_DEC::
get_new_size_for_shrink() const
{
const size_type half_size = m_next_grow_size / factor;
return std::max(static_cast<size_type>(min_size), half_size);
}
PB_DS_CLASS_T_DEC
inline typename PB_DS_CLASS_C_DEC::size_type
PB_DS_CLASS_C_DEC::
get_new_size_for_arbitrary(size_type size) const
{
size_type ret = min_size;
while (ret < size)
ret *= factor;
return ret;
}
PB_DS_CLASS_T_DEC
inline void
PB_DS_CLASS_C_DEC::
notify_grow_resize()
{
_GLIBCXX_DEBUG_ONLY(assert_valid();)
_GLIBCXX_DEBUG_ASSERT(m_next_grow_size >= min_size);
m_next_grow_size *= factor;
m_next_shrink_size = m_next_grow_size / ratio;
_GLIBCXX_DEBUG_ONLY(assert_valid();)
}
PB_DS_CLASS_T_DEC
inline void
PB_DS_CLASS_C_DEC::
notify_shrink_resize()
{
_GLIBCXX_DEBUG_ONLY(assert_valid();)
m_next_shrink_size /= factor;
if (m_next_shrink_size == 1)
m_next_shrink_size = 0;
m_next_grow_size =
std::max(m_next_grow_size / factor, static_cast<size_type>(min_size));
_GLIBCXX_DEBUG_ONLY(assert_valid();)
}
PB_DS_CLASS_T_DEC
inline void
PB_DS_CLASS_C_DEC::
notify_arbitrary(size_type actual_size)
{
m_next_grow_size = actual_size;
m_next_shrink_size = m_next_grow_size / ratio;
_GLIBCXX_DEBUG_ONLY(assert_valid();)
}
#ifdef _GLIBCXX_DEBUG
PB_DS_CLASS_T_DEC
void
PB_DS_CLASS_C_DEC::
assert_valid() const
{
_GLIBCXX_DEBUG_ASSERT(m_next_shrink_size == 0 ||
m_next_shrink_size* ratio == m_next_grow_size);
_GLIBCXX_DEBUG_ASSERT(m_next_grow_size >= min_size);
}
#endif
#ifdef PB_DS_BINARY_HEAP_TRACE_
PB_DS_CLASS_T_DEC
void
PB_DS_CLASS_C_DEC::
trace() const
{
std::cerr << "shrink = " << m_next_shrink_size <<
" grow = " << m_next_grow_size << std::endl;
}
#endif
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
} // namespace detail
} // namespace __gnu_pbds
#endif
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