hash_policy.hpp
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// -*- C++ -*-
// Copyright (C) 2005-2013 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 hash_policy.hpp
* Contains hash-related policies.
*/
#ifndef PB_DS_HASH_POLICY_HPP
#define PB_DS_HASH_POLICY_HPP
#include <bits/c++config.h>
#include <algorithm>
#include <vector>
#include <cmath>
#include <ext/pb_ds/exception.hpp>
#include <ext/pb_ds/detail/type_utils.hpp>
#include <ext/pb_ds/detail/hash_fn/mask_based_range_hashing.hpp>
#include <ext/pb_ds/detail/hash_fn/mod_based_range_hashing.hpp>
#include <ext/pb_ds/detail/resize_policy/hash_load_check_resize_trigger_size_base.hpp>
namespace __gnu_pbds
{
#define PB_DS_CLASS_T_DEC template<typename Size_Type>
#define PB_DS_CLASS_C_DEC linear_probe_fn<Size_Type>
/// A probe sequence policy using fixed increments.
template<typename Size_Type = std::size_t>
class linear_probe_fn
{
public:
typedef Size_Type size_type;
void
swap(PB_DS_CLASS_C_DEC& other);
protected:
/// Returns the i-th offset from the hash value.
inline size_type
operator()(size_type i) const;
};
#include <ext/pb_ds/detail/hash_fn/linear_probe_fn_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#define PB_DS_CLASS_T_DEC template<typename Size_Type>
#define PB_DS_CLASS_C_DEC quadratic_probe_fn<Size_Type>
/// A probe sequence policy using square increments.
template<typename Size_Type = std::size_t>
class quadratic_probe_fn
{
public:
typedef Size_Type size_type;
void
swap(PB_DS_CLASS_C_DEC& other);
protected:
/// Returns the i-th offset from the hash value.
inline size_type
operator()(size_type i) const;
};
#include <ext/pb_ds/detail/hash_fn/quadratic_probe_fn_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#define PB_DS_CLASS_T_DEC template<typename Size_Type>
#define PB_DS_CLASS_C_DEC direct_mask_range_hashing<Size_Type>
/// A mask range-hashing class (uses a bitmask).
template<typename Size_Type = std::size_t>
class direct_mask_range_hashing
: public detail::mask_based_range_hashing<Size_Type>
{
private:
typedef detail::mask_based_range_hashing<Size_Type> mask_based_base;
public:
typedef Size_Type size_type;
void
swap(PB_DS_CLASS_C_DEC& other);
protected:
void
notify_resized(size_type size);
/// Transforms the __hash value hash into a ranged-hash value
/// (using a bit-mask).
inline size_type
operator()(size_type hash) const;
};
#include <ext/pb_ds/detail/hash_fn/direct_mask_range_hashing_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#define PB_DS_CLASS_T_DEC template<typename Size_Type>
#define PB_DS_CLASS_C_DEC direct_mod_range_hashing<Size_Type>
/// A mod range-hashing class (uses the modulo function).
template<typename Size_Type = std::size_t>
class direct_mod_range_hashing
: public detail::mod_based_range_hashing<Size_Type>
{
public:
typedef Size_Type size_type;
void
swap(PB_DS_CLASS_C_DEC& other);
protected:
void
notify_resized(size_type size);
/// Transforms the __hash value hash into a ranged-hash value
/// (using a modulo operation).
inline size_type
operator()(size_type hash) const;
private:
typedef detail::mod_based_range_hashing<size_type> mod_based_base;
};
#include <ext/pb_ds/detail/hash_fn/direct_mod_range_hashing_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#define PB_DS_CLASS_T_DEC template<bool External_Load_Access, typename Size_Type>
#define PB_DS_CLASS_C_DEC hash_load_check_resize_trigger<External_Load_Access, Size_Type>
#define PB_DS_SIZE_BASE_C_DEC detail::hash_load_check_resize_trigger_size_base<Size_Type, External_Load_Access>
/// A resize trigger policy based on a load check. It keeps the
/// load factor between some load factors load_min and load_max.
template<bool External_Load_Access = false, typename Size_Type = std::size_t>
class hash_load_check_resize_trigger : private PB_DS_SIZE_BASE_C_DEC
{
public:
typedef Size_Type size_type;
enum
{
/// Specifies whether the load factor can be accessed
/// externally. The two options have different trade-offs in
/// terms of flexibility, genericity, and encapsulation.
external_load_access = External_Load_Access
};
/// Default constructor, or constructor taking load_min and
/// load_max load factors between which this policy will keep the
/// actual load.
hash_load_check_resize_trigger(float load_min = 0.125,
float load_max = 0.5);
void
swap(hash_load_check_resize_trigger& other);
virtual
~hash_load_check_resize_trigger();
/// Returns a pair of the minimal and maximal loads, respectively.
inline std::pair<float, float>
get_loads() const;
/// Sets the loads through a pair of the minimal and maximal
/// loads, respectively.
void
set_loads(std::pair<float, float> load_pair);
protected:
inline void
notify_insert_search_start();
inline void
notify_insert_search_collision();
inline void
notify_insert_search_end();
inline void
notify_find_search_start();
inline void
notify_find_search_collision();
inline void
notify_find_search_end();
inline void
notify_erase_search_start();
inline void
notify_erase_search_collision();
inline void
notify_erase_search_end();
/// Notifies an element was inserted. The total number of entries
/// in the table is num_entries.
inline void
notify_inserted(size_type num_entries);
inline void
notify_erased(size_type num_entries);
/// Notifies the table was cleared.
void
notify_cleared();
/// Notifies the table was resized as a result of this object's
/// signifying that a resize is needed.
void
notify_resized(size_type new_size);
void
notify_externally_resized(size_type new_size);
inline bool
is_resize_needed() const;
inline bool
is_grow_needed(size_type size, size_type num_entries) const;
private:
virtual void
do_resize(size_type new_size);
typedef PB_DS_SIZE_BASE_C_DEC size_base;
#ifdef _GLIBCXX_DEBUG
void
assert_valid(const char* file, int line) const;
#endif
float m_load_min;
float m_load_max;
size_type m_next_shrink_size;
size_type m_next_grow_size;
bool m_resize_needed;
};
#include <ext/pb_ds/detail/resize_policy/hash_load_check_resize_trigger_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#undef PB_DS_SIZE_BASE_C_DEC
#define PB_DS_CLASS_T_DEC template<bool External_Load_Access, typename Size_Type>
#define PB_DS_CLASS_C_DEC cc_hash_max_collision_check_resize_trigger<External_Load_Access, Size_Type>
/// A resize trigger policy based on collision checks. It keeps the
/// simulated load factor lower than some given load factor.
template<bool External_Load_Access = false, typename Size_Type = std::size_t>
class cc_hash_max_collision_check_resize_trigger
{
public:
typedef Size_Type size_type;
enum
{
/// Specifies whether the load factor can be accessed
/// externally. The two options have different trade-offs in
/// terms of flexibility, genericity, and encapsulation.
external_load_access = External_Load_Access
};
/// Default constructor, or constructor taking load, a __load
/// factor which it will attempt to maintain.
cc_hash_max_collision_check_resize_trigger(float load = 0.5);
void
swap(PB_DS_CLASS_C_DEC& other);
/// Returns the current load.
inline float
get_load() const;
/// Sets the load; does not resize the container.
void
set_load(float load);
protected:
/// Notifies an insert search started.
inline void
notify_insert_search_start();
/// Notifies a search encountered a collision.
inline void
notify_insert_search_collision();
/// Notifies a search ended.
inline void
notify_insert_search_end();
/// Notifies a find search started.
inline void
notify_find_search_start();
/// Notifies a search encountered a collision.
inline void
notify_find_search_collision();
/// Notifies a search ended.
inline void
notify_find_search_end();
/// Notifies an erase search started.
inline void
notify_erase_search_start();
/// Notifies a search encountered a collision.
inline void
notify_erase_search_collision();
/// Notifies a search ended.
inline void
notify_erase_search_end();
/// Notifies an element was inserted.
inline void
notify_inserted(size_type num_entries);
/// Notifies an element was erased.
inline void
notify_erased(size_type num_entries);
/// Notifies the table was cleared.
void
notify_cleared();
/// Notifies the table was resized as a result of this object's
/// signifying that a resize is needed.
void
notify_resized(size_type new_size);
/// Notifies the table was resized externally.
void
notify_externally_resized(size_type new_size);
/// Queries whether a resize is needed.
inline bool
is_resize_needed() const;
/// Queries whether a grow is needed. This method is called only
/// if this object indicated is needed.
inline bool
is_grow_needed(size_type size, size_type num_entries) const;
private:
void
calc_max_num_coll();
inline void
calc_resize_needed();
float m_load;
size_type m_size;
size_type m_num_col;
size_type m_max_col;
bool m_resize_needed;
};
#include <ext/pb_ds/detail/resize_policy/cc_hash_max_collision_check_resize_trigger_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#define PB_DS_CLASS_T_DEC template<typename Size_Type>
#define PB_DS_CLASS_C_DEC hash_exponential_size_policy<Size_Type>
/// A size policy whose sequence of sizes form an exponential
/// sequence (typically powers of 2.
template<typename Size_Type = std::size_t>
class hash_exponential_size_policy
{
public:
typedef Size_Type size_type;
/// Default constructor, or onstructor taking a start_size, or
/// constructor taking a start size and grow_factor. The policy
/// will use the sequence of sizes start_size, start_size*
/// grow_factor, start_size* grow_factor^2, ...
hash_exponential_size_policy(size_type start_size = 8,
size_type grow_factor = 2);
void
swap(PB_DS_CLASS_C_DEC& other);
protected:
size_type
get_nearest_larger_size(size_type size) const;
size_type
get_nearest_smaller_size(size_type size) const;
private:
size_type m_start_size;
size_type m_grow_factor;
};
#include <ext/pb_ds/detail/resize_policy/hash_exponential_size_policy_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#define PB_DS_CLASS_T_DEC
#define PB_DS_CLASS_C_DEC hash_prime_size_policy
/// A size policy whose sequence of sizes form a nearly-exponential
/// sequence of primes.
class hash_prime_size_policy
{
public:
/// Size type.
typedef std::size_t size_type;
/// Default constructor, or onstructor taking a start_size The
/// policy will use the sequence of sizes approximately
/// start_size, start_size* 2, start_size* 2^2, ...
hash_prime_size_policy(size_type start_size = 8);
inline void
swap(PB_DS_CLASS_C_DEC& other);
protected:
size_type
get_nearest_larger_size(size_type size) const;
size_type
get_nearest_smaller_size(size_type size) const;
private:
size_type m_start_size;
};
#include <ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
#define PB_DS_CLASS_T_DEC template<typename Size_Policy, typename Trigger_Policy, bool External_Size_Access, typename Size_Type>
#define PB_DS_CLASS_C_DEC hash_standard_resize_policy<Size_Policy, Trigger_Policy, External_Size_Access, Size_Type>
/// A resize policy which delegates operations to size and trigger policies.
template<typename Size_Policy = hash_exponential_size_policy<>,
typename Trigger_Policy = hash_load_check_resize_trigger<>,
bool External_Size_Access = false,
typename Size_Type = std::size_t>
class hash_standard_resize_policy
: public Size_Policy, public Trigger_Policy
{
public:
typedef Size_Type size_type;
typedef Trigger_Policy trigger_policy;
typedef Size_Policy size_policy;
enum
{
external_size_access = External_Size_Access
};
/// Default constructor.
hash_standard_resize_policy();
/// constructor taking some policies r_size_policy will be copied
/// by the Size_Policy object of this object.
hash_standard_resize_policy(const Size_Policy& r_size_policy);
/// constructor taking some policies. r_size_policy will be
/// copied by the Size_Policy object of this
/// object. r_trigger_policy will be copied by the Trigger_Policy
/// object of this object.
hash_standard_resize_policy(const Size_Policy& r_size_policy,
const Trigger_Policy& r_trigger_policy);
virtual
~hash_standard_resize_policy();
inline void
swap(PB_DS_CLASS_C_DEC& other);
/// Access to the Size_Policy object used.
Size_Policy&
get_size_policy();
/// Const access to the Size_Policy object used.
const Size_Policy&
get_size_policy() const;
/// Access to the Trigger_Policy object used.
Trigger_Policy&
get_trigger_policy();
/// Access to the Trigger_Policy object used.
const Trigger_Policy&
get_trigger_policy() const;
/// Returns the actual size of the container.
inline size_type
get_actual_size() const;
/// Resizes the container to suggested_new_size, a suggested size
/// (the actual size will be determined by the Size_Policy
/// object).
void
resize(size_type suggested_new_size);
protected:
inline void
notify_insert_search_start();
inline void
notify_insert_search_collision();
inline void
notify_insert_search_end();
inline void
notify_find_search_start();
inline void
notify_find_search_collision();
inline void
notify_find_search_end();
inline void
notify_erase_search_start();
inline void
notify_erase_search_collision();
inline void
notify_erase_search_end();
inline void
notify_inserted(size_type num_e);
inline void
notify_erased(size_type num_e);
void
notify_cleared();
void
notify_resized(size_type new_size);
inline bool
is_resize_needed() const;
/// Queries what the new size should be, when the container is
/// resized naturally. The current __size of the container is
/// size, and the number of used entries within the container is
/// num_used_e.
size_type
get_new_size(size_type size, size_type num_used_e) const;
private:
/// Resizes to new_size.
virtual void
do_resize(size_type new_size);
typedef Trigger_Policy trigger_policy_base;
typedef Size_Policy size_policy_base;
size_type m_size;
};
#include <ext/pb_ds/detail/resize_policy/hash_standard_resize_policy_imp.hpp>
#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC
} // namespace __gnu_pbds
#endif