libstdc++
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00001 // -*- C++ -*- 00002 00003 // Copyright (C) 2005-2015 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the terms 00007 // of the GNU General Public License as published by the Free Software 00008 // Foundation; either version 3, or (at your option) any later 00009 // version. 00010 00011 // This library is distributed in the hope that it will be useful, but 00012 // WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00014 // General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 00026 00027 // Permission to use, copy, modify, sell, and distribute this software 00028 // is hereby granted without fee, provided that the above copyright 00029 // notice appears in all copies, and that both that copyright notice 00030 // and this permission notice appear in supporting documentation. None 00031 // of the above authors, nor IBM Haifa Research Laboratories, make any 00032 // representation about the suitability of this software for any 00033 // purpose. It is provided "as is" without express or implied 00034 // warranty. 00035 00036 /** 00037 * @file list_update_policy.hpp 00038 * Contains policies for list update containers. 00039 */ 00040 00041 #ifndef PB_DS_LU_POLICY_HPP 00042 #define PB_DS_LU_POLICY_HPP 00043 00044 #include <bits/c++config.h> 00045 #include <cstdlib> 00046 #include <ext/pb_ds/detail/list_update_policy/lu_counter_metadata.hpp> 00047 #include <ext/pb_ds/tag_and_trait.hpp> 00048 00049 namespace __gnu_pbds 00050 { 00051 /** 00052 * A list-update policy that unconditionally moves elements to the 00053 * front of the list. A null type means that each link in a 00054 * list-based container does not actually need metadata. 00055 */ 00056 template<typename _Alloc = std::allocator<char> > 00057 class lu_move_to_front_policy 00058 { 00059 public: 00060 typedef _Alloc allocator_type; 00061 00062 /// Metadata on which this functor operates. 00063 typedef null_type metadata_type; 00064 00065 private: 00066 typedef typename _Alloc::template rebind<metadata_type> __rebind_m; 00067 00068 public: 00069 /// Reference to metadata on which this functor operates. 00070 typedef typename __rebind_m::other::reference metadata_reference; 00071 00072 /// Creates a metadata object. 00073 metadata_type 00074 operator()() const 00075 { return s_metadata; } 00076 00077 /// Decides whether a metadata object should be moved to the front 00078 /// of the list. 00079 inline bool 00080 operator()(metadata_reference r_metadata) const 00081 { return true; } 00082 00083 private: 00084 static null_type s_metadata; 00085 }; 00086 00087 /** 00088 * A list-update policy that moves elements to the front of the 00089 * list based on the counter algorithm. 00090 */ 00091 template<std::size_t Max_Count = 5, typename _Alloc = std::allocator<char> > 00092 class lu_counter_policy 00093 : private detail::lu_counter_policy_base<typename _Alloc::size_type> 00094 { 00095 public: 00096 typedef _Alloc allocator_type; 00097 typedef typename allocator_type::size_type size_type; 00098 00099 enum 00100 { 00101 /// When some element is accessed this number of times, it 00102 /// will be moved to the front of the list. 00103 max_count = Max_Count 00104 }; 00105 00106 /// Metadata on which this functor operates. 00107 typedef detail::lu_counter_metadata<size_type> metadata_type; 00108 00109 private: 00110 typedef detail::lu_counter_policy_base<size_type> base_type; 00111 typedef typename _Alloc::template rebind<metadata_type> __rebind_m; 00112 00113 public: 00114 /// Reference to metadata on which this functor operates. 00115 typedef typename __rebind_m::other::reference metadata_reference; 00116 00117 /// Creates a metadata object. 00118 metadata_type 00119 operator()() const 00120 { return base_type::operator()(max_count); } 00121 00122 /// Decides whether a metadata object should be moved to the front 00123 /// of the list. 00124 bool 00125 operator()(metadata_reference r_data) const 00126 { return base_type::operator()(r_data, max_count); } 00127 }; 00128 } // namespace __gnu_pbds 00129 00130 #endif