libstdc++
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00001 // -*- C++ -*- 00002 00003 // Copyright (C) 2005, 2006, 2007, 2009, 2010, 2011 00004 // Free Software Foundation, Inc. 00005 // 00006 // This file is part of the GNU ISO C++ Library. This library is free 00007 // software; you can redistribute it and/or modify it under the terms 00008 // of the GNU General Public License as published by the Free Software 00009 // Foundation; either version 3, or (at your option) any later 00010 // version. 00011 00012 // This library is distributed in the hope that it will be useful, but 00013 // WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 // General Public License for more details. 00016 00017 // Under Section 7 of GPL version 3, you are granted additional 00018 // permissions described in the GCC Runtime Library Exception, version 00019 // 3.1, as published by the Free Software Foundation. 00020 00021 // You should have received a copy of the GNU General Public License and 00022 // a copy of the GCC Runtime Library Exception along with this program; 00023 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00024 // <http://www.gnu.org/licenses/>. 00025 00026 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 00027 00028 // Permission to use, copy, modify, sell, and distribute this software 00029 // is hereby granted without fee, provided that the above copyright 00030 // notice appears in all copies, and that both that copyright notice 00031 // and this permission notice appear in supporting documentation. None 00032 // of the above authors, nor IBM Haifa Research Laboratories, make any 00033 // representation about the suitability of this software for any 00034 // purpose. It is provided "as is" without express or implied 00035 // warranty. 00036 00037 /** 00038 * @file list_update_policy.hpp 00039 * Contains policies for list update containers. 00040 */ 00041 00042 #ifndef PB_DS_LU_POLICY_HPP 00043 #define PB_DS_LU_POLICY_HPP 00044 00045 #include <bits/c++config.h> 00046 #include <cstdlib> 00047 #include <ext/pb_ds/detail/list_update_policy/lu_counter_metadata.hpp> 00048 #include <ext/pb_ds/tag_and_trait.hpp> 00049 00050 namespace __gnu_pbds 00051 { 00052 /** 00053 * A list-update policy that unconditionally moves elements to the 00054 * front of the list. A null type means that each link in a 00055 * list-based container does not actually need metadata. 00056 */ 00057 template<typename _Alloc = std::allocator<char> > 00058 class lu_move_to_front_policy 00059 { 00060 public: 00061 typedef _Alloc allocator_type; 00062 00063 /// Metadata on which this functor operates. 00064 typedef null_type metadata_type; 00065 00066 private: 00067 typedef typename _Alloc::template rebind<metadata_type> __rebind_m; 00068 00069 public: 00070 /// Reference to metadata on which this functor operates. 00071 typedef typename __rebind_m::other::reference metadata_reference; 00072 00073 /// Creates a metadata object. 00074 metadata_type 00075 operator()() const 00076 { return s_metadata; } 00077 00078 /// Decides whether a metadata object should be moved to the front 00079 /// of the list. 00080 inline bool 00081 operator()(metadata_reference r_metadata) const 00082 { return true; } 00083 00084 private: 00085 static null_type s_metadata; 00086 }; 00087 00088 /** 00089 * A list-update policy that moves elements to the front of the 00090 * list based on the counter algorithm. 00091 */ 00092 template<std::size_t Max_Count = 5, typename _Alloc = std::allocator<char> > 00093 class lu_counter_policy 00094 : private detail::lu_counter_policy_base<typename _Alloc::size_type> 00095 { 00096 public: 00097 typedef _Alloc allocator_type; 00098 typedef typename allocator_type::size_type size_type; 00099 00100 enum 00101 { 00102 /// When some element is accessed this number of times, it 00103 /// will be moved to the front of the list. 00104 max_count = Max_Count 00105 }; 00106 00107 /// Metadata on which this functor operates. 00108 typedef detail::lu_counter_metadata<size_type> metadata_type; 00109 00110 private: 00111 typedef detail::lu_counter_policy_base<size_type> base_type; 00112 typedef typename _Alloc::template rebind<metadata_type> __rebind_m; 00113 00114 public: 00115 /// Reference to metadata on which this functor operates. 00116 typedef typename __rebind_m::other::reference metadata_reference; 00117 00118 /// Creates a metadata object. 00119 metadata_type 00120 operator()() const 00121 { return base_type::operator()(max_count); } 00122 00123 /// Decides whether a metadata object should be moved to the front 00124 /// of the list. 00125 bool 00126 operator()(metadata_reference r_data) const 00127 { return base_type::operator()(r_data, max_count); } 00128 }; 00129 } // namespace __gnu_pbds 00130 00131 #endif