1 // -*- C++ -*- 2 3 // Copyright (C) 2005, 2006, 2007, 2009, 2010, 2011 4 // Free Software Foundation, Inc. 5 // 6 // This file is part of the GNU ISO C++ Library. This library is free 7 // software; you can redistribute it and/or modify it under the terms 8 // of the GNU General Public License as published by the Free Software 9 // Foundation; either version 3, or (at your option) any later 10 // version. 11 12 // This library is distributed in the hope that it will be useful, but 13 // WITHOUT ANY WARRANTY; without even the implied warranty of 14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 // General Public License for more details. 16 17 // Under Section 7 of GPL version 3, you are granted additional 18 // permissions described in the GCC Runtime Library Exception, version 19 // 3.1, as published by the Free Software Foundation. 20 21 // You should have received a copy of the GNU General Public License and 22 // a copy of the GCC Runtime Library Exception along with this program; 23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 // <http://www.gnu.org/licenses/>. 25 26 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 27 28 // Permission to use, copy, modify, sell, and distribute this software 29 // is hereby granted without fee, provided that the above copyright 30 // notice appears in all copies, and that both that copyright notice 31 // and this permission notice appear in supporting documentation. None 32 // of the above authors, nor IBM Haifa Research Laboratories, make any 33 // representation about the suitability of this software for any 34 // purpose. It is provided "as is" without express or implied 35 // warranty. 36 37 /** 38 * @file lu_counter_metadata.hpp 39 * Contains implementation of a lu counter policy's metadata. 40 */ 41 42 namespace __gnu_pbds 43 { 44 namespace detail 45 { 46 template<typename Size_Type> 47 class lu_counter_policy_base; 48 49 /// A list-update metadata type that moves elements to the front of 50 /// the list based on the counter algorithm. 51 template<typename Size_Type = std::size_t> 52 class lu_counter_metadata 53 { 54 public: 55 typedef Size_Type size_type; 56 57 private: 58 lu_counter_metadata(size_type init_count) : m_count(init_count) 59 { } 60 61 friend class lu_counter_policy_base<size_type>; 62 63 mutable size_type m_count; 64 }; 65 66 /// Base class for list-update counter policy. 67 template<typename Size_Type> 68 class lu_counter_policy_base 69 { 70 protected: 71 typedef Size_Type size_type; 72 73 lu_counter_metadata<size_type> 74 operator()(size_type max_size) const 75 { return lu_counter_metadata<Size_Type>(std::rand() % max_size); } 76 77 template<typename Metadata_Reference> 78 bool 79 operator()(Metadata_Reference r_data, size_type m_max_count) const 80 { 81 if (++r_data.m_count != m_max_count) 82 return false; 83 r_data.m_count = 0; 84 return true; 85 } 86 }; 87 } // namespace detail 88 } // namespace __gnu_pbds 89