1 // -*- C++ -*- 2 3 // Copyright (C) 2005-2018 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the terms 7 // of the GNU General Public License as published by the Free Software 8 // Foundation; either version 3, or (at your option) any later 9 // version. 10 11 // This library is distributed in the hope that it will be useful, but 12 // WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 // General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 26 27 // Permission to use, copy, modify, sell, and distribute this software 28 // is hereby granted without fee, provided that the above copyright 29 // notice appears in all copies, and that both that copyright notice 30 // and this permission notice appear in supporting documentation. None 31 // of the above authors, nor IBM Haifa Research Laboratories, make any 32 // representation about the suitability of this software for any 33 // purpose. It is provided "as is" without express or implied 34 // warranty. 35 36 /** 37 * @file lu_counter_metadata.hpp 38 * Contains implementation of a lu counter policy's metadata. 39 */ 40 41 namespace __gnu_pbds 42 { 43 namespace detail 44 { 45 template<typename Size_Type> 46 class lu_counter_policy_base; 47 48 /// A list-update metadata type that moves elements to the front of 49 /// the list based on the counter algorithm. 50 template<typename Size_Type = std::size_t> 51 class lu_counter_metadata 52 { 53 public: 54 typedef Size_Type size_type; 55 56 private: 57 lu_counter_metadata(size_type init_count) : m_count(init_count) 58 { } 59 60 friend class lu_counter_policy_base<size_type>; 61 62 mutable size_type m_count; 63 }; 64 65 /// Base class for list-update counter policy. 66 template<typename Size_Type> 67 class lu_counter_policy_base 68 { 69 protected: 70 typedef Size_Type size_type; 71 72 lu_counter_metadata<size_type> 73 operator()(size_type max_size) const 74 { return lu_counter_metadata<Size_Type>(std::rand() % max_size); } 75 76 template<typename Metadata_Reference> 77 bool 78 operator()(Metadata_Reference r_data, size_type m_max_count) const 79 { 80 if (++r_data.m_count != m_max_count) 81 return false; 82 r_data.m_count = 0; 83 return true; 84 } 85 }; 86 } // namespace detail 87 } // namespace __gnu_pbds 88