1 // -*- C++ -*- 2 3 // Copyright (C) 2005, 2006 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 2, 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 // You should have received a copy of the GNU General Public License 17 // along with this library; see the file COPYING. If not, write to 18 // the Free Software Foundation, 59 Temple Place - Suite 330, Boston, 19 // MA 02111-1307, USA. 20 21 // As a special exception, you may use this file as part of a free 22 // software library without restriction. Specifically, if other files 23 // instantiate templates or use macros or inline functions from this 24 // file, or you compile this file and link it with other files to 25 // produce an executable, this file does not by itself cause the 26 // resulting executable to be covered by the GNU General Public 27 // License. This exception does not however invalidate any other 28 // reasons why the executable file might be covered by the GNU General 29 // Public License. 30 31 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 32 33 // Permission to use, copy, modify, sell, and distribute this software 34 // is hereby granted without fee, provided that the above copyright 35 // notice appears in all copies, and that both that copyright notice 36 // and this permission notice appear in supporting documentation. None 37 // of the above authors, nor IBM Haifa Research Laboratories, make any 38 // representation about the suitability of this software for any 39 // purpose. It is provided "as is" without express or implied 40 // warranty. 41 42 /** 43 * @file counter_lu_metadata.hpp 44 * Contains implementation of a lu counter policy's metadata. 45 */ 46 47 namespace pb_ds 48 { 49 namespace detail 50 { 51 template<typename Size_Type> 52 class counter_lu_policy_base; 53 54 // A list-update metadata type that moves elements to the front of 55 // the list based on the counter algorithm. 56 template<typename Size_Type = size_t> 57 class counter_lu_metadata 58 { 59 public: 60 typedef Size_Type size_type; 61 62 private: counter_lu_metadata(size_type init_count)63 counter_lu_metadata(size_type init_count) : m_count(init_count) 64 { } 65 66 friend class counter_lu_policy_base<size_type>; 67 68 mutable size_type m_count; 69 }; 70 71 template<typename Size_Type> 72 class counter_lu_policy_base 73 { 74 protected: 75 typedef Size_Type size_type; 76 77 counter_lu_metadata<size_type> operator ()(size_type max_size) const78 operator()(size_type max_size) const 79 { return counter_lu_metadata<Size_Type>(rand() % max_size); } 80 81 template<typename Metadata_Reference> 82 bool operator ()(Metadata_Reference r_data,size_type m_max_count) const83 operator()(Metadata_Reference r_data, size_type m_max_count) const 84 { 85 if (++r_data.m_count != m_max_count) 86 return false; 87 r_data.m_count = 0; 88 return true; 89 } 90 }; 91 } // namespace detail 92 } // namespace pb_ds 93