3 * Implementation of helper classes for using the remember option
4 * in GiNaC functions */
7 * GiNaC Copyright (C) 1999-2000 Johannes Gutenberg University Mainz, Germany
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
27 #include "utils.h" // for log_2
30 #ifndef NO_NAMESPACE_GINAC
32 #endif // ndef NO_NAMESPACE_GINAC
35 // class remember_table_entry
38 remember_table_entry::remember_table_entry(function const & f, ex const & r) :
39 hashvalue(f.gethash()), seq(f.seq), result(r)
41 last_access=access_counter++;
45 bool remember_table_entry::is_equal(function const & f) const
47 GINAC_ASSERT(f.seq.size()==seq.size());
48 if (f.gethash()!=hashvalue) return false;
49 for (unsigned i=0; i<seq.size(); ++i) {
50 if (!seq[i].is_equal(f.seq[i])) return false;
52 last_access=access_counter++;
57 unsigned long remember_table_entry::access_counter=0;
60 // class remember_table_list
63 remember_table_list::remember_table_list(unsigned as, unsigned strat)
66 remember_strategy=strat;
70 void remember_table_list::add_entry(function const & f, ex const & result)
72 if ((max_assoc_size!=0)&&
73 (remember_strategy!=remember_strategies::delete_never)&&
74 (size()>=max_assoc_size)) {
75 // table is full, we must delete an older entry
76 GINAC_ASSERT(size()>0); // there must be at least one entry
78 switch (remember_strategy) {
79 case remember_strategies::delete_cyclic:
80 // delete oldest entry (first in list)
83 case remember_strategies::delete_lru:
85 // delete least recently used entry
87 iterator lowest_access_it=it;
88 unsigned long lowest_access=it->get_last_access();
91 if (it->get_last_access()<lowest_access) {
92 lowest_access=it->get_last_access();
97 erase(lowest_access_it);
100 case remember_strategies::delete_lfu:
102 // delete least frequently used entry
104 iterator lowest_hits_it=it;
105 unsigned lowest_hits=it->get_successful_hits();
108 if (it->get_successful_hits()<lowest_hits) {
109 lowest_hits=it->get_successful_hits();
114 erase(lowest_hits_it);
118 throw(std::logic_error("remember_table_list::add_entry(): invalid remember_strategy"));
120 GINAC_ASSERT(size()==max_assoc_size-1);
122 push_back(remember_table_entry(f,result));
125 bool remember_table_list::lookup_entry(function const & f, ex & result) const
127 for (const_iterator cit=begin(); cit!=end(); ++cit) {
128 if (cit->is_equal(f)) {
129 result=cit->get_result();
137 // class remember_table
140 remember_table::remember_table()
144 remember_strategy=remember_strategies::delete_never;
147 remember_table::remember_table(unsigned s, unsigned as, unsigned strat) :
148 max_assoc_size(as), remember_strategy(strat)
150 // we keep max_assoc_size and remember_strategy if we need to clear
153 // use some power of 2 next to s
154 table_size=1 << log2(s);
158 bool remember_table::lookup_entry(function const & f, ex & result) const
160 unsigned entry=f.gethash() & (table_size-1);
161 GINAC_ASSERT(entry<size());
162 return operator[](entry).lookup_entry(f,result);
165 void remember_table::add_entry(function const & f, ex const & result)
167 unsigned entry=f.gethash() & (table_size-1);
168 GINAC_ASSERT(entry<size());
169 operator[](entry).add_entry(f,result);
172 void remember_table::clear_all_entries(void)
178 void remember_table::init_table(void)
181 for (unsigned i=0; i<table_size; ++i) {
182 push_back(remember_table_list(max_assoc_size,remember_strategy));
186 vector<remember_table> & remember_table::remember_tables(void)
188 static vector<remember_table> * rt=new vector<remember_table>;
192 #ifndef NO_NAMESPACE_GINAC
194 #endif // ndef NO_NAMESPACE_GINAC