3 * Interface to sequences of expression pairs. */
6 * GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 #ifndef __GINAC_EXPAIRSEQ_H__
24 #define __GINAC_EXPAIRSEQ_H__
28 // CINT needs <algorithm> to work properly with <vector> and <list>
35 /** Using hash tables can potentially enhance the asymptotic behaviour of
36 * combining n terms into one large sum (or n terms into one large product)
37 * from O(n*log(n)) to about O(n). There are, however, several drawbacks.
38 * The constant in front of O(n) is quite large, when copying such an object
39 * one also has to copy the has table, comparison is quite expensive because
40 * there is no ordering any more, it doesn't help at all when combining two
41 * expairseqs because due to the presorted nature the behaviour would be
42 * O(n) anyways, the code is quite messy, etc, etc. The code is here as
43 * an example for following generations to tinker with. */
44 #define EXPAIRSEQ_USE_HASHTAB 0
46 typedef std::vector<expair> epvector; ///< expair-vector
47 typedef epvector::iterator epp; ///< expair-vector pointer
48 typedef std::list<epp> epplist; ///< list of expair-vector pointers
49 typedef std::vector<epplist> epplistvector; ///< vector of epplist
51 /** A sequence of class expair.
52 * This is used for time-critical classes like sums and products of terms
53 * since handling a list of coeff and rest is much faster than handling a
54 * list of products or powers, respectively. (Not incidentally, Maple does it
55 * the same way, maybe others too.) The semantics is (at least) twofold:
56 * one for addition and one for multiplication and several methods have to
57 * be overridden by derived classes to reflect the change in semantics.
58 * However, most functionality turns out to be shared between addition and
59 * multiplication, which is the reason why there is this base class. */
60 class expairseq : public basic
62 GINAC_DECLARE_REGISTERED_CLASS(expairseq, basic)
66 expairseq(const ex & lh, const ex & rh);
67 expairseq(const exvector & v);
68 expairseq(const epvector & v, const ex & oc);
69 expairseq(epvector * vp, const ex & oc); // vp will be deleted
71 // functions overriding virtual functions from base classes
73 unsigned precedence() const {return 10;}
74 bool info(unsigned inf) const;
76 ex op(size_t i) const;
77 ex map(map_function & f) const;
78 ex eval(int level=0) const;
79 ex to_rational(lst &repl_lst) const;
80 ex to_polynomial(lst &repl_lst) const;
81 bool match(const ex & pattern, lst & repl_lst) const;
82 ex subs(const exmap & m, unsigned options = 0) const;
84 bool is_equal_same_type(const basic & other) const;
85 unsigned return_type() const;
86 unsigned calchash() const;
87 ex expand(unsigned options=0) const;
89 // new virtual functions which can be overridden by derived classes
91 virtual ex thisexpairseq(const epvector & v, const ex & oc) const;
92 virtual ex thisexpairseq(epvector * vp, const ex & oc) const;
93 virtual void printseq(const print_context & c, char delim,
94 unsigned this_precedence,
95 unsigned upper_precedence) const;
96 virtual void printpair(const print_context & c, const expair & p,
97 unsigned upper_precedence) const;
98 virtual expair split_ex_to_pair(const ex & e) const;
99 virtual expair combine_ex_with_coeff_to_pair(const ex & e,
101 virtual expair combine_pair_with_coeff_to_pair(const expair & p,
103 virtual ex recombine_pair_to_ex(const expair & p) const;
104 virtual bool expair_needs_further_processing(epp it);
105 virtual ex default_overall_coeff() const;
106 virtual void combine_overall_coeff(const ex & c);
107 virtual void combine_overall_coeff(const ex & c1, const ex & c2);
108 virtual bool can_make_flat(const expair & p) const;
110 // non-virtual functions in this class
112 void do_print(const print_context & c, unsigned level) const;
113 void do_print_tree(const print_tree & c, unsigned level) const;
114 void construct_from_2_ex_via_exvector(const ex & lh, const ex & rh);
115 void construct_from_2_ex(const ex & lh, const ex & rh);
116 void construct_from_2_expairseq(const expairseq & s1,
117 const expairseq & s2);
118 void construct_from_expairseq_ex(const expairseq & s,
120 void construct_from_exvector(const exvector & v);
121 void construct_from_epvector(const epvector & v);
122 void make_flat(const exvector & v);
123 void make_flat(const epvector & v);
125 void combine_same_terms_sorted_seq();
126 #if EXPAIRSEQ_USE_HASHTAB
127 void combine_same_terms();
128 unsigned calc_hashtabsize(unsigned sz) const;
129 unsigned calc_hashindex(const ex & e) const;
130 void shrink_hashtab();
131 void remove_hashtab_entry(epvector::const_iterator element);
132 void move_hashtab_entry(epvector::const_iterator oldpos,
133 epvector::iterator newpos);
134 void sorted_insert(epplist & eppl, epvector::const_iterator elem);
135 void build_hashtab_and_combine(epvector::iterator & first_numeric,
136 epvector::iterator & last_non_zero,
137 vector<bool> & touched,
138 unsigned & number_of_zeroes);
139 void drop_coeff_0_terms(epvector::iterator & first_numeric,
140 epvector::iterator & last_non_zero,
141 vector<bool> & touched,
142 unsigned & number_of_zeroes);
143 bool has_coeff_0() const;
144 void add_numerics_to_hashtab(epvector::iterator first_numeric,
145 epvector::const_iterator last_non_zero);
146 #endif // EXPAIRSEQ_USE_HASHTAB
147 bool is_canonical() const;
148 epvector * expandchildren(unsigned options) const;
149 epvector * evalchildren(int level) const;
150 epvector * subschildren(const exmap & m, unsigned options = 0) const;
157 #if EXPAIRSEQ_USE_HASHTAB
158 epplistvector hashtab;
159 unsigned hashtabsize;
161 static unsigned maxhashtabsize;
162 static unsigned minhashtabsize;
163 static unsigned hashtabfactor;
164 #endif // EXPAIRSEQ_USE_HASHTAB
169 /** Specialization of is_exactly_a<expairseq>(obj) for expairseq objects. */
170 template<> inline bool is_exactly_a<expairseq>(const basic & obj)
172 return obj.tinfo()==TINFO_expairseq;
177 #endif // ndef __GINAC_EXPAIRSEQ_H__