* Added output-support for Python bindings and LaTeX printing for
[ginac.git] / ginac / relational.cpp
1 /** @file relational.cpp
2  *
3  *  Implementation of relations between expressions */
4
5 /*
6  *  GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
7  *
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.
12  *
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.
17  *
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
21  */
22
23 #include <iostream>
24 #include <stdexcept>
25
26 #include "relational.h"
27 #include "numeric.h"
28 #include "print.h"
29 #include "archive.h"
30 #include "utils.h"
31
32 namespace GiNaC {
33
34 GINAC_IMPLEMENT_REGISTERED_CLASS(relational, basic)
35
36 //////////
37 // default ctor, dtor, copy ctor, assignment operator and helpers
38 //////////
39
40 relational::relational() : basic(TINFO_relational) {}
41
42 void relational::copy(const relational & other)
43 {
44         basic::copy(other);
45         lh=other.lh;
46         rh=other.rh;
47         o=other.o;
48 }
49
50 DEFAULT_DESTROY(relational)
51
52 //////////
53 // other ctors
54 //////////
55
56 // public
57
58 relational::relational(const ex & lhs, const ex & rhs, operators oper) : basic(TINFO_relational), lh(lhs), rh(rhs), o(oper) {}
59
60 //////////
61 // archiving
62 //////////
63
64 relational::relational(const archive_node &n, const lst &sym_lst) : inherited(n, sym_lst)
65 {
66         unsigned int opi;
67         if (!(n.find_unsigned("op", opi)))
68                 throw (std::runtime_error("unknown relational operator in archive"));
69         o = (operators)opi;
70         n.find_ex("lh", lh, sym_lst);
71         n.find_ex("rh", rh, sym_lst);
72 }
73
74 void relational::archive(archive_node &n) const
75 {
76         inherited::archive(n);
77         n.add_ex("lh", lh);
78         n.add_ex("rh", rh);
79         n.add_unsigned("op", o);
80 }
81
82 DEFAULT_UNARCHIVE(relational)
83
84 //////////
85 // functions overriding virtual functions from base classes
86 //////////
87
88 // public
89
90 void relational::print(const print_context & c, unsigned level) const
91 {
92         if (is_a<print_tree>(c)) {
93
94                 inherited::print(c, level);
95
96         } else {
97
98                 if (is_a<print_python_repr>(c)) {
99                         c.s << class_name() << '(';
100                         lh.print(c);
101                         c.s << ',';
102                         rh.print(c);
103                         c.s << ",'";
104                 } else {
105                         if (precedence() <= level)
106                                 c.s << "(";
107                         lh.print(c, precedence());
108                 }
109                 switch (o) {
110                         case equal:
111                                 c.s << "==";
112                                 break;
113                         case not_equal:
114                                 c.s << "!=";
115                                 break;
116                         case less:
117                                 c.s << "<";
118                                 break;
119                         case less_or_equal:
120                                 c.s << "<=";
121                                 break;
122                         case greater:
123                                 c.s << ">";
124                                 break;
125                         case greater_or_equal:
126                                 c.s << ">=";
127                                 break;
128                         default:
129                                 c.s << "(INVALID RELATIONAL OPERATOR)";
130                 }
131                 if (is_a<print_python_repr>(c))
132                         c.s << "')";
133                 else {
134                         rh.print(c, precedence());
135                         if (precedence() <= level)
136                                 c.s << ")";
137                 }
138         }
139 }
140
141 bool relational::info(unsigned inf) const
142 {
143         switch (inf) {
144                 case info_flags::relation:
145                         return 1;
146                 case info_flags::relation_equal:
147                         return o==equal;
148                 case info_flags::relation_not_equal:
149                         return o==not_equal;
150                 case info_flags::relation_less:
151                         return o==less;
152                 case info_flags::relation_less_or_equal:
153                         return o==less_or_equal;
154                 case info_flags::relation_greater:
155                         return o==greater;
156                 case info_flags::relation_greater_or_equal:
157                         return o==greater_or_equal;
158         }
159         return 0;
160 }
161
162 unsigned relational::nops() const
163 {
164         return 2;
165 }
166
167 ex & relational::let_op(int i)
168 {
169         GINAC_ASSERT(i>=0);
170         GINAC_ASSERT(i<2);
171
172         return i==0 ? lh : rh;
173 }
174
175 ex relational::eval(int level) const
176 {
177         if (level==1)
178                 return this->hold();
179         
180         if (level == -max_recursion_level)
181                 throw(std::runtime_error("max recursion level reached"));
182         
183         return (new relational(lh.eval(level-1),rh.eval(level-1),o))->setflag(status_flags::dynallocated | status_flags::evaluated);
184 }
185
186 ex relational::simplify_ncmul(const exvector & v) const
187 {
188         return lh.simplify_ncmul(v);
189 }
190
191 // protected
192
193 int relational::compare_same_type(const basic & other) const
194 {
195         GINAC_ASSERT(is_exactly_a<relational>(other));
196         const relational &oth = static_cast<const relational &>(other);
197         if (o==oth.o && lh.is_equal(oth.lh) && rh.is_equal(oth.rh))
198                 return 0;
199         switch (o) {
200                 case equal:
201                 case not_equal:
202                         if (oth.o!=o)
203                                 return (o < oth.o) ? -1 : 1;
204                         break;
205                 case less:
206                         if (oth.o!=greater)
207                                 return (o < oth.o) ? -1 : 1;
208                         break;
209                 case less_or_equal:
210                         if (oth.o!=greater_or_equal)
211                                 return (o < oth.o) ? -1 : 1;
212                         break;
213                 case greater:
214                         if (oth.o!=less)
215                                 return (o < oth.o) ? -1 : 1;
216                         break;
217                 case greater_or_equal:
218                         if (oth.o!=less_or_equal)
219                                 return (o < oth.o) ? -1 : 1;
220                         break;
221         }
222         const int lcmpval = lh.compare(oth.rh);
223         return (lcmpval!=0) ? lcmpval : rh.compare(oth.lh);
224 }
225
226 bool relational::match_same_type(const basic & other) const
227 {
228         GINAC_ASSERT(is_exactly_a<relational>(other));
229         const relational &oth = static_cast<const relational &>(other);
230
231         return o == oth.o;
232 }
233
234 unsigned relational::return_type(void) const
235 {
236         GINAC_ASSERT(lh.return_type()==rh.return_type());
237         return lh.return_type();
238 }
239    
240 unsigned relational::return_type_tinfo(void) const
241 {
242         GINAC_ASSERT(lh.return_type_tinfo()==rh.return_type_tinfo());
243         return lh.return_type_tinfo();
244 }
245
246 unsigned relational::calchash(void) const
247 {
248         unsigned v = golden_ratio_hash(tinfo());
249         unsigned lhash = lh.gethash();
250         unsigned rhash = rh.gethash();
251
252         v = rotate_left_31(v);
253         switch(o) {
254                 case equal:
255                 case not_equal:
256                         if (lhash>rhash) {
257                                 v ^= lhash;
258                                 lhash = rhash;
259                         } else {
260                                 v ^= rhash;
261                         }
262                         break;
263                 case less:
264                 case less_or_equal:
265                         v ^= rhash;
266                         break;
267                 case greater:
268                 case greater_or_equal:
269                         v ^= lhash;
270                         lhash = rhash;
271                         break;
272         }
273         v = rotate_left_31(v);
274         v ^= lhash;
275
276         // mask out numeric hashes:
277         v &= 0x7FFFFFFFU;
278
279         // store calculated hash value only if object is already evaluated
280         if (flags & status_flags::evaluated) {
281                 setflag(status_flags::hash_calculated);
282                 hashvalue = v;
283         }
284
285         return v;
286 }
287
288 //////////
289 // new virtual functions which can be overridden by derived classes
290 //////////
291
292 /** Left hand side of relational. */
293 ex relational::lhs(void) const
294 {
295         return lh;
296 }
297
298 /** Right hand side of relational. */
299 ex relational::rhs(void) const
300 {
301         return rh;    
302 }
303
304 //////////
305 // non-virtual functions in this class
306 //////////
307
308 /** Cast the relational into a boolean, mainly for evaluation within an 
309  *  if-statement.  Note that (a<b) == false does not imply (a>=b) == true in
310  *  the general symbolic case.  A false result means the comparison is either
311  *  false or undecidable (except of course for !=, where true means either
312  *  unequal or undecidable). */
313 relational::operator bool() const
314 {
315         const ex df = lh-rh;
316         if (!is_ex_exactly_of_type(df,numeric))
317                 // cannot decide on non-numerical results
318                 return o==not_equal ? true : false;
319         
320         switch (o) {
321                 case equal:
322                         return ex_to<numeric>(df).is_zero();
323                 case not_equal:
324                         return !ex_to<numeric>(df).is_zero();
325                 case less:
326                         return ex_to<numeric>(df)<_num0;
327                 case less_or_equal:
328                         return ex_to<numeric>(df)<=_num0;
329                 case greater:
330                         return ex_to<numeric>(df)>_num0;
331                 case greater_or_equal:
332                         return ex_to<numeric>(df)>=_num0;
333                 default:
334                         throw(std::logic_error("invalid relational operator"));
335         }
336 }
337
338 } // namespace GiNaC