ginac/relational.cpp

   1 /** @file relational.cpp
   2  *
   3  *  Implementation of relations between expressions */
   4
   5 /*
   6  *  GiNaC Copyright (C) 1999-2003 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 "operators.h"
  28 #include "numeric.h"
  29 #include "print.h"
  30 #include "archive.h"
  31 #include "utils.h"
  32
  33 namespace GiNaC {
  34
  35 GINAC_IMPLEMENT_REGISTERED_CLASS(relational, basic)
  36
  37 //////////
  38 // default ctor, dtor, copy ctor, assignment operator and helpers
  39 //////////
  40
  41 relational::relational() : basic(TINFO_relational) {}
  42
  43 void relational::copy(const relational & other)
  44 {
  45         basic::copy(other);
  46         lh=other.lh;
  47         rh=other.rh;
  48         o=other.o;
  49 }
  50
  51 DEFAULT_DESTROY(relational)
  52
  53 //////////
  54 // other ctors
  55 //////////
  56
  57 // public
  58
  59 relational::relational(const ex & lhs, const ex & rhs, operators oper) : basic(TINFO_relational), lh(lhs), rh(rhs), o(oper) {}
  60
  61 //////////
  62 // archiving
  63 //////////
  64
  65 relational::relational(const archive_node &n, lst &sym_lst) : inherited(n, sym_lst)
  66 {
  67         unsigned int opi;
  68         if (!(n.find_unsigned("op", opi)))
  69                 throw (std::runtime_error("unknown relational operator in archive"));
  70         o = (operators)opi;
  71         n.find_ex("lh", lh, sym_lst);
  72         n.find_ex("rh", rh, sym_lst);
  73 }
  74
  75 void relational::archive(archive_node &n) const
  76 {
  77         inherited::archive(n);
  78         n.add_ex("lh", lh);
  79         n.add_ex("rh", rh);
  80         n.add_unsigned("op", o);
  81 }
  82
  83 DEFAULT_UNARCHIVE(relational)
  84
  85 //////////
  86 // functions overriding virtual functions from base classes
  87 //////////
  88
  89 // public
  90
  91 void relational::print(const print_context & c, unsigned level) const
  92 {
  93         if (is_a<print_tree>(c)) {
  94
  95                 inherited::print(c, level);
  96
  97         } else {
  98
  99                 if (is_a<print_python_repr>(c)) {
 100                         c.s << class_name() << '(';
 101                         lh.print(c);
 102                         c.s << ',';
 103                         rh.print(c);
 104                         c.s << ",'";
 105                 } else {
 106                         if (precedence() <= level)
 107                                 c.s << "(";
 108                         lh.print(c, precedence());
 109                 }
 110                 switch (o) {
 111                         case equal:
 112                                 c.s << "==";
 113                                 break;
 114                         case not_equal:
 115                                 c.s << "!=";
 116                                 break;
 117                         case less:
 118                                 c.s << "<";
 119                                 break;
 120                         case less_or_equal:
 121                                 c.s << "<=";
 122                                 break;
 123                         case greater:
 124                                 c.s << ">";
 125                                 break;
 126                         case greater_or_equal:
 127                                 c.s << ">=";
 128                                 break;
 129                         default:
 130                                 c.s << "(INVALID RELATIONAL OPERATOR)";
 131                 }
 132                 if (is_a<print_python_repr>(c))
 133                         c.s << "')";
 134                 else {
 135                         rh.print(c, precedence());
 136                         if (precedence() <= level)
 137                                 c.s << ")";
 138                 }
 139         }
 140 }
 141
 142 bool relational::info(unsigned inf) const
 143 {
 144         switch (inf) {
 145                 case info_flags::relation:
 146                         return 1;
 147                 case info_flags::relation_equal:
 148                         return o==equal;
 149                 case info_flags::relation_not_equal:
 150                         return o==not_equal;
 151                 case info_flags::relation_less:
 152                         return o==less;
 153                 case info_flags::relation_less_or_equal:
 154                         return o==less_or_equal;
 155                 case info_flags::relation_greater:
 156                         return o==greater;
 157                 case info_flags::relation_greater_or_equal:
 158                         return o==greater_or_equal;
 159         }
 160         return 0;
 161 }
 162
 163 size_t relational::nops() const
 164 {
 165         return 2;
 166 }
 167
 168 ex relational::op(size_t i) const
 169 {
 170         GINAC_ASSERT(i<2);
 171
 172         return i==0 ? lh : rh;
 173 }
 174
 175 ex relational::map(map_function & f) const
 176 {
 177         return (new relational(f(lh), f(rh), o))->setflag(status_flags::dynallocated);
 178 }
 179
 180 ex relational::eval(int level) const
 181 {
 182         if (level==1)
 183                 return this->hold();
 184
 185         if (level == -max_recursion_level)
 186                 throw(std::runtime_error("max recursion level reached"));
 187
 188         return (new relational(lh.eval(level-1),rh.eval(level-1),o))->setflag(status_flags::dynallocated | status_flags::evaluated);
 189 }
 190
 191 ex relational::subs(const lst & ls, const lst & lr, unsigned options) const
 192 {
 193         const ex & subsed_lh = lh.subs(ls, lr, options);
 194         const ex & subsed_rh = rh.subs(ls, lr, options);
 195
 196         if (!are_ex_trivially_equal(lh, subsed_lh) || !are_ex_trivially_equal(rh, subsed_rh))
 197                 return relational(subsed_lh, subsed_rh, o).basic::subs(ls, lr, options);
 198         else
 199                 return basic::subs(ls, lr, options);
 200 }
 201
 202 ex relational::eval_ncmul(const exvector & v) const
 203 {
 204         return lh.eval_ncmul(v);
 205 }
 206
 207 // protected
 208
 209 int relational::compare_same_type(const basic & other) const
 210 {
 211         GINAC_ASSERT(is_exactly_a<relational>(other));
 212         const relational &oth = static_cast<const relational &>(other);
 213         if (o==oth.o && lh.is_equal(oth.lh) && rh.is_equal(oth.rh))
 214                 return 0;
 215         switch (o) {
 216                 case equal:
 217                 case not_equal:
 218                         if (oth.o!=o)
 219                                 return (o < oth.o) ? -1 : 1;
 220                         break;
 221                 case less:
 222                         if (oth.o!=greater)
 223                                 return (o < oth.o) ? -1 : 1;
 224                         break;
 225                 case less_or_equal:
 226                         if (oth.o!=greater_or_equal)
 227                                 return (o < oth.o) ? -1 : 1;
 228                         break;
 229                 case greater:
 230                         if (oth.o!=less)
 231                                 return (o < oth.o) ? -1 : 1;
 232                         break;
 233                 case greater_or_equal:
 234                         if (oth.o!=less_or_equal)
 235                                 return (o < oth.o) ? -1 : 1;
 236                         break;
 237         }
 238         const int lcmpval = lh.compare(oth.rh);
 239         return (lcmpval!=0) ? lcmpval : rh.compare(oth.lh);
 240 }
 241
 242 bool relational::match_same_type(const basic & other) const
 243 {
 244         GINAC_ASSERT(is_exactly_a<relational>(other));
 245         const relational &oth = static_cast<const relational &>(other);
 246
 247         return o == oth.o;
 248 }
 249
 250 unsigned relational::return_type(void) const
 251 {
 252         GINAC_ASSERT(lh.return_type()==rh.return_type());
 253         return lh.return_type();
 254 }
 255
 256 unsigned relational::return_type_tinfo(void) const
 257 {
 258         GINAC_ASSERT(lh.return_type_tinfo()==rh.return_type_tinfo());
 259         return lh.return_type_tinfo();
 260 }
 261
 262 unsigned relational::calchash(void) const
 263 {
 264         unsigned v = golden_ratio_hash(tinfo());
 265         unsigned lhash = lh.gethash();
 266         unsigned rhash = rh.gethash();
 267
 268         v = rotate_left(v);
 269         switch(o) {
 270                 case equal:
 271                 case not_equal:
 272                         if (lhash>rhash) {
 273                                 v ^= lhash;
 274                                 lhash = rhash;
 275                         } else {
 276                                 v ^= rhash;
 277                         }
 278                         break;
 279                 case less:
 280                 case less_or_equal:
 281                         v ^= rhash;
 282                         break;
 283                 case greater:
 284                 case greater_or_equal:
 285                         v ^= lhash;
 286                         lhash = rhash;
 287                         break;
 288         }
 289         v = rotate_left(v);
 290         v ^= lhash;
 291
 292         // store calculated hash value only if object is already evaluated
 293         if (flags & status_flags::evaluated) {
 294                 setflag(status_flags::hash_calculated);
 295                 hashvalue = v;
 296         }
 297
 298         return v;
 299 }
 300
 301 //////////
 302 // new virtual functions which can be overridden by derived classes
 303 //////////
 304
 305 /** Left hand side of relational. */
 306 ex relational::lhs(void) const
 307 {
 308         return lh;
 309 }
 310
 311 /** Right hand side of relational. */
 312 ex relational::rhs(void) const
 313 {
 314         return rh;
 315 }
 316
 317 //////////
 318 // non-virtual functions in this class
 319 //////////
 320
 321 relational::safe_bool relational::make_safe_bool(bool cond) const
 322 {
 323         return cond? &safe_bool_helper::nonnull : 0;
 324 }
 325
 326 /** Cast the relational into a boolean, mainly for evaluation within an
 327  *  if-statement.  Note that (a<b) == false does not imply (a>=b) == true in
 328  *  the general symbolic case.  A false result means the comparison is either
 329  *  false or undecidable (except of course for !=, where true means either
 330  *  unequal or undecidable). */
 331 relational::operator relational::safe_bool() const
 332 {
 333         const ex df = lh-rh;
 334         if (!is_exactly_a<numeric>(df))
 335                 // cannot decide on non-numerical results
 336                 return o==not_equal ? make_safe_bool(true) : make_safe_bool(false);
 337
 338         switch (o) {
 339                 case equal:
 340                         return make_safe_bool(ex_to<numeric>(df).is_zero());
 341                 case not_equal:
 342                         return make_safe_bool(!ex_to<numeric>(df).is_zero());
 343                 case less:
 344                         return make_safe_bool(ex_to<numeric>(df)<_num0);
 345                 case less_or_equal:
 346                         return make_safe_bool(ex_to<numeric>(df)<=_num0);
 347                 case greater:
 348                         return make_safe_bool(ex_to<numeric>(df)>_num0);
 349                 case greater_or_equal:
 350                         return make_safe_bool(ex_to<numeric>(df)>=_num0);
 351                 default:
 352                         throw(std::logic_error("invalid relational operator"));
 353         }
 354 }
 355
 356 } // namespace GiNaC