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 <stdexcept>
  24
  25 #include "relational.h"
  26 #include "numeric.h"
  27 #include "print.h"
  28 #include "archive.h"
  29 #include "utils.h"
  30 #include "debugmsg.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         debugmsg("relational default ctor",LOGLEVEL_CONSTRUCT);
  43 }
  44
  45 void relational::copy(const relational & other)
  46 {
  47         basic::copy(other);
  48         lh=other.lh;
  49         rh=other.rh;
  50         o=other.o;
  51 }
  52
  53 DEFAULT_DESTROY(relational)
  54
  55 //////////
  56 // other ctors
  57 //////////
  58
  59 // public
  60
  61 relational::relational(const ex & lhs, const ex & rhs, operators oper) : basic(TINFO_relational)
  62 {
  63         debugmsg("relational ctor ex,ex,operator",LOGLEVEL_CONSTRUCT);
  64         lh=lhs;
  65         rh=rhs;
  66         o=oper;
  67 }
  68
  69 //////////
  70 // archiving
  71 //////////
  72
  73 relational::relational(const archive_node &n, const lst &sym_lst) : inherited(n, sym_lst)
  74 {
  75         debugmsg("relational ctor from archive_node", LOGLEVEL_CONSTRUCT);
  76         unsigned int opi;
  77         if (!(n.find_unsigned("op", opi)))
  78                 throw (std::runtime_error("unknown relational operator in archive"));
  79         o = (operators)opi;
  80         n.find_ex("lh", lh, sym_lst);
  81         n.find_ex("rh", rh, sym_lst);
  82 }
  83
  84 void relational::archive(archive_node &n) const
  85 {
  86         inherited::archive(n);
  87         n.add_ex("lh", lh);
  88         n.add_ex("rh", rh);
  89         n.add_unsigned("op", o);
  90 }
  91
  92 DEFAULT_UNARCHIVE(relational)
  93
  94 //////////
  95 // functions overriding virtual functions from base classes
  96 //////////
  97
  98 // public
  99
 100 void relational::print(const print_context & c, unsigned level) const
 101 {
 102         debugmsg("relational print",LOGLEVEL_PRINT);
 103
 104         if (is_of_type(c, print_tree)) {
 105
 106                 inherited::print(c, level);
 107
 108         } else {
 109
 110                 if (precedence() <= level)
 111                         c.s << "(";
 112                 lh.print(c, precedence());
 113                 switch (o) {
 114                 case equal:
 115                         c.s << "==";
 116                         break;
 117                 case not_equal:
 118                         c.s << "!=";
 119                         break;
 120                 case less:
 121                         c.s << "<";
 122                         break;
 123                 case less_or_equal:
 124                         c.s << "<=";
 125                         break;
 126                 case greater:
 127                         c.s << ">";
 128                         break;
 129                 case greater_or_equal:
 130                         c.s << ">=";
 131                         break;
 132                 default:
 133                         c.s << "(INVALID RELATIONAL OPERATOR)";
 134                 }
 135                 rh.print(c, precedence());
 136                 if (precedence() <= level)
 137                         c.s << ")";
 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_of_type(other, relational));
 196         const relational &oth = static_cast<const relational &>(other);
 197
 198         if (o == oth.o) {
 199                 int cmpval = lh.compare(oth.lh);
 200                 if (cmpval)
 201                         return cmpval;
 202                 else
 203                         return rh.compare(oth.rh);
 204         }
 205         return (o < oth.o) ? -1 : 1;
 206 }
 207
 208 bool relational::match_same_type(const basic & other) const
 209 {
 210         GINAC_ASSERT(is_exactly_of_type(other, relational));
 211         const relational &oth = static_cast<const relational &>(other);
 212
 213         return o == oth.o;
 214 }
 215
 216 unsigned relational::return_type(void) const
 217 {
 218         GINAC_ASSERT(lh.return_type()==rh.return_type());
 219         return lh.return_type();
 220 }
 221
 222 unsigned relational::return_type_tinfo(void) const
 223 {
 224         GINAC_ASSERT(lh.return_type_tinfo()==rh.return_type_tinfo());
 225         return lh.return_type_tinfo();
 226 }
 227
 228 //////////
 229 // new virtual functions which can be overridden by derived classes
 230 //////////
 231
 232 /** Left hand side of relational. */
 233 ex relational::lhs(void) const
 234 {
 235         return lh;
 236 }
 237
 238 /** Right hand side of relational. */
 239 ex relational::rhs(void) const
 240 {
 241         return rh;
 242 }
 243
 244 //////////
 245 // non-virtual functions in this class
 246 //////////
 247
 248 /** Cast the relational into a boolean, mainly for evaluation within an
 249  *  if-statement.  Note that (a<b) == false does not imply (a>=b) == true in
 250  *  the general symbolic case.  A false result means the comparison is either
 251  *  false or undecidable (except of course for !=, where true means either
 252  *  unequal or undecidable). */
 253 relational::operator bool() const
 254 {
 255         const ex df = lh-rh;
 256         if (!is_ex_exactly_of_type(df,numeric))
 257                 // cannot decide on non-numerical results
 258                 return o==not_equal ? true : false;
 259
 260         switch (o) {
 261         case equal:
 262                 return ex_to<numeric>(df).is_zero();
 263         case not_equal:
 264                 return !ex_to<numeric>(df).is_zero();
 265         case less:
 266                 return ex_to<numeric>(df)<_num0();
 267         case less_or_equal:
 268                 return ex_to<numeric>(df)<=_num0();
 269         case greater:
 270                 return ex_to<numeric>(df)>_num0();
 271         case greater_or_equal:
 272                 return ex_to<numeric>(df)>=_num0();
 273         default:
 274                 throw(std::logic_error("invalid relational operator"));
 275         }
 276 }
 277
 278 } // namespace GiNaC