ginac/relational.cpp

   1 /** @file relational.cpp
   2  *
   3  *  Implementation of relations between expressions */
   4
   5 /*
   6  *  GiNaC Copyright (C) 1999-2017 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  21  */
  22
  23 #include "relational.h"
  24 #include "operators.h"
  25 #include "numeric.h"
  26 #include "archive.h"
  27 #include "utils.h"
  28 #include "hash_seed.h"
  29
  30 #include <iostream>
  31 #include <stdexcept>
  32
  33 namespace GiNaC {
  34
  35 GINAC_IMPLEMENT_REGISTERED_CLASS_OPT(relational, basic,
  36   print_func<print_context>(&relational::do_print).
  37   print_func<print_tree>(&relational::do_print_tree).
  38   print_func<print_python_repr>(&relational::do_print_python_repr))
  39
  40 //////////
  41 // default constructor
  42 //////////
  43
  44 relational::relational() { }
  45
  46 //////////
  47 // other constructors
  48 //////////
  49
  50 // public
  51
  52 relational::relational(const ex & lhs, const ex & rhs, operators oper) :
  53         lh(lhs), rh(rhs), o(oper) { }
  54
  55 //////////
  56 // archiving
  57 //////////
  58
  59 void relational::read_archive(const archive_node& n, lst& sym_lst)
  60 {
  61         inherited::read_archive(n, sym_lst);
  62         unsigned int opi;
  63         if (!(n.find_unsigned("op", opi)))
  64                 throw (std::runtime_error("unknown relational operator in archive"));
  65         o = (operators)opi;
  66         n.find_ex("lh", lh, sym_lst);
  67         n.find_ex("rh", rh, sym_lst);
  68 }
  69 GINAC_BIND_UNARCHIVER(relational);
  70
  71 void relational::archive(archive_node &n) const
  72 {
  73         inherited::archive(n);
  74         n.add_ex("lh", lh);
  75         n.add_ex("rh", rh);
  76         n.add_unsigned("op", o);
  77 }
  78
  79 //////////
  80 // functions overriding virtual functions from base classes
  81 //////////
  82
  83 // public
  84
  85 static void print_operator(const print_context & c, relational::operators o)
  86 {
  87         switch (o) {
  88         case relational::equal:
  89                 c.s << "==";
  90                 break;
  91         case relational::not_equal:
  92                 c.s << "!=";
  93                 break;
  94         case relational::less:
  95                 c.s << "<";
  96                 break;
  97         case relational::less_or_equal:
  98                 c.s << "<=";
  99                 break;
 100         case relational::greater:
 101                 c.s << ">";
 102                 break;
 103         case relational::greater_or_equal:
 104                 c.s << ">=";
 105                 break;
 106         default:
 107                 c.s << "(INVALID RELATIONAL OPERATOR)";
 108                 break;
 109         }
 110 }
 111
 112 void relational::do_print(const print_context & c, unsigned level) const
 113 {
 114         if (precedence() <= level)
 115                 c.s << "(";
 116         lh.print(c, precedence());
 117         print_operator(c, o);
 118         rh.print(c, precedence());
 119         if (precedence() <= level)
 120                 c.s << ")";
 121 }
 122
 123 void relational::do_print_python_repr(const print_python_repr & c, unsigned level) const
 124 {
 125         c.s << class_name() << '(';
 126         lh.print(c);
 127         c.s << ',';
 128         rh.print(c);
 129         c.s << ",'";
 130         print_operator(c, o);
 131         c.s << "')";
 132 }
 133
 134 bool relational::info(unsigned inf) const
 135 {
 136         switch (inf) {
 137                 case info_flags::relation:
 138                         return 1;
 139                 case info_flags::relation_equal:
 140                         return o==equal;
 141                 case info_flags::relation_not_equal:
 142                         return o==not_equal;
 143                 case info_flags::relation_less:
 144                         return o==less;
 145                 case info_flags::relation_less_or_equal:
 146                         return o==less_or_equal;
 147                 case info_flags::relation_greater:
 148                         return o==greater;
 149                 case info_flags::relation_greater_or_equal:
 150                         return o==greater_or_equal;
 151         }
 152         return 0;
 153 }
 154
 155 size_t relational::nops() const
 156 {
 157         return 2;
 158 }
 159
 160 ex relational::op(size_t i) const
 161 {
 162         GINAC_ASSERT(i<2);
 163
 164         return i==0 ? lh : rh;
 165 }
 166
 167 ex relational::map(map_function & f) const
 168 {
 169         const ex &mapped_lh = f(lh);
 170         const ex &mapped_rh = f(rh);
 171
 172         if (!are_ex_trivially_equal(lh, mapped_lh)
 173          || !are_ex_trivially_equal(rh, mapped_rh))
 174                 return dynallocate<relational>(mapped_lh, mapped_rh, o);
 175         else
 176                 return *this;
 177 }
 178
 179 ex relational::subs(const exmap & m, unsigned options) const
 180 {
 181         const ex & subsed_lh = lh.subs(m, options);
 182         const ex & subsed_rh = rh.subs(m, options);
 183
 184         if (!are_ex_trivially_equal(lh, subsed_lh) || !are_ex_trivially_equal(rh, subsed_rh))
 185                 return relational(subsed_lh, subsed_rh, o).subs_one_level(m, options);
 186         else
 187                 return subs_one_level(m, options);
 188 }
 189
 190 ex relational::eval_ncmul(const exvector & v) const
 191 {
 192         return lh.eval_ncmul(v);
 193 }
 194
 195 // protected
 196
 197 int relational::compare_same_type(const basic & other) const
 198 {
 199         GINAC_ASSERT(is_exactly_a<relational>(other));
 200         const relational &oth = static_cast<const relational &>(other);
 201         if (o==oth.o && lh.is_equal(oth.lh) && rh.is_equal(oth.rh))
 202                 return 0;
 203         switch (o) {
 204                 case equal:
 205                 case not_equal:
 206                         if (oth.o!=o)
 207                                 return (o < oth.o) ? -1 : 1;
 208                         break;
 209                 case less:
 210                         if (oth.o!=greater)
 211                                 return (o < oth.o) ? -1 : 1;
 212                         break;
 213                 case less_or_equal:
 214                         if (oth.o!=greater_or_equal)
 215                                 return (o < oth.o) ? -1 : 1;
 216                         break;
 217                 case greater:
 218                         if (oth.o!=less)
 219                                 return (o < oth.o) ? -1 : 1;
 220                         break;
 221                 case greater_or_equal:
 222                         if (oth.o!=less_or_equal)
 223                                 return (o < oth.o) ? -1 : 1;
 224                         break;
 225         }
 226         const int lcmpval = lh.compare(oth.rh);
 227         return (lcmpval!=0) ? lcmpval : rh.compare(oth.lh);
 228 }
 229
 230 bool relational::match_same_type(const basic & other) const
 231 {
 232         GINAC_ASSERT(is_exactly_a<relational>(other));
 233         const relational &oth = static_cast<const relational &>(other);
 234
 235         return o == oth.o;
 236 }
 237
 238 unsigned relational::return_type() const
 239 {
 240         GINAC_ASSERT(lh.return_type()==rh.return_type());
 241         return lh.return_type();
 242 }
 243
 244 return_type_t relational::return_type_tinfo() const
 245 {
 246         GINAC_ASSERT(lh.return_type_tinfo()==rh.return_type_tinfo());
 247         return lh.return_type_tinfo();
 248 }
 249
 250 unsigned relational::calchash() const
 251 {
 252         unsigned v = make_hash_seed(typeid(*this));
 253         unsigned lhash = lh.gethash();
 254         unsigned rhash = rh.gethash();
 255
 256         v = rotate_left(v);
 257         switch(o) {
 258                 case equal:
 259                 case not_equal:
 260                         if (lhash>rhash) {
 261                                 v ^= lhash;
 262                                 lhash = rhash;
 263                         } else {
 264                                 v ^= rhash;
 265                         }
 266                         break;
 267                 case less:
 268                 case less_or_equal:
 269                         v ^= rhash;
 270                         break;
 271                 case greater:
 272                 case greater_or_equal:
 273                         v ^= lhash;
 274                         lhash = rhash;
 275                         break;
 276         }
 277         v = rotate_left(v);
 278         v ^= lhash;
 279
 280         // store calculated hash value only if object is already evaluated
 281         if (flags & status_flags::evaluated) {
 282                 setflag(status_flags::hash_calculated);
 283                 hashvalue = v;
 284         }
 285
 286         return v;
 287 }
 288
 289 //////////
 290 // new virtual functions which can be overridden by derived classes
 291 //////////
 292
 293 // none
 294
 295 //////////
 296 // non-virtual functions in this class
 297 //////////
 298
 299 relational::safe_bool relational::make_safe_bool(bool cond) const
 300 {
 301         return cond? &safe_bool_helper::nonnull : nullptr;
 302 }
 303
 304 /** Cast the relational into a Boolean, mainly for evaluation within an
 305  *  if-statement.  Note that (a<b) == false does not imply (a>=b) == true in
 306  *  the general symbolic case.  A false result means the comparison is either
 307  *  false or undecidable (except of course for !=, where true means either
 308  *  unequal or undecidable). */
 309 relational::operator relational::safe_bool() const
 310 {
 311         const ex df = lh-rh;
 312         if (!is_exactly_a<numeric>(df))
 313                 // cannot decide on non-numerical results
 314                 return o==not_equal ? make_safe_bool(true) : make_safe_bool(false);
 315
 316         switch (o) {
 317                 case equal:
 318                         return make_safe_bool(ex_to<numeric>(df).is_zero());
 319                 case not_equal:
 320                         return make_safe_bool(!ex_to<numeric>(df).is_zero());
 321                 case less:
 322                         return make_safe_bool(ex_to<numeric>(df)<(*_num0_p));
 323                 case less_or_equal:
 324                         return make_safe_bool(ex_to<numeric>(df)<=(*_num0_p));
 325                 case greater:
 326                         return make_safe_bool(ex_to<numeric>(df)>(*_num0_p));
 327                 case greater_or_equal:
 328                         return make_safe_bool(ex_to<numeric>(df)>=(*_num0_p));
 329                 default:
 330                         throw(std::logic_error("invalid relational operator"));
 331         }
 332 }
 333
 334 } // namespace GiNaC