tests/rewriting.cc

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //  This file is generated automatically using Prop (version 2.3.2),
   3 //  last updated on Mar 14, 1997.
   4 //  The original source file is "rewriting.pcc".
   5 ///////////////////////////////////////////////////////////////////////////////
   6
   7 #define PROP_REWRITING_USED
   8 #define PROP_REFCOUNT_USED
   9 #define PROP_QUARK_USED
  10 #include <propdefs.h>
  11 #line 1 "rewriting.pcc"
  12 //////////////////////////////////////////////////////////////////////////////
  13 //  Testing the rewriting features.
  14 //////////////////////////////////////////////////////////////////////////////
  15 #include <new>
  16 #include <iostream.h>
  17
  18 int balance;     // number of allocation - number of deallocation
  19 int div_by_zero; // number of division by zeros
  20
  21 //////////////////////////////////////////////////////////////////////////////
  22 // We'll use reference counting with rewriting.
  23 // The operators new and delete are redefined to keep track of
  24 // the number of allocations and deallocation.
  25 // This is for demonstration use only.  In practice, it is
  26 // unnecessary to redefine these operators if the normal ones
  27 // suffice.
  28 //////////////////////////////////////////////////////////////////////////////
  29 class MEM {
  30 public:
  31    inline void * operator new (size_t n)
  32       { balance++; return new char [n]; }
  33    inline void   operator delete (void * x)
  34       { balance--; delete [] ((char*)x); }
  35 };
  36
  37 //////////////////////////////////////////////////////////////////////////////
  38 //  Define the datatypes EXP and EXP_LIST.  Currently, rewriting can only be
  39 //  performed on datatypes(and not views) in Prop.  If replacement is
  40 //  to be performed on a datatype, then it should be declared using
  41 //  the ``rewrite'' qualifier.
  42 //
  43 //  We'll extend these datatypes from class MEM so that it'll inherit
  44 //  MEM's operator new and delete.
  45 //////////////////////////////////////////////////////////////////////////////
  46 #line 35 "rewriting.pcc"
  47 #line 48 "rewriting.pcc"
  48 ///////////////////////////////////////////////////////////////////////////////
  49 //
  50 // Forward class definition for EXP
  51 //
  52 ///////////////////////////////////////////////////////////////////////////////
  53 #ifndef datatype_EXP_defined
  54 #define datatype_EXP_defined
  55    class a_EXP;
  56    typedef a_EXP * EXP;
  57 #endif
  58
  59 #  define om (EXP)0
  60
  61 ///////////////////////////////////////////////////////////////////////////////
  62 //
  63 // Forward class definition for EXP_LIST
  64 //
  65 ///////////////////////////////////////////////////////////////////////////////
  66 #ifndef datatype_EXP_LIST_defined
  67 #define datatype_EXP_LIST_defined
  68    class a_EXP_LIST;
  69    typedef a_EXP_LIST * EXP_LIST;
  70 #endif
  71
  72 #  define nil_1_ (EXP_LIST)0
  73
  74 ///////////////////////////////////////////////////////////////////////////////
  75 //
  76 // Base class for datatype EXP
  77 //
  78 ///////////////////////////////////////////////////////////////////////////////
  79 class a_EXP : public MEM, public TermObj {
  80 public:
  81    enum Tag_EXP {
  82       tag_num = 0, tag_var = 1, tag_add = 2,
  83       tag_sub = 3, tag_mul = 4, tag_div = 5,
  84       tag_exp_list = 6
  85    };
  86
  87 public:
  88    const Tag_EXP tag__; // variant tag
  89 protected:
  90    inline a_EXP(Tag_EXP t__) : tag__(t__) {}
  91 public:
  92 };
  93 inline int boxed(const a_EXP * x) { return x != 0; }
  94 inline int untag(const a_EXP * x) { return x ? (x->tag__+1) : 0; }
  95 ///////////////////////////////////////////////////////////////////////////////
  96 //
  97 // Class for datatype constructor EXP::num
  98 //
  99 ///////////////////////////////////////////////////////////////////////////////
 100 class EXP_num : public a_EXP {
 101 public:
 102 #line 36 "rewriting.pcc"
 103    int num;
 104    inline EXP_num (int x_num)
 105     : a_EXP(tag_num), num(x_num)
 106    {
 107    }
 108 };
 109
 110 ///////////////////////////////////////////////////////////////////////////////
 111 //
 112 // Class for datatype constructor EXP::var
 113 //
 114 ///////////////////////////////////////////////////////////////////////////////
 115 class EXP_var : public a_EXP {
 116 public:
 117 #line 37 "rewriting.pcc"
 118    char var;
 119    inline EXP_var (char x_var)
 120     : a_EXP(tag_var), var(x_var)
 121    {
 122    }
 123 };
 124
 125 ///////////////////////////////////////////////////////////////////////////////
 126 //
 127 // Class for datatype constructor EXP::add
 128 //
 129 ///////////////////////////////////////////////////////////////////////////////
 130 class EXP_add : public a_EXP {
 131 public:
 132 #line 38 "rewriting.pcc"
 133    EXP _1; EXP _2;
 134    inline EXP_add (EXP x_1, EXP x_2)
 135     : a_EXP(tag_add), _1(x_1), _2(x_2)
 136    {
 137    }
 138 };
 139
 140 ///////////////////////////////////////////////////////////////////////////////
 141 //
 142 // Class for datatype constructor EXP::sub
 143 //
 144 ///////////////////////////////////////////////////////////////////////////////
 145 class EXP_sub : public a_EXP {
 146 public:
 147 #line 39 "rewriting.pcc"
 148    EXP _1; EXP _2;
 149    inline EXP_sub (EXP x_1, EXP x_2)
 150     : a_EXP(tag_sub), _1(x_1), _2(x_2)
 151    {
 152    }
 153 };
 154
 155 ///////////////////////////////////////////////////////////////////////////////
 156 //
 157 // Class for datatype constructor EXP::mul
 158 //
 159 ///////////////////////////////////////////////////////////////////////////////
 160 class EXP_mul : public a_EXP {
 161 public:
 162 #line 40 "rewriting.pcc"
 163    EXP _1; EXP _2;
 164    inline EXP_mul (EXP x_1, EXP x_2)
 165     : a_EXP(tag_mul), _1(x_1), _2(x_2)
 166    {
 167    }
 168 };
 169
 170 ///////////////////////////////////////////////////////////////////////////////
 171 //
 172 // Class for datatype constructor EXP::div
 173 //
 174 ///////////////////////////////////////////////////////////////////////////////
 175 class EXP_div : public a_EXP {
 176 public:
 177 #line 41 "rewriting.pcc"
 178    EXP _1; EXP _2;
 179    inline EXP_div (EXP x_1, EXP x_2)
 180     : a_EXP(tag_div), _1(x_1), _2(x_2)
 181    {
 182    }
 183 };
 184
 185 ///////////////////////////////////////////////////////////////////////////////
 186 //
 187 // Class for datatype constructor EXP::exp_list
 188 //
 189 ///////////////////////////////////////////////////////////////////////////////
 190 class EXP_exp_list : public a_EXP {
 191 public:
 192 #line 42 "rewriting.pcc"
 193    EXP_LIST exp_list;
 194    inline EXP_exp_list (EXP_LIST x_exp_list)
 195     : a_EXP(tag_exp_list), exp_list(x_exp_list)
 196    {
 197    }
 198 };
 199
 200 ///////////////////////////////////////////////////////////////////////////////
 201 //
 202 // Datatype constructor functions for EXP
 203 //
 204 ///////////////////////////////////////////////////////////////////////////////
 205 inline a_EXP * num (int x_num)
 206 { return new EXP_num (x_num); }
 207 inline a_EXP * var (char x_var)
 208 { return new EXP_var (x_var); }
 209 inline a_EXP * add (EXP x_1, EXP x_2)
 210 { return new EXP_add (x_1, x_2); }
 211 inline a_EXP * sub (EXP x_1, EXP x_2)
 212 { return new EXP_sub (x_1, x_2); }
 213 inline a_EXP * mul (EXP x_1, EXP x_2)
 214 { return new EXP_mul (x_1, x_2); }
 215 inline a_EXP * div (EXP x_1, EXP x_2)
 216 { return new EXP_div (x_1, x_2); }
 217 inline a_EXP * exp_list (EXP_LIST x_exp_list)
 218 { return new EXP_exp_list (x_exp_list); }
 219 ///////////////////////////////////////////////////////////////////////////////
 220 //
 221 // Downcasting functions for EXP
 222 //
 223 ///////////////////////////////////////////////////////////////////////////////
 224 inline EXP_num * _num(const a_EXP * _x_) { return (EXP_num *)_x_; }
 225 inline EXP_var * _var(const a_EXP * _x_) { return (EXP_var *)_x_; }
 226 inline EXP_add * _add(const a_EXP * _x_) { return (EXP_add *)_x_; }
 227 inline EXP_sub * _sub(const a_EXP * _x_) { return (EXP_sub *)_x_; }
 228 inline EXP_mul * _mul(const a_EXP * _x_) { return (EXP_mul *)_x_; }
 229 inline EXP_div * _div(const a_EXP * _x_) { return (EXP_div *)_x_; }
 230 inline EXP_exp_list * _exp_list(const a_EXP * _x_) { return (EXP_exp_list *)_x_; }
 231
 232 ///////////////////////////////////////////////////////////////////////////////
 233 //
 234 // Class for datatype constructor EXP_LIST::#[...]
 235 //
 236 ///////////////////////////////////////////////////////////////////////////////
 237 class a_EXP_LIST : public MEM, public TermObj {
 238 public:
 239 #line 46 "rewriting.pcc"
 240    EXP _1; EXP_LIST _2;
 241    inline a_EXP_LIST (EXP x_1, EXP_LIST x_2)
 242     : _1(x_1), _2(x_2)
 243    {
 244    }
 245    inline a_EXP_LIST (EXP x_1, int x_2)
 246     : _1(x_1), _2((a_EXP_LIST *)x_2)
 247    {
 248    }
 249 };
 250 inline int boxed(const a_EXP_LIST * x) { return x != 0; }
 251 inline int untag(const a_EXP_LIST * x) { return x ? 1 : 0; }
 252 ///////////////////////////////////////////////////////////////////////////////
 253 //
 254 // Datatype constructor functions for EXP_LIST
 255 //
 256 ///////////////////////////////////////////////////////////////////////////////
 257 inline a_EXP_LIST * list_1_ (EXP x_1, EXP_LIST x_2)
 258 { return new a_EXP_LIST (x_1, x_2); }
 259 inline a_EXP_LIST * list_1_ (EXP x_1, int x_2)
 260 { return new a_EXP_LIST (x_1, x_2); }
 261 ///////////////////////////////////////////////////////////////////////////////
 262 //
 263 // Downcasting functions for EXP_LIST
 264 //
 265 ///////////////////////////////////////////////////////////////////////////////
 266
 267
 268 #line 48 "rewriting.pcc"
 269 #line 48 "rewriting.pcc"
 270
 271
 272 //////////////////////////////////////////////////////////////////////////////
 273 //  Define a method that prints an expression.  This is a simple
 274 //  inductive definition
 275 //////////////////////////////////////////////////////////////////////////////
 276 ostream& operator << (ostream& f, EXP_LIST l);
 277 ostream& operator << (ostream& f, EXP e)
 278 {
 279 #line 56 "rewriting.pcc"
 280 #line 64 "rewriting.pcc"
 281 {
 282    if (e) {
 283       switch (e->tag__) {
 284          case a_EXP::tag_num: {
 285 #line 58 "rewriting.pcc"
 286            return f << _num(e)->num;
 287 #line 58 "rewriting.pcc"
 288             } break;
 289          case a_EXP::tag_var: {
 290 #line 59 "rewriting.pcc"
 291            return f << _var(e)->var;
 292 #line 59 "rewriting.pcc"
 293             } break;
 294          case a_EXP::tag_add: {
 295 #line 60 "rewriting.pcc"
 296            return f << '(' << _add(e)->_1 << " + " << _add(e)->_2 << ')';
 297 #line 60 "rewriting.pcc"
 298             } break;
 299          case a_EXP::tag_sub: {
 300 #line 61 "rewriting.pcc"
 301            return f << '(' << _sub(e)->_1 << " - " << _sub(e)->_2 << ')';
 302 #line 61 "rewriting.pcc"
 303             } break;
 304          case a_EXP::tag_mul: {
 305 #line 62 "rewriting.pcc"
 306            return f << '(' << _mul(e)->_1 << " * " << _mul(e)->_2 << ')';
 307 #line 62 "rewriting.pcc"
 308             } break;
 309          case a_EXP::tag_div: {
 310 #line 63 "rewriting.pcc"
 311            return f << '(' << _div(e)->_1 << " / " << _div(e)->_2 << ')';
 312 #line 63 "rewriting.pcc"
 313             } break;
 314          default: {
 315 #line 64 "rewriting.pcc"
 316            return f << '[' << _exp_list(e)->exp_list << ']';
 317 #line 64 "rewriting.pcc"
 318             } break;
 319       }
 320    } else {
 321 #line 57 "rewriting.pcc"
 322      return f << "om";
 323 #line 57 "rewriting.pcc"
 324    }
 325 }
 326 #line 65 "rewriting.pcc"
 327 #line 65 "rewriting.pcc"
 328
 329 }
 330
 331 //////////////////////////////////////////////////////////////////////////////
 332 //  This prints an expression list
 333 //////////////////////////////////////////////////////////////////////////////
 334 ostream& operator << (ostream& f, EXP_LIST l)
 335 {
 336 #line 72 "rewriting.pcc"
 337 #line 75 "rewriting.pcc"
 338 {
 339    if (l) {
 340       if (l->_2) {
 341 #line 75 "rewriting.pcc"
 342         return f << l->_1 << ", " << l->_2;
 343 #line 75 "rewriting.pcc"
 344       } else {
 345 #line 74 "rewriting.pcc"
 346         return f << l->_1;
 347 #line 74 "rewriting.pcc"
 348       }
 349    } else {
 350 #line 73 "rewriting.pcc"
 351      return f;
 352 #line 73 "rewriting.pcc"
 353    }
 354 }
 355 #line 76 "rewriting.pcc"
 356 #line 76 "rewriting.pcc"
 357
 358 }
 359
 360 //////////////////////////////////////////////////////////////////////////////
 361 //  Define the interface to a ``rewriting class.''  A rewriting class
 362 //  is simply a C++ class with rewriting rules attached.  In real programs
 363 //  this definition should be placed in some definition (i.e. .ph) files.
 364 //
 365 //  In parenthesis, we must list all datatypes involved.   Unlike
 366 //  simple pattern matching, rewriting can involve a set of mutually
 367 //  recursive (or mutually exclusive, if desired) datatype definitions.
 368 //  So in general this is a comma delimited list.
 369 //
 370 //  In this example it involves only the datatypes EXP and EXP_LIST.
 371 //////////////////////////////////////////////////////////////////////////////
 372 #line 91 "rewriting.pcc"
 373 #line 95 "rewriting.pcc"
 374 class Simplify : public BURS {
 375 private:
 376    Simplify(const Simplify&);               // no copy constructor
 377    void operator = (const Simplify&); // no assignment
 378 public:
 379    struct Simplify_StateRec * stack__, * stack_top__;
 380 public:
 381    void labeler(const char *, int&, int);
 382    void labeler(Quark, int&, int);
 383           void  labeler(EXP & redex, int&, int);
 384    inline virtual void  operator () (EXP & redex) { int s; labeler(redex,s,0); }
 385           void  labeler(EXP_LIST & redex, int&, int);
 386    inline virtual void  operator () (EXP_LIST & redex) { int s; labeler(redex,s,0); }
 387 private:
 388 #line 92 "rewriting.pcc"
 389  // nothing here for now.
 390    public:
 391       Simplify() {}
 392 #line 95 "rewriting.pcc"
 393 };
 394 #line 95 "rewriting.pcc"
 395 #line 95 "rewriting.pcc"
 396
 397
 398 //////////////////////////////////////////////////////////////////////////////
 399 //  Now we define the rewriting rules in the rewriting class Simplify.  These
 400 //  rules should be placed in an implementation file (.pcc, .pC, .pc++ etc).
 401 //
 402 //  In this brief sample class we have some rules that perform
 403 //  simple constant folding and strength reduction.
 404 //
 405 //  Currently, all the rules for a rewrite class must be placed in
 406 //  the same rewrite construct.  This will probably change in the future
 407 //  once I work out the details on incremental tree automata compilation.
 408 //////////////////////////////////////////////////////////////////////////////
 409 #line 108 "rewriting.pcc"
 410 #line 128 "rewriting.pcc"
 411 static const TreeTables::Offset Simplify_accept_base [ 15 ] = {
 412    0, 1, 2, 3, 5, 7, 11, 13, 15, 18, 22, 30, 34, 37, 42
 413 };
 414 static const TreeTables::Rule Simplify_accept_vector [ 44 ] = {
 415    -1, 17, -1, 16, -1, 1, -1, 0, 1, 10, -1, 0, -1, 2, -1, 2,
 416    11, -1, 3, 5, 7, -1, 3, 4, 5, 6, 7, 8, 12, -1, 4, 6,
 417    8, -1, 9, 14, -1, 9, 13, 14, 15, -1, 15, -1
 418 };
 419 static const TreeTables::State Simplify_theta_3[2][2] = {
 420    { 0, 4 },
 421    { 6, 5 }
 422 };
 423
 424
 425 static const TreeTables::State Simplify_theta_4[2][2] = {
 426    { 0, 7 },
 427    { 0, 8 }
 428 };
 429
 430
 431 static const TreeTables::State Simplify_theta_5[2][2] = {
 432    { 0, 9 },
 433    { 11, 10 }
 434 };
 435
 436
 437 static const TreeTables::State Simplify_theta_6[2][2] = {
 438    { 0, 12 },
 439    { 14, 13 }
 440 };
 441
 442
 443 static const TreeTables::State Simplify_mu_3_0[15] = {
 444    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 445 };
 446
 447
 448 static const TreeTables::State Simplify_mu_3_1[15] = {
 449    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 450 };
 451
 452
 453 static const TreeTables::State Simplify_mu_4_0[15] = {
 454    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 455 };
 456
 457
 458 static const TreeTables::State Simplify_mu_4_1[15] = {
 459    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 460 };
 461
 462
 463 static const TreeTables::State Simplify_mu_5_0[15] = {
 464    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 465 };
 466
 467
 468 static const TreeTables::State Simplify_mu_5_1[15] = {
 469    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 470 };
 471
 472
 473 static const TreeTables::State Simplify_mu_6_0[15] = {
 474    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 475 };
 476
 477
 478 static const TreeTables::State Simplify_mu_6_1[15] = {
 479    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 480 };
 481
 482
 483 inline void  Simplify::labeler(char const * redex,int& s__,int)
 484 {
 485    {
 486 s__ = 0;
 487    }
 488 }
 489
 490 inline void  Simplify::labeler(Quark redex,int& s__,int)
 491 {
 492    {
 493 s__ = 0;
 494    }
 495 }
 496
 497 void  Simplify::labeler (EXP & redex, int& s__, int r__)
 498 {
 499 replacement__:
 500    int cached__;
 501    if (r__ && boxed(redex) && (cached__ = redex->get_rewrite_state()) != BURS::undefined_state)
 502    { s__ = cached__; return; }
 503    if ((redex)) {
 504       switch(redex->tag__) {
 505          case a_EXP::tag_num: {
 506             int s0__;
 507             s0__ = 0; // int
 508             s__ = 2;} break;
 509          case a_EXP::tag_var: {
 510             int s0__;
 511             s0__ = 0; // char
 512             s__ = 0;} break;
 513          case a_EXP::tag_add: {
 514             int s0__;
 515             int s1__;
 516             labeler(_add(redex)->_1, s0__, r__);
 517             labeler(_add(redex)->_2, s1__, r__);
 518             s__ = Simplify_theta_3[Simplify_mu_3_0[s0__]][Simplify_mu_3_1[s1__]]; } break;
 519          case a_EXP::tag_sub: {
 520             int s0__;
 521             int s1__;
 522             labeler(_sub(redex)->_1, s0__, r__);
 523             labeler(_sub(redex)->_2, s1__, r__);
 524             s__ = Simplify_theta_4[Simplify_mu_4_0[s0__]][Simplify_mu_4_1[s1__]]; } break;
 525          case a_EXP::tag_mul: {
 526             int s0__;
 527             int s1__;
 528             labeler(_mul(redex)->_1, s0__, r__);
 529             labeler(_mul(redex)->_2, s1__, r__);
 530             s__ = Simplify_theta_5[Simplify_mu_5_0[s0__]][Simplify_mu_5_1[s1__]]; } break;
 531          case a_EXP::tag_div: {
 532             int s0__;
 533             int s1__;
 534             labeler(_div(redex)->_1, s0__, r__);
 535             labeler(_div(redex)->_2, s1__, r__);
 536             s__ = Simplify_theta_6[Simplify_mu_6_0[s0__]][Simplify_mu_6_1[s1__]]; } break;
 537          default: {
 538             int s0__;
 539             labeler(_exp_list(redex)->exp_list, s0__, r__);
 540             s__ = 0;} break;
 541       }
 542    } else {s__ = 0;
 543    }
 544    const TreeTables::Rule * o__ = Simplify_accept_vector + Simplify_accept_base[s__];
 545 accept__:
 546    switch (*o__) {
 547       case 15: if ((_num(_div(redex)->_1)->num == 0))
 548       {
 549 #line 126 "rewriting.pcc"
 550          { redex = _div(redex)->_1; r__ = 1; goto replacement__; }
 551 #line 126 "rewriting.pcc"
 552 }
 553       else { ++o__; goto accept__; } break;
 554       case 14: if ((_num(_div(redex)->_2)->num == 0))
 555       {
 556 #line 123 "rewriting.pcc"
 557        cout << "Division by zero!\n";
 558          div_by_zero++;
 559
 560 #line 125 "rewriting.pcc"
 561 }
 562       else { ++o__; goto accept__; } break;
 563       case 13: if ((_num(_div(redex)->_2)->num != 0))
 564       {
 565 #line 122 "rewriting.pcc"
 566          { redex = num((_num(_div(redex)->_1)->num / _num(_div(redex)->_2)->num)); r__ = 1; goto replacement__; }
 567 #line 122 "rewriting.pcc"
 568 }
 569       else { ++o__; goto accept__; } break;
 570       case 12: {
 571 #line 121 "rewriting.pcc"
 572          { redex = num((_num(_mul(redex)->_1)->num * _num(_mul(redex)->_2)->num)); r__ = 1; goto replacement__; }
 573 #line 121 "rewriting.pcc"
 574 } break;
 575       case 11: {
 576 #line 120 "rewriting.pcc"
 577          { redex = num((_num(_sub(redex)->_1)->num - _num(_sub(redex)->_2)->num)); r__ = 1; goto replacement__; }
 578 #line 120 "rewriting.pcc"
 579 } break;
 580       case 10: {
 581 #line 119 "rewriting.pcc"
 582          { redex = num((_num(_add(redex)->_1)->num + _num(_add(redex)->_2)->num)); r__ = 1; goto replacement__; }
 583 #line 119 "rewriting.pcc"
 584 } break;
 585       case 9: if ((_num(_div(redex)->_2)->num == 1))
 586       {
 587 #line 118 "rewriting.pcc"
 588          { redex = _div(redex)->_1; r__ = 1; goto replacement__; }
 589 #line 118 "rewriting.pcc"
 590 }
 591       else { ++o__; goto accept__; } break;
 592       case 8: if ((_num(_mul(redex)->_1)->num == 2))
 593       {
 594 #line 117 "rewriting.pcc"
 595          { redex = add(_mul(redex)->_2,_mul(redex)->_2); r__ = 1; goto replacement__; }
 596 #line 117 "rewriting.pcc"
 597 }
 598       else { ++o__; goto accept__; } break;
 599       case 7: if ((_num(_mul(redex)->_2)->num == 2))
 600       {
 601 #line 116 "rewriting.pcc"
 602          { redex = add(_mul(redex)->_1,_mul(redex)->_1); r__ = 1; goto replacement__; }
 603 #line 116 "rewriting.pcc"
 604 }
 605       else { ++o__; goto accept__; } break;
 606       case 6: if ((_num(_mul(redex)->_1)->num == 1))
 607       {
 608 #line 115 "rewriting.pcc"
 609          { redex = _mul(redex)->_2; r__ = 1; goto replacement__; }
 610 #line 115 "rewriting.pcc"
 611 }
 612       else { ++o__; goto accept__; } break;
 613       case 5: if ((_num(_mul(redex)->_2)->num == 1))
 614       {
 615 #line 114 "rewriting.pcc"
 616          { redex = _mul(redex)->_1; r__ = 1; goto replacement__; }
 617 #line 114 "rewriting.pcc"
 618 }
 619       else { ++o__; goto accept__; } break;
 620       case 4: if ((_num(_mul(redex)->_1)->num == 0))
 621       {
 622 #line 113 "rewriting.pcc"
 623          { redex = num(0); r__ = 1; goto replacement__; }
 624 #line 113 "rewriting.pcc"
 625 }
 626       else { ++o__; goto accept__; } break;
 627       case 3: if ((_num(_mul(redex)->_2)->num == 0))
 628       {
 629 #line 112 "rewriting.pcc"
 630          { redex = num(0); r__ = 1; goto replacement__; }
 631 #line 112 "rewriting.pcc"
 632 }
 633       else { ++o__; goto accept__; } break;
 634       case 2: if ((_num(_sub(redex)->_2)->num == 0))
 635       {
 636 #line 111 "rewriting.pcc"
 637          { redex = _sub(redex)->_1; r__ = 1; goto replacement__; }
 638 #line 111 "rewriting.pcc"
 639 }
 640       else { ++o__; goto accept__; } break;
 641       case 1: if ((_num(_add(redex)->_2)->num == 0))
 642       {
 643 #line 110 "rewriting.pcc"
 644          { redex = _add(redex)->_1; r__ = 1; goto replacement__; }
 645 #line 110 "rewriting.pcc"
 646 }
 647       else { ++o__; goto accept__; } break;
 648       case 0: if ((_num(_add(redex)->_1)->num == 0))
 649       {
 650 #line 109 "rewriting.pcc"
 651          { redex = _add(redex)->_2; r__ = 1; goto replacement__; }
 652 #line 109 "rewriting.pcc"
 653 }
 654       else { ++o__; goto accept__; } break;
 655    }
 656    if (boxed(redex)) {
 657       redex->set_rewrite_state(s__);
 658    }
 659
 660 }
 661
 662 void  Simplify::labeler (EXP_LIST & redex, int& s__, int r__)
 663 {
 664 replacement__:
 665    int cached__;
 666    if (r__ && boxed(redex) && (cached__ = redex->get_rewrite_state()) != BURS::undefined_state)
 667    { s__ = cached__; return; }
 668    if ((redex)) {
 669       int s0__;
 670       int s1__;
 671       labeler(redex->_1, s0__, r__);
 672       labeler(redex->_2, s1__, r__);
 673       s__ = 3;
 674    } else {s__ = 1;
 675    }
 676    switch (s__) {
 677       case 1: {
 678 #line 128 "rewriting.pcc"
 679         cout << "nil found\n";
 680 #line 128 "rewriting.pcc"
 681 } break;
 682       case 3: {
 683 #line 127 "rewriting.pcc"
 684         cout << "list found\n";
 685 #line 127 "rewriting.pcc"
 686 } break;
 687    }
 688    if (boxed(redex)) {
 689       redex->set_rewrite_state(s__);
 690    }
 691
 692 }
 693
 694 #line 129 "rewriting.pcc"
 695 #line 129 "rewriting.pcc"
 696
 697
 698 //////////////////////////////////////////////////////////////////////////////
 699 //  Instantiate the datatypes
 700 //////////////////////////////////////////////////////////////////////////////
 701 #line 134 "rewriting.pcc"
 702 #line 134 "rewriting.pcc"
 703 ///////////////////////////////////////////////////////////////////////////////
 704 // Instantiation of datatype EXP
 705 ///////////////////////////////////////////////////////////////////////////////
 706 #line 134 "rewriting.pcc"
 707
 708
 709 ///////////////////////////////////////////////////////////////////////////////
 710 // Instantiation of datatype EXP_LIST
 711 ///////////////////////////////////////////////////////////////////////////////
 712 #line 134 "rewriting.pcc"
 713
 714
 715 #line 134 "rewriting.pcc"
 716 #line 134 "rewriting.pcc"
 717
 718
 719 //////////////////////////////////////////////////////////////////////////////
 720 //  Now defines the main program that uses all this stuff.
 721 //////////////////////////////////////////////////////////////////////////////
 722 int main()
 723 {
 724    //
 725    // Instantiate a rewriting class
 726    //
 727    Simplify sim;
 728
 729    //
 730    // (0 + x * 2) / (1 * 5 + 1 * 3) / (0 / y);
 731    //
 732    EXP t1 = div(div(add(num(0), mul(var('x'),num(2))),
 733                     add(mul(num(1), num(5)),mul(num(1),num(3)))),
 734                 div(num(0),var('y')));
 735    EXP term = mul(t1,t1);
 736
 737    //
 738    //  Rewrite the big term above.
 739    //
 740    cout << "Before: " << term << '\n';
 741    sim(term);
 742    cout << "After: " << term << '\n';
 743
 744    //
 745    //  Rewrite it again.  It should have no effect since the term
 746    //  is already in normal form.
 747    //
 748    sim(term);
 749    cout << "Again (should have no effect): " << term << '\n';
 750
 751    //
 752    //  Rewrite some other term.
 753    //
 754    EXP term2 = add(sub(num(3),num(3)), var('z'));
 755    cout << "Before: " << term2 << '\n';
 756    sim(term2);
 757    cout << "After: " << term2 << '\n';
 758
 759    //
 760    //  Rewrite some other term.
 761    //
 762    EXP term3 = div(num(1),num(0));
 763    sim(term3);
 764
 765    //
 766    //  Rewrite some other term.
 767    //  Notice that even though the patterns do not involve `exp_list'
 768    //  directly the internal components of `exp_list' are still candidates
 769    //  for rewrites: rewriting operates on the entire tree, and not just
 770    //  on the cover like vanilla pattern matching.
 771    //
 772    EXP term4 = exp_list(
 773 #line 189 "rewriting.pcc"
 774 #line 189 "rewriting.pcc"
 775 list_1_(div(num(1),num(0)),list_1_(var('x'),nil_1_))
 776 #line 189 "rewriting.pcc"
 777 #line 189 "rewriting.pcc"
 778 );
 779    sim(term4);
 780
 781    //
 782    //
 783    //  Set the terms to 'om' so that their storage is released.
 784    //
 785    t1 = term = term2 = term3 = term4 = om;
 786    if (div_by_zero != 6) { cerr << "BUG in rewriting!\n"; return 1; }
 787    if (balance != 0)     { cerr << "BUG in reference counting!\n"; return 1; }
 788    return 0;
 789 }
 790 #line 201 "rewriting.pcc"
 791 /*
 792 ------------------------------- Statistics -------------------------------
 793 Merge matching rules         = yes
 794 Number of DFA nodes merged   = 1
 795 Number of ifs generated      = 3
 796 Number of switches generated = 1
 797 Number of labels             = 0
 798 Number of gotos              = 0
 799 Adaptive matching            = disabled
 800 Fast string matching         = disabled
 801 Inline downcasts             = disabled
 802 --------------------------------------------------------------------------
 803 */