| 1 | /***** tl_spin: tl_parse.c *****/ |
| 2 | |
| 3 | /* Copyright (c) 1995-2003 by Lucent Technologies, Bell Laboratories. */ |
| 4 | /* All Rights Reserved. This software is for educational purposes only. */ |
| 5 | /* No guarantee whatsoever is expressed or implied by the distribution of */ |
| 6 | /* this code. Permission is given to distribute this code provided that */ |
| 7 | /* this introductory message is not removed and no monies are exchanged. */ |
| 8 | /* Software written by Gerard J. Holzmann. For tool documentation see: */ |
| 9 | /* http://spinroot.com/ */ |
| 10 | /* Send all bug-reports and/or questions to: bugs@spinroot.com */ |
| 11 | |
| 12 | /* Based on the translation algorithm by Gerth, Peled, Vardi, and Wolper, */ |
| 13 | /* presented at the PSTV Conference, held in 1995, Warsaw, Poland 1995. */ |
| 14 | |
| 15 | #include "tl.h" |
| 16 | |
| 17 | extern int tl_yylex(void); |
| 18 | extern int tl_verbose, tl_errs; |
| 19 | |
| 20 | int tl_yychar = 0; |
| 21 | YYSTYPE tl_yylval; |
| 22 | |
| 23 | static Node *tl_formula(void); |
| 24 | static Node *tl_factor(void); |
| 25 | static Node *tl_level(int); |
| 26 | |
| 27 | static int prec[2][4] = { |
| 28 | { U_OPER, V_OPER, 0, 0 }, /* left associative */ |
| 29 | { OR, AND, IMPLIES, EQUIV, }, /* left associative */ |
| 30 | }; |
| 31 | |
| 32 | static Node * |
| 33 | tl_factor(void) |
| 34 | { Node *ptr = ZN; |
| 35 | |
| 36 | switch (tl_yychar) { |
| 37 | case '(': |
| 38 | ptr = tl_formula(); |
| 39 | if (tl_yychar != ')') |
| 40 | tl_yyerror("expected ')'"); |
| 41 | tl_yychar = tl_yylex(); |
| 42 | break; |
| 43 | case NOT: |
| 44 | ptr = tl_yylval; |
| 45 | tl_yychar = tl_yylex(); |
| 46 | ptr->lft = tl_factor(); |
| 47 | ptr = push_negation(ptr); |
| 48 | break; |
| 49 | case ALWAYS: |
| 50 | tl_yychar = tl_yylex(); |
| 51 | |
| 52 | ptr = tl_factor(); |
| 53 | #ifndef NO_OPT |
| 54 | if (ptr->ntyp == FALSE |
| 55 | || ptr->ntyp == TRUE) |
| 56 | break; /* [] false == false */ |
| 57 | |
| 58 | if (ptr->ntyp == V_OPER) |
| 59 | { if (ptr->lft->ntyp == FALSE) |
| 60 | break; /* [][]p = []p */ |
| 61 | |
| 62 | ptr = ptr->rgt; /* [] (p V q) = [] q */ |
| 63 | } |
| 64 | #endif |
| 65 | ptr = tl_nn(V_OPER, False, ptr); |
| 66 | break; |
| 67 | #ifdef NXT |
| 68 | case NEXT: |
| 69 | tl_yychar = tl_yylex(); |
| 70 | ptr = tl_factor(); |
| 71 | if (ptr->ntyp == TRUE) |
| 72 | break; /* X true = true */ |
| 73 | ptr = tl_nn(NEXT, ptr, ZN); |
| 74 | break; |
| 75 | #endif |
| 76 | case EVENTUALLY: |
| 77 | tl_yychar = tl_yylex(); |
| 78 | |
| 79 | ptr = tl_factor(); |
| 80 | #ifndef NO_OPT |
| 81 | if (ptr->ntyp == TRUE |
| 82 | || ptr->ntyp == FALSE) |
| 83 | break; /* <> true == true */ |
| 84 | |
| 85 | if (ptr->ntyp == U_OPER |
| 86 | && ptr->lft->ntyp == TRUE) |
| 87 | break; /* <><>p = <>p */ |
| 88 | |
| 89 | if (ptr->ntyp == U_OPER) |
| 90 | { /* <> (p U q) = <> q */ |
| 91 | ptr = ptr->rgt; |
| 92 | /* fall thru */ |
| 93 | } |
| 94 | #endif |
| 95 | ptr = tl_nn(U_OPER, True, ptr); |
| 96 | |
| 97 | break; |
| 98 | case PREDICATE: |
| 99 | ptr = tl_yylval; |
| 100 | tl_yychar = tl_yylex(); |
| 101 | break; |
| 102 | case TRUE: |
| 103 | case FALSE: |
| 104 | ptr = tl_yylval; |
| 105 | tl_yychar = tl_yylex(); |
| 106 | break; |
| 107 | } |
| 108 | if (!ptr) tl_yyerror("expected predicate"); |
| 109 | #if 0 |
| 110 | printf("factor: "); |
| 111 | tl_explain(ptr->ntyp); |
| 112 | printf("\n"); |
| 113 | #endif |
| 114 | return ptr; |
| 115 | } |
| 116 | |
| 117 | static Node * |
| 118 | bin_simpler(Node *ptr) |
| 119 | { Node *a, *b; |
| 120 | |
| 121 | if (ptr) |
| 122 | switch (ptr->ntyp) { |
| 123 | case U_OPER: |
| 124 | #ifndef NO_OPT |
| 125 | if (ptr->rgt->ntyp == TRUE |
| 126 | || ptr->rgt->ntyp == FALSE |
| 127 | || ptr->lft->ntyp == FALSE) |
| 128 | { ptr = ptr->rgt; |
| 129 | break; |
| 130 | } |
| 131 | if (isequal(ptr->lft, ptr->rgt)) |
| 132 | { /* p U p = p */ |
| 133 | ptr = ptr->rgt; |
| 134 | break; |
| 135 | } |
| 136 | if (ptr->lft->ntyp == U_OPER |
| 137 | && isequal(ptr->lft->lft, ptr->rgt)) |
| 138 | { /* (p U q) U p = (q U p) */ |
| 139 | ptr->lft = ptr->lft->rgt; |
| 140 | break; |
| 141 | } |
| 142 | if (ptr->rgt->ntyp == U_OPER |
| 143 | && ptr->rgt->lft->ntyp == TRUE) |
| 144 | { /* p U (T U q) = (T U q) */ |
| 145 | ptr = ptr->rgt; |
| 146 | break; |
| 147 | } |
| 148 | #ifdef NXT |
| 149 | /* X p U X q == X (p U q) */ |
| 150 | if (ptr->rgt->ntyp == NEXT |
| 151 | && ptr->lft->ntyp == NEXT) |
| 152 | { ptr = tl_nn(NEXT, |
| 153 | tl_nn(U_OPER, |
| 154 | ptr->lft->lft, |
| 155 | ptr->rgt->lft), ZN); |
| 156 | } |
| 157 | #endif |
| 158 | #endif |
| 159 | break; |
| 160 | case V_OPER: |
| 161 | #ifndef NO_OPT |
| 162 | if (ptr->rgt->ntyp == FALSE |
| 163 | || ptr->rgt->ntyp == TRUE |
| 164 | || ptr->lft->ntyp == TRUE) |
| 165 | { ptr = ptr->rgt; |
| 166 | break; |
| 167 | } |
| 168 | if (isequal(ptr->lft, ptr->rgt)) |
| 169 | { /* p V p = p */ |
| 170 | ptr = ptr->rgt; |
| 171 | break; |
| 172 | } |
| 173 | /* F V (p V q) == F V q */ |
| 174 | if (ptr->lft->ntyp == FALSE |
| 175 | && ptr->rgt->ntyp == V_OPER) |
| 176 | { ptr->rgt = ptr->rgt->rgt; |
| 177 | break; |
| 178 | } |
| 179 | /* p V (F V q) == F V q */ |
| 180 | if (ptr->rgt->ntyp == V_OPER |
| 181 | && ptr->rgt->lft->ntyp == FALSE) |
| 182 | { ptr->lft = False; |
| 183 | ptr->rgt = ptr->rgt->rgt; |
| 184 | break; |
| 185 | } |
| 186 | #endif |
| 187 | break; |
| 188 | case IMPLIES: |
| 189 | #ifndef NO_OPT |
| 190 | if (isequal(ptr->lft, ptr->rgt)) |
| 191 | { ptr = True; |
| 192 | break; |
| 193 | } |
| 194 | #endif |
| 195 | ptr = tl_nn(OR, Not(ptr->lft), ptr->rgt); |
| 196 | ptr = rewrite(ptr); |
| 197 | break; |
| 198 | case EQUIV: |
| 199 | #ifndef NO_OPT |
| 200 | if (isequal(ptr->lft, ptr->rgt)) |
| 201 | { ptr = True; |
| 202 | break; |
| 203 | } |
| 204 | #endif |
| 205 | a = rewrite(tl_nn(AND, |
| 206 | dupnode(ptr->lft), |
| 207 | dupnode(ptr->rgt))); |
| 208 | b = rewrite(tl_nn(AND, |
| 209 | Not(ptr->lft), |
| 210 | Not(ptr->rgt))); |
| 211 | ptr = tl_nn(OR, a, b); |
| 212 | ptr = rewrite(ptr); |
| 213 | break; |
| 214 | case AND: |
| 215 | #ifndef NO_OPT |
| 216 | /* p && (q U p) = p */ |
| 217 | if (ptr->rgt->ntyp == U_OPER |
| 218 | && isequal(ptr->rgt->rgt, ptr->lft)) |
| 219 | { ptr = ptr->lft; |
| 220 | break; |
| 221 | } |
| 222 | if (ptr->lft->ntyp == U_OPER |
| 223 | && isequal(ptr->lft->rgt, ptr->rgt)) |
| 224 | { ptr = ptr->rgt; |
| 225 | break; |
| 226 | } |
| 227 | |
| 228 | /* p && (q V p) == q V p */ |
| 229 | if (ptr->rgt->ntyp == V_OPER |
| 230 | && isequal(ptr->rgt->rgt, ptr->lft)) |
| 231 | { ptr = ptr->rgt; |
| 232 | break; |
| 233 | } |
| 234 | if (ptr->lft->ntyp == V_OPER |
| 235 | && isequal(ptr->lft->rgt, ptr->rgt)) |
| 236 | { ptr = ptr->lft; |
| 237 | break; |
| 238 | } |
| 239 | |
| 240 | /* (p U q) && (r U q) = (p && r) U q*/ |
| 241 | if (ptr->rgt->ntyp == U_OPER |
| 242 | && ptr->lft->ntyp == U_OPER |
| 243 | && isequal(ptr->rgt->rgt, ptr->lft->rgt)) |
| 244 | { ptr = tl_nn(U_OPER, |
| 245 | tl_nn(AND, ptr->lft->lft, ptr->rgt->lft), |
| 246 | ptr->lft->rgt); |
| 247 | break; |
| 248 | } |
| 249 | |
| 250 | /* (p V q) && (p V r) = p V (q && r) */ |
| 251 | if (ptr->rgt->ntyp == V_OPER |
| 252 | && ptr->lft->ntyp == V_OPER |
| 253 | && isequal(ptr->rgt->lft, ptr->lft->lft)) |
| 254 | { ptr = tl_nn(V_OPER, |
| 255 | ptr->rgt->lft, |
| 256 | tl_nn(AND, ptr->lft->rgt, ptr->rgt->rgt)); |
| 257 | break; |
| 258 | } |
| 259 | #ifdef NXT |
| 260 | /* X p && X q == X (p && q) */ |
| 261 | if (ptr->rgt->ntyp == NEXT |
| 262 | && ptr->lft->ntyp == NEXT) |
| 263 | { ptr = tl_nn(NEXT, |
| 264 | tl_nn(AND, |
| 265 | ptr->rgt->lft, |
| 266 | ptr->lft->lft), ZN); |
| 267 | break; |
| 268 | } |
| 269 | #endif |
| 270 | |
| 271 | if (isequal(ptr->lft, ptr->rgt) /* (p && p) == p */ |
| 272 | || ptr->rgt->ntyp == FALSE /* (p && F) == F */ |
| 273 | || ptr->lft->ntyp == TRUE) /* (T && p) == p */ |
| 274 | { ptr = ptr->rgt; |
| 275 | break; |
| 276 | } |
| 277 | if (ptr->rgt->ntyp == TRUE /* (p && T) == p */ |
| 278 | || ptr->lft->ntyp == FALSE) /* (F && p) == F */ |
| 279 | { ptr = ptr->lft; |
| 280 | break; |
| 281 | } |
| 282 | |
| 283 | /* (p V q) && (r U q) == p V q */ |
| 284 | if (ptr->rgt->ntyp == U_OPER |
| 285 | && ptr->lft->ntyp == V_OPER |
| 286 | && isequal(ptr->lft->rgt, ptr->rgt->rgt)) |
| 287 | { ptr = ptr->lft; |
| 288 | break; |
| 289 | } |
| 290 | #endif |
| 291 | break; |
| 292 | |
| 293 | case OR: |
| 294 | #ifndef NO_OPT |
| 295 | /* p || (q U p) == q U p */ |
| 296 | if (ptr->rgt->ntyp == U_OPER |
| 297 | && isequal(ptr->rgt->rgt, ptr->lft)) |
| 298 | { ptr = ptr->rgt; |
| 299 | break; |
| 300 | } |
| 301 | |
| 302 | /* p || (q V p) == p */ |
| 303 | if (ptr->rgt->ntyp == V_OPER |
| 304 | && isequal(ptr->rgt->rgt, ptr->lft)) |
| 305 | { ptr = ptr->lft; |
| 306 | break; |
| 307 | } |
| 308 | |
| 309 | /* (p U q) || (p U r) = p U (q || r) */ |
| 310 | if (ptr->rgt->ntyp == U_OPER |
| 311 | && ptr->lft->ntyp == U_OPER |
| 312 | && isequal(ptr->rgt->lft, ptr->lft->lft)) |
| 313 | { ptr = tl_nn(U_OPER, |
| 314 | ptr->rgt->lft, |
| 315 | tl_nn(OR, ptr->lft->rgt, ptr->rgt->rgt)); |
| 316 | break; |
| 317 | } |
| 318 | |
| 319 | if (isequal(ptr->lft, ptr->rgt) /* (p || p) == p */ |
| 320 | || ptr->rgt->ntyp == FALSE /* (p || F) == p */ |
| 321 | || ptr->lft->ntyp == TRUE) /* (T || p) == T */ |
| 322 | { ptr = ptr->lft; |
| 323 | break; |
| 324 | } |
| 325 | if (ptr->rgt->ntyp == TRUE /* (p || T) == T */ |
| 326 | || ptr->lft->ntyp == FALSE) /* (F || p) == p */ |
| 327 | { ptr = ptr->rgt; |
| 328 | break; |
| 329 | } |
| 330 | |
| 331 | /* (p V q) || (r V q) = (p || r) V q */ |
| 332 | if (ptr->rgt->ntyp == V_OPER |
| 333 | && ptr->lft->ntyp == V_OPER |
| 334 | && isequal(ptr->lft->rgt, ptr->rgt->rgt)) |
| 335 | { ptr = tl_nn(V_OPER, |
| 336 | tl_nn(OR, ptr->lft->lft, ptr->rgt->lft), |
| 337 | ptr->rgt->rgt); |
| 338 | break; |
| 339 | } |
| 340 | |
| 341 | /* (p V q) || (r U q) == r U q */ |
| 342 | if (ptr->rgt->ntyp == U_OPER |
| 343 | && ptr->lft->ntyp == V_OPER |
| 344 | && isequal(ptr->lft->rgt, ptr->rgt->rgt)) |
| 345 | { ptr = ptr->rgt; |
| 346 | break; |
| 347 | } |
| 348 | #endif |
| 349 | break; |
| 350 | } |
| 351 | return ptr; |
| 352 | } |
| 353 | |
| 354 | static Node * |
| 355 | tl_level(int nr) |
| 356 | { int i; Node *ptr = ZN; |
| 357 | |
| 358 | if (nr < 0) |
| 359 | return tl_factor(); |
| 360 | |
| 361 | ptr = tl_level(nr-1); |
| 362 | again: |
| 363 | for (i = 0; i < 4; i++) |
| 364 | if (tl_yychar == prec[nr][i]) |
| 365 | { tl_yychar = tl_yylex(); |
| 366 | ptr = tl_nn(prec[nr][i], |
| 367 | ptr, tl_level(nr-1)); |
| 368 | ptr = bin_simpler(ptr); |
| 369 | goto again; |
| 370 | } |
| 371 | if (!ptr) tl_yyerror("syntax error"); |
| 372 | #if 0 |
| 373 | printf("level %d: ", nr); |
| 374 | tl_explain(ptr->ntyp); |
| 375 | printf("\n"); |
| 376 | #endif |
| 377 | return ptr; |
| 378 | } |
| 379 | |
| 380 | static Node * |
| 381 | tl_formula(void) |
| 382 | { tl_yychar = tl_yylex(); |
| 383 | return tl_level(1); /* 2 precedence levels, 1 and 0 */ |
| 384 | } |
| 385 | |
| 386 | void |
| 387 | tl_parse(void) |
| 388 | { Node *n = tl_formula(); |
| 389 | if (tl_verbose) |
| 390 | { printf("formula: "); |
| 391 | dump(n); |
| 392 | printf("\n"); |
| 393 | } |
| 394 | if (tl_Getchar() != -1) |
| 395 | { tl_yyerror("syntax error"); |
| 396 | tl_errs++; |
| 397 | return; |
| 398 | } |
| 399 | trans(n); |
| 400 | } |