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annotate lwlib/lw_expr.c @ 367:34dfc9747f23
Reduction passes complete
| author | lost@starbug |
|---|---|
| date | Thu, 15 Apr 2010 21:56:06 -0600 |
| parents | 1649bc7bda5a |
| children | 6b33faa21a0a |
| rev | line source |
|---|---|
| 334 | 1 /* |
| 2 lwexpr.c | |
| 3 | |
| 4 Copyright © 2010 William Astle | |
| 5 | |
| 6 This file is part of LWTOOLS. | |
| 7 | |
| 8 LWTOOLS is free software: you can redistribute it and/or modify it under the | |
| 9 terms of the GNU General Public License as published by the Free Software | |
| 10 Foundation, either version 3 of the License, or (at your option) any later | |
| 11 version. | |
| 12 | |
| 13 This program is distributed in the hope that it will be useful, but WITHOUT | |
| 14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
| 16 more details. | |
| 17 | |
| 18 You should have received a copy of the GNU General Public License along with | |
| 19 this program. If not, see <http://www.gnu.org/licenses/>. | |
| 20 */ | |
| 21 | |
| 22 #include <config.h> | |
| 23 | |
| 24 #include <stdarg.h> | |
| 25 #include <stdio.h> | |
| 26 #include <string.h> | |
| 27 | |
| 28 #define ___lw_expr_c_seen___ | |
| 29 #include "lw_alloc.h" | |
| 30 #include "lw_expr.h" | |
| 31 #include "lw_error.h" | |
| 32 #include "lw_string.h" | |
| 33 | |
| 342 | 34 static lw_expr_fn_t *evaluate_special = NULL; |
| 35 static lw_expr_fn2_t *evaluate_var = NULL; | |
|
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36 static lw_expr_fn3_t *parse_term = NULL; |
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37 |
| 347 | 38 int lw_expr_istype(lw_expr_t e, int t) |
| 39 { | |
| 40 if (e -> type == t) | |
| 41 return 1; | |
| 42 return 0; | |
| 43 } | |
| 44 | |
| 45 int lw_expr_intval(lw_expr_t e) | |
| 46 { | |
| 47 if (e -> type == lw_expr_type_int) | |
| 48 return e -> value; | |
| 49 return -1; | |
| 50 } | |
| 51 | |
| 367 | 52 int lw_expr_specint(lw_expr_t e) |
| 53 { | |
| 54 if (e -> type == lw_expr_type_special) | |
| 55 return e -> value; | |
| 56 return -1; | |
| 57 } | |
| 58 | |
|
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59 void lw_expr_set_term_parser(lw_expr_fn3_t *fn) |
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60 { |
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61 parse_term = fn; |
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62 } |
| 337 | 63 |
| 342 | 64 void lw_expr_set_special_handler(lw_expr_fn_t *fn) |
| 337 | 65 { |
| 66 evaluate_special = fn; | |
| 67 } | |
| 68 | |
| 342 | 69 void lw_expr_set_var_handler(lw_expr_fn2_t *fn) |
| 337 | 70 { |
| 71 evaluate_var = fn; | |
| 72 } | |
| 73 | |
| 334 | 74 lw_expr_t lw_expr_create(void) |
| 75 { | |
| 76 lw_expr_t r; | |
| 77 | |
| 78 r = lw_alloc(sizeof(struct lw_expr_priv)); | |
| 79 r -> operands = NULL; | |
| 80 | |
| 81 return r; | |
| 82 } | |
| 83 | |
| 84 void lw_expr_destroy(lw_expr_t E) | |
| 85 { | |
| 337 | 86 struct lw_expr_opers *o; |
| 87 for (o = E -> operands; o; o = o -> next) | |
| 88 lw_expr_destroy(o -> p); | |
| 89 if (E -> type == lw_expr_type_var) | |
| 90 lw_free(E -> value2); | |
| 91 lw_free(E); | |
| 334 | 92 } |
| 93 | |
| 337 | 94 /* actually duplicates the entire expression */ |
| 95 void lw_expr_add_operand(lw_expr_t E, lw_expr_t O); | |
| 334 | 96 lw_expr_t lw_expr_copy(lw_expr_t E) |
| 97 { | |
| 337 | 98 lw_expr_t r, t; |
| 99 struct lw_expr_opers *o; | |
| 100 | |
| 101 r = lw_alloc(sizeof(struct lw_expr_priv)); | |
| 102 *r = *E; | |
| 103 r -> operands = NULL; | |
| 104 | |
| 105 if (E -> type == lw_expr_type_var) | |
| 106 r -> value2 = lw_strdup(E -> value2); | |
| 107 for (o = E -> operands; o; o = o -> next) | |
| 108 { | |
| 109 lw_expr_add_operand(r, lw_expr_copy(o -> p)); | |
| 110 } | |
| 111 | |
| 112 return r; | |
| 334 | 113 } |
| 114 | |
| 115 void lw_expr_add_operand(lw_expr_t E, lw_expr_t O) | |
| 116 { | |
| 117 struct lw_expr_opers *o, *t; | |
| 118 | |
| 119 o = lw_alloc(sizeof(struct lw_expr_opers)); | |
| 120 o -> p = lw_expr_copy(O); | |
| 121 o -> next = NULL; | |
| 122 for (t = E -> operands; t && t -> next; t = t -> next) | |
| 123 /* do nothing */ ; | |
| 124 | |
| 125 if (t) | |
| 126 t -> next = o; | |
| 127 else | |
| 128 E -> operands = o; | |
| 129 } | |
| 130 | |
| 335 | 131 lw_expr_t lw_expr_build_aux(int exprtype, va_list args) |
| 334 | 132 { |
| 133 lw_expr_t r; | |
| 134 int t; | |
| 135 void *p; | |
| 136 | |
| 137 lw_expr_t te1, te2; | |
| 138 | |
| 139 r = lw_expr_create(); | |
| 140 | |
| 141 switch (exprtype) | |
| 142 { | |
| 143 case lw_expr_type_int: | |
| 144 t = va_arg(args, int); | |
| 145 r -> type = lw_expr_type_int; | |
| 146 r -> value = t; | |
| 147 break; | |
| 148 | |
| 149 case lw_expr_type_var: | |
| 150 p = va_arg(args, char *); | |
| 151 r -> type = lw_expr_type_var; | |
| 152 r -> value2 = lw_strdup(p); | |
| 153 break; | |
| 154 | |
| 155 case lw_expr_type_special: | |
| 156 t = va_arg(args, int); | |
| 157 p = va_arg(args, char *); | |
| 158 r -> type = lw_expr_type_special; | |
| 337 | 159 r -> value = t; |
| 334 | 160 r -> value2 = p; |
| 161 break; | |
| 162 | |
| 163 case lw_expr_type_oper: | |
| 164 t = va_arg(args, int); | |
| 165 te1 = va_arg(args, lw_expr_t); | |
| 166 if (t != lw_expr_oper_com && t != lw_expr_oper_neg) | |
| 167 te2 = va_arg(args, lw_expr_t); | |
| 168 else | |
| 169 te2 = NULL; | |
| 170 | |
| 171 r -> type = lw_expr_type_oper; | |
| 172 r -> value = t; | |
| 173 lw_expr_add_operand(r, te1); | |
| 174 lw_expr_add_operand(r, te2); | |
| 175 break; | |
| 176 | |
| 177 default: | |
| 178 lw_error("Invalid expression type specified to lw_expr_build"); | |
| 179 } | |
| 180 | |
| 335 | 181 return r; |
| 182 } | |
| 183 | |
| 184 lw_expr_t lw_expr_build(int exprtype, ...) | |
| 185 { | |
| 186 va_list args; | |
| 187 lw_expr_t r; | |
| 188 | |
| 189 va_start(args, exprtype); | |
| 190 r = lw_expr_build_aux(exprtype, args); | |
| 191 va_end(args); | |
| 192 return r; | |
| 193 } | |
| 194 | |
| 334 | 195 void lw_expr_print(lw_expr_t E) |
| 196 { | |
| 197 struct lw_expr_opers *o; | |
| 335 | 198 int c = 0; |
| 199 | |
| 334 | 200 for (o = E -> operands; o; o = o -> next) |
| 201 { | |
| 335 | 202 c++; |
| 334 | 203 lw_expr_print(o -> p); |
| 204 } | |
| 205 | |
| 206 switch (E -> type) | |
| 207 { | |
| 208 case lw_expr_type_int: | |
| 209 printf("%d ", E -> value); | |
| 210 break; | |
| 335 | 211 |
| 212 case lw_expr_type_var: | |
| 213 printf("V(%s) ", (char *)(E -> value2)); | |
| 214 break; | |
| 215 | |
| 216 case lw_expr_type_special: | |
| 217 printf("S(%d,%p) ", E -> value, E -> value2); | |
| 218 break; | |
| 219 | |
| 334 | 220 case lw_expr_type_oper: |
| 335 | 221 printf("[%d]", c); |
| 334 | 222 switch (E -> value) |
| 223 { | |
| 224 case lw_expr_oper_plus: | |
| 225 printf("+ "); | |
| 226 break; | |
| 227 | |
| 228 case lw_expr_oper_minus: | |
| 229 printf("- "); | |
| 230 break; | |
| 231 | |
| 232 case lw_expr_oper_times: | |
| 233 printf("* "); | |
| 234 break; | |
| 235 | |
| 236 case lw_expr_oper_divide: | |
| 237 printf("/ "); | |
| 238 break; | |
| 239 | |
| 240 case lw_expr_oper_mod: | |
| 241 printf("%% "); | |
| 242 break; | |
| 243 | |
| 244 case lw_expr_oper_intdiv: | |
| 245 printf("\\ "); | |
| 246 break; | |
| 247 | |
| 248 case lw_expr_oper_bwand: | |
| 249 printf("BWAND "); | |
| 250 break; | |
| 251 | |
| 252 case lw_expr_oper_bwor: | |
| 253 printf("BWOR "); | |
| 254 break; | |
| 255 | |
| 256 case lw_expr_oper_bwxor: | |
| 257 printf("BWXOR "); | |
| 258 break; | |
| 259 | |
| 260 case lw_expr_oper_and: | |
| 261 printf("AND "); | |
| 262 break; | |
| 263 | |
| 264 case lw_expr_oper_or: | |
| 265 printf("OR "); | |
| 266 break; | |
| 267 | |
| 268 case lw_expr_oper_neg: | |
| 269 printf("NEG "); | |
| 270 break; | |
| 271 | |
| 272 case lw_expr_oper_com: | |
| 273 printf("COM "); | |
| 274 break; | |
| 275 | |
| 276 default: | |
| 277 printf("OPER "); | |
| 278 break; | |
| 279 } | |
| 280 break; | |
| 281 default: | |
| 282 printf("ERR "); | |
| 283 break; | |
| 284 } | |
| 285 } | |
| 286 | |
| 287 /* | |
| 288 Return: | |
| 289 nonzero if expressions are the same (identical pointers or matching values) | |
| 290 zero if expressions are not the same | |
| 291 | |
| 292 */ | |
| 293 int lw_expr_compare(lw_expr_t E1, lw_expr_t E2) | |
| 294 { | |
| 295 struct lw_expr_opers *o1, *o2; | |
| 296 | |
| 297 if (E1 == E2) | |
| 298 return 1; | |
| 299 | |
| 300 if (!(E1 -> type == E2 -> type && E1 -> value == E2 -> value)) | |
| 301 return 0; | |
| 302 | |
| 303 if (E1 -> type == lw_expr_type_var) | |
| 304 { | |
| 305 if (!strcmp(E1 -> value2, E2 -> value2)) | |
| 306 return 1; | |
| 307 else | |
| 308 return 0; | |
| 309 } | |
| 310 | |
| 311 if (E1 -> type == lw_expr_type_special) | |
| 312 { | |
| 313 if (E1 -> value2 == E2 -> value2) | |
| 314 return 1; | |
| 315 else | |
| 316 return 0; | |
| 317 } | |
| 318 | |
| 319 for (o1 = E1 -> operands, o2 = E2 -> operands; o1 && o2; o1 = o1 -> next, o2 = o2 -> next) | |
| 320 if (lw_expr_compare(o1 -> p, o2 -> p) == 0) | |
| 321 return 0; | |
| 322 if (o1 || o2) | |
| 323 return 0; | |
| 324 | |
| 325 return 1; | |
| 326 } | |
| 327 | |
| 328 /* return true if E is an operator of type oper */ | |
| 329 int lw_expr_isoper(lw_expr_t E, int oper) | |
| 330 { | |
| 331 if (E -> type == lw_expr_type_oper && E -> value == oper) | |
| 332 return 1; | |
| 333 return 0; | |
| 334 } | |
| 335 | 335 |
| 336 | |
| 337 void lw_expr_simplify_sortconstfirst(lw_expr_t E) | |
| 338 { | |
| 339 struct lw_expr_opers *o; | |
| 340 | |
| 341 for (o = E -> operands; o; o = o -> next) | |
| 342 lw_expr_simplify_sortconstfirst(o -> p); | |
| 343 | |
| 344 for (o = E -> operands; o; o = o -> next) | |
| 345 { | |
| 346 if (o -> p -> type == lw_expr_type_int && o != E -> operands) | |
| 347 { | |
| 348 struct lw_expr_opers *o2; | |
| 349 for (o2 = E -> operands; o2 -> next != o; o2 = o2 -> next) | |
| 350 /* do nothing */ ; | |
| 351 o2 -> next = o -> next; | |
| 352 o -> next = E -> operands; | |
| 353 E -> operands = o; | |
| 354 o = o2; | |
| 355 } | |
| 356 } | |
| 357 } | |
| 358 | |
| 336 | 359 void lw_expr_sortoperandlist(struct lw_expr_opers **o) |
| 360 { | |
| 361 fprintf(stderr, "lw_expr_sortoperandlist() not yet implemented\n"); | |
| 362 } | |
| 363 | |
| 335 | 364 // return 1 if the operand lists match, 0 if not |
| 365 // may re-order the argument lists | |
| 366 int lw_expr_simplify_compareoperandlist(struct lw_expr_opers **ol1, struct lw_expr_opers **ol2) | |
| 367 { | |
| 368 struct lw_expr_opers *o1, *o2; | |
| 369 | |
| 370 lw_expr_sortoperandlist(ol1); | |
| 371 lw_expr_sortoperandlist(ol2); | |
| 372 | |
| 373 for (o1 = *ol1, o2 = *ol2; o1 && o2; o1 = o1 -> next, o2 = o2 -> next) | |
| 374 { | |
| 375 if (!lw_expr_compare(o1 -> p, o2 -> p)) | |
| 376 return 0; | |
| 377 } | |
| 378 if (o1 || o2) | |
| 379 return 0; | |
| 380 return 1; | |
| 381 } | |
| 382 | |
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383 void lw_expr_simplify(lw_expr_t E, void *priv) |
| 335 | 384 { |
| 385 struct lw_expr_opers *o; | |
| 386 | |
| 337 | 387 again: |
| 388 // try to resolve non-constant terms to constants here | |
| 389 if (E -> type == lw_expr_type_special && evaluate_special) | |
| 390 { | |
| 391 lw_expr_t te; | |
| 392 | |
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393 te = evaluate_special(E -> value, E -> value2, priv); |
| 337 | 394 if (te) |
| 395 { | |
| 396 for (o = E -> operands; o; o = o -> next) | |
| 397 lw_expr_destroy(o -> p); | |
| 398 if (E -> type == lw_expr_type_var) | |
| 399 lw_free(E -> value2); | |
| 400 *E = *te; | |
| 401 E -> operands = NULL; | |
| 402 | |
| 403 if (te -> type == lw_expr_type_var) | |
| 404 E -> value2 = lw_strdup(te -> value2); | |
| 405 for (o = te -> operands; o; o = o -> next) | |
| 406 { | |
| 407 lw_expr_add_operand(E, lw_expr_copy(o -> p)); | |
| 408 } | |
| 409 lw_expr_destroy(te); | |
| 410 goto again; | |
| 411 } | |
| 412 return; | |
| 413 } | |
| 414 | |
| 415 if (E -> type == lw_expr_type_var && evaluate_var) | |
| 416 { | |
| 417 lw_expr_t te; | |
| 418 | |
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419 te = evaluate_var(E -> value2, priv); |
| 337 | 420 if (te) |
| 421 { | |
| 422 for (o = E -> operands; o; o = o -> next) | |
| 423 lw_expr_destroy(o -> p); | |
| 424 if (E -> type == lw_expr_type_var) | |
| 425 lw_free(E -> value2); | |
| 426 *E = *te; | |
| 427 E -> operands = NULL; | |
| 428 | |
| 429 if (te -> type == lw_expr_type_var) | |
| 430 E -> value2 = lw_strdup(te -> value2); | |
| 431 for (o = te -> operands; o; o = o -> next) | |
| 432 { | |
| 433 lw_expr_add_operand(E, lw_expr_copy(o -> p)); | |
| 434 } | |
| 435 lw_expr_destroy(te); | |
| 436 goto again; | |
| 437 } | |
| 438 return; | |
| 439 } | |
| 440 | |
| 441 // non-operators have no simplification to do! | |
| 442 if (E -> type != lw_expr_type_oper) | |
| 443 return; | |
| 444 | |
| 335 | 445 // sort "constants" to the start of each operand list for + and * |
| 446 lw_expr_simplify_sortconstfirst(E); | |
| 447 | |
| 337 | 448 // simplify operands |
| 449 for (o = E -> operands; o; o = o -> next) | |
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450 lw_expr_simplify(o -> p, priv); |
| 337 | 451 |
| 452 for (o = E -> operands; o; o = o -> next) | |
| 453 { | |
| 454 if (o -> p -> type != lw_expr_type_int) | |
| 455 break; | |
| 456 } | |
| 457 | |
| 458 if (!o) | |
| 459 { | |
| 460 // we can do the operation here! | |
| 461 int tr = -42424242; | |
| 462 | |
| 463 switch (E -> value) | |
| 464 { | |
| 465 case lw_expr_oper_neg: | |
| 466 tr = -(E -> operands -> p -> value); | |
| 467 break; | |
| 468 | |
| 469 case lw_expr_oper_com: | |
| 470 tr = ~(E -> operands -> p -> value); | |
| 471 break; | |
| 472 | |
| 473 case lw_expr_oper_plus: | |
| 474 tr = E -> operands -> p -> value; | |
| 475 for (o = E -> operands -> next; o; o = o -> next) | |
| 476 tr += o -> p -> value; | |
| 477 break; | |
| 478 | |
| 479 case lw_expr_oper_minus: | |
| 480 tr = E -> operands -> p -> value; | |
| 481 for (o = E -> operands -> next; o; o = o -> next) | |
| 482 tr -= o -> p -> value; | |
| 483 break; | |
| 484 | |
| 485 case lw_expr_oper_times: | |
| 486 tr = E -> operands -> p -> value; | |
| 487 for (o = E -> operands -> next; o; o = o -> next) | |
| 488 tr *= o -> p -> value; | |
| 489 break; | |
| 490 | |
| 491 case lw_expr_oper_divide: | |
| 492 tr = E -> operands -> p -> value / E -> operands -> next -> p -> value; | |
| 493 break; | |
| 494 | |
| 495 case lw_expr_oper_mod: | |
| 496 tr = E -> operands -> p -> value % E -> operands -> next -> p -> value; | |
| 497 break; | |
| 498 | |
| 499 case lw_expr_oper_intdiv: | |
| 500 tr = E -> operands -> p -> value / E -> operands -> next -> p -> value; | |
| 501 break; | |
| 502 | |
| 503 case lw_expr_oper_bwand: | |
| 504 tr = E -> operands -> p -> value & E -> operands -> next -> p -> value; | |
| 505 break; | |
| 506 | |
| 507 case lw_expr_oper_bwor: | |
| 508 tr = E -> operands -> p -> value | E -> operands -> next -> p -> value; | |
| 509 break; | |
| 510 | |
| 511 case lw_expr_oper_bwxor: | |
| 512 tr = E -> operands -> p -> value ^ E -> operands -> next -> p -> value; | |
| 513 break; | |
| 514 | |
| 515 case lw_expr_oper_and: | |
| 516 tr = E -> operands -> p -> value && E -> operands -> next -> p -> value; | |
| 517 break; | |
| 518 | |
| 519 case lw_expr_oper_or: | |
| 520 tr = E -> operands -> p -> value || E -> operands -> next -> p -> value; | |
| 521 break; | |
| 522 | |
| 523 } | |
| 524 | |
| 525 while (E -> operands) | |
| 526 { | |
| 527 o = E -> operands; | |
| 528 E -> operands = o -> next; | |
| 529 lw_expr_destroy(o -> p); | |
| 530 lw_free(o); | |
| 531 } | |
| 532 E -> type = lw_expr_type_int; | |
| 533 E -> value = tr; | |
| 335 | 534 return; |
| 337 | 535 } |
| 335 | 536 |
| 537 if (E -> value == lw_expr_oper_times) | |
| 538 { | |
| 539 for (o = E -> operands; o; o = o -> next) | |
| 540 { | |
| 541 if (o -> p -> type == lw_expr_type_int && o -> p -> value == 0) | |
| 542 { | |
| 543 // one operand of times is 0, replace operation with 0 | |
| 544 while (E -> operands) | |
| 545 { | |
| 546 o = E -> operands; | |
| 547 E -> operands = o -> next; | |
| 548 lw_expr_destroy(o -> p); | |
| 549 lw_free(o); | |
| 550 } | |
| 551 E -> type = lw_expr_type_int; | |
| 552 E -> value = 0; | |
| 553 return; | |
| 554 } | |
| 555 } | |
| 556 } | |
| 557 | |
| 558 // look for like terms and collect them together | |
| 559 if (E -> value == lw_expr_oper_plus) | |
| 560 { | |
| 561 for (o = E -> operands; o; o = o -> next) | |
| 562 { | |
| 563 if (o -> p -> type == lw_expr_type_oper && o -> p -> value == lw_expr_oper_times) | |
| 564 { | |
| 565 // we have a "times" here | |
| 566 // find first non-const operand | |
| 567 struct lw_expr_opers *op1, *op2, *o2; | |
| 568 for (op1 = o -> p -> operands; op1; op1 = op1 -> next) | |
| 569 if (op1 -> p -> type != lw_expr_type_int) | |
| 570 break; | |
| 571 | |
| 572 for (o2 = o -> next; o2; o2 = o2 -> next) | |
| 573 { | |
| 574 if (o2 -> p -> type == lw_expr_type_oper && o2 -> p -> value == lw_expr_oper_times) | |
| 575 { | |
| 576 // another "times" | |
| 577 for (op2 = o2 -> p -> operands; op2; op2 = op2 -> next) | |
| 578 if (op2 -> p -> type != lw_expr_type_int) | |
| 579 break; | |
| 580 | |
| 336 | 581 if (lw_expr_simplify_compareoperandlist(&op1, &op2)) |
| 335 | 582 { |
| 583 // we have like terms here | |
| 584 // do something about it | |
| 585 } | |
| 586 } | |
| 587 } | |
| 588 } | |
| 589 } | |
| 590 } | |
| 591 | |
| 592 | |
| 593 if (E -> value == lw_expr_oper_plus) | |
| 594 { | |
| 595 int c = 0, t = 0; | |
| 596 for (o = E -> operands; o; o = o -> next) | |
| 597 { | |
| 598 t++; | |
| 599 if (!(o -> p -> type == lw_expr_type_int && o -> p -> value == 0)) | |
| 600 { | |
| 601 c++; | |
| 602 } | |
| 603 } | |
| 604 if (c == 1) | |
| 605 { | |
| 606 lw_expr_t r; | |
| 607 // find the value and "move it up" | |
| 608 while (E -> operands) | |
| 609 { | |
| 610 o = E -> operands; | |
| 611 if (o -> p -> type != lw_expr_type_int || o -> p -> value != 0) | |
| 612 { | |
| 337 | 613 r = lw_expr_copy(o -> p); |
| 335 | 614 } |
| 615 E -> operands = o -> next; | |
| 616 lw_expr_destroy(o -> p); | |
| 617 lw_free(o); | |
| 618 } | |
| 619 *E = *r; | |
| 620 return; | |
| 621 } | |
| 622 else if (c == 0) | |
| 623 { | |
| 624 // replace with 0 | |
| 625 while (E -> operands) | |
| 626 { | |
| 627 o = E -> operands; | |
| 628 E -> operands = o -> next; | |
| 629 lw_expr_destroy(o -> p); | |
| 630 lw_free(o); | |
| 631 } | |
| 632 E -> type = lw_expr_type_int; | |
| 633 E -> value = 0; | |
| 634 return; | |
| 635 } | |
| 636 else if (c != t) | |
| 637 { | |
| 638 // collapse out zero terms | |
| 639 struct lw_expr_opers *o2; | |
| 640 | |
| 641 for (o = E -> operands; o; o = o -> next) | |
| 642 { | |
| 643 if (o -> p -> type == lw_expr_type_int && o -> p -> value == 0) | |
| 644 { | |
| 645 if (o == E -> operands) | |
| 646 { | |
| 647 E -> operands = o -> next; | |
| 648 lw_expr_destroy(o -> p); | |
| 649 lw_free(o); | |
| 650 o = E -> operands; | |
| 651 } | |
| 652 else | |
| 653 { | |
| 654 for (o2 = E -> operands; o2 -> next == o; o2 = o2 -> next) | |
| 655 /* do nothing */ ; | |
| 656 o2 -> next = o -> next; | |
| 657 lw_expr_destroy(o -> p); | |
| 658 lw_free(o); | |
| 659 o = o2; | |
| 660 } | |
| 661 } | |
| 662 } | |
| 663 } | |
| 664 return; | |
| 665 } | |
| 666 } | |
|
346
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667 |
|
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668 /* |
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669 |
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|
670 The following two functions are co-routines which evaluate an infix |
|
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671 expression. lw_expr_parse_term checks for unary prefix operators then, if |
|
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672 none found, passes the string off the the defined helper function to |
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|
673 determine what the term really is. It also handles parentheses. |
|
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|
674 |
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|
675 lw_expr_parse_expr evaluates actual expressions with infix operators. It |
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|
676 respects the order of operations. |
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|
677 |
|
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678 The end of an expression is determined by the presence of any of the |
|
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|
679 following conditions: |
|
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|
680 |
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681 1. a NUL character |
|
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682 2. a whitespace character |
|
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683 3. a ) |
|
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|
684 4. a , |
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|
685 5. any character that is not recognized as a term |
|
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|
686 |
|
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|
687 lw_expr_parse_term returns NULL if there is no term (end of expr, etc.) |
|
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|
688 |
|
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|
689 lw_expr_parse_expr returns NULL if there is no expression or on a syntax |
|
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|
690 error. |
|
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|
691 |
|
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|
692 */ |
|
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|
693 |
|
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|
694 lw_expr_t lw_expr_parse_expr(char **p, void *priv, int prec); |
|
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|
695 |
|
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|
696 lw_expr_t lw_expr_parse_term(char **p, void *priv) |
|
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|
697 { |
|
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|
698 lw_expr_t term, term2; |
|
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|
699 |
|
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|
700 eval_next: |
|
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|
701 if (!**p || isspace(**p) || **p == ')' || **p == ']') |
|
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|
702 return NULL; |
|
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|
703 |
|
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|
704 // parentheses |
|
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|
705 if (**p == '(') |
|
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|
706 { |
|
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|
707 (*p)++; |
|
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|
708 term = lw_expr_parse_expr(p, priv, 0); |
|
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|
709 if (**p != ')') |
|
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|
710 { |
|
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|
711 lw_expr_destroy(term); |
|
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|
712 return NULL; |
|
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|
713 } |
|
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|
714 (*p)++; |
|
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|
715 return term; |
|
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|
716 } |
|
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|
717 |
|
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|
718 // unary + |
|
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|
719 if (**p == '+') |
|
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|
720 { |
|
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|
721 (*p)++; |
|
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|
722 goto eval_next; |
|
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|
723 } |
|
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|
724 |
|
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|
725 // unary - (prec 200) |
|
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|
726 if (**p == '-') |
|
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diff
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|
727 { |
|
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diff
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|
728 (*p)++; |
|
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diff
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|
729 term = lw_expr_parse_expr(p, priv, 200); |
|
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diff
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|
730 if (!term) |
|
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|
731 return NULL; |
|
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diff
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|
732 |
|
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|
733 term2 = lw_expr_build(lw_expr_type_oper, lw_expr_oper_neg, term); |
|
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|
734 lw_expr_destroy(term); |
|
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diff
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|
735 return term2; |
|
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342
diff
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|
736 } |
|
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342
diff
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|
737 |
|
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diff
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|
738 // unary ^ or ~ (complement, prec 200) |
|
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342
diff
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|
739 if (**p == '^' || **p == '~') |
|
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342
diff
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|
740 { |
|
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Added expression parsing infrastructure and misc fixes
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diff
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|
741 (*p)++; |
|
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|
742 term = lw_expr_parse_expr(p, priv, 200); |
|
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diff
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|
743 if (!term) |
|
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diff
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|
744 return NULL; |
|
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diff
changeset
|
745 |
|
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diff
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|
746 term2 = lw_expr_build(lw_expr_type_oper, lw_expr_oper_com, term); |
|
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|
747 lw_expr_destroy(term); |
|
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342
diff
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|
748 return term2; |
|
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342
diff
changeset
|
749 } |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
750 |
|
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342
diff
changeset
|
751 // non-operator - pass to caller |
|
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342
diff
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|
752 return parse_term(p, priv); |
|
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diff
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|
753 } |
|
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diff
changeset
|
754 |
|
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diff
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|
755 lw_expr_t lw_expr_parse_expr(char **p, void *priv, int prec) |
|
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diff
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|
756 { |
|
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342
diff
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|
757 static const struct operinfo |
|
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diff
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|
758 { |
|
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342
diff
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|
759 int opernum; |
|
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diff
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|
760 char *operstr; |
|
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diff
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|
761 int operprec; |
|
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diff
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|
762 } operators[] = |
|
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diff
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|
763 { |
|
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diff
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|
764 { lw_expr_oper_plus, "+", 100 }, |
|
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342
diff
changeset
|
765 { lw_expr_oper_minus, "-", 100 }, |
|
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Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
766 { lw_expr_oper_times, "*", 100 }, |
|
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342
diff
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|
767 { lw_expr_oper_divide, "/", 150 }, |
|
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342
diff
changeset
|
768 { lw_expr_oper_mod, "%", 150 }, |
|
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342
diff
changeset
|
769 { lw_expr_oper_intdiv, "\\", 150 }, |
|
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342
diff
changeset
|
770 |
|
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342
diff
changeset
|
771 { lw_expr_oper_and, "&&", 25 }, |
|
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342
diff
changeset
|
772 { lw_expr_oper_or, "||", 25 }, |
|
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diff
changeset
|
773 |
|
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342
diff
changeset
|
774 { lw_expr_oper_bwand, "&", 50 }, |
|
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342
diff
changeset
|
775 { lw_expr_oper_bwor, "|", 50 }, |
|
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342
diff
changeset
|
776 { lw_expr_oper_bwxor, "^", 50 }, |
|
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342
diff
changeset
|
777 |
|
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342
diff
changeset
|
778 { lw_expr_oper_none, "", 0 } |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
779 }; |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
780 |
|
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342
diff
changeset
|
781 int opern, i; |
|
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342
diff
changeset
|
782 lw_expr_t term1, term2, term3; |
|
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342
diff
changeset
|
783 |
|
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342
diff
changeset
|
784 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']') |
|
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342
diff
changeset
|
785 return NULL; |
|
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Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
786 |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
787 term1 = lw_expr_parse_term(p, priv); |
|
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Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
788 if (!term1) |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
789 return NULL; |
|
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342
diff
changeset
|
790 |
|
a82c55070624
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342
diff
changeset
|
791 eval_next: |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
792 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']') |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
793 return term1; |
|
a82c55070624
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342
diff
changeset
|
794 |
|
a82c55070624
Added expression parsing infrastructure and misc fixes
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342
diff
changeset
|
795 // expecting an operator here |
|
a82c55070624
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342
diff
changeset
|
796 for (opern = 0; operators[opern].opernum != lw_expr_oper_none; opern++) |
|
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diff
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797 { |
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798 for (i = 0; (*p)[i] && operators[opern].operstr[i] && ((*p)[i] == operators[opern].operstr[i]); i++) |
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799 /* do nothing */; |
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800 if (operators[opern].operstr[i] == '\0') |
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801 break; |
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802 } |
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803 |
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804 if (operators[opern].opernum == lw_expr_oper_none) |
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805 { |
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806 // unrecognized operator |
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807 lw_expr_destroy(term1); |
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808 return NULL; |
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809 } |
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810 |
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811 // operator number is in opern, length of oper in i |
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812 |
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813 // logic: |
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814 // if the precedence of this operation is <= to the "prec" flag, |
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815 // we simply return without advancing the input pointer; the operator |
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816 // will be evaluated again in the enclosing function call |
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817 if (operators[opern].operprec <= prec) |
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818 return term1; |
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819 |
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820 // logic: |
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821 // we have a higher precedence operator here so we will advance the |
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822 // input pointer to the next term and let the expression evaluator |
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823 // loose on it after which time we will push our operator onto the |
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824 // stack and then go on with the expression evaluation |
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825 (*p) += i; |
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826 |
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827 // evaluate next expression(s) of higher precedence |
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828 term2 = lw_expr_parse_expr(p, priv, operators[opern].operprec); |
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829 if (!term2) |
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830 { |
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831 lw_expr_destroy(term1); |
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832 return NULL; |
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833 } |
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834 |
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835 // now create operator |
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836 term3 = lw_expr_build(lw_expr_type_oper, operators[opern].opernum, term1, term2); |
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837 lw_expr_destroy(term1); |
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838 lw_expr_destroy(term2); |
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839 |
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840 // the new "expression" is the next "left operand" |
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841 term1 = term3; |
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842 |
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843 // continue evaluating |
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844 goto eval_next; |
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845 } |
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846 |
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847 lw_expr_t lw_expr_parse(char **p, void *priv) |
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848 { |
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849 return lw_expr_parse_expr(p, priv, 0); |
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850 } |
| 367 | 851 |
| 852 int lw_expr_testterms(lw_expr_t e, lw_expr_testfn_t *fn, void *priv) | |
| 853 { | |
| 854 struct lw_expr_opers *o; | |
| 855 int r; | |
| 856 | |
| 857 for (o = e -> operands; o; o = o -> next) | |
| 858 { | |
| 859 r = lw_expr_testterms(o -> p, fn, priv); | |
| 860 if (r) | |
| 861 return r; | |
| 862 } | |
| 863 return (fn)(e, priv); | |
| 864 } |