| 1 | /* Copyright (c) 1979 Regents of the University of California */ |
| 2 | # |
| 3 | /* |
| 4 | * pi - Pascal interpreter code translator |
| 5 | * |
| 6 | * Charles Haley, Bill Joy UCB |
| 7 | * Version 1.1 February 1978 |
| 8 | * |
| 9 | * |
| 10 | * pxp - Pascal execution profiler |
| 11 | * |
| 12 | * Bill Joy UCB |
| 13 | * Version 1.1 February 1978 |
| 14 | */ |
| 15 | |
| 16 | #include "0.h" |
| 17 | #include "yy.h" |
| 18 | |
| 19 | /* |
| 20 | * Very simplified version of Graham-Rhodes error recovery |
| 21 | * method for LALR parsers. Backward move is embodied in |
| 22 | * default reductions of the yacc parser until an error condition |
| 23 | * is reached. Forward move is over a small number of input tokens |
| 24 | * and cannot "condense". The basic corrections are: |
| 25 | * |
| 26 | * 1) Delete the input token. |
| 27 | * |
| 28 | * 2) Replace the current input with a legal input. |
| 29 | * |
| 30 | * 3) Insert a legal token. |
| 31 | * |
| 32 | * All corrections are weighted, considered only if they allow |
| 33 | * at least two shifts, and the cost of a correction increases if |
| 34 | * it allows shifting over only a part of the lookahead. |
| 35 | * |
| 36 | * Another error situation is that which occurs when an identifier "fails" |
| 37 | * a reduction because it is not the required "class". |
| 38 | * In this case, we also consider replacing this identifier, which has |
| 39 | * already been shifted over, with an identifier of the correct class. |
| 40 | * |
| 41 | * Another correction performed here is unique symbol insertion. |
| 42 | * If the current state admits only one input, and no other alternative |
| 43 | * correction presents itself, then that symbol will be inserted. |
| 44 | * There is a danger in this of looping, and it is handled |
| 45 | * by counting true shifts over input (see below). |
| 46 | * |
| 47 | * |
| 48 | * A final class of corrections, considered only when the error |
| 49 | * occurred immediately after a shift over a terminal, involves |
| 50 | * the three basic corrections above, but with the point of error |
| 51 | * considered to be before this terminal was shifted over, effectively |
| 52 | * "unreading" this terminal. This is a feeble attempt at elimination |
| 53 | * of the left-right bias and because "if" has a low weight and some |
| 54 | * statements are quite simple i.e. |
| 55 | * |
| 56 | * cse ch of ... |
| 57 | * |
| 58 | * we can get a small number of errors. The major deficiency of |
| 59 | * this is that we back up only one token, and that the forward |
| 60 | * move is over a small number of tokens, often not enough to really |
| 61 | * tell what the input should be, e.g. in |
| 62 | * |
| 63 | * a[i] > a[i - 1] ... |
| 64 | * |
| 65 | * In such cases a bad identifier (misspelled keyword) or omitted |
| 66 | * keyword will be change or inserted as "if" as it has the lowest cost. |
| 67 | * This is not terribly bad, as "if"s are most common. |
| 68 | * This also allows the correction of other errors. |
| 69 | * |
| 70 | * This recovery depends on the default reductions which delay |
| 71 | * noticing the error until the parse reaches a state where the |
| 72 | * relevant "alternatives" are visible. Note that it does not |
| 73 | * consider tokens which will cause reductions before being |
| 74 | * shifted over. This requires the grammar to be written in a |
| 75 | * certain way for the recovery to work correctly. |
| 76 | * In some sense, also, the recovery suffers because we have |
| 77 | * LALR(1) tables rather than LR(1) tables, e.g. in |
| 78 | * |
| 79 | * if rec.field < rec2,field2 then |
| 80 | */ |
| 81 | \f |
| 82 | /* |
| 83 | * Definitions of possible corrective actions |
| 84 | */ |
| 85 | #define CPANIC 0 |
| 86 | #define CDELETE 1 |
| 87 | #define CREPLACE 2 |
| 88 | #define CINSERT 3 |
| 89 | #define CUNIQUE 4 |
| 90 | #define CCHIDENT 5 |
| 91 | |
| 92 | /* |
| 93 | * Multiplicative cost factors for corrective actions. |
| 94 | * |
| 95 | * When an error occurs we take YCSIZ - 1 look-ahead tokens. |
| 96 | * If a correction being considered will shift over only part of |
| 97 | * that look-ahead, it is not completely discarded, but rather |
| 98 | * "weighted", its cost being multiplied by a weighting factor. |
| 99 | * For a correction to be considered its weighted cost must be less |
| 100 | * than CLIMIT. |
| 101 | * |
| 102 | * Non-weighted costs are considered: |
| 103 | * |
| 104 | * LOW <= 3 |
| 105 | * MEDIUM 4,5 |
| 106 | * HIGH >= 6 |
| 107 | * |
| 108 | * CURRENT WEIGHTING STRATEGY: Aug 20, 1977 |
| 109 | * |
| 110 | * For all kinds of corrections we demand shifts over two symbols. |
| 111 | * Corrections have high weight even after two symbol |
| 112 | * shifts because the costs for deleting and inserting symbols are actually |
| 113 | * quite low; we do not want to change weighty symbols |
| 114 | * on inconclusive evidence. |
| 115 | * |
| 116 | * The weights are the same after the third look ahead. |
| 117 | * This prevents later, unrelated errors from causing "funny" |
| 118 | * biases of the weights toward one type of correction. |
| 119 | * |
| 120 | * Current look ahead is 5 symbols. |
| 121 | */ |
| 122 | |
| 123 | /*** CLIMIT is defined in yy.h for yycosts ***/ |
| 124 | #define CPRLIMIT 50 |
| 125 | #define CCHIDCOST 3 |
| 126 | |
| 127 | char insmult[8] = {INFINITY, INFINITY, INFINITY, 15, 8, 6, 3, 1}; |
| 128 | char repmult[7] = {INFINITY, INFINITY, INFINITY, 8, 6, 3, 1}; |
| 129 | char delmult[6] = {INFINITY, INFINITY, INFINITY, 6, 3, 1}; |
| 130 | \f |
| 131 | #define NOCHAR -1 |
| 132 | |
| 133 | #define Eprintf if (errtrace) printf |
| 134 | #define Tprintf if (testtrace) printf |
| 135 | |
| 136 | /* |
| 137 | * Action arrays of the parser needed here |
| 138 | */ |
| 139 | int yyact[], yypact[], *yypv; |
| 140 | |
| 141 | /* |
| 142 | * Yytips is the tip of the stack when using |
| 143 | * the function loccor to check for local |
| 144 | * syntactic correctness. As we don't want |
| 145 | * to copy the whole parser stack, but want |
| 146 | * to simulate parser moves, we "split" |
| 147 | * the parser stack and keep the tip here. |
| 148 | */ |
| 149 | #define YYTIPSIZ 16 |
| 150 | int yytips[YYTIPSIZ], yytipct; |
| 151 | int yytipv[YYTIPSIZ]; |
| 152 | |
| 153 | /* |
| 154 | * The array YC saves the lookahead tokens for the |
| 155 | * forward moves. |
| 156 | * Yccnt is the number of tokens in the YC array. |
| 157 | */ |
| 158 | #define YCSIZ 6 |
| 159 | |
| 160 | int yCcnt; |
| 161 | struct yytok YC0[YCSIZ + 1]; |
| 162 | struct yytok *YC; |
| 163 | |
| 164 | /* |
| 165 | * YCps gives the top of stack at |
| 166 | * the point of error. |
| 167 | */ |
| 168 | |
| 169 | char yyunique = 1; |
| 170 | |
| 171 | STATIC unsigned yyTshifts; |
| 172 | \f |
| 173 | /* |
| 174 | * Cact is the corrective action we have decided on |
| 175 | * so far, ccost its cost, and cchar the associated token. |
| 176 | * Cflag tells if the correction is over the previous input token. |
| 177 | */ |
| 178 | int cact, ccost, cchar, cflag; |
| 179 | |
| 180 | /* |
| 181 | * ACtok holds the token under |
| 182 | * consideration when examining |
| 183 | * the lookaheads in a state. |
| 184 | */ |
| 185 | struct yytok ACtok; |
| 186 | |
| 187 | #define acchar ACtok.Yychar |
| 188 | #define aclval ACtok.Yylval |
| 189 | |
| 190 | /* |
| 191 | * Make a correction to the current stack which has |
| 192 | * top of stack pointer Ps. |
| 193 | */ |
| 194 | yyrecover(Ps0, idfail) |
| 195 | int *Ps0, idfail; |
| 196 | { |
| 197 | register int c, i; |
| 198 | int yyrwant, yyrhave; |
| 199 | |
| 200 | #ifdef PI |
| 201 | Recovery = 1; |
| 202 | #endif |
| 203 | |
| 204 | YC = &YC0[1]; |
| 205 | #ifdef DEBUG |
| 206 | if (errtrace) { |
| 207 | setpfx('p'); |
| 208 | yerror("Point of error"); |
| 209 | printf("States %d %d ...", Ps0[0], Ps0[-1]); |
| 210 | if (idfail) |
| 211 | printf(" [Idfail]"); |
| 212 | putchar('\n'); |
| 213 | printf("Input %s%s", tokname(&Y , 0) |
| 214 | , tokname(&Y , 1)); |
| 215 | } |
| 216 | |
| 217 | #endif |
| 218 | /* |
| 219 | * We first save the current input token |
| 220 | * and its associated semantic information. |
| 221 | */ |
| 222 | if (yychar < 0) |
| 223 | yychar = yylex(); |
| 224 | copy(&YC[0], &Y, sizeof Y); |
| 225 | |
| 226 | /* |
| 227 | * Set the default action and cost |
| 228 | */ |
| 229 | cact = CPANIC, ccost = CLIMIT, cflag = 0; |
| 230 | |
| 231 | /* |
| 232 | * Peek ahead |
| 233 | */ |
| 234 | for (yCcnt = 1; yCcnt < YCSIZ; yCcnt++) { |
| 235 | yychar = yylex(); |
| 236 | copy(&YC[yCcnt], &Y, sizeof YC[0]); |
| 237 | #ifdef DEBUG |
| 238 | Eprintf(" | %s%s", tokname(&YC[yCcnt] , 0 ) |
| 239 | , tokname(&YC[yCcnt] , 1 )); |
| 240 | #endif |
| 241 | } |
| 242 | #ifdef DEBUG |
| 243 | Eprintf("\n"); |
| 244 | #endif |
| 245 | |
| 246 | /* |
| 247 | * If we are here because a reduction failed, try |
| 248 | * correcting that. |
| 249 | */ |
| 250 | if (idfail) { |
| 251 | /* |
| 252 | * Save the particulars about |
| 253 | * the kind of identifier we want/have. |
| 254 | */ |
| 255 | yyrwant = yyidwant; |
| 256 | yyrhave = yyidhave; |
| 257 | #ifdef DEBUG |
| 258 | Tprintf(" Try Replace %s identifier with %s identifier cost=%d\n", |
| 259 | classes[yyidhave], classes[yyidwant], CCHIDCOST); |
| 260 | #endif |
| 261 | |
| 262 | /* |
| 263 | * Save the semantics of the ID on the |
| 264 | * stack, and null them out to free |
| 265 | * up the reduction in question. |
| 266 | */ |
| 267 | i = yypv[0]; |
| 268 | yypv[0] = nullsem(YID); |
| 269 | c = correct(NOCHAR, 0, CCHIDCOST, &repmult[2], Ps0, yypv); |
| 270 | yypv[0] = i; |
| 271 | #ifdef DEBUG |
| 272 | if (c < CPRLIMIT || fulltrace) |
| 273 | Eprintf("Cost %2d Replace %s identifier with %s identifier\n", c, classes[yyrhave], classes[yyrwant]); |
| 274 | #endif |
| 275 | if (c < ccost) |
| 276 | cact = CCHIDENT, ccost = c, cchar = YID; |
| 277 | } |
| 278 | |
| 279 | /* |
| 280 | * First try correcting the state we are in |
| 281 | */ |
| 282 | trystate(Ps0, yypv, 0, &insmult[1], &delmult[1], &repmult[1]); |
| 283 | |
| 284 | /* |
| 285 | * Now, if we just shifted over a terminal, try |
| 286 | * correcting it. |
| 287 | */ |
| 288 | if (OY.Yychar != -1 && OY.Yylval != nullsem(OY.Yychar)) { |
| 289 | YC--; |
| 290 | copy(&YC[0], &OY, sizeof YC[0]); |
| 291 | trystate(Ps0 - 1, yypv - 1, 1, insmult, delmult, repmult); |
| 292 | if (cflag == 0) |
| 293 | YC++; |
| 294 | else { |
| 295 | yypv--; |
| 296 | #ifdef PXP |
| 297 | yypw--; |
| 298 | #endif |
| 299 | Ps0--; |
| 300 | yCcnt++; |
| 301 | } |
| 302 | } |
| 303 | |
| 304 | /* |
| 305 | * Restoring the first look ahead into |
| 306 | * the scanner token allows the error message |
| 307 | * routine to print the error message with the text |
| 308 | * of the correct line. |
| 309 | */ |
| 310 | copy(&Y, &YC[0], sizeof Y); |
| 311 | |
| 312 | /* |
| 313 | * Unique symbol insertion. |
| 314 | * |
| 315 | * If there was no reasonable correction found, |
| 316 | * but only one input to the parser is acceptable |
| 317 | * we report that, and try it. |
| 318 | * |
| 319 | * Special precautions here to prevent looping. |
| 320 | * The number of true inputs shifted over at the point |
| 321 | * of the last unique insertion is recorded in the |
| 322 | * variable yyTshifts. If this is not less than |
| 323 | * the current number in yytshifts, we do not insert. |
| 324 | * Thus, after one unique insertion, no more unique |
| 325 | * insertions will be made until an input is shifted |
| 326 | * over. This guarantees termination. |
| 327 | */ |
| 328 | if (cact == CPANIC && !idfail) { |
| 329 | register int *ap; |
| 330 | |
| 331 | ap = &yyact[yypact[*Ps0 + 1]]; |
| 332 | if (*ap == -ERROR) |
| 333 | ap =+ 2; |
| 334 | if (ap[0] <= 0 && ap[2] > 0) { |
| 335 | cchar = -ap[0]; |
| 336 | if (cchar == YEOF) |
| 337 | yyexeof(); |
| 338 | if (cchar != ERROR && yyTshifts < yytshifts) { |
| 339 | cact = CUNIQUE; |
| 340 | #ifdef DEBUG |
| 341 | Eprintf("Unique symbol %s%s\n", charname(cchar)); |
| 342 | #endif |
| 343 | /* |
| 344 | * Note that the inserted symbol |
| 345 | * will not be counted as a true input |
| 346 | * (i.e. the "yytshifts--" below) |
| 347 | * so that a true shift will be needed |
| 348 | * to make yytshifts > yyTshifts. |
| 349 | */ |
| 350 | yyTshifts = yytshifts; |
| 351 | } |
| 352 | } |
| 353 | } |
| 354 | |
| 355 | /* |
| 356 | * Set up to perform the correction. |
| 357 | * Build a token appropriate for replacement |
| 358 | * or insertion in the yytok structure ACchar |
| 359 | * having the attributes of the input at the |
| 360 | * point of error. |
| 361 | */ |
| 362 | copy(&ACtok, &YC[0], sizeof ACtok); |
| 363 | acchar = cchar; |
| 364 | aclval = nullsem(acchar); |
| 365 | if (aclval != NIL) |
| 366 | recovered(); |
| 367 | switch (cact) { |
| 368 | /* |
| 369 | * Panic, just restore the |
| 370 | * lookahead and return. |
| 371 | */ |
| 372 | case CPANIC: |
| 373 | setpfx('E'); |
| 374 | if (idfail) { |
| 375 | copy(&Y, &OY, sizeof Y); |
| 376 | if (yyrhave == NIL) { |
| 377 | #ifdef PI |
| 378 | if (yybaduse(yypv[0], yyeline, ISUNDEF) == NIL) |
| 379 | #endif |
| 380 | yerror("Undefined identifier"); |
| 381 | } else { |
| 382 | yerror("Improper %s identifier", classes[yyrhave]); |
| 383 | #ifdef PI |
| 384 | yybaduse(yypv[0], yyeline, NIL); |
| 385 | #endif |
| 386 | } |
| 387 | /* |
| 388 | * Suppress message from panic routine |
| 389 | */ |
| 390 | yyshifts = 1; |
| 391 | } |
| 392 | i = 0; |
| 393 | /* Note that on one path we dont touch yyshifts ! */ |
| 394 | break; |
| 395 | /* |
| 396 | * Delete the input. |
| 397 | * Mark this as a shift over true input. |
| 398 | * Restore the lookahead starting at |
| 399 | * the second token. |
| 400 | */ |
| 401 | case CDELETE: |
| 402 | if (ccost != 0) |
| 403 | yerror("Deleted %s%s", tokname(&YC[0] , 0 ) |
| 404 | , tokname(&YC[0] , 1 )); |
| 405 | yytshifts++; |
| 406 | i = 1; |
| 407 | yyshifts = 0; |
| 408 | break; |
| 409 | /* |
| 410 | * Replace the input with a new token. |
| 411 | */ |
| 412 | case CREPLACE: |
| 413 | if (acchar == YEOF) |
| 414 | yyexeof(); |
| 415 | if (acchar == YEND) |
| 416 | aclval = NIL; |
| 417 | yerror("Replaced %s%s with a %s%s", |
| 418 | tokname(&YC[0] , 0 ), |
| 419 | tokname(&YC[0] , 1 ), |
| 420 | tokname(&ACtok , 0 ), |
| 421 | tokname(&ACtok , 1 )); |
| 422 | copy(&YC[0], &ACtok, sizeof YC[0]); |
| 423 | i = 0; |
| 424 | yyshifts = 0; |
| 425 | break; |
| 426 | /* |
| 427 | * Insert a token. |
| 428 | * Don't count this token as a true input shift. |
| 429 | * For inserted "end"s pas.y is responsible |
| 430 | * for the error message later so suppress it. |
| 431 | * Restore all the lookahead. |
| 432 | */ |
| 433 | case CINSERT: |
| 434 | if (acchar == YEOF) |
| 435 | yyexeof(); |
| 436 | if (acchar != YEND) |
| 437 | yerror("Inserted %s%s", |
| 438 | tokname(&ACtok , 0 ), |
| 439 | tokname(&ACtok , 1 )); |
| 440 | yytshifts--; |
| 441 | i = 0; |
| 442 | yyshifts = 0; |
| 443 | break; |
| 444 | /* |
| 445 | * Make a unique symbol correction. |
| 446 | * Like an insertion but a different message. |
| 447 | */ |
| 448 | case CUNIQUE: |
| 449 | setpfx('E'); |
| 450 | yerror("Expected %s%s", |
| 451 | tokname(&ACtok , 0 ), |
| 452 | tokname(&ACtok , 1 )); |
| 453 | yytshifts--; |
| 454 | i = 0; |
| 455 | if (ccost == 0 || yyunique) |
| 456 | yyshifts = 0; |
| 457 | else |
| 458 | yyshifts = -1; |
| 459 | break; |
| 460 | /* |
| 461 | * Change an identifier's type |
| 462 | * to make it work. |
| 463 | */ |
| 464 | case CCHIDENT: |
| 465 | copy(&Y, &OY, sizeof Y); |
| 466 | #ifdef PI |
| 467 | i = 1 << yyrwant; |
| 468 | #endif |
| 469 | if (yyrhave == NIL) { |
| 470 | yerror("Undefined %s", classes[yyrwant]); |
| 471 | #ifdef PI |
| 472 | i =| ISUNDEF; |
| 473 | #endif |
| 474 | } else |
| 475 | yerror("Replaced %s id with a %s id", classes[yyrhave], classes[yyrwant]); |
| 476 | #ifdef PI |
| 477 | yybaduse(yypv[0], yyeline, i); |
| 478 | #endif |
| 479 | yypv[0] = nullsem(YID); |
| 480 | i = 0; |
| 481 | yyshifts = 0; |
| 482 | break; |
| 483 | } |
| 484 | |
| 485 | /* |
| 486 | * Restore the desired portion of the lookahead, |
| 487 | * and possibly the inserted or unique inserted token. |
| 488 | */ |
| 489 | for (yCcnt--; yCcnt >= i; yCcnt--) |
| 490 | unyylex(&YC[yCcnt]); |
| 491 | if (cact == CINSERT || cact == CUNIQUE) |
| 492 | unyylex(&ACtok); |
| 493 | |
| 494 | /* |
| 495 | * Put the scanner back in sync. |
| 496 | */ |
| 497 | yychar = yylex(); |
| 498 | |
| 499 | /* |
| 500 | * We succeeded if we didn't "panic". |
| 501 | */ |
| 502 | Recovery = 0; |
| 503 | Ps = Ps0; |
| 504 | return (cact != CPANIC); |
| 505 | } |
| 506 | |
| 507 | yyexeof() |
| 508 | { |
| 509 | |
| 510 | yerror("End-of-file expected - QUIT"); |
| 511 | pexit(ERRS); |
| 512 | } |
| 513 | |
| 514 | yyunexeof() |
| 515 | { |
| 516 | |
| 517 | yerror("Unexpected end-of-file - QUIT"); |
| 518 | pexit(ERRS); |
| 519 | } |
| 520 | \f |
| 521 | /* |
| 522 | * Try corrections with the state at Ps0. |
| 523 | * Flag is 0 if this is the top of stack state, |
| 524 | * 1 if it is the state below. |
| 525 | */ |
| 526 | trystate(Ps0, Pv0, flag, insmult, delmult, repmult) |
| 527 | int *Ps0, *Pv0, flag; |
| 528 | char *insmult, *delmult, *repmult; |
| 529 | { |
| 530 | /* |
| 531 | * C is a working cost, ap a pointer into the action |
| 532 | * table for looking at feasible alternatives. |
| 533 | */ |
| 534 | register int c, *ap; |
| 535 | int i, *actions; |
| 536 | |
| 537 | #ifdef DEBUG |
| 538 | Eprintf("Trying state %d\n", *Ps0); |
| 539 | #endif |
| 540 | /* |
| 541 | * Try deletion. |
| 542 | * Correct returns a cost. |
| 543 | */ |
| 544 | #ifdef DEBUG |
| 545 | Tprintf(" Try Delete %s%s cost=%d\n", |
| 546 | tokname(&YC[0] , 0 ), |
| 547 | tokname(&YC[0] , 1 ), |
| 548 | delcost(YC[0].Yychar)); |
| 549 | #endif |
| 550 | c = delcost(YC[0].Yychar); |
| 551 | #ifndef DEBUG |
| 552 | if (c < ccost) { |
| 553 | #endif |
| 554 | c = correct(NOCHAR, 1, c, delmult, Ps0, Pv0); |
| 555 | #ifdef DEBUG |
| 556 | if (c < CPRLIMIT || fulltrace) |
| 557 | Eprintf("Cost %2d Delete %s%s\n", c, |
| 558 | tokname(&YC[0] , 0 ), |
| 559 | tokname(&YC[0] , 1 )); |
| 560 | #endif |
| 561 | if (c < ccost) |
| 562 | cact = CDELETE, ccost = c, cflag = flag; |
| 563 | #ifndef DEBUG |
| 564 | } |
| 565 | #endif |
| 566 | |
| 567 | /* |
| 568 | * Look at the inputs to this state |
| 569 | * which will cause parse action shift. |
| 570 | */ |
| 571 | aclval = NIL; |
| 572 | ap = &yyact[yypact[*Ps0 + 1]]; |
| 573 | |
| 574 | /* |
| 575 | * Skip action on error to |
| 576 | * detect true unique inputs. |
| 577 | * Error action is always first. |
| 578 | */ |
| 579 | if (*ap == -ERROR) |
| 580 | ap=+ 2; |
| 581 | |
| 582 | /* |
| 583 | * Loop through the test actions |
| 584 | * for this state. |
| 585 | */ |
| 586 | for (actions = ap; *ap <= 0; ap =+ 2) { |
| 587 | /* |
| 588 | * Extract the token of this action |
| 589 | */ |
| 590 | acchar = -*ap; |
| 591 | |
| 592 | /* |
| 593 | * Try insertion |
| 594 | */ |
| 595 | #ifdef DEBUG |
| 596 | Tprintf(" Try Insert %s%s cost=%d\n", charname(acchar), inscost(acchar)); |
| 597 | #endif |
| 598 | c = inscost(acchar, YC[0].Yychar); |
| 599 | #ifndef DEBUG |
| 600 | if (c < ccost) { |
| 601 | #endif |
| 602 | if (c == 0) { |
| 603 | c = correct(acchar, 0, 1, insmult + 1, Ps0, Pv0); |
| 604 | #ifdef DEBUG |
| 605 | Eprintf("Cost %2d Freebie %s%s\n", c, charname(acchar)); |
| 606 | #endif |
| 607 | if (c < ccost) |
| 608 | cact = CUNIQUE, ccost = 0, cchar = acchar, cflag = flag; |
| 609 | } else { |
| 610 | c = correct(acchar, 0, c, insmult, Ps0, Pv0); |
| 611 | #ifdef DEBUG |
| 612 | if (c < CPRLIMIT || fulltrace) |
| 613 | Eprintf("Cost %2d Insert %s%s\n", c, charname(acchar)); |
| 614 | #endif |
| 615 | if (c < ccost) |
| 616 | cact = CINSERT, ccost = c, cchar = acchar, cflag = flag; |
| 617 | } |
| 618 | #ifndef DEBUG |
| 619 | } |
| 620 | #endif |
| 621 | |
| 622 | /* |
| 623 | * Try replacement |
| 624 | */ |
| 625 | #ifdef DEBUG |
| 626 | Tprintf(" Try Replace %s%s with %s%s cost=%d\n", |
| 627 | tokname(&YC[0] , 0 ), |
| 628 | tokname(&YC[0] , 1 ), |
| 629 | charname(acchar , 0 ), |
| 630 | charname(acchar , 1 ), |
| 631 | repcost(YC[0].Yychar, acchar)); |
| 632 | #endif |
| 633 | c = repcost(YC[0].Yychar, acchar); |
| 634 | #ifndef DEBUG |
| 635 | if (c < ccost) { |
| 636 | #endif |
| 637 | c = correct(acchar, 1, repcost(YC[0].Yychar, acchar), repmult, Ps0, Pv0); |
| 638 | #ifdef DEBUG |
| 639 | if (c < CPRLIMIT || fulltrace) |
| 640 | Eprintf("Cost %2d Replace %s%s with %s%s\n", |
| 641 | c, |
| 642 | tokname(&YC[0] , 0 ), |
| 643 | tokname(&YC[0] , 1 ), |
| 644 | tokname(&ACtok , 0 ), |
| 645 | tokname(&ACtok , 1 )); |
| 646 | #endif |
| 647 | if (c < ccost) |
| 648 | cact = CREPLACE, ccost = c, cchar = acchar, cflag = flag; |
| 649 | #ifndef DEBUG |
| 650 | } |
| 651 | #endif |
| 652 | } |
| 653 | } |
| 654 | \f |
| 655 | int *yCpv; |
| 656 | char yyredfail; |
| 657 | |
| 658 | /* |
| 659 | * The ntok structure is used to build a |
| 660 | * scanner structure for tokens inserted |
| 661 | * from the argument "fchar" to "correct" below. |
| 662 | */ |
| 663 | static struct yytok ntok; |
| 664 | |
| 665 | /* |
| 666 | * Compute the cost of a correction |
| 667 | * C is the base cost for it. |
| 668 | * Fchar is the first input character from |
| 669 | * the current state, NOCHAR if none. |
| 670 | * The rest of the inputs come from the array |
| 671 | * YC, starting at origin and continuing to the |
| 672 | * last character there, YC[yCcnt - 1].Yychar. |
| 673 | * |
| 674 | * The cost returned is INFINITE if this correction |
| 675 | * allows no shifts, otherwise is weighted based |
| 676 | * on the number of shifts this allows against the |
| 677 | * maximum number possible with the available lookahead. |
| 678 | */ |
| 679 | correct(fchar, origin, c, multvec, Ps0, Pv0) |
| 680 | register int fchar, c; |
| 681 | int origin; |
| 682 | char *multvec; |
| 683 | int *Ps0, *Pv0; |
| 684 | { |
| 685 | register char *mv; |
| 686 | |
| 687 | /* |
| 688 | * Ps is the top of the parse stack after the most |
| 689 | * recent local correctness check. Loccor returns |
| 690 | * NIL when we cannot shift. |
| 691 | */ |
| 692 | register int *ps; |
| 693 | |
| 694 | yyredfail = 0; |
| 695 | /* |
| 696 | * Initialize the tip parse and semantic stacks. |
| 697 | */ |
| 698 | ps = Ps0; |
| 699 | yytips[0] = *ps; |
| 700 | ps--; |
| 701 | yytipv[0] = Pv0[0]; |
| 702 | yCpv = Pv0 - 1; |
| 703 | yytipct = 1; |
| 704 | |
| 705 | /* |
| 706 | * Shift while possible. |
| 707 | * Adjust cost as necessary. |
| 708 | */ |
| 709 | mv = multvec; |
| 710 | do { |
| 711 | if (fchar != NOCHAR) { |
| 712 | copy(&ntok, &YC[0], sizeof ntok); |
| 713 | ntok.Yychar = fchar, ntok.Yylval = nullsem(fchar); |
| 714 | fchar = NOCHAR; |
| 715 | ps = loccor(ps, &ntok); |
| 716 | } else |
| 717 | ps = loccor(ps, &YC[origin++]); |
| 718 | if (ps == NIL) { |
| 719 | if (yyredfail && mv > multvec) |
| 720 | mv--; |
| 721 | c =* *mv; |
| 722 | break; |
| 723 | } |
| 724 | mv++; |
| 725 | } while (*mv != 1); |
| 726 | return (c); |
| 727 | } |
| 728 | \f |
| 729 | extern int yygo[], yypgo[], yyr1[], yyr2[]; |
| 730 | /* |
| 731 | * Local syntactic correctness check. |
| 732 | * The arguments to this routine are a |
| 733 | * top of stack pointer, ps, and an input |
| 734 | * token tok. Also, implicitly, the contents |
| 735 | * of the yytips array which contains the tip |
| 736 | * of the stack, and into which the new top |
| 737 | * state on the stack will be placed if we shift. |
| 738 | * |
| 739 | * If we succeed, we return a new top of stack |
| 740 | * pointer, else we return NIL. |
| 741 | */ |
| 742 | loccor(ps, ntok) |
| 743 | int *ps; |
| 744 | struct yytok *ntok; |
| 745 | { |
| 746 | register int *p, n; |
| 747 | register int nchar; |
| 748 | int i; |
| 749 | |
| 750 | if (ps == NIL) |
| 751 | return (NIL); |
| 752 | nchar = ntok->Yychar; |
| 753 | yyeline = ntok->Yyeline; |
| 754 | #ifdef DEBUG |
| 755 | Tprintf(" Stack "); |
| 756 | for (i = yytipct - 1; i >= 0; i--) |
| 757 | Tprintf("%d ", yytips[i]); |
| 758 | Tprintf("| %d, Input %s%s\n", *ps, charname(nchar)); |
| 759 | #endif |
| 760 | /* |
| 761 | * As in the yacc parser yyparse, |
| 762 | * p traces through the action list |
| 763 | * and "n" is the information associated |
| 764 | * with the action. |
| 765 | */ |
| 766 | newstate: |
| 767 | p = &yyact[ yypact[yytips[yytipct - 1]+1] ]; |
| 768 | |
| 769 | actn: |
| 770 | /* |
| 771 | * Search the parse actions table |
| 772 | * for something useful to do. |
| 773 | * While n is non-positive, it is the |
| 774 | * arithmetic inverse of the token to be tested. |
| 775 | * This allows a fast check. |
| 776 | */ |
| 777 | while ((n = *p++) <= 0) |
| 778 | if ((n =+ nchar) != 0) |
| 779 | p++; |
| 780 | switch (n >> 12) { |
| 781 | /* |
| 782 | * SHIFT |
| 783 | */ |
| 784 | case 2: |
| 785 | n =& 07777; |
| 786 | yyredfail = 0; |
| 787 | if (nchar == YID) |
| 788 | yyredfail++; |
| 789 | if (yytipct == YYTIPSIZ) { |
| 790 | tipover: |
| 791 | #ifdef DEBUG |
| 792 | Tprintf("\tTIP OVFLO\n"); |
| 793 | #endif |
| 794 | return (NIL); |
| 795 | } |
| 796 | yytips[yytipct] = n; |
| 797 | yytipv[yytipct] = ntok->Yylval; |
| 798 | yytipct++; |
| 799 | #ifdef DEBUG |
| 800 | Tprintf("\tShift to state %d\n", n); |
| 801 | #endif |
| 802 | return (ps); |
| 803 | /* |
| 804 | * REDUCE |
| 805 | */ |
| 806 | case 3: |
| 807 | n =& 07777; |
| 808 | if (yyEactr(n, yytipv[yytipct - 1]) == 0) { |
| 809 | #ifdef DEBUG |
| 810 | Tprintf("\tYyEactr objects: have %s id, want %s id\n", classes[yyidhave], classes[yyidwant]); |
| 811 | #endif |
| 812 | return (NIL); |
| 813 | } |
| 814 | yyredfail = 0; |
| 815 | i = yyr2[n]; |
| 816 | #ifdef DEBUG |
| 817 | Tprintf("\tReduce, length %d,", i); |
| 818 | #endif |
| 819 | if (i > yytipct) { |
| 820 | i =- yytipct; |
| 821 | yytipct = 0; |
| 822 | ps =- i; |
| 823 | yCpv =- i; |
| 824 | } else |
| 825 | yytipct =- i; |
| 826 | if (yytipct >= YYTIPSIZ) |
| 827 | goto tipover; |
| 828 | /* |
| 829 | * Use goto table to find next state |
| 830 | */ |
| 831 | p = &yygo[yypgo[yyr1[n]]]; |
| 832 | i = yytipct ? yytips[yytipct - 1] : *ps; |
| 833 | while (*p != i && *p >= 0) |
| 834 | p =+ 2; |
| 835 | #ifdef DEBUG |
| 836 | Tprintf(" new state %d\n", p[1]); |
| 837 | #endif |
| 838 | yytips[yytipct] = p[1]; |
| 839 | yytipct++; |
| 840 | goto newstate; |
| 841 | /* |
| 842 | * ACCEPT |
| 843 | */ |
| 844 | case 4: |
| 845 | #ifdef DEBUG |
| 846 | Tprintf("\tAccept\n"); |
| 847 | #endif |
| 848 | return (ps); |
| 849 | /* |
| 850 | * ERROR |
| 851 | */ |
| 852 | case 1: |
| 853 | #ifdef DEBUG |
| 854 | Tprintf("\tError\n"); |
| 855 | #endif |
| 856 | return (0); |
| 857 | } |
| 858 | panic("loccor"); |
| 859 | } |