expr.c revision 1.2
1 1.2 glass /* File : expr.c 2 1.2 glass Authors: Mike Lutz & Bob Harper 3 1.2 glass Editors: Ozan Yigit & Richard A. O'Keefe 4 1.2 glass Updated: %G% 5 1.2 glass Purpose: arithmetic expression evaluator. 6 1.1 cgd 7 1.2 glass expr() performs a standard recursive descent parse to evaluate any 8 1.2 glass expression permitted byf the following grammar: 9 1.2 glass 10 1.2 glass expr : query EOS 11 1.2 glass query : lor 12 1.2 glass | lor "?" query ":" query 13 1.2 glass lor : land { "||" land } or OR, for Pascal 14 1.2 glass land : bor { "&&" bor } or AND, for Pascal 15 1.2 glass bor : bxor { "|" bxor } 16 1.2 glass bxor : band { "^" band } 17 1.2 glass band : eql { "&" eql } 18 1.2 glass eql : relat { eqrel relat } 19 1.2 glass relat : shift { rel shift } 20 1.2 glass shift : primary { shop primary } 21 1.2 glass primary : term { addop term } 22 1.2 glass term : unary { mulop unary } 23 1.2 glass unary : factor 24 1.2 glass | unop unary 25 1.2 glass factor : constant 26 1.2 glass | "(" query ")" 27 1.2 glass constant: num 28 1.2 glass | "'" CHAR "'" or '"' CHAR '"' 29 1.2 glass num : DIGIT full ANSI C syntax 30 1.2 glass | DIGIT num 31 1.2 glass shop : "<<" 32 1.2 glass | ">>" 33 1.2 glass eqlrel : "=" 34 1.2 glass | "==" 35 1.2 glass | "!=" 36 1.2 glass rel : "<" or <>, Pascal not-equal 37 1.2 glass | ">" 38 1.2 glass | "<=" or =<, for Prolog users. 39 1.2 glass | ">=" 40 1.2 glass 41 1.2 glass This expression evaluator was lifted from a public-domain 42 1.2 glass C Pre-Processor included with the DECUS C Compiler distribution. 43 1.2 glass It has been hacked somewhat to be suitable for m4. 44 1.2 glass 45 1.2 glass 26-Mar-1993 Changed to work in any of EBCDIC, ASCII, DEC MNCS, 46 1.2 glass or ISO 8859/n. 47 1.2 glass 48 1.2 glass 26-Mar-1993 Changed to use "long int" rather than int, so that 49 1.2 glass we get the same 32-bit arithmetic on a PC as on a Sun. 50 1.2 glass It isn't fully portable, of course, but then on a 64- 51 1.2 glass bit machine we _want_ 64-bit arithmetic... 52 1.2 glass Shifting rewritten (using LONG_BIT) to give signed 53 1.2 glass shifts even when (long) >> (long) is unsigned. 54 1.2 glass 55 1.2 glass 26-Mar-1993 I finally got sick of the fact that &&, ||, and ?: 56 1.2 glass don't do conditional evaluation. What is the good 57 1.2 glass of having eval(0&&(1/0)) crash and dump core? Now 58 1.2 glass every function has a doit? argument. 59 1.2 glass 60 1.2 glass 26-Mar-1993 charcon() didn't actually accept 'abcd', which it 61 1.2 glass should have. Fixed it. 62 1.2 glass 63 1.2 glass 20-Apr-1993 eval(1/0) and eval(1%0) dumped core and crashed. 64 1.2 glass This is also true of the System V r 3.2 m4, but 65 1.2 glass it isn't good enough for ours! Changed it so that 66 1.2 glass x % 0 => x as per Concrete Mathematics 67 1.2 glass x / 0 => error and return 0 from expr(). 68 1.2 glass */ 69 1.2 glass 70 1.2 glass #define FALSE 0 71 1.2 glass #define TRUE 1 72 1.2 glass 73 1.2 glass #include <stdio.h> 74 1.1 cgd #include <setjmp.h> 75 1.2 glass static jmp_buf expjump; /* Error exit point for expr() */ 76 1.2 glass 77 1.2 glass static unsigned char *nxtchr; /* Parser scan pointer */ 78 1.2 glass 79 1.2 glass #define deblank0 while ((unsigned)(*nxtchr-1) < ' ') nxtchr++ 80 1.2 glass #define deblank1 while ((unsigned)(*++nxtchr - 1) < ' ') 81 1.2 glass #define deblank2 nxtchr++; deblank1 82 1.2 glass 83 1.2 glass #include "ourlims.h" 84 1.2 glass static char digval[1+UCHAR_MAX]; 85 1.2 glass 86 1.2 glass /* This file should work in any C implementation that doesn't have too 87 1.2 glass many characters to fit in one table. We use a table to convert 88 1.2 glass (unsigned) characters to numeric codes: 89 1.2 glass 0 to 9 for '0' to '9' 90 1.2 glass 10 to 35 for 'a' to 'z' 91 1.2 glass 10 to 35 for 'A' to 'Z' 92 1.2 glass 36 for '_' 93 1.2 glass Instead of asking whether tolower(c) == 'a' we ask whether 94 1.2 glass digval[c] == DIGIT_A, and so on. This essentially duplicates the 95 1.2 glass chtype[] table in main.c; we should use just one table. 96 1.2 glass */ 97 1.2 glass #define DIGIT_A 10 98 1.2 glass #define DIGIT_B 11 99 1.2 glass #define DIGIT_C 12 100 1.2 glass #define DIGIT_D 13 101 1.2 glass #define DIGIT_E 14 102 1.2 glass #define DIGIT_F 15 103 1.2 glass #define DIGIT_G 16 104 1.2 glass #define DIGIT_H 17 105 1.2 glass #define DIGIT_I 18 106 1.2 glass #define DIGIT_J 19 107 1.2 glass #define DIGIT_K 20 108 1.2 glass #define DIGIT_L 21 109 1.2 glass #define DIGIT_M 22 110 1.2 glass #define DIGIT_N 23 111 1.2 glass #define DIGIT_O 24 112 1.2 glass #define DIGIT_P 25 113 1.2 glass #define DIGIT_Q 26 114 1.2 glass #define DIGIT_R 27 115 1.2 glass #define DIGIT_S 28 116 1.2 glass #define DIGIT_T 29 117 1.2 glass #define DIGIT_U 30 118 1.2 glass #define DIGIT_V 31 119 1.2 glass #define DIGIT_W 32 120 1.2 glass #define DIGIT_X 33 121 1.2 glass #define DIGIT_Y 34 122 1.2 glass #define DIGIT_Z 35 123 1.2 glass 124 1.2 glass 125 1.2 glass #ifdef __STDC__ 126 1.2 glass static long int query(int); 127 1.2 glass #else 128 1.2 glass static long int query(); 129 1.2 glass #endif 130 1.2 glass 131 1.2 glass 132 1.2 glass /* experr(msg) 133 1.2 glass prints an error message, resets environment to expr(), and 134 1.2 glass forces expr() to return FALSE. 135 1.2 glass */ 136 1.2 glass void experr(msg) 137 1.2 glass char *msg; 138 1.2 glass { 139 1.2 glass (void) fprintf(stderr, "m4: %s\n", msg); 140 1.2 glass longjmp(expjump, -1); /* Force expr() to return FALSE */ 141 1.2 glass } 142 1.2 glass 143 1.2 glass 144 1.2 glass /* <numcon> ::= '0x' <hex> | '0X' <hex> | '0' <oct> | <dec> 145 1.2 glass For ANSI C, an integer may be followed by u, l, ul, or lu, 146 1.2 glass in any mix of cases. We accept and ignore those letters; 147 1.2 glass all the numbers are treated as long. 148 1.2 glass */ 149 1.2 glass static long int numcon(doit) 150 1.2 glass int doit; 151 1.2 glass { 152 1.2 glass register long int v; /* current value */ 153 1.2 glass register int b; /* base (radix) */ 154 1.2 glass register int c; /* character or digit value */ 155 1.2 glass 156 1.2 glass if (!doit) { 157 1.2 glass do nxtchr++; while (digval[*nxtchr] <= 36); 158 1.2 glass deblank0; 159 1.2 glass return 0; 160 1.2 glass } 161 1.2 glass 162 1.2 glass v = digval[*nxtchr++]; /* We already know it's a digit */ 163 1.2 glass if (v != 0) { 164 1.2 glass b = 10; /* decimal number */ 165 1.2 glass } else 166 1.2 glass if (digval[*nxtchr] == DIGIT_X) { 167 1.2 glass nxtchr++; 168 1.2 glass b = 16; /* hexadecimal number */ 169 1.2 glass } else { 170 1.2 glass b = 8; /* octal number */ 171 1.2 glass } 172 1.2 glass do { 173 1.2 glass while (digval[c = *nxtchr++] < b) v = v*b + digval[c]; 174 1.2 glass } while (c == '_'); 175 1.2 glass while (digval[c] == DIGIT_L || digval[c] == DIGIT_U) c = *nxtchr++; 176 1.2 glass nxtchr--; /* unread c */ 177 1.2 glass if ((unsigned)(c-1) < ' ') { deblank1; } 178 1.2 glass return v; 179 1.2 glass } 180 1.2 glass 181 1.2 glass 182 1.2 glass /* <charcon> ::= <qt> { <char> } <qt> 183 1.2 glass Note: multibyte constants are accepted. 184 1.2 glass Note: BEL (\a) and ESC (\e) have the same values in EBCDIC and ASCII. 185 1.2 glass */ 186 1.2 glass static long int charcon(doit) 187 1.2 glass int doit; 188 1.2 glass { 189 1.2 glass register int i; 190 1.2 glass long int value; 191 1.2 glass register int c; 192 1.2 glass int q; 193 1.2 glass int v[sizeof value]; 194 1.2 glass 195 1.2 glass q = *nxtchr++; /* the quote character */ 196 1.2 glass for (i = 0; ; i++) { 197 1.2 glass c = *nxtchr++; 198 1.2 glass if (c == q) { /* end of literal, or doubled quote */ 199 1.2 glass if (*nxtchr != c) break; 200 1.2 glass nxtchr++; /* doubled quote stands for one quote */ 201 1.2 glass } 202 1.2 glass if (i == sizeof value) experr("Unterminated character constant"); 203 1.2 glass if (c == '\\') { 204 1.2 glass switch (c = *nxtchr++) { 205 1.2 glass case '0': case '1': case '2': case '3': 206 1.2 glass case '4': case '5': case '6': case '7': 207 1.2 glass c -= '0'; 208 1.2 glass if ((unsigned)(*nxtchr - '0') < 8) 209 1.2 glass c = (c << 3) | (*nxtchr++ - '0'); 210 1.2 glass if ((unsigned)(*nxtchr - '0') < 8) 211 1.2 glass c = (c << 3) | (*nxtchr++ - '0'); 212 1.2 glass break; 213 1.2 glass case 'n': case 'N': c = '\n'; break; 214 1.2 glass case 'r': case 'R': c = '\r'; break; 215 1.2 glass case 't': case 'T': c = '\t'; break; 216 1.2 glass case 'b': case 'B': c = '\b'; break; 217 1.2 glass case 'f': case 'F': c = '\f'; break; 218 1.2 glass case 'a': case 'A': c = 007; break; 219 1.2 glass case 'e': case 'E': c = 033; break; 220 1.2 glass #if ' ' == 64 221 1.2 glass case 'd': case 'D': c = 045; break; /*EBCDIC DEL */ 222 1.2 glass #else 223 1.2 glass case 'd': case 'D': c = 127; break; /* ASCII DEL */ 224 1.2 glass #endif 225 1.2 glass default : break; 226 1.2 glass } 227 1.2 glass } 228 1.2 glass v[i] = c; 229 1.2 glass } 230 1.2 glass deblank0; 231 1.2 glass if (!doit) return 0; 232 1.2 glass for (value = 0; --i >= 0; ) value = (value << CHAR_BIT) | v[i]; 233 1.2 glass return value; 234 1.2 glass } 235 1.2 glass 236 1.2 glass 237 1.2 glass /* <unary> ::= <unop> <unary> | <factor> 238 1.2 glass <unop> ::= '!' || '~' | '-' 239 1.2 glass <factor> ::= '(' <query> ')' | <'> <char> <'> | <"> <char> <"> | <num> 240 1.2 glass */ 241 1.2 glass static long int unary(doit) 242 1.2 glass int doit; 243 1.2 glass { 244 1.2 glass long int v; 245 1.2 glass 246 1.2 glass switch (nxtchr[0]) { 247 1.2 glass case 'n': case 'N': 248 1.2 glass if (digval[nxtchr[1]] != DIGIT_O 249 1.2 glass || digval[nxtchr[2]] != DIGIT_T) 250 1.2 glass experr("Bad 'not'"); 251 1.2 glass nxtchr += 2; 252 1.2 glass case '!': deblank1; return !unary(doit); 253 1.2 glass case '~': deblank1; return ~unary(doit); 254 1.2 glass case '-': deblank1; return -unary(doit); 255 1.2 glass case '+': deblank1; return unary(doit); 256 1.2 glass case '(': deblank1; v = query(doit); 257 1.2 glass if (nxtchr[0] != ')') experr("Bad factor"); 258 1.2 glass deblank1; return v; 259 1.2 glass case '\'': 260 1.2 glass case '\"': return charcon(doit); 261 1.2 glass case '0': case '1': case '2': 262 1.2 glass case '3': case '4': case '5': 263 1.2 glass case '6': case '7': case '8': 264 1.2 glass case '9': return numcon(doit); 265 1.2 glass default : experr("Bad constant"); 266 1.2 glass } 267 1.2 glass return 0; /*NOTREACHED*/ 268 1.2 glass } 269 1.2 glass 270 1.2 glass 271 1.2 glass /* <term> ::= <unary> { <mulop> <unary> } 272 1.2 glass <mulop> ::= '*' | '/' || '%' 273 1.2 glass */ 274 1.2 glass static long int term(doit) 275 1.2 glass int doit; 276 1.2 glass { 277 1.2 glass register long int vl, vr; 278 1.2 glass 279 1.2 glass vl = unary(doit); 280 1.2 glass for (;;) 281 1.2 glass switch (nxtchr[0]) { 282 1.2 glass case '*': 283 1.2 glass deblank1; 284 1.2 glass vr = unary(doit); 285 1.2 glass if (doit) vl *= vr; 286 1.2 glass break; 287 1.2 glass case 'd': case 'D': 288 1.2 glass if (digval[nxtchr[1]] != DIGIT_I 289 1.2 glass || digval[nxtchr[2]] != DIGIT_V) 290 1.2 glass experr("Bad 'div'"); 291 1.2 glass nxtchr += 2; 292 1.2 glass /*FALLTHROUGH*/ 293 1.2 glass case '/': 294 1.2 glass deblank1; 295 1.2 glass vr = unary(doit); 296 1.2 glass if (doit) { 297 1.2 glass if (vr == 0) experr("Division by 0"); 298 1.2 glass vl /= vr; 299 1.2 glass } 300 1.2 glass break; 301 1.2 glass case 'm': case 'M': 302 1.2 glass if (digval[nxtchr[1]] != DIGIT_O 303 1.2 glass || digval[nxtchr[2]] != DIGIT_D) 304 1.2 glass experr("Bad 'mod'"); 305 1.2 glass nxtchr += 2; 306 1.2 glass /*FALLTHROUGH*/ 307 1.2 glass case '%': 308 1.2 glass deblank1; 309 1.2 glass vr = unary(doit); 310 1.2 glass if (doit) { 311 1.2 glass if (vr != 0) vl %= vr; 312 1.2 glass } 313 1.2 glass break; 314 1.2 glass default: 315 1.2 glass return vl; 316 1.2 glass } 317 1.2 glass /*NOTREACHED*/ 318 1.2 glass } 319 1.2 glass 320 1.2 glass /* <primary> ::= <term> { <addop> <term> } 321 1.2 glass <addop> ::= '+' | '-' 322 1.2 glass */ 323 1.2 glass static long int primary(doit) 324 1.2 glass int doit; 325 1.2 glass { 326 1.2 glass register long int vl; 327 1.2 glass 328 1.2 glass vl = term(doit); 329 1.2 glass for (;;) 330 1.2 glass if (nxtchr[0] == '+') { 331 1.2 glass deblank1; 332 1.2 glass if (doit) vl += term(doit); else (void)term(doit); 333 1.2 glass } else 334 1.2 glass if (nxtchr[0] == '-') { 335 1.2 glass deblank1; 336 1.2 glass if (doit) vl -= term(doit); else (void)term(doit); 337 1.2 glass } else 338 1.2 glass return vl; 339 1.2 glass /*NOTREACHED*/ 340 1.2 glass } 341 1.2 glass 342 1.2 glass 343 1.2 glass /* <shift> ::= <primary> { <shop> <primary> } 344 1.2 glass <shop> ::= '<<' | '>>' 345 1.2 glass */ 346 1.2 glass static long int shift(doit) 347 1.2 glass int doit; 348 1.2 glass { 349 1.2 glass register long int vl, vr; 350 1.2 glass 351 1.2 glass vl = primary(doit); 352 1.2 glass for (;;) { 353 1.2 glass if (nxtchr[0] == '<' && nxtchr[1] == '<') { 354 1.2 glass deblank2; 355 1.2 glass vr = primary(doit); 356 1.2 glass } else 357 1.2 glass if (nxtchr[0] == '>' && nxtchr[1] == '>') { 358 1.2 glass deblank2; 359 1.2 glass vr = -primary(doit); 360 1.2 glass } else { 361 1.2 glass return vl; 362 1.2 glass } 363 1.2 glass /* The following code implements shifts portably */ 364 1.2 glass /* Shifts are signed shifts, and the shift count */ 365 1.2 glass /* acts like repeated one-bit shifts, not modulo anything */ 366 1.2 glass if (doit) { 367 1.2 glass if (vr >= LONG_BIT) { 368 1.2 glass vl = 0; 369 1.2 glass } else 370 1.2 glass if (vr <= -LONG_BIT) { 371 1.2 glass vl = -(vl < 0); 372 1.2 glass } else 373 1.2 glass if (vr > 0) { 374 1.2 glass vl <<= vr; 375 1.2 glass } else 376 1.2 glass if (vr < 0) { 377 1.2 glass vl = (vl >> -vr) | (-(vl < 0) << (LONG_BIT + vr)); 378 1.2 glass } 379 1.2 glass } 380 1.2 glass } 381 1.2 glass /*NOTREACHED*/ 382 1.2 glass } 383 1.2 glass 384 1.2 glass 385 1.2 glass /* <relat> ::= <shift> { <rel> <shift> } 386 1.2 glass <rel> ::= '<=' | '>=' | '=<' | '=>' | '<' | '>' 387 1.2 glass Here I rely on the fact that '<<' and '>>' are swallowed by <shift> 388 1.2 glass */ 389 1.2 glass static long int relat(doit) 390 1.2 glass int doit; 391 1.2 glass { 392 1.2 glass register long int vl; 393 1.2 glass 394 1.2 glass vl = shift(doit); 395 1.2 glass for (;;) 396 1.2 glass switch (nxtchr[0]) { 397 1.2 glass case '=': 398 1.2 glass switch (nxtchr[1]) { 399 1.2 glass case '<': /* =<, take as <= */ 400 1.2 glass deblank2; 401 1.2 glass vl = vl <= shift(doit); 402 1.2 glass break; 403 1.2 glass case '>': /* =>, take as >= */ 404 1.2 glass deblank2; 405 1.2 glass vl = vl >= shift(doit); 406 1.2 glass break; 407 1.2 glass default: /* == or =; OOPS */ 408 1.2 glass return vl; 409 1.2 glass } 410 1.2 glass break; 411 1.2 glass case '<': 412 1.2 glass if (nxtchr[1] == '=') { /* <= */ 413 1.2 glass deblank2; 414 1.2 glass vl = vl <= shift(doit); 415 1.2 glass } else 416 1.2 glass if (nxtchr[1] == '>') { /* <> (Pascal) */ 417 1.2 glass deblank2; 418 1.2 glass vl = vl != shift(doit); 419 1.2 glass } else { /* < */ 420 1.2 glass deblank1; 421 1.2 glass vl = vl < shift(doit); 422 1.2 glass } 423 1.2 glass break; 424 1.2 glass case '>': 425 1.2 glass if (nxtchr[1] == '=') { /* >= */ 426 1.2 glass deblank2; 427 1.2 glass vl = vl >= shift(doit); 428 1.2 glass } else { /* > */ 429 1.2 glass deblank1; 430 1.2 glass vl = vl > shift(doit); 431 1.2 glass } 432 1.2 glass break; 433 1.2 glass default: 434 1.2 glass return vl; 435 1.2 glass } 436 1.2 glass /*NOTREACHED*/ 437 1.2 glass } 438 1.2 glass 439 1.2 glass 440 1.2 glass /* <eql> ::= <relat> { <eqrel> <relat> } 441 1.2 glass <eqlrel> ::= '!=' | '==' | '=' 442 1.2 glass */ 443 1.2 glass static long int eql(doit) 444 1.2 glass int doit; 445 1.2 glass { 446 1.2 glass register long int vl; 447 1.2 glass 448 1.2 glass vl = relat(doit); 449 1.2 glass for (;;) 450 1.2 glass if (nxtchr[0] == '!' && nxtchr[1] == '=') { 451 1.2 glass deblank2; 452 1.2 glass vl = vl != relat(doit); 453 1.2 glass } else 454 1.2 glass if (nxtchr[0] == '=' && nxtchr[1] == '=') { 455 1.2 glass deblank2; 456 1.2 glass vl = vl == relat(doit); 457 1.2 glass } else 458 1.2 glass if (nxtchr[0] == '=') { 459 1.2 glass deblank1; 460 1.2 glass vl = vl == relat(doit); 461 1.2 glass } else 462 1.2 glass return vl; 463 1.2 glass /*NOTREACHED*/ 464 1.2 glass } 465 1.2 glass 466 1.2 glass 467 1.2 glass /* <band> ::= <eql> { '&' <eql> } 468 1.2 glass */ 469 1.2 glass static long int band(doit) 470 1.2 glass int doit; 471 1.2 glass { 472 1.2 glass register long int vl; 473 1.2 glass 474 1.2 glass vl = eql(doit); 475 1.2 glass while (nxtchr[0] == '&' && nxtchr[1] != '&') { 476 1.2 glass deblank1; 477 1.2 glass if (doit) vl &= eql(doit); else (void)eql(doit); 478 1.2 glass } 479 1.2 glass return vl; 480 1.2 glass } 481 1.2 glass 482 1.2 glass 483 1.2 glass /* <bxor> ::= <band> { '^' <band> } 484 1.2 glass */ 485 1.2 glass static long int bxor(doit) 486 1.2 glass int doit; 487 1.2 glass { 488 1.2 glass register long int vl; 489 1.2 glass 490 1.2 glass vl = band(doit); 491 1.2 glass while (nxtchr[0] == '^') { 492 1.2 glass deblank1; 493 1.2 glass if (doit) vl ^= band(doit); else (void)band(doit); 494 1.2 glass } 495 1.2 glass return vl; 496 1.2 glass } 497 1.2 glass 498 1.2 glass 499 1.2 glass /* <bor> ::= <bxor> { '|' <bxor> } 500 1.2 glass */ 501 1.2 glass static long int bor(doit) 502 1.2 glass int doit; 503 1.2 glass { 504 1.2 glass register long int vl; 505 1.2 glass 506 1.2 glass vl = bxor(doit); 507 1.2 glass while (nxtchr[0] == '|' && nxtchr[1] != '|') { 508 1.2 glass deblank1; 509 1.2 glass if (doit) vl |= bxor(doit); else (void)bxor(doit); 510 1.2 glass } 511 1.2 glass return vl; 512 1.2 glass } 513 1.2 glass 514 1.2 glass 515 1.2 glass /* <land> ::= <bor> { '&&' <bor> } 516 1.2 glass */ 517 1.2 glass static long int land(doit) 518 1.2 glass int doit; 519 1.2 glass { 520 1.2 glass register long int vl; 521 1.2 glass 522 1.2 glass vl = bor(doit); 523 1.2 glass for (;;) { 524 1.2 glass if (nxtchr[0] == '&') { 525 1.2 glass if (nxtchr[1] != '&') break; 526 1.2 glass deblank2; 527 1.2 glass } else 528 1.2 glass if (digval[nxtchr[0]] == DIGIT_A) { 529 1.2 glass if (digval[nxtchr[1]] != DIGIT_N) break; 530 1.2 glass if (digval[nxtchr[2]] != DIGIT_D) break; 531 1.2 glass nxtchr += 2; deblank1; 532 1.2 glass } else { 533 1.2 glass /* neither && nor and */ 534 1.2 glass break; 535 1.2 glass } 536 1.2 glass vl = bor(doit && vl) != 0; 537 1.2 glass } 538 1.2 glass return vl; 539 1.2 glass } 540 1.2 glass 541 1.2 glass 542 1.2 glass /* <lor> ::= <land> { '||' <land> } 543 1.2 glass */ 544 1.2 glass static long int lor(doit) 545 1.2 glass int doit; 546 1.2 glass { 547 1.2 glass register long int vl; 548 1.2 glass 549 1.2 glass vl = land(doit); 550 1.2 glass for (;;) { 551 1.2 glass if (nxtchr[0] == '|') { 552 1.2 glass if (nxtchr[1] != '|') break; 553 1.2 glass } else 554 1.2 glass if (digval[nxtchr[0]] == DIGIT_O) { 555 1.2 glass if (digval[nxtchr[1]] != DIGIT_R) break; 556 1.2 glass } else { 557 1.2 glass /* neither || nor or */ 558 1.2 glass break; 559 1.2 glass } 560 1.2 glass deblank2; 561 1.2 glass vl = land(doit && !vl) != 0; 562 1.2 glass } 563 1.2 glass return vl; 564 1.2 glass } 565 1.2 glass 566 1.2 glass 567 1.2 glass /* <query> ::= <lor> [ '?' <query> ':' <query> ] 568 1.2 glass */ 569 1.2 glass static long int query(doit) 570 1.2 glass int doit; 571 1.2 glass { 572 1.2 glass register long int bool, true_val, false_val; 573 1.2 glass 574 1.2 glass bool = lor(doit); 575 1.2 glass if (*nxtchr != '?') return bool; 576 1.2 glass deblank1; 577 1.2 glass true_val = query(doit && bool); 578 1.2 glass if (*nxtchr != ':') experr("Bad query"); 579 1.2 glass deblank1; 580 1.2 glass false_val = query(doit && !bool); 581 1.2 glass return bool ? true_val : false_val; 582 1.2 glass } 583 1.2 glass 584 1.2 glass 585 1.2 glass static void initialise_digval() 586 1.2 glass { 587 1.2 glass register unsigned char *s; 588 1.2 glass register int c; 589 1.2 glass 590 1.2 glass for (c = 0; c <= UCHAR_MAX; c++) digval[c] = 99; 591 1.2 glass for (c = 0, s = (unsigned char *)"0123456789"; 592 1.2 glass /*while*/ *s; 593 1.2 glass /*doing*/ digval[*s++] = c++) /* skip */; 594 1.2 glass for (c = 10, s = (unsigned char *)"ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 595 1.2 glass /*while*/ *s; 596 1.2 glass /*doing*/ digval[*s++] = c++) /* skip */; 597 1.2 glass for (c = 10, s = (unsigned char *)"abcdefghijklmnopqrstuvwxyz"; 598 1.2 glass /*while*/ *s; 599 1.2 glass /*doing*/ digval[*s++] = c++) /* skip */; 600 1.2 glass digval['_'] = 36; 601 1.2 glass } 602 1.2 glass 603 1.2 glass 604 1.2 glass long int expr(expbuf) 605 1.2 glass char *expbuf; 606 1.2 glass { 607 1.2 glass register int rval; 608 1.2 glass 609 1.2 glass if (digval['1'] == 0) initialise_digval(); 610 1.2 glass nxtchr = (unsigned char *)expbuf; 611 1.2 glass deblank0; 612 1.2 glass if (setjmp(expjump) != 0) return FALSE; 613 1.2 glass rval = query(TRUE); 614 1.2 glass if (*nxtchr) experr("Ill-formed expression"); 615 1.2 glass return rval; 616 1.2 glass } 617 1.1 cgd 618
Indexes created Sun Sep 21 20:09:37 GMT 2025