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1.1 ! deraadt 1: /* $NetBSD: expr.c,v 1.7 1995/09/28 05:37:31 tls Exp $ */
! 2:
! 3: /*
! 4: * Copyright (c) 1989, 1993
! 5: * The Regents of the University of California. All rights reserved.
! 6: *
! 7: * This code is derived from software contributed to Berkeley by
! 8: * Ozan Yigit at York University.
! 9: *
! 10: * Redistribution and use in source and binary forms, with or without
! 11: * modification, are permitted provided that the following conditions
! 12: * are met:
! 13: * 1. Redistributions of source code must retain the above copyright
! 14: * notice, this list of conditions and the following disclaimer.
! 15: * 2. Redistributions in binary form must reproduce the above copyright
! 16: * notice, this list of conditions and the following disclaimer in the
! 17: * documentation and/or other materials provided with the distribution.
! 18: * 3. All advertising materials mentioning features or use of this software
! 19: * must display the following acknowledgement:
! 20: * This product includes software developed by the University of
! 21: * California, Berkeley and its contributors.
! 22: * 4. Neither the name of the University nor the names of its contributors
! 23: * may be used to endorse or promote products derived from this software
! 24: * without specific prior written permission.
! 25: *
! 26: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 27: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 28: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 29: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 30: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 31: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 32: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 33: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 34: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 35: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 36: * SUCH DAMAGE.
! 37: */
! 38:
! 39: #ifndef lint
! 40: #if 0
! 41: static char sccsid[] = "@(#)expr.c 8.2 (Berkeley) 4/29/95";
! 42: #else
! 43: static char rcsid[] = "$NetBSD: expr.c,v 1.7 1995/09/28 05:37:31 tls Exp $";
! 44: #endif
! 45: #endif /* not lint */
! 46:
! 47: #include <sys/cdefs.h>
! 48: #include <stdio.h>
! 49:
! 50: /*
! 51: * expression evaluator: performs a standard recursive
! 52: * descent parse to evaluate any expression permissible
! 53: * within the following grammar:
! 54: *
! 55: * expr : query EOS
! 56: * query : lor
! 57: * | lor "?" query ":" query
! 58: * lor : land { "||" land }
! 59: * land : not { "&&" not }
! 60: * not : eqrel
! 61: * | '!' not
! 62: * eqrel : shift { eqrelop shift }
! 63: * shift : primary { shop primary }
! 64: * primary : term { addop term }
! 65: * term : exp { mulop exp }
! 66: * exp : unary { expop unary }
! 67: * unary : factor
! 68: * | unop unary
! 69: * factor : constant
! 70: * | "(" query ")"
! 71: * constant: num
! 72: * | "'" CHAR "'"
! 73: * num : DIGIT
! 74: * | DIGIT num
! 75: * shop : "<<"
! 76: * | ">>"
! 77: * eqrel : "="
! 78: * | "=="
! 79: * | "!="
! 80: * | "<"
! 81: * | ">"
! 82: * | "<="
! 83: * | ">="
! 84: *
! 85: *
! 86: * This expression evaluator is lifted from a public-domain
! 87: * C Pre-Processor included with the DECUS C Compiler distribution.
! 88: * It is hacked somewhat to be suitable for m4.
! 89: *
! 90: * Originally by: Mike Lutz
! 91: * Bob Harper
! 92: */
! 93:
! 94: #define TRUE 1
! 95: #define FALSE 0
! 96: #define EOS (char) 0
! 97: #define EQL 0
! 98: #define NEQ 1
! 99: #define LSS 2
! 100: #define LEQ 3
! 101: #define GTR 4
! 102: #define GEQ 5
! 103: #define OCTAL 8
! 104: #define DECIMAL 10
! 105:
! 106: static char *nxtch; /* Parser scan pointer */
! 107:
! 108: static int query __P((void));
! 109: static int lor __P((void));
! 110: static int land __P((void));
! 111: static int not __P((void));
! 112: static int eqrel __P((void));
! 113: static int shift __P((void));
! 114: static int primary __P((void));
! 115: static int term __P((void));
! 116: static int exp __P((void));
! 117: static int unary __P((void));
! 118: static int factor __P((void));
! 119: static int constant __P((void));
! 120: static int num __P((void));
! 121: static int geteqrel __P((void));
! 122: static int skipws __P((void));
! 123: static void experr __P((char *));
! 124:
! 125: /*
! 126: * For longjmp
! 127: */
! 128: #include <setjmp.h>
! 129: static jmp_buf expjump;
! 130:
! 131: /*
! 132: * macros:
! 133: * ungetch - Put back the last character examined.
! 134: * getch - return the next character from expr string.
! 135: */
! 136: #define ungetch() nxtch--
! 137: #define getch() *nxtch++
! 138:
! 139: int
! 140: expr(expbuf)
! 141: char *expbuf;
! 142: {
! 143: register int rval;
! 144:
! 145: nxtch = expbuf;
! 146: if (setjmp(expjump) != 0)
! 147: return FALSE;
! 148:
! 149: rval = query();
! 150: if (skipws() == EOS)
! 151: return rval;
! 152:
! 153: printf("m4: ill-formed expression.\n");
! 154: return FALSE;
! 155: }
! 156:
! 157: /*
! 158: * query : lor | lor '?' query ':' query
! 159: */
! 160: static int
! 161: query()
! 162: {
! 163: register int bool, true_val, false_val;
! 164:
! 165: bool = lor();
! 166: if (skipws() != '?') {
! 167: ungetch();
! 168: return bool;
! 169: }
! 170:
! 171: true_val = query();
! 172: if (skipws() != ':')
! 173: experr("bad query");
! 174:
! 175: false_val = query();
! 176: return bool ? true_val : false_val;
! 177: }
! 178:
! 179: /*
! 180: * lor : land { '||' land }
! 181: */
! 182: static int
! 183: lor()
! 184: {
! 185: register int c, vl, vr;
! 186:
! 187: vl = land();
! 188: while ((c = skipws()) == '|') {
! 189: if (getch() != '|')
! 190: ungetch();
! 191: vr = land();
! 192: vl = vl || vr;
! 193: }
! 194:
! 195: ungetch();
! 196: return vl;
! 197: }
! 198:
! 199: /*
! 200: * land : not { '&&' not }
! 201: */
! 202: static int
! 203: land()
! 204: {
! 205: register int c, vl, vr;
! 206:
! 207: vl = not();
! 208: while ((c = skipws()) == '&') {
! 209: if (getch() != '&')
! 210: ungetch();
! 211: vr = not();
! 212: vl = vl && vr;
! 213: }
! 214:
! 215: ungetch();
! 216: return vl;
! 217: }
! 218:
! 219: /*
! 220: * not : eqrel | '!' not
! 221: */
! 222: static int
! 223: not()
! 224: {
! 225: register int val, c;
! 226:
! 227: if ((c = skipws()) == '!' && getch() != '=') {
! 228: ungetch();
! 229: val = not();
! 230: return !val;
! 231: }
! 232:
! 233: if (c == '!')
! 234: ungetch();
! 235: ungetch();
! 236: return eqrel();
! 237: }
! 238:
! 239: /*
! 240: * eqrel : shift { eqrelop shift }
! 241: */
! 242: static int
! 243: eqrel()
! 244: {
! 245: register int vl, vr, eqrel;
! 246:
! 247: vl = shift();
! 248: while ((eqrel = geteqrel()) != -1) {
! 249: vr = shift();
! 250:
! 251: switch (eqrel) {
! 252:
! 253: case EQL:
! 254: vl = (vl == vr);
! 255: break;
! 256: case NEQ:
! 257: vl = (vl != vr);
! 258: break;
! 259:
! 260: case LEQ:
! 261: vl = (vl <= vr);
! 262: break;
! 263: case LSS:
! 264: vl = (vl < vr);
! 265: break;
! 266: case GTR:
! 267: vl = (vl > vr);
! 268: break;
! 269: case GEQ:
! 270: vl = (vl >= vr);
! 271: break;
! 272: }
! 273: }
! 274: return vl;
! 275: }
! 276:
! 277: /*
! 278: * shift : primary { shop primary }
! 279: */
! 280: static int
! 281: shift()
! 282: {
! 283: register int vl, vr, c;
! 284:
! 285: vl = primary();
! 286: while (((c = skipws()) == '<' || c == '>') && getch() == c) {
! 287: vr = primary();
! 288:
! 289: if (c == '<')
! 290: vl <<= vr;
! 291: else
! 292: vl >>= vr;
! 293: }
! 294:
! 295: if (c == '<' || c == '>')
! 296: ungetch();
! 297: ungetch();
! 298: return vl;
! 299: }
! 300:
! 301: /*
! 302: * primary : term { addop term }
! 303: */
! 304: static int
! 305: primary()
! 306: {
! 307: register int c, vl, vr;
! 308:
! 309: vl = term();
! 310: while ((c = skipws()) == '+' || c == '-') {
! 311: vr = term();
! 312:
! 313: if (c == '+')
! 314: vl += vr;
! 315: else
! 316: vl -= vr;
! 317: }
! 318:
! 319: ungetch();
! 320: return vl;
! 321: }
! 322:
! 323: /*
! 324: * <term> := <exp> { <mulop> <exp> }
! 325: */
! 326: static int
! 327: term()
! 328: {
! 329: register int c, vl, vr;
! 330:
! 331: vl = exp();
! 332: while ((c = skipws()) == '*' || c == '/' || c == '%') {
! 333: vr = exp();
! 334:
! 335: switch (c) {
! 336: case '*':
! 337: vl *= vr;
! 338: break;
! 339: case '/':
! 340: vl /= vr;
! 341: break;
! 342: case '%':
! 343: vl %= vr;
! 344: break;
! 345: }
! 346: }
! 347: ungetch();
! 348: return vl;
! 349: }
! 350:
! 351: /*
! 352: * <term> := <unary> { <expop> <unary> }
! 353: */
! 354: static int
! 355: exp()
! 356: {
! 357: register c, vl, vr, n;
! 358:
! 359: vl = unary();
! 360: switch (c = skipws()) {
! 361:
! 362: case '*':
! 363: if (getch() != '*') {
! 364: ungetch();
! 365: break;
! 366: }
! 367:
! 368: case '^':
! 369: vr = exp();
! 370: n = 1;
! 371: while (vr-- > 0)
! 372: n *= vl;
! 373: return n;
! 374: }
! 375:
! 376: ungetch();
! 377: return vl;
! 378: }
! 379:
! 380: /*
! 381: * unary : factor | unop unary
! 382: */
! 383: static int
! 384: unary()
! 385: {
! 386: register int val, c;
! 387:
! 388: if ((c = skipws()) == '+' || c == '-' || c == '~') {
! 389: val = unary();
! 390:
! 391: switch (c) {
! 392: case '+':
! 393: return val;
! 394: case '-':
! 395: return -val;
! 396: case '~':
! 397: return ~val;
! 398: }
! 399: }
! 400:
! 401: ungetch();
! 402: return factor();
! 403: }
! 404:
! 405: /*
! 406: * factor : constant | '(' query ')'
! 407: */
! 408: static int
! 409: factor()
! 410: {
! 411: register int val;
! 412:
! 413: if (skipws() == '(') {
! 414: val = query();
! 415: if (skipws() != ')')
! 416: experr("bad factor");
! 417: return val;
! 418: }
! 419:
! 420: ungetch();
! 421: return constant();
! 422: }
! 423:
! 424: /*
! 425: * constant: num | 'char'
! 426: * Note: constant() handles multi-byte constants
! 427: */
! 428: static int
! 429: constant()
! 430: {
! 431: register int i;
! 432: register int value;
! 433: register char c;
! 434: int v[sizeof(int)];
! 435:
! 436: if (skipws() != '\'') {
! 437: ungetch();
! 438: return num();
! 439: }
! 440: for (i = 0; i < sizeof(int); i++) {
! 441: if ((c = getch()) == '\'') {
! 442: ungetch();
! 443: break;
! 444: }
! 445: if (c == '\\') {
! 446: switch (c = getch()) {
! 447: case '0':
! 448: case '1':
! 449: case '2':
! 450: case '3':
! 451: case '4':
! 452: case '5':
! 453: case '6':
! 454: case '7':
! 455: ungetch();
! 456: c = num();
! 457: break;
! 458: case 'n':
! 459: c = 012;
! 460: break;
! 461: case 'r':
! 462: c = 015;
! 463: break;
! 464: case 't':
! 465: c = 011;
! 466: break;
! 467: case 'b':
! 468: c = 010;
! 469: break;
! 470: case 'f':
! 471: c = 014;
! 472: break;
! 473: }
! 474: }
! 475: v[i] = c;
! 476: }
! 477: if (i == 0 || getch() != '\'')
! 478: experr("illegal character constant");
! 479: for (value = 0; --i >= 0;) {
! 480: value <<= 8;
! 481: value += v[i];
! 482: }
! 483: return value;
! 484: }
! 485:
! 486: /*
! 487: * num : digit | num digit
! 488: */
! 489: static int
! 490: num()
! 491: {
! 492: register int rval, c, base;
! 493: int ndig;
! 494:
! 495: base = ((c = skipws()) == '0') ? OCTAL : DECIMAL;
! 496: rval = 0;
! 497: ndig = 0;
! 498: while (c >= '0' && c <= (base == OCTAL ? '7' : '9')) {
! 499: rval *= base;
! 500: rval += (c - '0');
! 501: c = getch();
! 502: ndig++;
! 503: }
! 504: ungetch();
! 505:
! 506: if (ndig == 0)
! 507: experr("bad constant");
! 508:
! 509: return rval;
! 510:
! 511: }
! 512:
! 513: /*
! 514: * eqrel : '=' | '==' | '!=' | '<' | '>' | '<=' | '>='
! 515: */
! 516: static int
! 517: geteqrel()
! 518: {
! 519: register int c1, c2;
! 520:
! 521: c1 = skipws();
! 522: c2 = getch();
! 523:
! 524: switch (c1) {
! 525:
! 526: case '=':
! 527: if (c2 != '=')
! 528: ungetch();
! 529: return EQL;
! 530:
! 531: case '!':
! 532: if (c2 == '=')
! 533: return NEQ;
! 534: ungetch();
! 535: ungetch();
! 536: return -1;
! 537:
! 538: case '<':
! 539: if (c2 == '=')
! 540: return LEQ;
! 541: ungetch();
! 542: return LSS;
! 543:
! 544: case '>':
! 545: if (c2 == '=')
! 546: return GEQ;
! 547: ungetch();
! 548: return GTR;
! 549:
! 550: default:
! 551: ungetch();
! 552: ungetch();
! 553: return -1;
! 554: }
! 555: }
! 556:
! 557: /*
! 558: * Skip over any white space and return terminating char.
! 559: */
! 560: static int
! 561: skipws()
! 562: {
! 563: register char c;
! 564:
! 565: while ((c = getch()) <= ' ' && c > EOS)
! 566: ;
! 567: return c;
! 568: }
! 569:
! 570: /*
! 571: * resets environment to eval(), prints an error
! 572: * and forces eval to return FALSE.
! 573: */
! 574: static void
! 575: experr(msg)
! 576: char *msg;
! 577: {
! 578: printf("m4: %s in expr.\n", msg);
! 579: longjmp(expjump, -1);
! 580: }