314 lines
7.0 KiB
C
314 lines
7.0 KiB
C
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/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Jim R. Oldroyd at The Instruction Set and Keith Gabryelski at
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* Commodore Business Machines.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static char sccsid[] = "@(#)rxp.c 8.1 (Berkeley) 5/31/93";
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#endif /* not lint */
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/*
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* regular expression parser
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*
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* external functions and return values are:
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* rxp_compile(s)
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* TRUE success
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* FALSE parse failure; error message will be in char rxperr[]
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* metas are:
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* {...} optional pattern, equialent to [...|]
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* | alternate pattern
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* [...] pattern delimiters
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*
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* rxp_match(s)
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* TRUE string s matches compiled pattern
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* FALSE match failure or regexp error
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*
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* rxp_expand()
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* char * reverse-engineered regular expression string
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* NULL regexp error
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*/
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#include <stdio.h>
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#include <ctype.h>
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#include "quiz.h"
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/* regexp tokens, arg */
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#define LIT (-1) /* literal character, char */
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#define SOT (-2) /* start text anchor, - */
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#define EOT (-3) /* end text anchor, - */
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#define GRP_S (-4) /* start alternate grp, ptr_to_end */
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#define GRP_E (-5) /* end group, - */
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#define ALT_S (-6) /* alternate starts, ptr_to_next */
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#define ALT_E (-7) /* alternate ends, - */
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#define END (-8) /* end of regexp, - */
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typedef short Rxp_t; /* type for regexp tokens */
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static Rxp_t rxpbuf[RXP_LINE_SZ]; /* compiled regular expression buffer */
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char rxperr[128]; /* parser error message */
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static int rxp__compile __P((char *, int));
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static char *rxp__expand __P((int));
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static int rxp__match __P((char *, int, Rxp_t *, Rxp_t *, char *));
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int
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rxp_compile(s)
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register char * s;
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{
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return (rxp__compile(s, TRUE));
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}
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static int
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rxp__compile(s, first)
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register char *s;
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int first;
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{
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static Rxp_t *rp;
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static char *sp;
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Rxp_t *grp_ptr;
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Rxp_t *alt_ptr;
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int esc, err;
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esc = 0;
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if (first) {
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rp = rxpbuf;
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sp = s;
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*rp++ = SOT; /* auto-anchor: pat is really ^pat$ */
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*rp++ = GRP_S; /* auto-group: ^pat$ is really ^[pat]$ */
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*rp++ = 0;
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}
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*rp++ = ALT_S;
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alt_ptr = rp;
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*rp++ = 0;
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for (; *sp; ++sp) {
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if (rp - rxpbuf >= RXP_LINE_SZ - 4) {
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(void)snprintf(rxperr, sizeof(rxperr),
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"regular expression too long %s", s);
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return (FALSE);
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}
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if (*sp == ':' && !esc)
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break;
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if (esc) {
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*rp++ = LIT;
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*rp++ = *sp;
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esc = 0;
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}
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else switch (*sp) {
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case '\\':
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esc = 1;
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break;
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case '{':
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case '[':
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*rp++ = GRP_S;
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grp_ptr = rp;
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*rp++ = 0;
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sp++;
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if ((err = rxp__compile(s, FALSE)) != TRUE)
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return (err);
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*rp++ = GRP_E;
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*grp_ptr = rp - rxpbuf;
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break;
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case '}':
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case ']':
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case '|':
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*rp++ = ALT_E;
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*alt_ptr = rp - rxpbuf;
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if (*sp != ']') {
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*rp++ = ALT_S;
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alt_ptr = rp;
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*rp++ = 0;
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}
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if (*sp != '|') {
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if (*sp != ']') {
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*rp++ = ALT_E;
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*alt_ptr = rp - rxpbuf;
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}
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if (first) {
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(void)snprintf(rxperr, sizeof(rxperr),
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"unmatched alternator in regexp %s",
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s);
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return (FALSE);
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}
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return (TRUE);
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}
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break;
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default:
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*rp++ = LIT;
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*rp++ = *sp;
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esc = 0;
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break;
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}
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}
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if (!first) {
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(void)snprintf(rxperr, sizeof(rxperr),
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"unmatched alternator in regexp %s", s);
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return (FALSE);
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}
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*rp++ = ALT_E;
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*alt_ptr = rp - rxpbuf;
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*rp++ = GRP_E;
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*(rxpbuf + 2) = rp - rxpbuf;
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*rp++ = EOT;
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*rp = END;
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return (TRUE);
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}
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/*
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* match string against compiled regular expression
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*/
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int
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rxp_match(s)
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register char * s;
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{
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return (rxp__match(s, TRUE, NULL, NULL, NULL));
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}
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static int
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rxp__match(s, first, j_succ, j_fail, sp_fail)
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char *s;
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int first;
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Rxp_t *j_succ; /* jump here on successful alt match */
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Rxp_t *j_fail; /* jump here on failed match */
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char *sp_fail; /* reset sp to here on failed match */
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{
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static Rxp_t *rp;
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static char *sp;
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register int ch;
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Rxp_t *grp_end;
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int err;
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if (first) {
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rp = rxpbuf;
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sp = s;
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}
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while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
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switch(*rp) {
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case LIT:
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rp++;
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ch = isascii(*rp) && isupper(*rp) ? tolower(*rp) : *rp;
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if (ch != *sp++) {
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rp = j_fail;
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sp = sp_fail;
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return (TRUE);
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}
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rp++;
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break;
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case SOT:
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if (sp != s)
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return (FALSE);
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rp++;
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break;
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case EOT:
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if (*sp != 0)
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return (FALSE);
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rp++;
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break;
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case GRP_S:
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rp++;
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grp_end = rxpbuf + *rp++;
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break;
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case ALT_S:
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rp++;
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if ((err = rxp__match(sp,
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FALSE, grp_end, rxpbuf + *rp++, sp)) != TRUE)
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return (err);
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break;
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case ALT_E:
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rp = j_succ;
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return (TRUE);
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case GRP_E:
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default:
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return (FALSE);
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}
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return (*rp != END ? FALSE : TRUE);
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}
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/*
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* Reverse engineer the regular expression, by picking first of all alternates.
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*/
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char *
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rxp_expand()
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{
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return (rxp__expand(TRUE));
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}
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static char *
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rxp__expand(first)
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int first;
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{
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static char buf[RXP_LINE_SZ/2];
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static Rxp_t *rp;
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static char *bp;
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Rxp_t *grp_ptr;
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char *err;
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if (first) {
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rp = rxpbuf;
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bp = buf;
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}
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while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
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switch(*rp) {
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case LIT:
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rp++;
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*bp++ = *rp++;
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break;
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case GRP_S:
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rp++;
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grp_ptr = rxpbuf + *rp;
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rp++;
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if ((err = rxp__expand(FALSE)) == NULL)
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return (err);
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rp = grp_ptr;
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break;
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case ALT_E:
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return (buf);
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case ALT_S:
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rp++;
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/* FALLTHROUGH */
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case SOT:
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case EOT:
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case GRP_E:
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rp++;
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break;
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default:
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return (NULL);
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}
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if (first) {
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if (*rp != END)
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return (NULL);
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*bp = '\0';
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}
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return (buf);
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}
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