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#ifndef lint |
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static const char RCSid[] = "$Id: rexpr.c,v 2.7 2003/06/07 12:50:20 schorsch Exp $"; |
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#endif |
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/* |
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* Regular expression parsing routines. |
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* |
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* External symbols declared in standard.h |
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*/ |
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|
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#include "copyright.h" |
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|
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <ctype.h> |
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#include <string.h> |
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|
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/* |
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* rexpr.c - regular expression parser (ala grep) |
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*/ |
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|
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#define CCHR 2 |
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#define CDOT 4 |
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#define CCL 6 |
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#define NCCL 8 |
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#define CDOL 10 |
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#define CEOF 11 |
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#define CBRC 14 |
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#define CLET 15 |
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#define STAR 01 |
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|
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#define ESIZE 255 |
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|
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#define same(a,b) (a==b || (iflag && (a^b)==' ' && isalpha(a))) |
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|
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|
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static int advance(), cclass(); |
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|
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static char expbuf[ESIZE]; |
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static int iflag; |
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static int circf; |
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|
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int explen; /* length of the last expression found */ |
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|
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int |
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ecompile(sp, iflg, wflag) /* compile the expression */ |
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register char *sp; |
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int iflg, wflag; |
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{ |
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register c; |
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register char *ep; |
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char *lastep; |
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int cclcnt; |
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|
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iflag = iflg; |
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ep = expbuf; |
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explen = 0; |
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if (*sp == '^') { |
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circf = 1; |
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sp++; |
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} else |
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circf = 0; |
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if (wflag) |
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*ep++ = CBRC; |
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for (;;) { |
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if (ep >= &expbuf[ESIZE]) |
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return(-1); |
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if ((c = *sp++) != '*') |
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lastep = ep; |
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switch (c) { |
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|
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case '\0': |
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if (wflag) |
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*ep++ = CLET; |
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*ep++ = CEOF; |
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explen = ep - expbuf; |
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return(0); |
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|
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case '.': |
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*ep++ = CDOT; |
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continue; |
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|
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case '*': |
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if (lastep==0) |
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goto defchar; |
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*lastep |= STAR; |
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continue; |
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|
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case '$': |
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if (*sp != '\0') |
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goto defchar; |
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*ep++ = CDOL; |
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continue; |
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|
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case '[': |
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*ep++ = CCL; |
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*ep++ = 0; |
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cclcnt = 1; |
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if ((c = *sp++) == '^') { |
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c = *sp++; |
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ep[-2] = NCCL; |
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} |
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do { |
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*ep++ = c; |
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cclcnt++; |
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if (c=='\0' || ep >= &expbuf[ESIZE]) |
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return(-1); |
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} while ((c = *sp++) != ']'); |
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lastep[1] = cclcnt; |
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continue; |
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|
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case '\\': |
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if ((c = *sp++) == '\0') |
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return(-1); |
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if (c == '<') { |
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if (ep == expbuf || ep[-1] != CBRC) |
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*ep++ = CBRC; |
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continue; |
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} |
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if (c == '>') { |
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*ep++ = CLET; |
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continue; |
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} |
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defchar: |
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default: |
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*ep++ = CCHR; |
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*ep++ = c; |
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} |
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} |
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} |
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|
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char * |
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expsave() /* save compiled string */ |
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{ |
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register char *ep; |
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|
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if (explen == 0) |
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return(NULL); |
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if ((ep = (char *)malloc(explen+3)) == NULL) |
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return(NULL); |
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ep[0] = iflag; |
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ep[1] = circf; |
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ep[2] = explen; |
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(void)memcpy(ep+3, expbuf, explen); |
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return(ep); |
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} |
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|
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void |
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expset(ep) /* install saved string */ |
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register char *ep; |
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{ |
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iflag = ep[0]; |
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circf = ep[1]; |
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(void)memcpy(expbuf, ep+3, ep[2]&0xff); |
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} |
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|
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char * |
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eindex(sp) /* find the expression in string sp */ |
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register char *sp; |
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{ |
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/* check for match at beginning of line, watch CBRC */ |
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if (advance(sp, expbuf[0]==CBRC ? expbuf+1 : expbuf)) |
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return(sp); |
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if (circf) |
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return(NULL); |
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/* fast check for first character */ |
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if (expbuf[0]==CCHR) { |
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register c = expbuf[1]; |
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while (*++sp) |
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if (same(*sp, c) && advance(sp, expbuf)) |
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return(sp); |
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return(NULL); |
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} |
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/* regular algorithm */ |
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while (*++sp) |
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if (advance(sp, expbuf)) |
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return(sp); |
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return(NULL); |
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} |
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|
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static int |
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advance(alp, ep) |
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char *alp; |
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register char *ep; |
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{ |
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register char *lp; |
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char *curlp; |
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|
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lp = alp; |
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for (;;) switch (*ep++) { |
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|
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case CCHR: |
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if (!same(*ep, *lp)) |
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return (0); |
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ep++, lp++; |
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continue; |
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|
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case CDOT: |
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if (*lp++) |
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continue; |
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return(0); |
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|
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case CDOL: |
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if (*lp==0) |
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continue; |
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return(0); |
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|
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case CEOF: |
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explen = lp - alp; |
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return(1); |
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|
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case CCL: |
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if (cclass(ep, *lp++, 1)) { |
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ep += *ep; |
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continue; |
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} |
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return(0); |
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|
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case NCCL: |
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if (cclass(ep, *lp++, 0)) { |
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ep += *ep; |
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continue; |
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} |
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return(0); |
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|
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case CDOT|STAR: |
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curlp = lp; |
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while (*lp++); |
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goto star; |
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|
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case CCHR|STAR: |
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curlp = lp; |
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while (same(*lp, *ep)) |
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lp++; |
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lp++; |
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ep++; |
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goto star; |
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|
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case CCL|STAR: |
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case NCCL|STAR: |
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curlp = lp; |
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while (cclass(ep, *lp++, ep[-1]==(CCL|STAR))); |
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ep += *ep; |
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star: |
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do { |
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lp--; |
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if (advance(lp, ep)) { |
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explen += lp - alp; |
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return(1); |
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} |
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} while (lp > curlp); |
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return(0); |
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|
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case CBRC: |
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if ((isalnum(*lp) || *lp == '_') && !(isalnum(lp[-1]) || lp[-1] == '_')) |
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continue; |
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return (0); |
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|
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case CLET: |
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if (!isalnum(*lp) && *lp != '_') |
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continue; |
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return (0); |
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|
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default: |
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fprintf(stderr, "RE botch\n"); |
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} |
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} |
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|
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static int |
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cclass(set, c, af) |
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register char *set; |
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register c; |
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int af; |
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{ |
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register n; |
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|
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if (c == 0) |
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return(0); |
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n = *set++; |
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while (--n) |
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if (n > 2 && set[1] == '-') { |
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if (c >= set[0] && c <= set[2]) |
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return (af); |
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set += 3; |
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n -= 2; |
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} else |
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if (*set++ == c) |
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return(af); |
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return(!af); |
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} |
