v8regsub.c

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/* regsub
 *
 *      Copyright (c) 1986 by University of Toronto.
 *      Written by Henry Spencer.  Not derived from licensed software.
 *
 *      Permission is granted to anyone to use this software for any
 *      purpose on any computer system, and to redistribute it freely,
 *      subject to the following restrictions:
 *
 *      1. The author is not responsible for the consequences of use of
 *              this software, no matter how awful, even if they arise
 *              from defects in it.
 *
 *      2. The origin of this software must not be misrepresented, either
 *              by explicit claim or by omission.
 *
 *      3. Altered versions must be plainly marked as such, and must not
 *              be misrepresented as being the original software.
 */

#include <string.h>
#include <stdio.h>
#define const           /* avoid "const poisoning" */
#include <regexp.h>
#undef const

/* The first byte of the regexp internal "program" is actually this magic
 * number; the start node begins in the second byte.
 */
#define MAGIC   0234

#define CHARBITS 0377
#ifndef CHARBITS
#define UCHARAT(p)      ((int)*(unsigned char *)(p))
#else
#define UCHARAT(p)      ((int)*(p)&CHARBITS)
#endif

/*
 - regsub - perform substitutions after a regexp match
 */
void regsub(prog, source, dest)
regexp *prog;
char *source;
char *dest;
{
  register char *src;
  register char *dst;
  register char c;
  register int no;
  register int len;

  if (prog == (regexp *)NULL || source == (char *)NULL || dest == (char *)NULL) {
        regerror("NULL parm to regsub");
        return;
  }
  if (UCHARAT(prog->program) != MAGIC) {
        regerror("damaged regexp fed to regsub");
        return;
  }
  src = source;
  dst = dest;
  while ((c = *src++) != '\0') {
        if (c == '&')
                no = 0;
        else if (c == '\\' && '0' <= *src && *src <= '9')
                no = *src++ - '0';
        else
                no = -1;

        if (no < 0) {           /* Ordinary character. */
                if (c == '\\' && (*src == '\\' || *src == '&')) c = *src++;
                *dst++ = c;
        } else
        if (prog->startp[no] != (char *)NULL && prog->endp[no] != (char *)NULL) {
                len = (int) (prog->endp[no] - prog->startp[no]);
                strncpy(dst, prog->startp[no], len);
                dst += len;
                if (len != 0 && *(dst - 1) == '\0') {   /* strncpy hit NUL. */
                        regerror("damaged match string");
                        return;
                }
        }
  }
  *dst++ = '\0';
}

/*
 * $PchId: regsub.c,v 1.3 1995/11/27 20:18:16 philip Exp $
 */

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