/*
* re.c - compile regular expressions.
*/
/*
* Copyright (C) 1991-1996 the Free Software Foundation, Inc.
*
* This file is part of GAWK, the GNU implementation of the
* AWK Programming Language.
*
* GAWK is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GAWK is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include "awk.h"
static reg_syntax_t syn;
/* make_regexp --- generate compiled regular expressions */
Regexp *
make_regexp(s, len, ignorecase, dfa)
char *s;
size_t len;
int ignorecase;
int dfa;
{
Regexp *rp;
const char *rerr;
char *src = s;
char *temp;
char *end = s + len;
register char *dest;
register int c, c2;
/* Handle escaped characters first. */
/*
* Build a copy of the string (in dest) with the
* escaped characters translated, and generate the regex
* from that.
*/
emalloc(dest, char *, len + 2, "make_regexp");
temp = dest;
while (src < end) {
if (*src == '\\') {
c = *++src;
switch (c) {
case 'a':
case 'b':
case 'f':
case 'n':
case 'r':
case 't':
case 'v':
case 'x':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
c2 = parse_escape(&src);
if (c2 < 0)
cant_happen();
/*
* Unix awk treats octal (and hex?) chars
* literally in re's, so escape regexp
* metacharacters.
*/
if (do_traditional && ! do_posix && (isdigit(c) || c == 'x')
&& strchr("()|*+?.^$\\[]", c2) != NULL)
*dest++ = '\\';
*dest++ = (char) c2;
break;
case '8':
case '9': /* a\9b not valid */
*dest++ = c;
src++;
break;
case 'y': /* normally \b */
/* gnu regex op */
if (! do_traditional) {
*dest++ = '\\';
*dest++ = 'b';
src++;
break;
}
/* else, fall through */
default:
*dest++ = '\\';
*dest++ = (char) c;
src++;
break;
} /* switch */
} else
*dest++ = *src++; /* not '\\' */
} /* for */
*dest = '\0' ; /* Only necessary if we print dest ? */
emalloc(rp, Regexp *, sizeof(*rp), "make_regexp");
memset((char *) rp, 0, sizeof(*rp));
rp->pat.allocated = 0; /* regex will allocate the buffer */
emalloc(rp->pat.fastmap, char *, 256, "make_regexp");
if (ignorecase)
rp->pat.translate = casetable;
else
rp->pat.translate = NULL;
len = dest - temp;
if ((rerr = re_compile_pattern(temp, len, &(rp->pat))) != NULL)
fatal("%s: /%s/", rerr, temp);
/* gack. this must be done *after* re_compile_pattern */
rp->pat.newline_anchor = FALSE; /* don't get \n in middle of string */
if (dfa && ! ignorecase) {
dfacomp(temp, len, &(rp->dfareg), TRUE);
rp->dfa = TRUE;
} else
rp->dfa = FALSE;
free(temp);
return rp;
}
/* research --- do a regexp search. use dfa if possible */
int
research(rp, str, start, len, need_start)
Regexp *rp;
register char *str;
int start;
register size_t len;
int need_start;
{
char *ret = str;
int try_backref;
/*
* Always do dfa search if can; if it fails, then even if
* need_start is true, we won't bother with the regex search.
*/
if (rp->dfa) {
char save;
int count = 0;
/*
* dfa likes to stick a '\n' right after the matched
* text. So we just save and restore the character.
*/
save = str[start+len];
ret = dfaexec(&(rp->dfareg), str+start, str+start+len, TRUE,
&count, &try_backref);
str[start+len] = save;
}
if (ret) {
if (need_start || rp->dfa == FALSE || try_backref) {
int result = re_search(&(rp->pat), str, start+len,
start, len, &(rp->regs));
/* recover any space from C based alloca */
#ifdef C_ALLOCA
(void) alloca(0);
#endif
return result;
} else
return 1;
} else
return -1;
}
/* refree --- free up the dynamic memory used by a compiled regexp */
void
refree(rp)
Regexp *rp;
{
free(rp->pat.buffer);
free(rp->pat.fastmap);
if (rp->regs.start)
free(rp->regs.start);
if (rp->regs.end)
free(rp->regs.end);
if (rp->dfa)
dfafree(&(rp->dfareg));
free(rp);
}
/* dfaerror --- print an error message for the dfa routines */
void
dfaerror(s)
const char *s;
{
fatal("%s", s);
}
/* re_update --- recompile a dynamic regexp */
Regexp *
re_update(t)
NODE *t;
{
NODE *t1;
/* # define CASE 1 */
if ((t->re_flags & CASE) == IGNORECASE) {
if ((t->re_flags & CONST) != 0)
return t->re_reg;
t1 = force_string(tree_eval(t->re_exp));
if (t->re_text != NULL) {
if (cmp_nodes(t->re_text, t1) == 0) {
free_temp(t1);
return t->re_reg;
}
unref(t->re_text);
}
t->re_text = dupnode(t1);
free_temp(t1);
}
if (t->re_reg != NULL)
refree(t->re_reg);
if (t->re_cnt > 0)
t->re_cnt++;
if (t->re_cnt > 10)
t->re_cnt = 0;
if (t->re_text == NULL) {
t1 = force_string(tree_eval(t->re_exp));
t->re_text = dupnode(t1);
free_temp(t1);
}
t->re_reg = make_regexp(t->re_text->stptr, t->re_text->stlen,
IGNORECASE, t->re_cnt);
t->re_flags &= ~CASE;
t->re_flags |= IGNORECASE;
return t->re_reg;
}
/* resetup --- choose what kind of regexps we match */
void
resetup()
{
if (do_posix)
syn = RE_SYNTAX_POSIX_AWK; /* strict POSIX re's */
else if (do_traditional)
syn = RE_SYNTAX_AWK; /* traditional Unix awk re's */
else
syn = RE_SYNTAX_GNU_AWK; /* POSIX re's + GNU ops */
/*
* Interval expressions are off by default, since it's likely to
* break too many old programs to have them on.
*/
if (do_intervals)
syn |= RE_INTERVALS;
(void) re_set_syntax(syn);
dfasyntax(syn, FALSE);
}
/* avoid_dfa --- FIXME: temporary kludge function until we have a new dfa.c */
int
avoid_dfa(re, str, len)
NODE *re;
char *str;
size_t len;
{
char *restr;
int relen;
int anchor, i;
char *end;
if ((re->re_flags & CONST) != 0) {
restr = re->re_exp->stptr;
relen = re->re_exp->stlen;
} else {
restr = re->re_text->stptr;
relen = re->re_text->stlen;
}
for (anchor = FALSE, i = 0; i < relen; i++) {
if (restr[i] == '^' || restr[i] == '$') {
anchor = TRUE;
break;
}
}
if (! anchor)
return FALSE;
for (end = str + len; str < end; str++)
if (*str == '\n')
return TRUE;
return FALSE;
}
