310 lines
6.5 KiB
C
310 lines
6.5 KiB
C
/*
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* re.c - compile regular expressions.
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*/
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/*
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* Copyright (C) 1991-2000 the Free Software Foundation, Inc.
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*
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* This file is part of GAWK, the GNU implementation of the
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* AWK Programming Language.
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*
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* GAWK is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GAWK is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include "awk.h"
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static reg_syntax_t syn;
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/* make_regexp --- generate compiled regular expressions */
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Regexp *
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make_regexp(s, len, ignorecase, dfa)
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char *s;
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size_t len;
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int ignorecase;
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int dfa;
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{
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Regexp *rp;
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const char *rerr;
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char *src = s;
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char *temp;
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char *end = s + len;
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register char *dest;
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register int c, c2;
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/* Handle escaped characters first. */
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/*
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* Build a copy of the string (in dest) with the
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* escaped characters translated, and generate the regex
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* from that.
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*/
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emalloc(dest, char *, len + 2, "make_regexp");
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temp = dest;
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while (src < end) {
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if (*src == '\\') {
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c = *++src;
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switch (c) {
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case 'a':
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case 'b':
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case 'f':
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case 'n':
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case 'r':
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case 't':
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case 'v':
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case 'x':
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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c2 = parse_escape(&src);
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if (c2 < 0)
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cant_happen();
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/*
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* Unix awk treats octal (and hex?) chars
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* literally in re's, so escape regexp
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* metacharacters.
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*/
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if (do_traditional && ! do_posix && (isdigit(c) || c == 'x')
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&& strchr("()|*+?.^$\\[]", c2) != NULL)
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*dest++ = '\\';
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*dest++ = (char) c2;
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break;
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case '8':
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case '9': /* a\9b not valid */
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*dest++ = c;
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src++;
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break;
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case 'y': /* normally \b */
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/* gnu regex op */
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if (! do_traditional) {
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*dest++ = '\\';
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*dest++ = 'b';
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src++;
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break;
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}
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/* else, fall through */
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default:
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*dest++ = '\\';
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*dest++ = (char) c;
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src++;
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break;
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} /* switch */
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} else
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*dest++ = *src++; /* not '\\' */
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} /* for */
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*dest = '\0' ; /* Only necessary if we print dest ? */
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emalloc(rp, Regexp *, sizeof(*rp), "make_regexp");
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memset((char *) rp, 0, sizeof(*rp));
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rp->pat.allocated = 0; /* regex will allocate the buffer */
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emalloc(rp->pat.fastmap, char *, 256, "make_regexp");
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if (ignorecase)
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rp->pat.translate = casetable;
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else
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rp->pat.translate = NULL;
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len = dest - temp;
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if ((rerr = re_compile_pattern(temp, len, &(rp->pat))) != NULL)
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fatal("%s: /%s/", rerr, temp);
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/* gack. this must be done *after* re_compile_pattern */
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rp->pat.newline_anchor = FALSE; /* don't get \n in middle of string */
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if (dfa && ! ignorecase) {
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dfacomp(temp, len, &(rp->dfareg), TRUE);
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rp->dfa = TRUE;
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} else
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rp->dfa = FALSE;
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free(temp);
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return rp;
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}
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/* research --- do a regexp search. use dfa if possible */
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int
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research(rp, str, start, len, need_start)
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Regexp *rp;
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register char *str;
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int start;
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register size_t len;
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int need_start;
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{
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char *ret = str;
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int try_backref;
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/*
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* Always do dfa search if can; if it fails, then even if
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* need_start is true, we won't bother with the regex search.
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*/
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if (rp->dfa) {
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char save;
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int count = 0;
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/*
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* dfa likes to stick a '\n' right after the matched
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* text. So we just save and restore the character.
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*/
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save = str[start+len];
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ret = dfaexec(&(rp->dfareg), str+start, str+start+len, TRUE,
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&count, &try_backref);
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str[start+len] = save;
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}
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if (ret) {
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if (need_start || rp->dfa == FALSE || try_backref) {
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int result = re_search(&(rp->pat), str, start+len,
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start, len, &(rp->regs));
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/* recover any space from C based alloca */
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#ifdef C_ALLOCA
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(void) alloca(0);
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#endif
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return result;
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} else
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return 1;
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} else
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return -1;
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}
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/* refree --- free up the dynamic memory used by a compiled regexp */
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void
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refree(rp)
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Regexp *rp;
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{
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free(rp->pat.buffer);
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free(rp->pat.fastmap);
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if (rp->regs.start)
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free(rp->regs.start);
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if (rp->regs.end)
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free(rp->regs.end);
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if (rp->dfa)
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dfafree(&(rp->dfareg));
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free(rp);
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}
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/* dfaerror --- print an error message for the dfa routines */
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void
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dfaerror(s)
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const char *s;
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{
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fatal("%s", s);
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}
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/* re_update --- recompile a dynamic regexp */
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Regexp *
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re_update(t)
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NODE *t;
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{
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NODE *t1;
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if ((t->re_flags & CASE) == IGNORECASE) {
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if ((t->re_flags & CONST) != 0)
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return t->re_reg;
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t1 = force_string(tree_eval(t->re_exp));
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if (t->re_text != NULL) {
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if (cmp_nodes(t->re_text, t1) == 0) {
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free_temp(t1);
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return t->re_reg;
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}
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unref(t->re_text);
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}
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t->re_text = dupnode(t1);
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free_temp(t1);
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}
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if (t->re_reg != NULL)
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refree(t->re_reg);
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if (t->re_cnt > 0)
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t->re_cnt++;
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if (t->re_cnt > 10)
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t->re_cnt = 0;
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if (t->re_text == NULL || (t->re_flags & CASE) != IGNORECASE) {
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t1 = force_string(tree_eval(t->re_exp));
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t->re_text = dupnode(t1);
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free_temp(t1);
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}
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t->re_reg = make_regexp(t->re_text->stptr, t->re_text->stlen,
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IGNORECASE, t->re_cnt);
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t->re_flags &= ~CASE;
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t->re_flags |= IGNORECASE;
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return t->re_reg;
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}
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/* resetup --- choose what kind of regexps we match */
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void
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resetup()
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{
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if (do_posix)
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syn = RE_SYNTAX_POSIX_AWK; /* strict POSIX re's */
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else if (do_traditional)
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syn = RE_SYNTAX_AWK; /* traditional Unix awk re's */
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else
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syn = RE_SYNTAX_GNU_AWK; /* POSIX re's + GNU ops */
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/*
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* Interval expressions are off by default, since it's likely to
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* break too many old programs to have them on.
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*/
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if (do_intervals)
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syn |= RE_INTERVALS;
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(void) re_set_syntax(syn);
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dfasyntax(syn, FALSE);
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}
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/* avoid_dfa --- FIXME: temporary kludge function until we have a new dfa.c */
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int
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avoid_dfa(re, str, len)
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NODE *re;
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char *str;
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size_t len;
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{
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char *restr;
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int relen;
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int anchor, i;
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char *end;
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if ((re->re_flags & CONST) != 0) {
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restr = re->re_exp->stptr;
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relen = re->re_exp->stlen;
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} else {
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restr = re->re_text->stptr;
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relen = re->re_text->stlen;
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}
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for (anchor = FALSE, i = 0; i < relen; i++) {
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if (restr[i] == '^' || restr[i] == '$') {
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anchor = TRUE;
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break;
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}
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}
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if (! anchor)
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return FALSE;
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for (end = str + len; str < end; str++)
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if (*str == '\n')
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return TRUE;
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return FALSE;
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}
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