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rexp.c
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/********************************************
rexp.c
copyright 2008-2012,2013, Thomas E. Dickey
copyright 1991-1993,1996, Michael D. Brennan
This is a source file for mawk, an implementation of
the AWK programming language.
Mawk is distributed without warranty under the terms of
the GNU General Public License, version 2, 1991.
********************************************/
/*
* $MawkId: rexp.c,v 1.18 2013/02/19 10:51:21 tom Exp $
* @Log: rexp.c,v @
* Revision 1.3 1996/09/02 18:47:36 mike
* Make ^* and ^+ syntax errors.
*
* Revision 1.2 1993/07/23 13:21:32 mike
* cleanup rexp code
*
* Revision 1.1.1.1 1993/07/03 18:58:26 mike
* move source to cvs
*
* Revision 3.4 1991/08/13 09:09:59 brennan
* VERSION .9994
*
* Revision 3.3 91/08/04 15:45:03 brennan
* no longer attempt to recover mem on failed REcompile
* Its not worth the effort
*
* Revision 3.2 91/08/03 07:24:06 brennan
* check for empty machine stack (missing operand) wasn't quite right
*
* Revision 3.1 91/06/07 10:33:16 brennan
* VERSION 0.995
*
* Revision 1.7 91/06/05 08:58:47 brennan
* change RE_free to free
*
* Revision 1.6 91/06/03 07:07:17 brennan
* moved parser stacks inside REcompile
* removed unnecessary copying
*
*/
/* op precedence parser for regular expressions */
#include "rexp.h"
#include "regexp.h"
/* DATA */
int REerrno;
const char *REerrlist[] =
{(char *) 0,
/* 1 */ "missing '('",
/* 2 */ "missing ')'",
/* 3 */ "bad class -- [], [^] or [",
/* 4 */ "missing operand",
/* 5 */ "resource exhaustion -- regular expression too large",
/* 6 */ "syntax error ^* or ^+"
};
/* E5 is very unlikely to occur */
/* This table drives the operator precedence parser */
/* *INDENT-OFF* */
static short table[8][8] = {
/* 0 | CAT * + ? ( ) */
/* 0 */ {0, L, L, L, L, L, L, E1},
/* | */ {G, G, L, L, L, L, L, G},
/* CAT*/ {G, G, G, L, L, L, L, G},
/* * */ {G, G, G, G, G, G, E7, G},
/* + */ {G, G, G, G, G, G, E7, G},
/* ? */ {G, G, G, G, G, G, E7, G},
/* ( */ {E2, L, L, L, L, L, L, EQ},
/* ) */ {G , G, G, G, G, G, E7, G} } ;
/* *INDENT-ON* */
#define STACKSZ 64
static jmp_buf err_buf; /* used to trap on error */
#if OPT_TRACE > 0
static const char *
token_name(int token)
{
const char *result;
#define CASE(name) case name: result = #name; break
switch (token) {
CASE(T_NONE);
CASE(T_OR);
CASE(T_CAT);
CASE(T_STAR);
CASE(T_PLUS);
CASE(T_Q);
CASE(T_LP);
CASE(T_RP);
CASE(T_START);
CASE(T_END);
CASE(T_ANY);
CASE(T_CLASS);
CASE(T_SLASH);
CASE(T_CHAR);
CASE(T_STR);
CASE(T_U);
default:
result = "?";
break;
}
#undef CASE
return result;
}
#endif
void
RE_error_trap(int x)
{
REerrno = x;
longjmp(err_buf, 1);
}
PTR
REcompile(char *re, size_t len)
{
MACHINE m_stack[STACKSZ];
struct op {
int token;
int prec;
} op_stack[STACKSZ];
register MACHINE *m_ptr;
register struct op *op_ptr;
register int t;
/* do this first because it also checks if we have a
run time stack */
RE_lex_init(re, len);
if (len == 0) {
STATE *p = (STATE *) RE_malloc(sizeof(STATE));
p->s_type = M_ACCEPT;
return (PTR) p;
}
if (setjmp(err_buf))
return (PTR) 0;
/* we used to try to recover memory left on machine stack ;
but now m_ptr is in a register so it won't be right unless
we force it out of a register which isn't worth the trouble */
/* initialize the stacks */
m_ptr = m_stack - 1;
op_ptr = op_stack;
op_ptr->token = 0;
t = RE_lex(m_stack);
while (1) {
TRACE(("RE_lex token %s\n", token_name(t)));
switch (t) {
case T_STR:
case T_ANY:
case T_U:
case T_START:
case T_END:
case T_CLASS:
m_ptr++;
break;
case 0: /* end of reg expr */
if (op_ptr->token == 0) {
/* done */
if (m_ptr == m_stack)
return (PTR) m_ptr->start;
else {
/* machines still on the stack */
RE_panic("values still on machine stack");
}
}
/* otherwise fall thru to default
which is operator case */
default:
if ((op_ptr->prec = table[op_ptr->token][t]) == G) {
do { /* op_pop */
if (op_ptr->token <= T_CAT) { /*binary op */
if (m_ptr == m_stack
&& op_ptr->token == T_CAT) {
TRACE(("...ignoring empty T_CAT\n"));
op_ptr--;
continue;
}
m_ptr--;
}
/* if not enough values on machine stack
then we have a missing operand */
if (m_ptr < m_stack)
RE_error_trap(-E4);
switch (op_ptr->token) {
case T_CAT:
RE_cat(m_ptr, m_ptr + 1);
break;
case T_OR:
RE_or(m_ptr, m_ptr + 1);
break;
case T_STAR:
RE_close(m_ptr);
break;
case T_PLUS:
RE_poscl(m_ptr);
break;
case T_Q:
RE_01(m_ptr);
break;
default:
/*nothing on ( or ) */
break;
}
op_ptr--;
}
while (op_ptr->prec != L);
continue; /* back thru switch at top */
}
if (op_ptr->prec < 0) {
if (op_ptr->prec == E7)
RE_panic("parser returns E7");
else
RE_error_trap(-op_ptr->prec);
}
if (++op_ptr == op_stack + STACKSZ) {
/* stack overflow */
RE_error_trap(-E5);
}
op_ptr->token = t;
} /* end of switch */
if (m_ptr == m_stack + (STACKSZ - 1)) {
/*overflow */
RE_error_trap(-E5);
}
t = RE_lex(m_ptr + 1);
}
}
void
REdestroy(PTR ptr)
{
int done = 0;
int n = 0;
STATE *q = (STATE *) ptr;
TRACE(("REdestroy %p\n", ptr));
while (!done) {
TRACE(("...%d type %d\n", n, q->s_type));
switch (q->s_type) {
case M_ACCEPT:
done = 1;
break;
case M_STR:
RE_free(q->s_data.str);
break;
default:
if (q->s_type < 0 || q->s_type > END_ON)
done = -1;
break;
}
++q;
++n;
}
RE_free(ptr);
}
/* getting here means a logic flaw or unforeseen case */
void
RE_panic(const char *s)
{
fprintf(stderr, "REcompile() - panic: %s\n", s);
mawk_exit(100);
}
/* getting regexp error message */
const char *
REerror(void)
{
return REerrlist[REerrno];
}