fmtre.c revision 3f54fd611f536639ec30dd53c48e5ec1897cc7d9
/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2011 AT&T Intellectual Property *
* and is licensed under the *
* Eclipse Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.eclipse.org/org/documents/epl-v10.html *
* (with md5 checksum b35adb5213ca9657e911e9befb180842) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* Glenn Fowler
* AT&T Research
*
* return RE expression given strmatch() pattern
* 0 returned for invalid RE
*/
#include <ast.h>
typedef struct Stack_s
{
char* beg;
short len;
short min;
} Stack_t;
char*
fmtre(const char* as)
{
register char* s = (char*)as;
register int c;
register char* t;
register Stack_t* p;
char* x;
int n;
int end;
char* buf;
Stack_t stack[32];
end = 1;
c = 2 * strlen(s) + 1;
t = buf = fmtbuf(c);
p = stack;
if (*s != '*' || *(s + 1) == '(' || *(s + 1) == '-' && *(s + 2) == '(')
*t++ = '^';
else
s++;
for (;;)
{
switch (c = *s++)
{
case 0:
break;
case '\\':
if (!(c = *s++) || c == '{' || c == '}')
return 0;
*t++ = '\\';
if ((*t++ = c) == '(' && *s == '|')
{
*t++ = *s++;
goto logical;
}
continue;
case '[':
*t++ = c;
n = 0;
if ((c = *s++) == '!')
{
*t++ = '^';
c = *s++;
}
else if (c == '^')
{
if ((c = *s++) == ']')
{
*(t - 1) = '\\';
*t++ = '^';
continue;
}
n = '^';
}
for (;;)
{
if (!(*t++ = c))
return 0;
if ((c = *s++) == ']')
{
if (n)
*t++ = n;
*t++ = c;
break;
}
}
continue;
case '{':
for (x = s; *x && *x != '}'; x++);
if (*x++ && (*x == '(' || *x == '-' && *(x + 1) == '('))
{
if (p >= &stack[elementsof(stack)])
return 0;
p->beg = s - 1;
s = x;
p->len = s - p->beg;
if (p->min = *s == '-')
s++;
p++;
*t++ = *s++;
}
else
*t++ = c;
continue;
case '*':
if (!*s)
{
end = 0;
break;
}
/*FALLTHROUGH*/
case '?':
case '+':
case '@':
case '!':
case '~':
if (*s == '(' || c != '~' && *s == '-' && *(s + 1) == '(')
{
if (p >= &stack[elementsof(stack)])
return 0;
p->beg = s - 1;
if (c == '~')
{
if (*(s + 1) == 'E' && *(s + 2) == ')')
{
for (s += 3; *t = *s; t++, s++);
continue;
}
p->len = 0;
p->min = 0;
*t++ = *s++;
*t++ = '?';
}
else
{
p->len = c != '@';
if (p->min = *s == '-')
s++;
*t++ = *s++;
}
p++;
}
else
{
switch (c)
{
case '*':
*t++ = '.';
break;
case '?':
c = '.';
break;
case '+':
case '!':
*t++ = '\\';
break;
}
*t++ = c;
}
continue;
case '(':
if (p >= &stack[elementsof(stack)])
return 0;
p->beg = s - 1;
p->len = 0;
p->min = 0;
p++;
*t++ = c;
continue;
case ')':
if (p == stack)
return 0;
*t++ = c;
p--;
for (c = 0; c < p->len; c++)
*t++ = p->beg[c];
if (p->min)
*t++ = '?';
continue;
case '^':
case '.':
case '$':
*t++ = '\\';
*t++ = c;
continue;
case '|':
if (t == buf || *(t - 1) == '(')
return 0;
logical:
if (!*s || *s == ')')
return 0;
/*FALLTHROUGH*/
default:
*t++ = c;
continue;
}
break;
}
if (p != stack)
return 0;
if (end)
*t++ = '$';
*t = 0;
return buf;
}