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/*
** Case-Insensitive Boyer-Moore-Horspool pattern match
**
** Public Domain version by Thad Smith 7/21/1992,
** based on a 7/92 public domain BMH version by Raymond Gardner.
**
** This program is written in ANSI C and inherits the compilers
** ability (or lack thereof) to support non-"C" locales by use of
** toupper() and tolower() to perform case conversions.
** Limitation: pattern length + string length must be less than 32767.
**
** 10/21/93 rdg Fixed bugs found by Jeff Dunlop
*/
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
typedef unsigned char uchar;
#define LARGE 32767 /* flag for last character match */
static int patlen; /* # chars in pattern */
static int skip[UCHAR_MAX+1]; /* skip-ahead count for test chars */
static int skip2; /* skip-ahead after non-match with
** matching final character */
static uchar *pat = NULL; /* uppercase copy of pattern */
/*
** bmhi_init() is called prior to bmhi_search() to calculate the
** skip array for the given pattern.
** Error: exit(1) is called if no memory is available.
*/
void bmhi_init(const char *pattern)
{
int i, lastpatchar;
patlen = strlen(pattern);
/* Make uppercase copy of pattern */
pat = realloc ((void*)pat, patlen);
if (!pat)
exit(1);
for (i=0; i < patlen; i++)
pat[i] = toupper(pattern[i]);
/* initialize skip array */
for ( i = 0; i <= UCHAR_MAX; ++i ) /* rdg 10/93 */
skip[i] = patlen;
for ( i = 0; i < patlen - 1; ++i )
{
skip[ pat[i] ] = patlen - i - 1;
skip[tolower(pat[i])] = patlen - i - 1;
}
lastpatchar = pat[patlen - 1];
skip[ lastpatchar ] = LARGE;
skip[tolower(lastpatchar)] = LARGE;
skip2 = patlen; /* Horspool's fixed second shift */
for (i = 0; i < patlen - 1; ++i)
{
if ( pat[i] == lastpatchar )
skip2 = patlen - i - 1;
}
}
char *bmhi_search(const char *string, const int stringlen)
{
int i, j;
char *s;
i = patlen - 1 - stringlen;
if (i >= 0)
return NULL;
string += stringlen;
for ( ;; )
{
while ( (i += skip[((uchar *)string)[i]]) < 0 )
; /* mighty fast inner loop */
if (i < (LARGE - stringlen))
return NULL;
i -= LARGE;
j = patlen - 1;
s = (char *)string + (i - j);
while ( --j >= 0 && toupper(s[j]) == pat[j] )
;
if ( j < 0 ) /* rdg 10/93 */
return s; /* rdg 10/93 */
if ( (i += skip2) >= 0 ) /* rdg 10/93 */
return NULL; /* rdg 10/93 */
}
}
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