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/*
mxbmse -- Fast Boyer Moore Search Algorithm (Version 0.9)
The implementation is reentrant and thread safe. While the
general ideas behind the Boyer Moore algorithm are in the public
domain, this implementation falls under the following copyright:
Copyright (c) 1997-2000, Marc-Andre Lemburg; mailto:mal@lemburg.com
Copyright (c) 2000-2014, eGenix.com Software GmbH; mailto:info@egenix.com
All Rights Reserved
See the documentation for copying information or contact the author
(mal@lemburg.com).
*/
/* to turn on the debugging printfs (DPRINTF):*/
/* #define MAL_DEBUG */
/* Logging file used by debugging facility */
#ifndef MAL_DEBUG_OUTPUTFILE
# define MAL_DEBUG_OUTPUTFILE "mxTextSearch.log"
#endif
#ifdef MAL_DEBUG_WITH_PYTHON
# include "mx.h"
#endif
#ifdef MX_BUILDING_MXTEXTTOOLS
# include "mx.h"
# include "mxTextTools.h"
#else
# include "mxstdlib.h"
# include "mxbmse.h"
#endif
/* --- Fast Boyer-Moore Implementation (8-bit) ---------------------------- */
mxbmse_data *bm_init(char *match,
BM_LENGTH_TYPE match_len)
{
mxbmse_data *c;
BM_INDEX_TYPE i;
BM_SHIFT_TYPE *shift;
char *m;
c = newstruct(mxbmse_data);
c->match = match;
c->match_len = match_len;
c->eom = match + match_len - 1;
/* Length 1 matching does not use a shift table */
if (match_len == 1)
return c;
/* Init shift table */
for ( shift = c->shift, i = 256; i > 0; i--, shift++ )
*shift = (BM_SHIFT_TYPE) match_len;
DPRINTF("shift table for match='%s'\n",match);
for ( shift = c->shift, m = match, i = match_len - 1;
i >= 0;
i--, m++ ) {
shift[ (unsigned char) *m ] = (BM_SHIFT_TYPE) i;
DPRINTF(" char = '%c' shift = %i\n", *m, i);
}
return c;
}
void bm_free(mxbmse_data *c)
{
if (c)
free(c);
}
BM_INDEX_TYPE bm_search(mxbmse_data *c,
char *text,
BM_INDEX_TYPE start,
BM_LENGTH_TYPE text_len)
{
register char *pt;
register char *eot = text + text_len;
/* Error check */
if (c == NULL)
return -1;
/* Init text pointer */
pt = text + start + c->match_len - 1;
DPRINTF("Init : %2i %20.20s \t text: %2i %20.20s\n",
c->match_len,c->match,start,text+start);
if (c->match_len > 1)
for (;;) {
register char *pm;
pm = c->eom;
for (;pt < eot && *pt != *pm;
pt += c->shift[(unsigned char) *pt]);
if (pt >= eot)
break;
/* First char matches.. what about the others ? */
{
register BM_INDEX_TYPE im = c->match_len;
do {
DPRINTF("=match: %2i '%20.20s' \t text: '%20.20s'\n",
im,pm,pt);
if (--im == 0)
/* Match */
return pt - text + c->match_len;
pt--;
pm--;
} while (*pt == *pm);
/* Mismatch after match: use shift-table */
{
register BM_INDEX_TYPE a,b;
a = c->shift[(unsigned char) *pt];
b = c->match_len - im + 1;
DPRINTF("!match: %2i '%20.20s' \t text: '%20.20s' "
"(sh=%i)\n",
im,pm,pt,max(a,b));
pt += (a > b) ? a : b;
}
}
}
/* Special case: matching string has length 1 */
else {
register char m = *c->eom;
for (;pt < eot; pt++)
if (*pt == m)
/* Match */
return pt - text + 1;
}
return start; /* no match */
}
/* bm search using the translate table -- 45% slower */
BM_INDEX_TYPE bm_tr_search(mxbmse_data *c,
char *text,
BM_INDEX_TYPE start,
BM_LENGTH_TYPE text_len,
char *tr)
{
register char *pt;
register char *eot = text + text_len;
/* Error check */
if (c == NULL)
return -1;
/* Init text pointer */
pt = text + start + c->match_len - 1;
DPRINTF("Init : %2i '%20.20s' \t text: %2i '%20.20s'\n",
c->match_len,c->match,start,text+start);
if (c->match_len > 1)
for (;;) {
register char *pm;
pm = c->eom;
for (;pt < eot && tr[(unsigned char) *pt] != *pm;
pt += c->shift[(unsigned char) tr[(unsigned char) *pt]]);
if (pt >= eot)
break;
/* First char matches.. what about the others ? */
{
register BM_INDEX_TYPE im = c->match_len;
do {
DPRINTF("=match: %2i '%20.20s' \t text: '%20.20s'\n",
im,pm,pt);
if (--im == 0)
/* Match */
return pt - text + c->match_len;
pt--;
pm--;
} while (tr[(unsigned char) *pt] == *pm);
/* Mismatch after match: use shift-table */
{
register BM_INDEX_TYPE a,b;
a = c->shift[(unsigned char) tr[(unsigned char) *pt]];
b = c->match_len - im + 1;
DPRINTF("!match: %2i '%20.20s' \t text: '%20.20s' "
"(sh=%i)\n",
im,pm,pt,max(a,b));
pt += (a > b)?a:b;
}
}
}
/* Special case: matching string has length 1 */
else {
register char m = *c->eom;
for (;pt < eot; pt++)
if (*pt == m)
/* Match */
return pt - text + 1;
}
return start; /* no match */
}
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