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/* This file is part of GNU Dico
Copyright (C) 2007-2018 Sergey Poznyakoff
GNU Dico is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GNU Dico is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Dico. If not, see <http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <dico.h>
#include <string.h>
#ifndef MIN
# define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
#if 0
# define DEBUG(c) printf("%d ", c);
# define DEBUGNL() putchar('\n')
#else
# define DEBUG(c)
# define DEBUGNL()
#endif
int
dico_levenshtein_distance(const char *astr, const char *bstr, int flags)
{
unsigned *a, *b;
int alen;
int blen;
unsigned *rowptr;
unsigned *row[3];
int i, j, idx, prev, nrows;
int dist;
int (*conv) (const char *, unsigned **, size_t *) =
(flags & DICO_LEV_NORM) ? utf8_mbstr_to_norm_wc : utf8_mbstr_to_wc;
if (conv(astr, &a, NULL))
return -1;
if (conv(bstr, &b, NULL)) {
free(a);
return -1;
}
alen = utf8_wc_strlen(a);
blen = utf8_wc_strlen(b);
rowptr = calloc(sizeof(rowptr[0]),
(2 + !!(flags & DICO_LEV_DAMERAU)) * (blen + 1));
row[0] = rowptr;
row[1] = rowptr + blen + 1;
if (flags & DICO_LEV_DAMERAU) {
nrows = 3;
row[2] = row[1] + blen + 1;
} else
nrows = 2;
for (i = 0; i < blen + 1; i++) {
row[0][i] = i;
DEBUG(row[0][i]);
}
DEBUGNL();
idx = 1;
prev = 0;
for (i = 0; i < alen; i++, prev = idx, idx = (idx + 1) % nrows ) {
row[idx][0] = i + 1;
DEBUG(row[idx][0]);
for (j = 0; j < blen; j++) {
unsigned n, cost;
cost = !(utf8_wc_toupper(a[i]) == utf8_wc_toupper(b[j]));
n = MIN(row[prev][j+1] + 1, /* Deletion */
row[idx][j] + 1); /* Insertion */
n = MIN(n, row[prev][j] + cost); /* Substitution */
if (flags & DICO_LEV_DAMERAU) {
if (i > 0 && j > 0
&& utf8_wc_toupper(a[i]) == utf8_wc_toupper(b[j-1])
&& utf8_wc_toupper(a[i-1]) == utf8_wc_toupper(b[j]))
/* Transposition */
n = MIN(n, row[(idx + 1) % nrows][j - 1] + cost);
}
row[idx][j+1] = n;
DEBUG(row[idx][j+1]);
}
DEBUGNL();
}
dist = row[prev][blen];
free(rowptr);
free(a);
free(b);
return dist;
}
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