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/* dlm.c - 2004/07/04 - Santtu Lakkala */
#include <glib.h>
#include <string.h>
int dlm_cost (const gchar, const gchar);
int dlm_minimum (int a, int b, int c, int d);
/*
* Compute the Damerau-Levenshtein Distance between utf-8 strings ds and dt.
*/
int dlm (const gchar *ds, const gchar *dt)
{
int i, j, n, m, metric;
int *d;
/* Casefold for better matching of the strings. */
gchar *s = g_utf8_casefold(ds, -1);
gchar *t = g_utf8_casefold(dt, -1);
n = strlen(s);
m = strlen(t);
if (n && m)
{
n++;
m++;
d = (int *)g_malloc0(sizeof(int) * m * n);
for (i = 0; i < m; i++)
d[i * n] = i;
for (i = 1; i < n; i++)
{
d[i] = i;
for (j = 1; j < m; j++)
{
d[j * n + i] = dlm_minimum(
d[(j - 1) * n + i] + 1,
d[j * n + i - 1] + 1,
d[(j - 1) * n + i - 1] + dlm_cost(s[i - 1], t[j - 1]),
(j>1 && i>1 ?
d[(j - 2) * n + i - 2] + dlm_cost(s[i - 1], t[j])
+ dlm_cost(s[i], t[j - 1])
: 0x7fff)
);
}
}
metric = d[n * m - 1];
g_free(d);
/* Count a "similarity value" */
metric = 1000 - (1000 * (metric * 2)) / (m + n);
g_free(t);
g_free(s);
return metric;
}
g_free(t);
g_free(s);
/* Return value of -1 indicates an error */
return -1;
}
/* "Cost" of changing from a to b. */
int dlm_cost (const char a, const char b)
{
return a == b ? 0 : 1;
}
/* Return the smallest of four integers. */
int dlm_minimum (int a, int b, int c, int d)
{
int min = a;
if (b < min)
{
min = b;
}
if (c < min)
{
min = c;
}
if (d < min)
{
min = d;
}
return min;
}
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