Fix levenshtein with costs. The previous code multiplied by the cost in only

3 of the 7 relevant locations.

Marcin Mank, slightly adjusted by me.
This commit is contained in:
Robert Haas 2009-12-10 01:54:17 +00:00
parent 03d7b0647f
commit da07641481

View File

@ -5,7 +5,7 @@
* *
* Joe Conway <mail@joeconway.com> * Joe Conway <mail@joeconway.com>
* *
* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.c,v 1.30 2009/06/11 14:48:51 momjian Exp $ * $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.c,v 1.31 2009/12/10 01:54:17 rhaas Exp $
* Copyright (c) 2001-2009, PostgreSQL Global Development Group * Copyright (c) 2001-2009, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED; * ALL RIGHTS RESERVED;
* *
@ -207,13 +207,13 @@ levenshtein_internal(const char *s, const char *t,
n = strlen(t); n = strlen(t);
/* /*
* If either m or n is 0, the answer is the other value. This makes sense * We can transform an empty s into t with n insertions, or a non-empty t
* since it would take that many insertions to build a matching string * into an empty s with m deletions.
*/ */
if (!m) if (!m)
return n; return n * ins_c;
if (!n) if (!n)
return m; return m * del_c;
/* /*
* For security concerns, restrict excessive CPU+RAM usage. (This * For security concerns, restrict excessive CPU+RAM usage. (This
@ -241,7 +241,7 @@ levenshtein_internal(const char *s, const char *t,
/* Initialize the "previous" row to 0..cols */ /* Initialize the "previous" row to 0..cols */
for (i = 0; i < m; i++) for (i = 0; i < m; i++)
prev[i] = i; prev[i] = i * del_c;
/* Loop through rows of the notional array */ /* Loop through rows of the notional array */
for (y = t, j = 1; j < n; y++, j++) for (y = t, j = 1; j < n; y++, j++)
@ -252,7 +252,7 @@ levenshtein_internal(const char *s, const char *t,
* First cell must increment sequentially, as we're on the j'th row of * First cell must increment sequentially, as we're on the j'th row of
* the (m+1)x(n+1) array. * the (m+1)x(n+1) array.
*/ */
curr[0] = j; curr[0] = j * ins_c;
for (x = s, i = 1; i < m; x++, i++) for (x = s, i = 1; i < m; x++, i++)
{ {