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-rw-r--r--contrib/fuzzystrmatch/fuzzystrmatch.c244
1 files changed, 31 insertions, 213 deletions
diff --git a/contrib/fuzzystrmatch/fuzzystrmatch.c b/contrib/fuzzystrmatch/fuzzystrmatch.c
index 01084da4072..7265841dc5d 100644
--- a/contrib/fuzzystrmatch/fuzzystrmatch.c
+++ b/contrib/fuzzystrmatch/fuzzystrmatch.c
@@ -9,15 +9,6 @@
* Copyright (c) 2001-2010, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED;
*
- * levenshtein()
- * -------------
- * Written based on a description of the algorithm by Michael Gilleland
- * found at http://www.merriampark.com/ld.htm
- * Also looked at levenshtein.c in the PHP 4.0.6 distribution for
- * inspiration.
- * Configurable penalty costs extension is introduced by Volkan
- * YAZICI <volkan.yazici@gmail.com>.
- *
* metaphone()
* -----------
* Modified for PostgreSQL by Joe Conway.
@@ -61,6 +52,8 @@ PG_MODULE_MAGIC;
*/
extern Datum levenshtein_with_costs(PG_FUNCTION_ARGS);
extern Datum levenshtein(PG_FUNCTION_ARGS);
+extern Datum levenshtein_less_equal_with_costs(PG_FUNCTION_ARGS);
+extern Datum levenshtein_less_equal(PG_FUNCTION_ARGS);
extern Datum metaphone(PG_FUNCTION_ARGS);
extern Datum soundex(PG_FUNCTION_ARGS);
extern Datum difference(PG_FUNCTION_ARGS);
@@ -85,16 +78,6 @@ soundex_code(char letter)
return letter;
}
-
-/*
- * Levenshtein
- */
-#define MAX_LEVENSHTEIN_STRLEN 255
-
-static int levenshtein_internal(text *s, text *t,
- int ins_c, int del_c, int sub_c);
-
-
/*
* Metaphone
*/
@@ -197,224 +180,59 @@ rest_of_char_same(const char *s1, const char *s2, int len)
return true;
}
-/*
- * levenshtein_internal - Calculates Levenshtein distance metric
- * between supplied strings. Generally
- * (1, 1, 1) penalty costs suffices common
- * cases, but your mileage may vary.
- */
-static int
-levenshtein_internal(text *s, text *t,
- int ins_c, int del_c, int sub_c)
-{
- int m,
- n,
- s_bytes,
- t_bytes;
- int *prev;
- int *curr;
- int *s_char_len = NULL;
- int i,
- j;
- const char *s_data;
- const char *t_data;
- const char *y;
-
- /* Extract a pointer to the actual character data. */
- s_data = VARDATA_ANY(s);
- t_data = VARDATA_ANY(t);
-
- /* Determine length of each string in bytes and characters. */
- s_bytes = VARSIZE_ANY_EXHDR(s);
- t_bytes = VARSIZE_ANY_EXHDR(t);
- m = pg_mbstrlen_with_len(s_data, s_bytes);
- n = pg_mbstrlen_with_len(t_data, t_bytes);
-
- /*
- * We can transform an empty s into t with n insertions, or a non-empty t
- * into an empty s with m deletions.
- */
- if (!m)
- return n * ins_c;
- if (!n)
- return m * del_c;
-
- /*
- * For security concerns, restrict excessive CPU+RAM usage. (This
- * implementation uses O(m) memory and has O(mn) complexity.)
- */
- if (m > MAX_LEVENSHTEIN_STRLEN ||
- n > MAX_LEVENSHTEIN_STRLEN)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
- errmsg("argument exceeds the maximum length of %d bytes",
- MAX_LEVENSHTEIN_STRLEN)));
-
- /*
- * In order to avoid calling pg_mblen() repeatedly on each character in s,
- * we cache all the lengths before starting the main loop -- but if all the
- * characters in both strings are single byte, then we skip this and use
- * a fast-path in the main loop. If only one string contains multi-byte
- * characters, we still build the array, so that the fast-path needn't
- * deal with the case where the array hasn't been initialized.
- */
- if (m != s_bytes || n != t_bytes)
- {
- int i;
- const char *cp = s_data;
-
- s_char_len = (int *) palloc((m + 1) * sizeof(int));
- for (i = 0; i < m; ++i)
- {
- s_char_len[i] = pg_mblen(cp);
- cp += s_char_len[i];
- }
- s_char_len[i] = 0;
- }
-
- /* One more cell for initialization column and row. */
- ++m;
- ++n;
-
- /*
- * One way to compute Levenshtein distance is to incrementally construct
- * an (m+1)x(n+1) matrix where cell (i, j) represents the minimum number
- * of operations required to transform the first i characters of s into
- * the first j characters of t. The last column of the final row is the
- * answer.
- *
- * We use that algorithm here with some modification. In lieu of holding
- * the entire array in memory at once, we'll just use two arrays of size
- * m+1 for storing accumulated values. At each step one array represents
- * the "previous" row and one is the "current" row of the notional large
- * array.
- */
- prev = (int *) palloc(2 * m * sizeof(int));
- curr = prev + m;
-
- /*
- * To transform the first i characters of s into the first 0 characters
- * of t, we must perform i deletions.
- */
- for (i = 0; i < m; i++)
- prev[i] = i * del_c;
-
- /* Loop through rows of the notional array */
- for (y = t_data, j = 1; j < n; j++)
- {
- int *temp;
- const char *x = s_data;
- int y_char_len = n != t_bytes + 1 ? pg_mblen(y) : 1;
-
- /*
- * To transform the first 0 characters of s into the first j
- * characters of t, we must perform j insertions.
- */
- curr[0] = j * ins_c;
-
- /*
- * This inner loop is critical to performance, so we include a
- * fast-path to handle the (fairly common) case where no multibyte
- * characters are in the mix. The fast-path is entitled to assume
- * that if s_char_len is not initialized then BOTH strings contain
- * only single-byte characters.
- */
- if (s_char_len != NULL)
- {
- for (i = 1; i < m; i++)
- {
- int ins;
- int del;
- int sub;
- int x_char_len = s_char_len[i - 1];
-
- /*
- * Calculate costs for insertion, deletion, and substitution.
- *
- * When calculating cost for substitution, we compare the last
- * character of each possibly-multibyte character first,
- * because that's enough to rule out most mis-matches. If we
- * get past that test, then we compare the lengths and the
- * remaining bytes.
- */
- ins = prev[i] + ins_c;
- del = curr[i - 1] + del_c;
- if (x[x_char_len-1] == y[y_char_len-1]
- && x_char_len == y_char_len &&
- (x_char_len == 1 || rest_of_char_same(x, y, x_char_len)))
- sub = prev[i - 1];
- else
- sub = prev[i - 1] + sub_c;
-
- /* Take the one with minimum cost. */
- curr[i] = Min(ins, del);
- curr[i] = Min(curr[i], sub);
-
- /* Point to next character. */
- x += x_char_len;
- }
- }
- else
- {
- for (i = 1; i < m; i++)
- {
- int ins;
- int del;
- int sub;
+#include "levenshtein.c"
+#define LEVENSHTEIN_LESS_EQUAL
+#include "levenshtein.c"
- /* Calculate costs for insertion, deletion, and substitution. */
- ins = prev[i] + ins_c;
- del = curr[i - 1] + del_c;
- sub = prev[i - 1] + ((*x == *y) ? 0 : sub_c);
-
- /* Take the one with minimum cost. */
- curr[i] = Min(ins, del);
- curr[i] = Min(curr[i], sub);
+PG_FUNCTION_INFO_V1(levenshtein_with_costs);
+Datum
+levenshtein_with_costs(PG_FUNCTION_ARGS)
+{
+ text *src = PG_GETARG_TEXT_PP(0);
+ text *dst = PG_GETARG_TEXT_PP(1);
+ int ins_c = PG_GETARG_INT32(2);
+ int del_c = PG_GETARG_INT32(3);
+ int sub_c = PG_GETARG_INT32(4);
- /* Point to next character. */
- x++;
- }
- }
+ PG_RETURN_INT32(levenshtein_internal(src, dst, ins_c, del_c, sub_c));
+}
- /* Swap current row with previous row. */
- temp = curr;
- curr = prev;
- prev = temp;
- /* Point to next character. */
- y += y_char_len;
- }
+PG_FUNCTION_INFO_V1(levenshtein);
+Datum
+levenshtein(PG_FUNCTION_ARGS)
+{
+ text *src = PG_GETARG_TEXT_PP(0);
+ text *dst = PG_GETARG_TEXT_PP(1);
- /*
- * Because the final value was swapped from the previous row to the
- * current row, that's where we'll find it.
- */
- return prev[m - 1];
+ PG_RETURN_INT32(levenshtein_internal(src, dst, 1, 1, 1));
}
-PG_FUNCTION_INFO_V1(levenshtein_with_costs);
+PG_FUNCTION_INFO_V1(levenshtein_less_equal_with_costs);
Datum
-levenshtein_with_costs(PG_FUNCTION_ARGS)
+levenshtein_less_equal_with_costs(PG_FUNCTION_ARGS)
{
text *src = PG_GETARG_TEXT_PP(0);
text *dst = PG_GETARG_TEXT_PP(1);
int ins_c = PG_GETARG_INT32(2);
int del_c = PG_GETARG_INT32(3);
int sub_c = PG_GETARG_INT32(4);
+ int max_d = PG_GETARG_INT32(5);
- PG_RETURN_INT32(levenshtein_internal(src, dst, ins_c, del_c, sub_c));
+ PG_RETURN_INT32(levenshtein_less_equal_internal(src, dst, ins_c, del_c, sub_c, max_d));
}
-PG_FUNCTION_INFO_V1(levenshtein);
+PG_FUNCTION_INFO_V1(levenshtein_less_equal);
Datum
-levenshtein(PG_FUNCTION_ARGS)
+levenshtein_less_equal(PG_FUNCTION_ARGS)
{
text *src = PG_GETARG_TEXT_PP(0);
text *dst = PG_GETARG_TEXT_PP(1);
+ int max_d = PG_GETARG_INT32(2);
- PG_RETURN_INT32(levenshtein_internal(src, dst, 1, 1, 1));
+ PG_RETURN_INT32(levenshtein_less_equal_internal(src, dst, 1, 1, 1, max_d));
}
generated by cgit v1.2.3 (git 2.46.0) at 2025-10-24 14:17:13 +0000