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Postgres FD Implementation
Commit 55f6e5f6 authored by Tom Lane's avatar Tom Lane
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Add a variant of the Levenshtein string-distance function that lets the user 

specify the cost values to use, instead of always using 1's.
Volkan Yazici

In passing, remove fuzzystrmatch.h, which contained a bunch of stuff that had
no business being in a .h file; fold it into its only user, fuzzystrmatch.c.
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contrib/fuzzystrmatch/fuzzystrmatch.c
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contrib/fuzzystrmatch/fuzzystrmatch.h deleted 100644 → 0
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/*
* fuzzystrmatch.h
*
* Functions for "fuzzy" comparison of strings
*
* Joe Conway <mail@joeconway.com>
*
* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.h,v 1.17 2008/03/25 22:42:41 tgl Exp $
* Copyright (c) 2001-2008, 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.
*
* metaphone()
* -----------
* Modified for PostgreSQL by Joe Conway.
* Based on CPAN's "Text-Metaphone-1.96" by Michael G Schwern <schwern@pobox.com>
* Code slightly modified for use as PostgreSQL function (palloc, elog, etc).
* Metaphone was originally created by Lawrence Philips and presented in article
* in "Computer Language" December 1990 issue.
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose, without fee, and without a written agreement
* is hereby granted, provided that the above copyright notice and this
* paragraph and the following two paragraphs appear in all copies.
*
* IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
*/
#ifndef FUZZYSTRMATCH_H
#define FUZZYSTRMATCH_H
#include "postgres.h"
#include <ctype.h>
#include "fmgr.h"
#include "utils/builtins.h"
/*
* External declarations
*/
extern Datum levenshtein(PG_FUNCTION_ARGS);
extern Datum metaphone(PG_FUNCTION_ARGS);
extern Datum soundex(PG_FUNCTION_ARGS);
extern Datum difference(PG_FUNCTION_ARGS);
/*
* Soundex
*/
static void _soundex(const char *instr, char *outstr);
#define SOUNDEX_LEN 4
/* ABCDEFGHIJKLMNOPQRSTUVWXYZ */
static const char *soundex_table = "01230120022455012623010202";
#define soundex_code(letter) soundex_table[toupper((unsigned char) (letter)) - 'A']
/*
* Levenshtein
*/
#define MAX_LEVENSHTEIN_STRLEN 255
/*
* Metaphone
*/
#define MAX_METAPHONE_STRLEN 255
/*
* Original code by Michael G Schwern starts here.
* Code slightly modified for use as PostgreSQL
* function (combined *.h into here).
*------------------------------------------------------------------*/
/**************************************************************************
metaphone -- Breaks english phrases down into their phonemes.
Input
word -- An english word to be phonized
max_phonemes -- How many phonemes to calculate. If 0, then it
will phonize the entire phrase.
phoned_word -- The final phonized word. (We'll allocate the
memory.)
Output
error -- A simple error flag, returns TRUE or FALSE
NOTES: ALL non-alpha characters are ignored, this includes whitespace,
although non-alpha characters will break up phonemes.
****************************************************************************/
/**************************************************************************
my constants -- constants I like
Probably redundant.
***************************************************************************/
#define META_ERROR FALSE
#define META_SUCCESS TRUE
#define META_FAILURE FALSE
/* I add modifications to the traditional metaphone algorithm that you
might find in books. Define this if you want metaphone to behave
traditionally */
#undef USE_TRADITIONAL_METAPHONE
/* Special encodings */
#define SH 'X'
#define TH '0'
char Lookahead(char *word, int how_far);
int
_metaphone(
/* IN */
char *word,
int max_phonemes,
/* OUT */
char **phoned_word
);
/* Metachar.h ... little bits about characters for metaphone */
/*-- Character encoding array & accessing macros --*/
/* Stolen directly out of the book... */
char _codes[26] = {
1, 16, 4, 16, 9, 2, 4, 16, 9, 2, 0, 2, 2, 2, 1, 4, 0, 2, 4, 4, 1, 0, 0, 0, 8, 0
/* a b c d e f g h i j k l m n o p q r s t u v w x y z */
};
#define ENCODE(c) (isalpha((unsigned char) (c)) ? _codes[((toupper((unsigned char) (c))) - 'A')] : 0)
#define isvowel(c) (ENCODE(c) & 1) /* AEIOU */
/* These letters are passed through unchanged */
#define NOCHANGE(c) (ENCODE(c) & 2) /* FJMNR */
/* These form dipthongs when preceding H */
#define AFFECTH(c) (ENCODE(c) & 4) /* CGPST */
/* These make C and G soft */
#define MAKESOFT(c) (ENCODE(c) & 8) /* EIY */
/* These prevent GH from becoming F */
#define NOGHTOF(c) (ENCODE(c) & 16) /* BDH */
#endif /* FUZZYSTRMATCH_H */
contrib/fuzzystrmatch/fuzzystrmatch.sql.in
View file @ 55f6e5f6
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.sql.in,v 1.9 2007/11/13 04:24:28 momjian Exp $ */
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.sql.in,v 1.10 2008/04/03 21:13:07 tgl Exp $ */
-- Adjust this setting to control where the objects get created.
SET search_path = public;
......@@ -7,6 +7,10 @@ CREATE OR REPLACE FUNCTION levenshtein (text,text) RETURNS int
AS 'MODULE_PATHNAME','levenshtein'
LANGUAGE C IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION levenshtein (text,text,int,int,int) RETURNS int
AS 'MODULE_PATHNAME','levenshtein_with_costs'
LANGUAGE C IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION metaphone (text,int) RETURNS text
AS 'MODULE_PATHNAME','metaphone'
LANGUAGE C IMMUTABLE STRICT;
......
contrib/fuzzystrmatch/uninstall_fuzzystrmatch.sql
View file @ 55f6e5f6
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/uninstall_fuzzystrmatch.sql,v 1.3 2007/11/13 04:24:28 momjian Exp $ */
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/uninstall_fuzzystrmatch.sql,v 1.4 2008/04/03 21:13:07 tgl Exp $ */
-- Adjust this setting to control where the objects get dropped.
SET search_path = public;
......@@ -15,4 +15,6 @@ DROP FUNCTION soundex(text);
DROP FUNCTION metaphone (text,int);
DROP FUNCTION levenshtein (text,text,int,int,int);
DROP FUNCTION levenshtein (text,text);
doc/src/sgml/fuzzystrmatch.sgml
View file @ 55f6e5f6
<!-- $PostgreSQL: pgsql/doc/src/sgml/fuzzystrmatch.sgml,v 1.3 2007/12/06 04:12:10 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/fuzzystrmatch.sgml,v 1.4 2008/04/03 21:13:07 tgl Exp $ -->
<sect1 id="fuzzystrmatch">
<title>fuzzystrmatch</title>
......@@ -74,16 +74,20 @@ SELECT * FROM s WHERE difference(s.nm, 'john') &gt; 2;
</para>
<programlisting>
levenshtein(text source, text target, int ins_cost, int del_cost, int sub_cost) returns int
levenshtein(text source, text target) returns int
</programlisting>
<para>
Both <literal>source</literal> and <literal>target</literal> can be any
non-null string, with a maximum of 255 characters.
non-null string, with a maximum of 255 bytes. The cost parameters
specify how much to charge for a character insertion, deletion, or
substitution, respectively. You can omit the cost parameters, as in
the second version of the function; in that case they all default to 1.
</para>
<para>
Example:
Examples:
</para>
<programlisting>
......@@ -92,6 +96,12 @@ test=# SELECT levenshtein('GUMBO', 'GAMBOL');
-------------
2
(1 row)
test=# SELECT levenshtein('GUMBO', 'GAMBOL', 2,1,1);
levenshtein
-------------
3
(1 row)
</programlisting>
</sect2>
......
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