--- /dev/null
+/*
+ * fuzzystrmatch.c
+ *
+ * Functions for "fuzzy" comparison of strings
+ *
+ * Copyright (c) Joseph Conway <joseph.conway@home.com>, 2001;
+ *
+ * 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.
+ *
+ */
+
+
+Version 0.1 (3 August, 2001):
+ Functions to calculate the degree to which two strings match in a "fuzzy" way
+ Tested under Linux (Red Hat 6.2 and 7.0) and PostgreSQL 7.2devel
+
+Release Notes:
+
+ Version 0.1
+ - initial release
+
+Installation:
+ Place these files in a directory called 'fuzzystrmatch' under 'contrib' in the PostgreSQL source tree. Then run:
+
+ make
+ make install
+
+ You can use fuzzystrmatch.sql to create the functions in your database of choice, e.g.
+
+ psql -U postgres template1 < fuzzystrmatch.sql
+
+ installs following functions into database template1:
+
+ levenshtein() - calculates the levenshtein distance between two strings
+ metaphone() - calculates the metaphone code of an input string
+
+Documentation
+==================================================================
+Name
+
+levenshtein -- calculates the levenshtein distance between two strings
+
+Synopsis
+
+levenshtein(text source, text target)
+
+Inputs
+
+ source
+ any text string, 255 characters max, NOT NULL
+
+ target
+ any text string, 255 characters max, NOT NULL
+
+Outputs
+
+ Returns int
+
+Example usage
+
+ select levenshtein('GUMBO','GAMBOL');
+
+==================================================================
+Name
+
+metaphone -- calculates the metaphone code of an input string
+
+Synopsis
+
+metaphone(text source, int max_output_length)
+
+Inputs
+
+ source
+ any text string, 255 characters max, NOT NULL
+
+ max_output_length
+ maximum length of the output metaphone code; if longer, the output
+ is truncated to this length
+
+Outputs
+
+ Returns text
+
+Example usage
+
+ select metaphone('GUMBO',4);
+
+==================================================================
+-- Joe Conway
+
--- /dev/null
+/*
+ * fuzzystrmatch.c
+ *
+ * Functions for "fuzzy" comparison of strings
+ *
+ * Copyright (c) Joseph Conway <joseph.conway@home.com>, 2001;
+ *
+ * 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.
+ *
+ */
+
+#include "fuzzystrmatch.h"
+
+/*
+ * Calculates Levenshtein Distance between two strings.
+ * Uses simplest and fastest cost model only, i.e. assumes a cost of 1 for
+ * each deletion, substitution, or insertion.
+ */
+PG_FUNCTION_INFO_V1(levenshtein);
+Datum
+levenshtein(PG_FUNCTION_ARGS)
+{
+ char *str_s;
+ char *str_s0;
+ char *str_t;
+ int cols = 0;
+ int rows = 0;
+ int *u_cells;
+ int *l_cells;
+ int *tmp;
+ int i;
+ int j;
+
+ /*
+ * Fetch the arguments.
+ * str_s is referred to as the "source"
+ * cols = length of source + 1 to allow for the initialization column
+ * str_t is referred to as the "target", rows = length of target + 1
+ * rows = length of target + 1 to allow for the initialization row
+ */
+ str_s = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(0))));
+ str_t = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(1))));
+
+ cols = strlen(str_s) + 1;
+ rows = strlen(str_t) + 1;
+
+ /*
+ * Restrict the length of the strings being compared to something reasonable
+ * because we will have to perform rows * cols calcualtions. If longer strings need to be
+ * compared, increase MAX_LEVENSHTEIN_STRLEN to suit (but within your tolerance for
+ * speed and memory usage).
+ */
+ if ((cols > MAX_LEVENSHTEIN_STRLEN + 1) || (rows > MAX_LEVENSHTEIN_STRLEN + 1))
+ elog(ERROR, "levenshtein: Arguments may not exceed %d characters in length", MAX_LEVENSHTEIN_STRLEN);
+
+ /*
+ * If either rows or cols is 0, the answer is the other value.
+ * This makes sense since it would take that many insertions
+ * the build a matching string
+ */
+
+ if (cols == 0)
+ PG_RETURN_INT32(rows);
+
+ if (rows == 0)
+ PG_RETURN_INT32(cols);
+
+ /*
+ * Allocate two vectors of integers. One will be used for the "upper" row,
+ * the other for the "lower" row. Initialize the "upper" row to 0..cols
+ */
+ u_cells = palloc(sizeof(int) * cols);
+ for (i = 0; i < cols; i++)
+ u_cells[i] = i;
+
+ l_cells = palloc(sizeof(int) * cols);
+
+ /*
+ * Use str_s0 to "rewind" the pointer to str_s in the nested for loop below
+ */
+ str_s0 = str_s;
+
+ /*
+ * Loop throught the rows, starting at row 1. Row 0 is used for the initial
+ * "upper" row.
+ */
+ for (j = 1; j < rows; j++)
+ {
+ /*
+ * We'll always start with col 1,
+ * and initialize lower row col 0 to j
+ */
+ l_cells[0] = j;
+
+ for (i = 1; i < cols; i++)
+ {
+ int c = 0;
+ int c1 = 0;
+ int c2 = 0;
+ int c3 = 0;
+
+ /*
+ * The "cost" value is 0 if the character at the current col position
+ * in the source string, matches the character at the current row position
+ * in the target string; cost is 1 otherwise.
+ */
+ c = ((CHAREQ(str_s, str_t)) ? 0 : 1);
+
+ /*
+ * c1 is upper right cell plus 1
+ */
+ c1 = u_cells[i] + 1;
+
+ /*
+ * c2 is lower left cell plus 1
+ */
+ c2 = l_cells[i - 1] + 1;
+
+ /*
+ * c3 is cell diagonally above to the left plus "cost"
+ */
+ c3 = u_cells[i - 1] + c;
+
+ /*
+ * The lower right cell is set to the minimum
+ * of c1, c2, c3
+ */
+ l_cells[i] = (c1 < c2 ? c1 : c2) < c3 ? (c1 < c2 ? c1 : c2) : c3;
+
+ /*
+ * Increment the pointer to str_s
+ */
+ NextChar(str_s);
+ }
+
+ /*
+ * Lower row now becomes the upper row, and the upper row
+ * gets reused as the new lower row.
+ */
+ tmp = u_cells;
+ u_cells = l_cells;
+ l_cells = tmp;
+
+ /*
+ * Increment the pointer to str_t
+ */
+ NextChar(str_t);
+
+ /*
+ * Rewind the pointer to str_s
+ */
+ str_s = str_s0;
+ }
+
+ /*
+ * Because the final value (at position row, col) was swapped from
+ * the lower row to the upper row, that's where we'll find it.
+ */
+ PG_RETURN_INT32(u_cells[cols - 1]);
+}
+
+/*
+ * Calculates the metaphone of an input string.
+ * Returns number of characters requested
+ * (suggested value is 4)
+ */
+PG_FUNCTION_INFO_V1(metaphone);
+Datum
+metaphone(PG_FUNCTION_ARGS)
+{
+ int reqlen;
+ char *str_i;
+ size_t str_i_len;
+ char *metaph;
+ text *result_text;
+ int retval;
+
+ str_i = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(0))));
+ str_i_len = strlen(str_i);
+
+ if (str_i_len > MAX_METAPHONE_STRLEN)
+ elog(ERROR, "metaphone: Input string must not exceed %d characters", MAX_METAPHONE_STRLEN);
+ if (!(str_i_len > 0))
+ elog(ERROR, "metaphone: Input string length must be > 0");
+
+ reqlen = PG_GETARG_INT32(1);
+ if (reqlen > MAX_METAPHONE_STRLEN)
+ elog(ERROR, "metaphone: Requested Metaphone output length must not exceed %d characters", MAX_METAPHONE_STRLEN);
+ if (!(reqlen > 0))
+ elog(ERROR, "metaphone: Requested Metaphone output length must be > 0");
+
+ metaph = palloc(reqlen);
+ memset(metaph, '\0', reqlen);
+
+ retval = _metaphone(str_i, reqlen, &metaph);
+ if (retval == META_SUCCESS)
+ {
+ result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(metaph)));
+ PG_RETURN_TEXT_P(result_text);
+ }
+ else
+ {
+ elog(ERROR, "metaphone: failure");
+
+ /*
+ * Keep the compiler quiet
+ */
+ PG_RETURN_NULL();
+ }
+}
+
+
+/*
+ * Original code by Michael G Schwern starts here.
+ * Code slightly modified for use as PostgreSQL
+ * function (palloc, etc). Original includes
+ * are rolled into fuzzystrmatch.h
+ *------------------------------------------------------------------*/
+
+/* I suppose I could have been using a character pointer instead of
+ * accesssing the array directly... */
+
+/* Look at the next letter in the word */
+#define Next_Letter (toupper(word[w_idx+1]))
+/* Look at the current letter in the word */
+#define Curr_Letter (toupper(word[w_idx]))
+/* Go N letters back. */
+#define Look_Back_Letter(n) (w_idx >= n ? toupper(word[w_idx-n]) : '\0')
+/* Previous letter. I dunno, should this return null on failure? */
+#define Prev_Letter (Look_Back_Letter(1))
+/* Look two letters down. It makes sure you don't walk off the string. */
+#define After_Next_Letter (Next_Letter != '\0' ? toupper(word[w_idx+2]) \
+ : '\0')
+#define Look_Ahead_Letter(n) (toupper(Lookahead(word+w_idx, n)))
+
+
+/* Allows us to safely look ahead an arbitrary # of letters */
+/* I probably could have just used strlen... */
+char Lookahead(char * word, int how_far) {
+ char letter_ahead = '\0'; /* null by default */
+ int idx;
+ for(idx = 0; word[idx] != '\0' && idx < how_far; idx++);
+ /* Edge forward in the string... */
+
+ letter_ahead = word[idx]; /* idx will be either == to how_far or
+ * at the end of the string
+ */
+ return letter_ahead;
+}
+
+
+/* phonize one letter */
+#define Phonize(c) {(*phoned_word)[p_idx++] = c;}
+/* Slap a null character on the end of the phoned word */
+#define End_Phoned_Word {(*phoned_word)[p_idx] = '\0';}
+/* How long is the phoned word? */
+#define Phone_Len (p_idx)
+
+/* Note is a letter is a 'break' in the word */
+#define Isbreak(c) (!isalpha(c))
+
+
+int _metaphone (
+ /* IN */
+ char * word,
+ int max_phonemes,
+ /* OUT */
+ char ** phoned_word
+) {
+ int w_idx = 0; /* point in the phonization we're at. */
+ int p_idx = 0; /* end of the phoned phrase */
+
+ /*-- Parameter checks --*/
+
+ /*
+ * Shouldn't be necessary, but left these here anyway
+ * jec Aug 3, 2001
+ */
+
+ /* Negative phoneme length is meaningless */
+ if (!(max_phonemes > 0))
+ elog(ERROR, "metaphone: Requested output length must be > 0");
+
+ /* Empty/null string is meaningless */
+ if ((word == NULL) || !(strlen(word) > 0))
+ elog(ERROR, "metaphone: Input string length must be > 0");
+
+ /*-- Allocate memory for our phoned_phrase --*/
+ if (max_phonemes == 0) { /* Assume largest possible */
+ *phoned_word = palloc(sizeof(char) * strlen(word) + 1);
+ if (!*phoned_word)
+ return META_ERROR;
+ } else {
+ *phoned_word = palloc(sizeof(char) * max_phonemes + 1);
+ if (!*phoned_word)
+ return META_ERROR;
+ }
+
+ /*-- The first phoneme has to be processed specially. --*/
+ /* Find our first letter */
+ for( ; !isalpha(Curr_Letter); w_idx++ ) {
+ /* On the off chance we were given nothing but crap... */
+ if( Curr_Letter == '\0' ) {
+ End_Phoned_Word
+ return META_SUCCESS; /* For testing */
+ }
+ }
+
+ switch (Curr_Letter) {
+ /* AE becomes E */
+ case 'A':
+ if( Next_Letter == 'E' ) {
+ Phonize('E');
+ w_idx+=2;
+ }
+ /* Remember, preserve vowels at the beginning */
+ else {
+ Phonize('A');
+ w_idx++;
+ }
+ break;
+ /* [GKP]N becomes N */
+ case 'G':
+ case 'K':
+ case 'P':
+ if( Next_Letter == 'N' ) {
+ Phonize('N');
+ w_idx+=2;
+ }
+ break;
+ /* WH becomes H,
+ WR becomes R
+ W if followed by a vowel */
+ case 'W':
+ if( Next_Letter == 'H' ||
+ Next_Letter == 'R' )
+ {
+ Phonize(Next_Letter);
+ w_idx+=2;
+ }
+ else if ( isvowel(Next_Letter) ) {
+ Phonize('W');
+ w_idx+=2;
+ }
+ /* else ignore */
+ break;
+ /* X becomes S */
+ case 'X':
+ Phonize('S');
+ w_idx++;
+ break;
+ /* Vowels are kept */
+ /* We did A already
+ case 'A':
+ case 'a':
+ */
+ case 'E':
+ case 'I':
+ case 'O':
+ case 'U':
+ Phonize(Curr_Letter);
+ w_idx++;
+ break;
+ default:
+ /* do nothing */
+ break;
+ }
+
+
+
+ /* On to the metaphoning */
+ for(; Curr_Letter != '\0' &&
+ (max_phonemes == 0 || Phone_Len < max_phonemes);
+ w_idx++) {
+ /* How many letters to skip because an eariler encoding handled
+ * multiple letters */
+ unsigned short int skip_letter = 0;
+
+
+ /* THOUGHT: It would be nice if, rather than having things like...
+ * well, SCI. For SCI you encode the S, then have to remember
+ * to skip the C. So the phonome SCI invades both S and C. It would
+ * be better, IMHO, to skip the C from the S part of the encoding.
+ * Hell, I'm trying it.
+ */
+
+ /* Ignore non-alphas */
+ if( !isalpha(Curr_Letter) )
+ continue;
+
+ /* Drop duplicates, except CC */
+ if( Curr_Letter == Prev_Letter &&
+ Curr_Letter != 'C' )
+ continue;
+
+ switch (Curr_Letter) {
+ /* B -> B unless in MB */
+ case 'B':
+ if( Prev_Letter != 'M' )
+ Phonize('B');
+ break;
+ /* 'sh' if -CIA- or -CH, but not SCH, except SCHW.
+ * (SCHW is handled in S)
+ * S if -CI-, -CE- or -CY-
+ * dropped if -SCI-, SCE-, -SCY- (handed in S)
+ * else K
+ */
+ case 'C':
+ if( MAKESOFT(Next_Letter) ) { /* C[IEY] */
+ if( After_Next_Letter == 'A' &&
+ Next_Letter == 'I' ) { /* CIA */
+ Phonize(SH);
+ }
+ /* SC[IEY] */
+ else if ( Prev_Letter == 'S' ) {
+ /* Dropped */
+ }
+ else {
+ Phonize('S');
+ }
+ }
+ else if ( Next_Letter == 'H' ) {
+#ifndef USE_TRADITIONAL_METAPHONE
+ if( After_Next_Letter == 'R' ||
+ Prev_Letter == 'S' ) { /* Christ, School */
+ Phonize('K');
+ }
+ else {
+ Phonize(SH);
+ }
+#else
+ Phonize(SH);
+#endif
+ skip_letter++;
+ }
+ else {
+ Phonize('K');
+ }
+ break;
+ /* J if in -DGE-, -DGI- or -DGY-
+ * else T
+ */
+ case 'D':
+ if( Next_Letter == 'G' &&
+ MAKESOFT(After_Next_Letter) ) {
+ Phonize('J');
+ skip_letter++;
+ }
+ else
+ Phonize('T');
+ break;
+ /* F if in -GH and not B--GH, D--GH, -H--GH, -H---GH
+ * else dropped if -GNED, -GN,
+ * else dropped if -DGE-, -DGI- or -DGY- (handled in D)
+ * else J if in -GE-, -GI, -GY and not GG
+ * else K
+ */
+ case 'G':
+ if( Next_Letter == 'H' ) {
+ if( !( NOGHTOF(Look_Back_Letter(3)) ||
+ Look_Back_Letter(4) == 'H' ) ) {
+ Phonize('F');
+ skip_letter++;
+ }
+ else {
+ /* silent */
+ }
+ }
+ else if( Next_Letter == 'N' ) {
+ if( Isbreak(After_Next_Letter) ||
+ ( After_Next_Letter == 'E' &&
+ Look_Ahead_Letter(3) == 'D' ) ) {
+ /* dropped */
+ }
+ else
+ Phonize('K');
+ }
+ else if( MAKESOFT(Next_Letter) &&
+ Prev_Letter != 'G' ) {
+ Phonize('J');
+ }
+ else {
+ Phonize('K');
+ }
+ break;
+ /* H if before a vowel and not after C,G,P,S,T */
+ case 'H':
+ if( isvowel(Next_Letter) &&
+ !AFFECTH(Prev_Letter) )
+ Phonize('H');
+ break;
+ /* dropped if after C
+ * else K
+ */
+ case 'K':
+ if( Prev_Letter != 'C' )
+ Phonize('K');
+ break;
+ /* F if before H
+ * else P
+ */
+ case 'P':
+ if( Next_Letter == 'H' ) {
+ Phonize('F');
+ }
+ else {
+ Phonize('P');
+ }
+ break;
+ /* K
+ */
+ case 'Q':
+ Phonize('K');
+ break;
+ /* 'sh' in -SH-, -SIO- or -SIA- or -SCHW-
+ * else S
+ */
+ case 'S':
+ if( Next_Letter == 'I' &&
+ ( After_Next_Letter == 'O' ||
+ After_Next_Letter == 'A' ) ) {
+ Phonize(SH);
+ }
+ else if ( Next_Letter == 'H' ) {
+ Phonize(SH);
+ skip_letter++;
+ }
+#ifndef USE_TRADITIONAL_METAPHONE
+ else if ( Next_Letter == 'C' &&
+ Look_Ahead_Letter(2) == 'H' &&
+ Look_Ahead_Letter(3) == 'W' ) {
+ Phonize(SH);
+ skip_letter += 2;
+ }
+#endif
+ else {
+ Phonize('S');
+ }
+ break;
+ /* 'sh' in -TIA- or -TIO-
+ * else 'th' before H
+ * else T
+ */
+ case 'T':
+ if( Next_Letter == 'I' &&
+ ( After_Next_Letter == 'O' ||
+ After_Next_Letter == 'A' ) ) {
+ Phonize(SH);
+ }
+ else if ( Next_Letter == 'H' ) {
+ Phonize(TH);
+ skip_letter++;
+ }
+ else {
+ Phonize('T');
+ }
+ break;
+ /* F */
+ case 'V':
+ Phonize('F');
+ break;
+ /* W before a vowel, else dropped */
+ case 'W':
+ if( isvowel(Next_Letter) )
+ Phonize('W');
+ break;
+ /* KS */
+ case 'X':
+ Phonize('K');
+ Phonize('S');
+ break;
+ /* Y if followed by a vowel */
+ case 'Y':
+ if( isvowel(Next_Letter) )
+ Phonize('Y');
+ break;
+ /* S */
+ case 'Z':
+ Phonize('S');
+ break;
+ /* No transformation */
+ case 'F':
+ case 'J':
+ case 'L':
+ case 'M':
+ case 'N':
+ case 'R':
+ Phonize(Curr_Letter);
+ break;
+ default:
+ /* nothing */
+ break;
+ } /* END SWITCH */
+
+ w_idx += skip_letter;
+ } /* END FOR */
+
+ End_Phoned_Word;
+
+ return(META_SUCCESS);
+} /* END metaphone */
--- /dev/null
+/*
+ * fuzzystrmatch.h
+ *
+ * Functions for "fuzzy" comparison of strings
+ *
+ * Copyright (c) Joseph Conway <joseph.conway@home.com>, 2001;
+ *
+ * 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 <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "postgres.h"
+#include "fmgr.h"
+#include "utils/builtins.h"
+
+
+#define MAX_LEVENSHTEIN_STRLEN 255
+#define MAX_METAPHONE_STRLEN 255
+
+typedef struct dynmatrix
+{
+ int value;
+} dynmat;
+
+
+/*
+ * External declarations
+ */
+extern Datum levenshtein(PG_FUNCTION_ARGS);
+extern Datum metaphone(PG_FUNCTION_ARGS);
+
+/*
+ * Internal declarations
+ */
+
+
+
+#define STRLEN(p) strlen(p)
+#define CHAREQ(p1, p2) (*(p1) == *(p2))
+#define NextChar(p) ((p)++)
+
+
+/*
+ * 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(c) ? _codes[((toupper(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 */
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