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+/*
+ * fuzzystrmatch.c
+ *
+ * Functions for "fuzzy" comparison of strings
+ *
+ * Joe Conway <mail@joeconway.com>
+ *
+ * contrib/fuzzystrmatch/fuzzystrmatch.c
+ * Copyright (c) 2001-2022, PostgreSQL Global Development Group
+ * ALL RIGHTS RESERVED;
+ *
+ * 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 "postgres.h"
+
+#include <ctype.h>
+
+#include "mb/pg_wchar.h"
+#include "utils/builtins.h"
+#include "utils/varlena.h"
+
+PG_MODULE_MAGIC;
+
+/*
+ * Soundex
+ */
+static void _soundex(const char *instr, char *outstr);
+
+#define SOUNDEX_LEN 4
+
+/* ABCDEFGHIJKLMNOPQRSTUVWXYZ */
+static const char *soundex_table = "01230120022455012623010202";
+
+static char
+soundex_code(char letter)
+{
+ letter = toupper((unsigned char) letter);
+ /* Defend against non-ASCII letters */
+ if (letter >= 'A' && letter <= 'Z')
+ return soundex_table[letter - 'A'];
+ return letter;
+}
+
+/*
+ * Metaphone
+ */
+#define MAX_METAPHONE_STRLEN 255
+
+/*
+ * Original code by Michael G Schwern starts here.
+ * Code slightly modified for use as PostgreSQL function.
+ */
+
+
+/**************************************************************************
+ 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.
+****************************************************************************/
+
+
+/* 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'
+
+static char Lookahead(char *word, int how_far);
+static void _metaphone(char *word, int max_phonemes, char **phoned_word);
+
+/* Metachar.h ... little bits about characters for metaphone */
+
+
+/*-- Character encoding array & accessing macros --*/
+/* Stolen directly out of the book... */
+static const 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 */
+};
+
+static int
+getcode(char c)
+{
+ if (isalpha((unsigned char) c))
+ {
+ c = toupper((unsigned char) c);
+ /* Defend against non-ASCII letters */
+ if (c >= 'A' && c <= 'Z')
+ return _codes[c - 'A'];
+ }
+ return 0;
+}
+
+#define isvowel(c) (getcode(c) & 1) /* AEIOU */
+
+/* These letters are passed through unchanged */
+#define NOCHANGE(c) (getcode(c) & 2) /* FJMNR */
+
+/* These form diphthongs when preceding H */
+#define AFFECTH(c) (getcode(c) & 4) /* CGPST */
+
+/* These make C and G soft */
+#define MAKESOFT(c) (getcode(c) & 8) /* EIY */
+
+/* These prevent GH from becoming F */
+#define NOGHTOF(c) (getcode(c) & 16) /* BDH */
+
+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);
+ const char *s_data;
+ const char *t_data;
+ int s_bytes,
+ t_bytes;
+
+ /* Extract a pointer to the actual character data */
+ s_data = VARDATA_ANY(src);
+ t_data = VARDATA_ANY(dst);
+ /* Determine length of each string in bytes */
+ s_bytes = VARSIZE_ANY_EXHDR(src);
+ t_bytes = VARSIZE_ANY_EXHDR(dst);
+
+ PG_RETURN_INT32(varstr_levenshtein(s_data, s_bytes, t_data, t_bytes,
+ ins_c, del_c, sub_c, false));
+}
+
+
+PG_FUNCTION_INFO_V1(levenshtein);
+Datum
+levenshtein(PG_FUNCTION_ARGS)
+{
+ text *src = PG_GETARG_TEXT_PP(0);
+ text *dst = PG_GETARG_TEXT_PP(1);
+ const char *s_data;
+ const char *t_data;
+ int s_bytes,
+ t_bytes;
+
+ /* Extract a pointer to the actual character data */
+ s_data = VARDATA_ANY(src);
+ t_data = VARDATA_ANY(dst);
+ /* Determine length of each string in bytes */
+ s_bytes = VARSIZE_ANY_EXHDR(src);
+ t_bytes = VARSIZE_ANY_EXHDR(dst);
+
+ PG_RETURN_INT32(varstr_levenshtein(s_data, s_bytes, t_data, t_bytes,
+ 1, 1, 1, false));
+}
+
+
+PG_FUNCTION_INFO_V1(levenshtein_less_equal_with_costs);
+Datum
+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);
+ const char *s_data;
+ const char *t_data;
+ int s_bytes,
+ t_bytes;
+
+ /* Extract a pointer to the actual character data */
+ s_data = VARDATA_ANY(src);
+ t_data = VARDATA_ANY(dst);
+ /* Determine length of each string in bytes */
+ s_bytes = VARSIZE_ANY_EXHDR(src);
+ t_bytes = VARSIZE_ANY_EXHDR(dst);
+
+ PG_RETURN_INT32(varstr_levenshtein_less_equal(s_data, s_bytes,
+ t_data, t_bytes,
+ ins_c, del_c, sub_c,
+ max_d, false));
+}
+
+
+PG_FUNCTION_INFO_V1(levenshtein_less_equal);
+Datum
+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);
+ const char *s_data;
+ const char *t_data;
+ int s_bytes,
+ t_bytes;
+
+ /* Extract a pointer to the actual character data */
+ s_data = VARDATA_ANY(src);
+ t_data = VARDATA_ANY(dst);
+ /* Determine length of each string in bytes */
+ s_bytes = VARSIZE_ANY_EXHDR(src);
+ t_bytes = VARSIZE_ANY_EXHDR(dst);
+
+ PG_RETURN_INT32(varstr_levenshtein_less_equal(s_data, s_bytes,
+ t_data, t_bytes,
+ 1, 1, 1,
+ max_d, false));
+}
+
+
+/*
+ * 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)
+{
+ char *str_i = TextDatumGetCString(PG_GETARG_DATUM(0));
+ size_t str_i_len = strlen(str_i);
+ int reqlen;
+ char *metaph;
+
+ /* return an empty string if we receive one */
+ if (!(str_i_len > 0))
+ PG_RETURN_TEXT_P(cstring_to_text(""));
+
+ if (str_i_len > MAX_METAPHONE_STRLEN)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("argument exceeds the maximum length of %d bytes",
+ MAX_METAPHONE_STRLEN)));
+
+ reqlen = PG_GETARG_INT32(1);
+ if (reqlen > MAX_METAPHONE_STRLEN)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("output exceeds the maximum length of %d bytes",
+ MAX_METAPHONE_STRLEN)));
+
+ if (!(reqlen > 0))
+ ereport(ERROR,
+ (errcode(ERRCODE_ZERO_LENGTH_CHARACTER_STRING),
+ errmsg("output cannot be empty string")));
+
+ _metaphone(str_i, reqlen, &metaph);
+ PG_RETURN_TEXT_P(cstring_to_text(metaph));
+}
+
+
+/*
+ * Original code by Michael G Schwern starts here.
+ * Code slightly modified for use as PostgreSQL
+ * function (palloc, etc).
+ */
+
+/* I suppose I could have been using a character pointer instead of
+ * accessing the array directly... */
+
+/* Look at the next letter in the word */
+#define Next_Letter (toupper((unsigned char) word[w_idx+1]))
+/* Look at the current letter in the word */
+#define Curr_Letter (toupper((unsigned char) word[w_idx]))
+/* Go N letters back. */
+#define Look_Back_Letter(n) \
+ (w_idx >= (n) ? toupper((unsigned char) 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((unsigned char) word[w_idx+2]) : '\0')
+#define Look_Ahead_Letter(n) toupper((unsigned char) Lookahead(word+w_idx, n))
+
+
+/* Allows us to safely look ahead an arbitrary # of letters */
+/* I probably could have just used strlen... */
+static 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) do {(*phoned_word)[p_idx++] = c;} while (0)
+/* Slap a null character on the end of the phoned word */
+#define End_Phoned_Word do {(*phoned_word)[p_idx] = '\0';} while (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((unsigned char) (c)))
+
+
+static void
+_metaphone(char *word, /* IN */
+ int max_phonemes,
+ char **phoned_word) /* OUT */
+{
+ 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))
+ /* internal error */
+ elog(ERROR, "metaphone: Requested output length must be > 0");
+
+ /* Empty/null string is meaningless */
+ if ((word == NULL) || !(strlen(word) > 0))
+ /* internal error */
+ 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);
+ }
+ else
+ {
+ *phoned_word = palloc(sizeof(char) * max_phonemes + 1);
+ }
+
+ /*-- The first phoneme has to be processed specially. --*/
+ /* Find our first letter */
+ for (; !isalpha((unsigned char) (Curr_Letter)); w_idx++)
+ {
+ /* On the off chance we were given nothing but crap... */
+ if (Curr_Letter == '\0')
+ {
+ End_Phoned_Word;
+ return;
+ }
+ }
+
+ 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 earlier 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((unsigned char) (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');
+ if (max_phonemes == 0 || Phone_Len < max_phonemes)
+ 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;
+} /* END metaphone */
+
+
+/*
+ * SQL function: soundex(text) returns text
+ */
+PG_FUNCTION_INFO_V1(soundex);
+
+Datum
+soundex(PG_FUNCTION_ARGS)
+{
+ char outstr[SOUNDEX_LEN + 1];
+ char *arg;
+
+ arg = text_to_cstring(PG_GETARG_TEXT_PP(0));
+
+ _soundex(arg, outstr);
+
+ PG_RETURN_TEXT_P(cstring_to_text(outstr));
+}
+
+static void
+_soundex(const char *instr, char *outstr)
+{
+ int count;
+
+ AssertArg(instr);
+ AssertArg(outstr);
+
+ /* Skip leading non-alphabetic characters */
+ while (*instr && !isalpha((unsigned char) *instr))
+ ++instr;
+
+ /* If no string left, return all-zeroes buffer */
+ if (!*instr)
+ {
+ memset(outstr, '\0', SOUNDEX_LEN + 1);
+ return;
+ }
+
+ /* Take the first letter as is */
+ *outstr++ = (char) toupper((unsigned char) *instr++);
+
+ count = 1;
+ while (*instr && count < SOUNDEX_LEN)
+ {
+ if (isalpha((unsigned char) *instr) &&
+ soundex_code(*instr) != soundex_code(*(instr - 1)))
+ {
+ *outstr = soundex_code(*instr);
+ if (*outstr != '0')
+ {
+ ++outstr;
+ ++count;
+ }
+ }
+ ++instr;
+ }
+
+ /* Fill with 0's */
+ while (count < SOUNDEX_LEN)
+ {
+ *outstr = '0';
+ ++outstr;
+ ++count;
+ }
+
+ /* And null-terminate */
+ *outstr = '\0';
+}
+
+PG_FUNCTION_INFO_V1(difference);
+
+Datum
+difference(PG_FUNCTION_ARGS)
+{
+ char sndx1[SOUNDEX_LEN + 1],
+ sndx2[SOUNDEX_LEN + 1];
+ int i,
+ result;
+
+ _soundex(text_to_cstring(PG_GETARG_TEXT_PP(0)), sndx1);
+ _soundex(text_to_cstring(PG_GETARG_TEXT_PP(1)), sndx2);
+
+ result = 0;
+ for (i = 0; i < SOUNDEX_LEN; i++)
+ {
+ if (sndx1[i] == sndx2[i])
+ result++;
+ }
+
+ PG_RETURN_INT32(result);
+}