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php-src/ext/standard/metaphone.c
Andi Gutmans dbeb4158d2 - A belated happy holidays and PHP 5
2004-01-08 08:18:22 +00:00

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/*
+----------------------------------------------------------------------+
| PHP Version 5 |
+----------------------------------------------------------------------+
| Copyright (c) 1997-2004 The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 3.0 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| http://www.php.net/license/3_0.txt. |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Author: Thies C. Arntzen <thies@thieso.net> |
+----------------------------------------------------------------------+
*/
/* $Id$ */
/*
Based on CPANs "Text-Metaphone-1.96" by Michael G Schwern <schwern@pobox.com>
*/
#include "php.h"
#include "php_metaphone.h"
static int metaphone(char *word, int word_len, int max_phonemes, char **phoned_word, int traditional);
PHP_FUNCTION(metaphone);
/* {{{ proto string metaphone(string text, int phones)
Break english phrases down into their phonemes */
PHP_FUNCTION(metaphone)
{
char *str;
char *result = 0;
int str_len;
long phones = 0;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &str, &str_len,
&phones) == FAILURE) {
return;
}
if (metaphone(str, str_len, phones, &result, 1) == 0) {
RETVAL_STRING(result, 0);
} else {
if (result) {
efree(result);
}
RETURN_FALSE;
}
}
/* }}} */
/*
this is now the original code by Michael G Schwern:
i've changed it just a slightly bit (use emalloc,
get rid of includes etc)
- thies - 13.09.1999
*/
/*----------------------------- */
/* this used to be "metaphone.h" */
/*----------------------------- */
/* Special encodings */
#define SH 'X'
#define TH '0'
/*----------------------------- */
/* end of "metaphone.h" */
/*----------------------------- */
/*----------------------------- */
/* this used to be "metachar.h" */
/*----------------------------- */
/* 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 */
/*----------------------------- */
/* end of "metachar.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... */
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
* We don't know the buffers size in advance. On way to solve this is to just
* re-allocate the buffer size. We're using an extra of 2 characters (this
* could be one though; or more too). */
#define Phonize(c) { \
if (p_idx >= max_buffer_len) { \
*phoned_word = erealloc(*phoned_word, max_buffer_len + 2); \
max_buffer_len += 2; \
} \
(*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))
/* {{{ metaphone
*/
static int metaphone(char *word, int word_len, int max_phonemes, char **phoned_word, int traditional)
{
int w_idx = 0; /* point in the phonization we're at. */
int p_idx = 0; /* end of the phoned phrase */
int max_buffer_len = 0; /* maximum length of the destination buffer */
/*-- Parameter checks --*/
/* Negative phoneme length is meaningless */
if (max_phonemes < 0)
return -1;
/* Empty/null string is meaningless */
/* Overly paranoid */
/* assert(word != NULL && word[0] != '\0'); */
if (word == NULL)
return -1;
/*-- Allocate memory for our phoned_phrase --*/
if (max_phonemes == 0) { /* Assume largest possible */
max_buffer_len = word_len;
*phoned_word = safe_emalloc(sizeof(char), word_len, 1);
} else {
max_buffer_len = max_phonemes;
*phoned_word = safe_emalloc(sizeof(char), max_phonemes, 1);
}
/*-- 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 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') {
if ((!traditional) && (After_Next_Letter == 'R' || Prev_Letter == 'S')) { /* Christ, School */
Phonize('K');
} else {
Phonize(SH);
}
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++;
} else if ((!traditional) && (Next_Letter == 'C' && Look_Ahead_Letter(2) == 'H' && Look_Ahead_Letter(3) == 'W')) {
Phonize(SH);
skip_letter += 2;
} 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 0;
} /* END metaphone */
/* }}} */
/*
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* End:
* vim600: sw=4 ts=4 fdm=marker
* vim<600: sw=4 ts=4
*/
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