root/standard/soundex.c

DEFINITIONS

1. PHP_FUNCTION

/*
   +----------------------------------------------------------------------+
   | PHP Version 5                                                        |
   +----------------------------------------------------------------------+
   | Copyright (c) 1997-2013 The PHP Group                                |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 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_01.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: Bjørn Borud - Guardian Networks AS <borud@guardian.no>       |
   +----------------------------------------------------------------------+
 */
/* $Id$ */

#include "php.h"
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include "php_string.h"

/* Simple soundex algorithm as described by Knuth in TAOCP, vol 3 */
/* {{{ proto string soundex(string str)
   Calculate the soundex key of a string */
PHP_FUNCTION(soundex)
{
        char    *str;
        int     i, _small, str_len, code, last;
        char    soundex[4 + 1];

        static char soundex_table[26] =
        {0,                                                     /* A */
         '1',                                           /* B */
         '2',                                           /* C */
         '3',                                           /* D */
         0,                                                     /* E */
         '1',                                           /* F */
         '2',                                           /* G */
         0,                                                     /* H */
         0,                                                     /* I */
         '2',                                           /* J */
         '2',                                           /* K */
         '4',                                           /* L */
         '5',                                           /* M */
         '5',                                           /* N */
         0,                                                     /* O */
         '1',                                           /* P */
         '2',                                           /* Q */
         '6',                                           /* R */
         '2',                                           /* S */
         '3',                                           /* T */
         0,                                                     /* U */
         '1',                                           /* V */
         0,                                                     /* W */
         '2',                                           /* X */
         0,                                                     /* Y */
         '2'};                                          /* Z */

        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &str, &str_len) == FAILURE) {
                return;
        }
        if (str_len == 0) {
                RETURN_FALSE;
        }

        /* build soundex string */
        last = -1;
        for (i = 0, _small = 0; i < str_len && _small < 4; i++) {
                /* convert chars to upper case and strip non-letter chars */
                /* BUG: should also map here accented letters used in non */
                /* English words or names (also found in English text!): */
                /* esstsett, thorn, n-tilde, c-cedilla, s-caron, ... */
                code = toupper((int)(unsigned char)str[i]);
                if (code >= 'A' && code <= 'Z') {
                        if (_small == 0) {
                                /* remember first valid char */
                                soundex[_small++] = code;
                                last = soundex_table[code - 'A'];
                        }
                        else {
                                /* ignore sequences of consonants with same soundex */
                                /* code in trail, and vowels unless they separate */
                                /* consonant letters */
                                code = soundex_table[code - 'A'];
                                if (code != last) {
                                        if (code != 0) {
                                                soundex[_small++] = code;
                                        }
                                        last = code;
                                }
                        }
                }
        }
        /* pad with '0' and terminate with 0 ;-) */
        while (_small < 4) {
                soundex[_small++] = '0';
        }
        soundex[_small] = '\0';

        RETURN_STRINGL(soundex, _small, 1);
}
/* }}} */

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * End:
 * vim600: sw=4 ts=4 fdm=marker
 * vim<600: sw=4 ts=4
 */