php-src/ext/standard/levenshtein.c
2007-12-31 07:12:20 +00:00

171 lines
4.9 KiB
C

/*
+----------------------------------------------------------------------+
| PHP Version 5 |
+----------------------------------------------------------------------+
| Copyright (c) 1997-2008 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: Hartmut Holzgraefe <hholzgra@php.net> |
+----------------------------------------------------------------------+
*/
/* $Id$ */
#include "php.h"
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include "php_string.h"
#define LEVENSHTEIN_MAX_LENGTH 255
/* {{{ reference_levdist
* reference implementation, only optimized for memory usage, not speed */
static int reference_levdist(void *s1, int l1, void *s2, int l2, zend_uchar str_type, int cost_ins, int cost_rep, int cost_del )
{
int *p1, *p2, *tmp;
int32_t i1, i2, j1, j2, cp1, cp2;
int32_t c0, c1, c2;
UChar32 ch1, ch2;
if (str_type == IS_UNICODE) {
cp1 = u_countChar32((UChar *)s1, l1);
cp2 = u_countChar32((UChar *)s2, l2);
if (cp1 == 0) {
return cp2 * cost_ins;
}
if (cp2 == 0) {
return cp1 * cost_del;
}
if ((cp1 > LEVENSHTEIN_MAX_LENGTH) || (cp2 > LEVENSHTEIN_MAX_LENGTH)) {
return -1;
}
p1 = safe_emalloc((cp2 + 1), sizeof(int), 0);
p2 = safe_emalloc((cp2 + 1), sizeof(int), 0);
} else {
if (l1 == 0) {
return l2 * cost_ins;
}
if (l2 == 0) {
return l1 * cost_del;
}
if ((l1 > LEVENSHTEIN_MAX_LENGTH) || (l2 > LEVENSHTEIN_MAX_LENGTH)) {
return -1;
}
p1 = safe_emalloc((l2 + 1), sizeof(int), 0);
p2 = safe_emalloc((l2 + 1), sizeof(int), 0);
}
for (i2 = 0; i2 <= l2; i2++) {
p1[i2] = i2 * cost_ins;
}
for (i1 = 0, j1 = 0; i1 < l1; i1++) {
p2[0] = p1[0] + cost_del;
if (str_type == IS_UNICODE) {
U16_NEXT((UChar *)s1, j1, l1, ch1);
}
for (i2 = 0, j2 = 0; i2 < l2; i2++) {
if (str_type == IS_UNICODE) {
U16_NEXT((UChar *)s2, j2, l2, ch2);
c0 = p1[i2] + ((ch1 == ch2) ? 0 : cost_rep);
} else {
c0 = p1[i2] + ((*((char *)s1 + i1) == *((char *)s2 + i2)) ? 0 : cost_rep);
}
c1 = p1[i2 + 1] + cost_del;
if (c1 < c0) {
c0 = c1;
}
c2 = p2[i2] + cost_ins;
if (c2 < c0) {
c0 = c2;
}
p2[i2 + 1] = c0;
}
tmp = p1;
p1 = p2;
p2 = tmp;
}
c0 = p1[l2];
efree(p1);
efree(p2);
return c0;
}
/* }}} */
/* {{{ custom_levdist
*/
static int custom_levdist(void *str1, void *str2, char *callback_name TSRMLS_DC)
{
php_error_docref(NULL TSRMLS_CC, E_WARNING, "The general Levenshtein support is not there yet");
/* not there yet */
return -1;
}
/* }}} */
/* {{{ proto int levenshtein(string str1, string str2[, int cost_ins, int cost_rep, int cost_del]) U
Calculate Levenshtein distance between two strings */
PHP_FUNCTION(levenshtein)
{
int argc = ZEND_NUM_ARGS();
void *str1, *str2;
char *callback_name;
int str1_len, str2_len, callback_len;
zend_uchar str1_type, str2_type;
long cost_ins, cost_rep, cost_del;
int distance = -1;
switch (argc) {
case 2: /* just two strings: use maximum performance version */
if (zend_parse_parameters(2 TSRMLS_CC, "TT", &str1, &str1_len, &str1_type, &str2, &str2_len, &str2_type) == FAILURE) {
return;
}
distance = reference_levdist(str1, str1_len, str2, str2_len, str1_type, 1, 1, 1);
break;
case 5: /* more general version: calc cost by ins/rep/del weights */
if (zend_parse_parameters(5 TSRMLS_CC, "TTlll", &str1, &str1_len, &str1_type, &str2, &str2_len, &str2_type, &cost_ins, &cost_rep, &cost_del) == FAILURE) {
return;
}
distance = reference_levdist(str1, str1_len, str2, str2_len, str1_type, cost_ins, cost_rep, cost_del);
break;
case 3: /* most general version: calc cost by user-supplied function */
if (zend_parse_parameters(3 TSRMLS_CC, "TTs", &str1, &str1_len, &str1_type, &str2, &str2_len, &str2_type, &callback_name, &callback_len) == FAILURE) {
return;
}
distance = custom_levdist(str1, str2, callback_name TSRMLS_CC);
break;
default:
WRONG_PARAM_COUNT;
}
if (distance < 0 && /* TODO */ ZEND_NUM_ARGS() != 3) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument string(s) too long");
}
RETURN_LONG(distance);
}
/* }}} */
/*
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* End:
* vim600: sw=4 ts=4 fdm=marker
* vim<600: sw=4 ts=4
*/