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|
/*
+----------------------------------------------------------------------+
| Copyright (c) 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> |
+----------------------------------------------------------------------+
*/
#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 zend_long reference_levdist(const char *s1, size_t l1, const char *s2, size_t l2, zend_long cost_ins, zend_long cost_rep, zend_long cost_del )
{
zend_long *p1, *p2, *tmp;
zend_long c0, c1, c2;
size_t i1, i2;
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(zend_long), 0);
p2 = safe_emalloc((l2 + 1), sizeof(zend_long), 0);
for (i2 = 0; i2 <= l2; i2++) {
p1[i2] = i2 * cost_ins;
}
for (i1 = 0; i1 < l1 ; i1++) {
p2[0] = p1[0] + cost_del;
for (i2 = 0; i2 < l2; i2++) {
c0 = p1[i2] + ((s1[i1] == 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(char *str1, char *str2, char *callback_name)
{
php_error_docref(NULL, 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])
Calculate Levenshtein distance between two strings */
PHP_FUNCTION(levenshtein)
{
int argc = ZEND_NUM_ARGS();
char *str1, *str2;
char *callback_name;
size_t str1_len, str2_len, callback_len;
zend_long cost_ins, cost_rep, cost_del;
zend_long distance = -1;
switch (argc) {
case 2: /* just two strings: use maximum performance version */
if (zend_parse_parameters(2, "ss", &str1, &str1_len, &str2, &str2_len) == FAILURE) {
RETURN_THROWS();
}
distance = reference_levdist(str1, str1_len, str2, str2_len, 1, 1, 1);
break;
case 5: /* more general version: calc cost by ins/rep/del weights */
if (zend_parse_parameters(5, "sslll", &str1, &str1_len, &str2, &str2_len, &cost_ins, &cost_rep, &cost_del) == FAILURE) {
RETURN_THROWS();
}
distance = reference_levdist(str1, str1_len, str2, str2_len, cost_ins, cost_rep, cost_del);
break;
case 3: /* most general version: calc cost by user-supplied function */
if (zend_parse_parameters(3, "sss", &str1, &str1_len, &str2, &str2_len, &callback_name, &callback_len) == FAILURE) {
RETURN_THROWS();
}
distance = custom_levdist(str1, str2, callback_name);
break;
default:
WRONG_PARAM_COUNT;
}
if (distance < 0 && /* TODO */ ZEND_NUM_ARGS() != 3) {
php_error_docref(NULL, E_WARNING, "Argument string(s) too long");
}
RETURN_LONG(distance);
}
/* }}} */
|
