1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
/*
+----------------------------------------------------------------------+
| PHP version 4.0 |
+----------------------------------------------------------------------+
| Copyright (c) 1997, 1998, 1999, 2000 The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 2.02 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available at through the world-wide-web at |
| http://www.php.net/license/2_02.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 <hartmut@six.de> |
+----------------------------------------------------------------------+
*/
/* $Id$ */
#include "php.h"
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include "php_string.h"
static int calc_levdist(const char *s1, const char *s2) /* faster, but obfuscated */
{
register char *p1,*p2;
register int i,j,n;
int l1=0,l2=0;
char r[512];
const char *tmp;
/* skip equal start sequence, if any */
while(*s1==*s2) {
if(!*s1) break;
s1++; s2++;
}
/* if we already used up one string, then
the result is the length of the other */
if(*s1=='\0') return strlen(s2);
if(*s2=='\0') return strlen(s1);
/* length count */
while(*s1++) l1++;
while(*s2++) l2++;
/* cut of equal tail sequence, if any */
while(*--s1 == *--s2) {
l1--; l2--;
}
/* reset pointers, adjust length */
s1-=l1++;
s2-=l2++;
/* possible dist to great? */
if(abs(l1-l2)>=255) return -1;
/* swap if l2 longer than l1 */
if(l1<l2) {
tmp=s1; s1=s2; s2=tmp;
l1 ^= l2; l2 ^= l1; l1 ^= l2;
}
/* fill initial row */
n=(*s1!=*s2);
for(i=0,p1=r;i<l1;i++,*p1++=n++,p1++) {/*empty*/}
/* calc. rowwise */
for(j=1;j<l2;j++) {
/* init pointers and col#0 */
p1 = r + !(j&1);
p2 = r + (j&1);
n=*p1+1;
*p2++=n;p2++;
s2++;
/* foreach column */
for(i=1;i<l1;i++) {
if(*p1<n) n=*p1+(*(s1+i)!=*(s2)); /* replace cheaper than delete? */
p1++;
if(*++p1<n) n=*p1+1; /* insert cheaper then insert ? */
*p2++=n++; /* update field and cost for next col's delete */
p2++;
}
}
/* return result */
return n-1;
}
/* {{{ proto int levenshtein(string str1, string str2)
Calculate Levenshtein distance between two strings */
PHP_FUNCTION(levenshtein)
{
zval **str1, **str2;
int l;
if (ZEND_NUM_ARGS() != 2 || zend_get_parameters_ex(2, &str1, &str2) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_string_ex(str1);
convert_to_string_ex(str2);
l = calc_levdist((*str1)->value.str.val, (*str2)->value.str.val);
if(l<0) {
php_error(E_WARNING,"levenshtein(): argument string(s) too long");
}
RETURN_LONG(l);
}
/* }}} */
|
