1 /*
2 +----------------------------------------------------------------------+
3 | Copyright (c) The PHP Group |
4 +----------------------------------------------------------------------+
5 | This source file is subject to version 3.01 of the PHP license, |
6 | that is bundled with this package in the file LICENSE, and is |
7 | available through the world-wide-web at the following url: |
8 | https://www.php.net/license/3_01.txt |
9 | If you did not receive a copy of the PHP license and are unable to |
10 | obtain it through the world-wide-web, please send a note to |
11 | license@php.net so we can mail you a copy immediately. |
12 +----------------------------------------------------------------------+
13 | Author: Hartmut Holzgraefe <hholzgra@php.net> |
14 +----------------------------------------------------------------------+
15 */
16
17 #include "php.h"
18 #include "php_string.h"
19
20 /* {{{ reference_levdist
21 * reference implementation, only optimized for memory usage, not speed */
reference_levdist(const zend_string * string1,const zend_string * string2,zend_long cost_ins,zend_long cost_rep,zend_long cost_del)22 static zend_long reference_levdist(const zend_string *string1, const zend_string *string2, zend_long cost_ins, zend_long cost_rep, zend_long cost_del )
23 {
24 zend_long *p1, *p2, *tmp;
25 zend_long c0, c1, c2;
26 size_t i1, i2;
27
28 if (ZSTR_LEN(string1) == 0) {
29 return ZSTR_LEN(string2) * cost_ins;
30 }
31 if (ZSTR_LEN(string2) == 0) {
32 return ZSTR_LEN(string1) * cost_del;
33 }
34
35 p1 = safe_emalloc((ZSTR_LEN(string2) + 1), sizeof(zend_long), 0);
36 p2 = safe_emalloc((ZSTR_LEN(string2) + 1), sizeof(zend_long), 0);
37
38 for (i2 = 0; i2 <= ZSTR_LEN(string2); i2++) {
39 p1[i2] = i2 * cost_ins;
40 }
41 for (i1 = 0; i1 < ZSTR_LEN(string1) ; i1++) {
42 p2[0] = p1[0] + cost_del;
43
44 for (i2 = 0; i2 < ZSTR_LEN(string2); i2++) {
45 c0 = p1[i2] + ((ZSTR_VAL(string1)[i1] == ZSTR_VAL(string2)[i2]) ? 0 : cost_rep);
46 c1 = p1[i2 + 1] + cost_del;
47 if (c1 < c0) {
48 c0 = c1;
49 }
50 c2 = p2[i2] + cost_ins;
51 if (c2 < c0) {
52 c0 = c2;
53 }
54 p2[i2 + 1] = c0;
55 }
56 tmp = p1;
57 p1 = p2;
58 p2 = tmp;
59 }
60 c0 = p1[ZSTR_LEN(string2)];
61
62 efree(p1);
63 efree(p2);
64
65 return c0;
66 }
67 /* }}} */
68
69 /* {{{ Calculate Levenshtein distance between two strings */
PHP_FUNCTION(levenshtein)70 PHP_FUNCTION(levenshtein)
71 {
72 zend_string *string1, *string2;
73 zend_long cost_ins = 1;
74 zend_long cost_rep = 1;
75 zend_long cost_del = 1;
76
77 if (zend_parse_parameters(ZEND_NUM_ARGS(), "SS|lll", &string1, &string2, &cost_ins, &cost_rep, &cost_del) == FAILURE) {
78 RETURN_THROWS();
79 }
80
81
82 RETURN_LONG(reference_levdist(string1, string2, cost_ins, cost_rep, cost_del));
83 }
84 /* }}} */
85
