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|
/*
+----------------------------------------------------------------------+
| PHP version 4.0 |
+----------------------------------------------------------------------+
| Copyright (c) 1997-2001 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"
#define LEVENSHTEIN_MAX_LENTH 255
/* {{{ reference_levdist
* reference implementation, only optimized for memory usage, not speed */
static int reference_levdist(const char *s1, int l1,
const char *s2, int l2,
int cost_ins, int cost_rep, int cost_del )
{
int *p1, *p2, *tmp;
int i1, i2, c0, c1, c2;
if(l1==0) return l2*cost_ins;
if(l2==0) return l1*cost_del;
if((l1>LEVENSHTEIN_MAX_LENTH)||(l2>LEVENSHTEIN_MAX_LENTH))
return -1;
if(!(p1=emalloc(l2*sizeof(int)))) {
return -2;
}
if(!(p2=emalloc(l2*sizeof(int)))) {
free(p1);
return -2;
}
p1[0]=(s1[0]==s2[0])?0:cost_rep;
for(i2=1;i2<l2;i2++)
p1[i2]=i2*cost_ins;
for(i1=1;i1<l1;i1++)
{
p2[0]=i1*cost_del;
for(i2=1;i2<l2;i2++)
{
c0=p1[i2-1]+((s1[i1]==s2[i2])?0:cost_rep);
c1=p1[i2]+cost_del; if(c1<c0) c0=c1;
c2=p2[i2-1]+cost_ins; if(c2<c0) c0=c2;
p2[i2]=c0;
}
tmp=p1; p1=p2; p2=tmp;
}
c0=p1[l2-1];
efree(p1);
efree(p2);
return c0;
}
/* }}} */
/* {{{ custom_levdist
*/
static int custom_levdist(char *str1, char *str2, char *callback_name)
{
php_error(E_WARNING, "the general Levenshtein support is not there yet");
/* not there yet */
return -1;
}
/* }}} */
/* {{{ proto int levenshtein(string str1, string str2)
Calculate Levenshtein distance between two strings */
PHP_FUNCTION(levenshtein)
{
zval **str1, **str2, **cost_ins, **cost_rep, **cost_del, **callback_name;
int distance=-1;
switch(ZEND_NUM_ARGS()) {
case 2: /* just two string: use maximum performance version */
if (zend_get_parameters_ex(2, &str1, &str2) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_string_ex(str1);
convert_to_string_ex(str2);
distance = reference_levdist((*str1)->value.str.val, (*str1)->value.str.len,
(*str2)->value.str.val, (*str2)->value.str.len,
1, 1, 1);
break;
case 5: /* more general version: calc cost by ins/rep/del weights */
if (zend_get_parameters_ex(5, &str1, &str2, &cost_ins, &cost_rep, &cost_del) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_string_ex(str1);
convert_to_string_ex(str2);
convert_to_long_ex(cost_ins);
convert_to_long_ex(cost_rep);
convert_to_long_ex(cost_del);
distance = reference_levdist((*str1)->value.str.val, (*str1)->value.str.len,
(*str2)->value.str.val, (*str2)->value.str.len,
(*cost_ins)->value.lval,
(*cost_rep)->value.lval,
(*cost_del)->value.lval
);
break;
case 3: /* most general version: calc cost by user-supplied function */
if (zend_get_parameters_ex(3, &str1, &str2, &callback_name) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_string_ex(str1);
convert_to_string_ex(str2);
convert_to_string_ex(callback_name);
distance = custom_levdist((*str1)->value.str.val
, (*str2)->value.str.val
, (*callback_name)->value.str.val
);
break;
default:
WRONG_PARAM_COUNT;
}
if(distance<0) {
php_error(E_WARNING, "levenshtein(): argument string(s) too long");
}
RETURN_LONG(distance);
}
/* }}} */
/*
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* End:
* vim600: sw=4 ts=4 tw=78 fdm=marker
* vim<600: sw=4 ts=4 tw=78
*/
|
