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132 lines
3.8 KiB
C
132 lines
3.8 KiB
C
/*
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+----------------------------------------------------------------------+
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| Copyright (c) The PHP Group |
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+----------------------------------------------------------------------+
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| This source file is subject to version 3.01 of the PHP license, |
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| that is bundled with this package in the file LICENSE, and is |
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| available through the world-wide-web at the following url: |
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| http://www.php.net/license/3_01.txt |
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| If you did not receive a copy of the PHP license and are unable to |
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| obtain it through the world-wide-web, please send a note to |
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| license@php.net so we can mail you a copy immediately. |
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+----------------------------------------------------------------------+
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| Author: Hartmut Holzgraefe <hholzgra@php.net> |
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+----------------------------------------------------------------------+
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*/
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#include "php.h"
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#include <stdlib.h>
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#include <errno.h>
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#include <ctype.h>
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#include "php_string.h"
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#define LEVENSHTEIN_MAX_LENGTH 255
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/* {{{ reference_levdist
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* reference implementation, only optimized for memory usage, not speed */
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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 )
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{
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zend_long *p1, *p2, *tmp;
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zend_long c0, c1, c2;
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size_t i1, i2;
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if (l1 == 0) {
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return l2 * cost_ins;
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}
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if (l2 == 0) {
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return l1 * cost_del;
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}
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if ((l1 > LEVENSHTEIN_MAX_LENGTH) || (l2 > LEVENSHTEIN_MAX_LENGTH)) {
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return -1;
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}
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p1 = safe_emalloc((l2 + 1), sizeof(zend_long), 0);
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p2 = safe_emalloc((l2 + 1), sizeof(zend_long), 0);
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for (i2 = 0; i2 <= l2; i2++) {
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p1[i2] = i2 * cost_ins;
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}
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for (i1 = 0; i1 < l1 ; i1++) {
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p2[0] = p1[0] + cost_del;
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for (i2 = 0; i2 < l2; i2++) {
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c0 = p1[i2] + ((s1[i1] == s2[i2]) ? 0 : cost_rep);
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c1 = p1[i2 + 1] + cost_del;
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if (c1 < c0) {
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c0 = c1;
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}
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c2 = p2[i2] + cost_ins;
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if (c2 < c0) {
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c0 = c2;
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}
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p2[i2 + 1] = c0;
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}
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tmp = p1;
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p1 = p2;
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p2 = tmp;
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}
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c0 = p1[l2];
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efree(p1);
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efree(p2);
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return c0;
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}
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/* }}} */
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/* {{{ custom_levdist
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*/
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static int custom_levdist(char *str1, char *str2, char *callback_name)
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{
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php_error_docref(NULL, E_WARNING, "The general Levenshtein support is not there yet");
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/* not there yet */
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return -1;
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}
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/* }}} */
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/* {{{ proto int levenshtein(string str1, string str2[, int cost_ins, int cost_rep, int cost_del])
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Calculate Levenshtein distance between two strings */
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PHP_FUNCTION(levenshtein)
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{
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int argc = ZEND_NUM_ARGS();
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char *str1, *str2;
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char *callback_name;
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size_t str1_len, str2_len, callback_len;
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zend_long cost_ins, cost_rep, cost_del;
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zend_long distance = -1;
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switch (argc) {
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case 2: /* just two strings: use maximum performance version */
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if (zend_parse_parameters(2, "ss", &str1, &str1_len, &str2, &str2_len) == FAILURE) {
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RETURN_THROWS();
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}
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distance = reference_levdist(str1, str1_len, str2, str2_len, 1, 1, 1);
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break;
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case 5: /* more general version: calc cost by ins/rep/del weights */
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if (zend_parse_parameters(5, "sslll", &str1, &str1_len, &str2, &str2_len, &cost_ins, &cost_rep, &cost_del) == FAILURE) {
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RETURN_THROWS();
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}
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distance = reference_levdist(str1, str1_len, str2, str2_len, cost_ins, cost_rep, cost_del);
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break;
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case 3: /* most general version: calc cost by user-supplied function */
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if (zend_parse_parameters(3, "sss", &str1, &str1_len, &str2, &str2_len, &callback_name, &callback_len) == FAILURE) {
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RETURN_THROWS();
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}
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distance = custom_levdist(str1, str2, callback_name);
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break;
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default:
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WRONG_PARAM_COUNT;
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}
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if (distance < 0 && /* TODO */ ZEND_NUM_ARGS() != 3) {
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php_error_docref(NULL, E_WARNING, "Argument string(s) too long");
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}
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RETURN_LONG(distance);
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}
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/* }}} */
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