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Refactor levenshtein() #5816

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c00e0fa
Refactor levenshtein()
Girgias Jul 6, 2020
9b823f6
Pass zend_string to underlying implementation function
Girgias Jul 6, 2020
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2 changes: 1 addition & 1 deletion ext/standard/basic_functions.stub.php
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Original file line number Diff line number Diff line change
Expand Up @@ -985,7 +985,7 @@ function iptcparse(string $iptcblock): array|false {}

/* levenshtein.c */

function levenshtein(string $str1, string $str2, $cost_ins = UNKNOWN, int $cost_rep = UNKNOWN, int $cost_del = UNKNOWN): int {}
function levenshtein(string $str1, string $str2, int $cost_ins = 1, int $cost_rep = 1, int $cost_del = 1): int {}

/* link.c */

Expand Down
8 changes: 4 additions & 4 deletions ext/standard/basic_functions_arginfo.h
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/* This is a generated file, edit the .stub.php file instead.
* Stub hash: 9cf2c691c081d9aaefaa9d22337a9e00efb0af77 */
* Stub hash: 05b740207a70a9d272b4c327882fd0b52016a0af */

ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_set_time_limit, 0, 1, _IS_BOOL, 0)
ZEND_ARG_TYPE_INFO(0, seconds, IS_LONG, 0)
Expand Down Expand Up @@ -1568,9 +1568,9 @@ ZEND_END_ARG_INFO()
ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_levenshtein, 0, 2, IS_LONG, 0)
ZEND_ARG_TYPE_INFO(0, str1, IS_STRING, 0)
ZEND_ARG_TYPE_INFO(0, str2, IS_STRING, 0)
ZEND_ARG_INFO(0, cost_ins)
ZEND_ARG_TYPE_INFO(0, cost_rep, IS_LONG, 0)
ZEND_ARG_TYPE_INFO(0, cost_del, IS_LONG, 0)
ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, cost_ins, IS_LONG, 0, "1")
ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, cost_rep, IS_LONG, 0, "1")
ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, cost_del, IS_LONG, 0, "1")
ZEND_END_ARG_INFO()

#if defined(HAVE_SYMLINK) || defined(PHP_WIN32)
Expand Down
90 changes: 29 additions & 61 deletions ext/standard/levenshtein.c
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Expand Up @@ -15,42 +15,36 @@
*/

#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 )
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 )
{
zend_long *p1, *p2, *tmp;
zend_long c0, c1, c2;
size_t i1, i2;

if (l1 == 0) {
return l2 * cost_ins;
if (ZSTR_LEN(string1) == 0) {
return ZSTR_LEN(string2) * cost_ins;
}
if (l2 == 0) {
return l1 * cost_del;
if (ZSTR_LEN(string2) == 0) {
return ZSTR_LEN(string1) * 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);
p1 = safe_emalloc((ZSTR_LEN(string2) + 1), sizeof(zend_long), 0);
p2 = safe_emalloc((ZSTR_LEN(string2) + 1), sizeof(zend_long), 0);

for (i2 = 0; i2 <= l2; i2++) {
for (i2 = 0; i2 <= ZSTR_LEN(string2); i2++) {
p1[i2] = i2 * cost_ins;
}
for (i1 = 0; i1 < l1 ; i1++) {
for (i1 = 0; i1 < ZSTR_LEN(string1) ; i1++) {
p2[0] = p1[0] + cost_del;

for (i2 = 0; i2 < l2; i2++) {
c0 = p1[i2] + ((s1[i1] == s2[i2]) ? 0 : cost_rep);
for (i2 = 0; i2 < ZSTR_LEN(string2); i2++) {
c0 = p1[i2] + ((ZSTR_VAL(string1)[i1] == ZSTR_VAL(string2)[i2]) ? 0 : cost_rep);
c1 = p1[i2 + 1] + cost_del;
if (c1 < c0) {
c0 = c1;
Expand All @@ -65,7 +59,7 @@ static zend_long reference_levdist(const char *s1, size_t l1, const char *s2, si
p1 = p2;
p2 = tmp;
}
c0 = p1[l2];
c0 = p1[ZSTR_LEN(string2)];

efree(p1);
efree(p2);
Expand All @@ -74,58 +68,32 @@ static zend_long reference_levdist(const char *s1, size_t l1, const char *s2, si
}
/* }}} */

/* {{{ 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;
zend_string *string1, *string2;
zend_long cost_ins = 1;
zend_long cost_rep = 1;
zend_long cost_del = 1;
zend_long distance = 0;

if (zend_parse_parameters(ZEND_NUM_ARGS(), "SS|lll", &string1, &string2, &cost_ins, &cost_rep, &cost_del) == FAILURE) {
RETURN_THROWS();
}

default:
WRONG_PARAM_COUNT;
if (ZSTR_LEN(string1) > LEVENSHTEIN_MAX_LENGTH) {
zend_argument_value_error(1, "must be less than %d characters", LEVENSHTEIN_MAX_LENGTH + 1);
RETURN_THROWS();
}

if (distance < 0 && /* TODO */ ZEND_NUM_ARGS() != 3) {
php_error_docref(NULL, E_WARNING, "Argument string(s) too long");
if (ZSTR_LEN(string2) > LEVENSHTEIN_MAX_LENGTH) {
zend_argument_value_error(2, "must be less than %d characters", LEVENSHTEIN_MAX_LENGTH + 1);
RETURN_THROWS();
}

distance = reference_levdist(string1, string2, cost_ins, cost_rep, cost_del);

RETURN_LONG(distance);
}
/* }}} */
123 changes: 54 additions & 69 deletions ext/standard/tests/strings/levenshtein.phpt
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Expand Up @@ -3,76 +3,61 @@ levenshtein() function test
--FILE--
<?php

function test_me($title,$expect,$text1,$text2,$cost1="",$cost2="",$cost3="") {

if ($cost1=="") {
$result=levenshtein($text1,$text2);
}
elseif ($cost2=="") {
$result=levenshtein($text1,$text2,$cost1);
}
else {
$result=levenshtein($text1,$text2,$cost1,$cost2,$cost3);
}
if($result==$expect) return 0;

echo "$title: result is $result instead of $expect ";
echo "for '$text1'/'$text2' ";
if($cost1) echo "($cost1:$cost2:$cost3)";
echo "\n";

return 1;
}

$n=0;

$n += test_me("equal" , 0, "12345", "12345");
$n += test_me("1st empty" , 3, "", "xzy");
$n += test_me("2nd empty" , 3, "xzy", "");
$n += test_me("both empty" , 0, "", "");
$n += test_me("1 char" , 1, "1", "2");
$n += test_me("2 char swap", 2, "12", "21");

$n += test_me("inexpensive delete", 2, "2121", "11", 2, 1, 1);
$n += test_me("expensive delete" , 10, "2121", "11", 2, 1, 5);
$n += test_me("inexpensive insert", 2, "11", "2121", 1, 1, 1);
$n += test_me("expensive insert" , 10, "11", "2121", 5, 1, 1);

$n += test_me("expensive replace" , 3, "111", "121", 2, 3, 2);
$n += test_me("very expensive replace", 4, "111", "121", 2, 9, 2);

$n += test_me("bug #7368", 2, "13458", "12345");
$n += test_me("bug #7368", 2, "1345", "1234");

$n += test_me("bug #6562", 1, "debugg", "debug");
$n += test_me("bug #6562", 1, "ddebug", "debug");
$n += test_me("bug #6562", 2, "debbbug", "debug");
$n += test_me("bug #6562", 1, "debugging", "debuging");

$n += test_me("bug #16473", 2, "a", "bc");
$n += test_me("bug #16473", 2, "xa", "xbc");
$n += test_me("bug #16473", 2, "xax", "xbcx");
$n += test_me("bug #16473", 2, "ax", "bcx");

$n += test_me("custom", -1, "111", "121", "my_levcode");
$n += test_me("lt maxlength1", 254, "AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsu", "A");
$n += test_me("gt maxlength1", -1, "AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuv", "A");

$n += test_me("lt maxlength2", 254, "A", "AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsu");
$n += test_me("gt maxlength2", -1, "A", "AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuv");

echo ($n==0)?"all passed\n":"$n failed\n";

var_dump(levenshtein("", "", -1, -1, -1));
var_dump(levenshtein("", "", 10, 10, 10));
echo '--- Equal ---' . \PHP_EOL;
var_dump(levenshtein('12345', '12345'));

echo '--- First string empty ---' . \PHP_EOL;
var_dump(levenshtein('', 'xyz'));
echo '--- Second string empty ---' . \PHP_EOL;
var_dump(levenshtein('xyz', ''));
echo '--- Both empty ---' . \PHP_EOL;
var_dump(levenshtein('', ''));
var_dump(levenshtein('', '', 10, 10, 10));

echo '--- 1 character ---' . \PHP_EOL;
var_dump(levenshtein('1', '2'));
echo '--- 2 character swapped ---' . \PHP_EOL;
var_dump(levenshtein('12', '21'));

echo '--- Inexpensive deletion ---' . \PHP_EOL;
var_dump(levenshtein('2121', '11', 2));
echo '--- Expensive deletion ---' . \PHP_EOL;
var_dump(levenshtein('2121', '11', 2, 1, 5));

echo '--- Inexpensive insertion ---' . \PHP_EOL;
var_dump(levenshtein('11', '2121'));
echo '--- Expensive insertion ---' . \PHP_EOL;
var_dump(levenshtein('11', '2121', 5));

echo '--- Expensive replacement ---' . \PHP_EOL;
var_dump(levenshtein('111', '121', 2, 3, 2));
echo '--- Very expensive replacement ---' . \PHP_EOL;
var_dump(levenshtein('111', '121', 2, 9, 2));

?>
--EXPECTF--
Warning: levenshtein(): The general Levenshtein support is not there yet in %s on line %d

Warning: levenshtein(): Argument string(s) too long in %s on line %d

Warning: levenshtein(): Argument string(s) too long in %s on line %d
all passed
--EXPECT--
--- Equal ---
int(0)
--- First string empty ---
int(3)
--- Second string empty ---
int(3)
--- Both empty ---
int(0)
int(0)
--- 1 character ---
int(1)
--- 2 character swapped ---
int(2)
--- Inexpensive deletion ---
int(2)
--- Expensive deletion ---
int(10)
--- Inexpensive insertion ---
int(2)
--- Expensive insertion ---
int(10)
--- Expensive replacement ---
int(3)
--- Very expensive replacement ---
int(4)
16 changes: 16 additions & 0 deletions ext/standard/tests/strings/levenshtein_bug_16473.phpt
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@@ -0,0 +1,16 @@
--TEST--
levenshtein() bug 16473
--FILE--
<?php

var_dump(levenshtein('a', 'bc'));
var_dump(levenshtein('xa', 'xbc'));
var_dump(levenshtein('xax', 'xbcx'));
var_dump(levenshtein('ax', 'bcx'));

?>
--EXPECT--
int(2)
int(2)
int(2)
int(2)
16 changes: 16 additions & 0 deletions ext/standard/tests/strings/levenshtein_bug_6562.phpt
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@@ -0,0 +1,16 @@
--TEST--
levenshtein() bug 6562
--FILE--
<?php

var_dump(levenshtein('debugg', 'debug'));
var_dump(levenshtein('ddebug', 'debug'));
var_dump(levenshtein('debbbug', 'debug'));
var_dump(levenshtein('debugging', 'debuging'));

?>
--EXPECT--
int(1)
int(1)
int(2)
int(1)
12 changes: 12 additions & 0 deletions ext/standard/tests/strings/levenshtein_bug_7368.phpt
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@@ -0,0 +1,12 @@
--TEST--
levenshtein() bug 7368
--FILE--
<?php

var_dump(levenshtein('13458', '12345'));
var_dump(levenshtein('1345', '1234'));

?>
--EXPECT--
int(2)
int(2)
31 changes: 31 additions & 0 deletions ext/standard/tests/strings/levenshtein_error_conditions.phpt
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@@ -0,0 +1,31 @@
--TEST--
levenshtein() error conditions
--FILE--
<?php

echo '--- String 1 ---' . \PHP_EOL;
var_dump(levenshtein('AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsu', 'A'));
try {
var_dump(levenshtein('AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuv', 'A'));
} catch (\ValueError $e) {
echo $e->getMessage() . \PHP_EOL;
}
echo '--- String 2 ---' . \PHP_EOL;
var_dump(levenshtein('A', 'AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsu'));
try {
var_dump(levenshtein('A', 'AbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrstuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuvwxyzAbcdefghijklmnopqrtsuv'));
} catch (\ValueError $e) {
echo $e->getMessage() . \PHP_EOL;
}

// TODO ValueError for negative costs?
// var_dump(levenshtein("", "", -1, -1, -1));

?>
--EXPECT--
--- String 1 ---
int(254)
levenshtein(): Argument #1 ($str1) must be less than 256 characters
--- String 2 ---
int(254)
levenshtein(): Argument #2 ($str2) must be less than 256 characters