I want to make sure some string replacement's I'm running are multi byte safe. I've found a few mb_str_replace functions around the net but they're slow. I'm talking 20% increase after passing maybe 500-900 bytes through it.
Any recommendations? I'm thinking about using preg_replace as it's native and compiled in so it might be faster. Any thoughts would be appreciated.
As said there, str_replace is safe to use in utf-8 contexts, as long as all parameters are utf-8 valid, because it won't be any ambiguous match between both multibyte encoded strings. If you check the validity of your input, then you have no need to look for a different function.
As encoding is a real challenge when there are inputs from everywhere (utf8 or others), I prefer using only multibyte-safe functions. For str_replace, I am using this one which is fast enough.
if (!function_exists('mb_str_replace'))
{
function mb_str_replace($search, $replace, $subject, &$count = 0)
{
if (!is_array($subject))
{
$searches = is_array($search) ? array_values($search) : array($search);
$replacements = is_array($replace) ? array_values($replace) : array($replace);
$replacements = array_pad($replacements, count($searches), '');
foreach ($searches as $key => $search)
{
$parts = mb_split(preg_quote($search), $subject);
$count += count($parts) - 1;
$subject = implode($replacements[$key], $parts);
}
}
else
{
foreach ($subject as $key => $value)
{
$subject[$key] = mb_str_replace($search, $replace, $value, $count);
}
}
return $subject;
}
}
Here's my implementation, based off Alain's answer:
/**
* Replace all occurrences of the search string with the replacement string. Multibyte safe.
*
* @param string|array $search The value being searched for, otherwise known as the needle. An array may be used to designate multiple needles.
* @param string|array $replace The replacement value that replaces found search values. An array may be used to designate multiple replacements.
* @param string|array $subject The string or array being searched and replaced on, otherwise known as the haystack.
* If subject is an array, then the search and replace is performed with every entry of subject, and the return value is an array as well.
* @param string $encoding The encoding parameter is the character encoding. If it is omitted, the internal character encoding value will be used.
* @param int $count If passed, this will be set to the number of replacements performed.
* @return array|string
*/
public static function mbReplace($search, $replace, $subject, $encoding = 'auto', &$count=0) {
if(!is_array($subject)) {
$searches = is_array($search) ? array_values($search) : [$search];
$replacements = is_array($replace) ? array_values($replace) : [$replace];
$replacements = array_pad($replacements, count($searches), '');
foreach($searches as $key => $search) {
$replace = $replacements[$key];
$search_len = mb_strlen($search, $encoding);
$sb = [];
while(($offset = mb_strpos($subject, $search, 0, $encoding)) !== false) {
$sb[] = mb_substr($subject, 0, $offset, $encoding);
$subject = mb_substr($subject, $offset + $search_len, null, $encoding);
++$count;
}
$sb[] = $subject;
$subject = implode($replace, $sb);
}
} else {
foreach($subject as $key => $value) {
$subject[$key] = self::mbReplace($search, $replace, $value, $encoding, $count);
}
}
return $subject;
}
His doesn't accept a character encoding, although I suppose you could set it via mb_regex_encoding.
My unit tests pass:
function testMbReplace() {
$this->assertSame('bbb',Str::mbReplace('a','b','aaa','auto',$count1));
$this->assertSame(3,$count1);
$this->assertSame('ccc',Str::mbReplace(['a','b'],['b','c'],'aaa','auto',$count2));
$this->assertSame(6,$count2);
$this->assertSame("\xbf\x5c\x27",Str::mbReplace("\x27","\x5c\x27","\xbf\x27",'iso-8859-1'));
$this->assertSame("\xbf\x27",Str::mbReplace("\x27","\x5c\x27","\xbf\x27",'gbk'));
}
Top rated note on http://php.net/manual/en/ref.mbstring.php#109937 says str_replace works for multibyte strings.
