mb_str_replace（）...很慢。任何替代品？

Question

我想确保我正在运行的一些字符串替换是多字节安全的。我在网络上发现了一些mb_str_replace函数，但它们很慢。在通过500-900字节之后，我会说增加20％。

有什么建议吗？我正在考虑使用preg_replace，因为它是原生的并且被编译进来，所以它可能会更快。任何想法将不胜感激。

Answer 1

正如所说的there，只要所有参数都是utf-8有效，就可以安全地在utf-8上下文中使用str_replace，因为这两个多字节编码字符串之间不会有任何模糊的匹配。如果你检查输入的有效性，那么你不需要寻找一个不同的功能。

Answer 2

由于编码是来自任何地方（utf8或其他）的输入的真正挑战，我更喜欢只使用多字节安全函数。对于str_replace，我使用的是this one，它足够快。

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; 
    } 
} 

Answer 3

这里是我的实现，基于断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; 
} 

他不接受字符编码，但我想你可以通过mb_regex_encoding设置。

我的单元测试都通过了：

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')); 
}