PHP MIMEType class

Question

There isn't a very reliable way (in my opinion) to get the mime type of a specific extension, regardless of the file actually being of that type or not.

This type of thing usually is used when sending a different Content-type when you intend to send, for example, an image.

class MIMETypes {
 /**
 * @var string Contains the default type when none is found
 * @access protected
 */
 static private $default='application/octet-stream';
 /**
 * @var array Contains all the mime types and extensions
 * @access protected
 */
 static private $mimes=array(
 'text'=>array(
 'plain'=>array(
 'php','php5','php4','php3','inc','sphp','phps','phtml',
 'htm','html',
 'txt'
 )
 ),
 'audio'=>array(
 'aac'=>array('aac'),
 'midi'=>array('mid','midi'),
 'mp4'=>array('mp4','m4a'),
 'mpeg'=>array('m2a','mp1','mp2','mp3','mp4','mpg','mpeg','mpa','mpga'),
 'ogg'=>array('oga','ogg'),
 'wav'=>array('wav','wave','pcm'),
 'webm'=>array('webm'),
 'x-mpequrl'=>array('m3u')
 ),
 'video'=>array(
 'mp4'=>array('mp4','m4v','m1v','m2v'),
 'ogg'=>array('ogv'),
 'webm'=>array('webm')
 )
 );
 /**
 * @var array Contains the last accessed contents and comes pre-initialized with some extensions and mime types that didn't matched
 * @access protected
 */ 
 static private $cache=array(
 'ext'=>array(
 'txt'=>array('plain/text')
 ),
 'mime'=>array(
 '*/*'=>array()
 )
 );
 /**
 * Creates a list of matching mime types for that file extension
 * @param string $ext The extension to look for
 * @param string|null $hint Hint to reduce the search load for only that mime "group"<br/>
 * *WARNING*: Setting this parameter will ignore the cache!
 * @return array An array with the multiple mime types
 */
 static function fromExt( $ext, $hint=null )
 {
 //this will have all matched mime types
 $exts = array();
 //clean up the $ext var, to hold nothing but an extension
 $ext = preg_replace( '@^(?:.*\.)*([^.\\]+)$@', '1ドル', $ext );
 if( func_num_args() > 1 )
 {
 $hint = strtolower( trim($hint) );
 foreach( self::$mimes[$hint] as $mime=>$types)
 {
 if( in_array( $ext, $types) )
 {
 $exts[] = $hint . '/' . $mime;
 }
 }
 }
 else if( self::$cache['ext'][$ext] )
 {
 return self::$cache['ext'][$ext];
 }
 else
 {
 foreach( self::$mimes as $mime=>$mimes)
 {
 foreach( $mimes as $type=>$types)
 {
 if( in_array( $ext, $list) )
 {
 $exts[] = $mime . '/' . $type;
 }
 }
 }
 if(!$exts)
 {
 $exts=array( self::$default );
 }
 }
 return self::$cache['ext'][$ext] = $exts;
 }
 /**
 * Creates a list of matching extensions for that mime type
 * @param string $mime The extension to look for
 * @return array An array with the multiple extensions
 */
 static function fromMIME( $mime )
 {
 //'clean' blindly-exploded mime type 
 $mime_c=explode('/', $mime, 2);
 if( self::$cache['mime'][$mime] )
 {
 return array(); //self::$cache['mime'][$mime];
 }
 else if( self::$mimes[$mime_c[0]] )
 {
 return self::$mimes[$mime_c[0]][$mime_c[1]];
 }
 else
 {
 return self::$cache['mime'][$mime] = array();
 }
 }
}

The functioning of the class is complete, but I'm aware that there are lots of missing mime types like the image/* or application/*.

What can I do to improve my code in quality and make a better class and (maybe) make it production-ready?

What should I improve in terms of performance?

• Professor of programming: What if you have two different mime types that share the same file extension? This is a possibility. Personally, I would determine the mime type based on the data contain in the file, and cache the findings. Then when the file is requested, get the mime type from the cache.
• Ismael Miguel: @Bonner If you already have a 'hint' on what mime type the file will have (if you are dealing with audio files, for example), you can set the 2nd parameter on the method fromExt(). E.g.: MIMETypes::fromExt('mp4','audio') and it should return an array with only 1 mime type. If you don't set, it will return an array with all the mime types matching that extension. An example would be the extension mp4 (MIMETypes::fromExt('mp4')) which will return an array containing the mime types audio/mp4 and video/mp4.

Answer 1

This is mostly a style review, but I'll be back to work on it further later.

---

Your usage of whitespace leaves a bit to be desired.

1. You should have whitespace in between your key => value, rather than none.
2. You should have spaces between commas
3. You should have spaces in between your binary operators static private $default='application/octet-stream'
4. You shouldn't have whitespace before and after your brackets

---

You should consider moving the regex statement in the following line to an external variable.

$ext = preg_replace( '@^(?:.*\.)*([^.\\]+)$@', '1ドル', $ext );