Best way to automatically remove comments from PHP code

What’s the best way to remove comments from a PHP file?

I want to do something similar to strip-whitespace() - but it shouldn't remove the line breaks as well.

For example,

I want this:

<?PHP
// something
if ($whatsit) {
    do_something(); # we do something here
    echo '<html>Some embedded HTML</html>';
}
/* another long
comment
*/
some_more_code();
?>

to become:

<?PHP
if ($whatsit) {
    do_something();
    echo '<html>Some embedded HTML</html>';
}
some_more_code();
?>

(Although if the empty lines remain where comments are removed, that wouldn't be OK.)

It may not be possible, because of the requirement to preserve embedded HTML - that’s what’s tripped up the things that have come up on Google.

Solution

I'd use tokenizer. Here's my solution. It should work on both PHP 4 and 5:

$fileStr = file_get_contents('path/to/file');
$newStr  = '';

$commentTokens = array(T_COMMENT);
    
if (defined('T_DOC_COMMENT')) {
    $commentTokens[] = T_DOC_COMMENT; // PHP 5
}

if (defined('T_ML_COMMENT')) {
    $commentTokens[] = T_ML_COMMENT;  // PHP 4
}

$tokens = token_get_all($fileStr);

foreach ($tokens as $token) {    
    if (is_array($token)) {
        if (in_array($token[0], $commentTokens)) {
            continue;
        }
        
        $token = $token[1];
    }

    $newStr .= $token;
}

echo $newStr;