Question

I would like to preg_replace some text but only if it’s not commented. Here’s an example of a given text:

// delete_me('First');
delete_me('Second');
/* delete_me('Third'); */
delete_me('Fourth'); // Some comment behind a command.
/* Tiny bit of comment */ delete_me('Fifth');

Now in this example I would only want the second, fourth and fifth row to be replaced. I want to replace the parameter with a new one. All the text is in one big string, separated by newlines.

I do have some preg_replaces to remove comment sections, but since I don’t want to delete them it’s not much use, but perhaps it helps someone helping me.

$text = preg_replace("/\/\/(.*)/", $replace, $text);
$text = preg_replace('!/\*(.*)\*/!s', $replace, $text);

Can anyone help me to replace the given parameters on lines that are not PHP commented? Thanks!

Answer 1

First split the text into chunks of comment and non-comment, then only alter the non-comment pieces, and finally glue them together:

$in = "// delete_me('First');
delete_me('Second');
/* delete_me('Third'); */
delete_me('Fourth'); // Some comment behind a command.
/* Tiny bit of comment */ delete_me('Fifth');\n";

$split = preg_split("#(//[^\n]*\n|/\\*.*?\\*/)#s",$in,-1,PREG_SPLIT_DELIM_CAPTURE);

foreach ( $split as $i=>$chunk )
{
    if ( $i%2==0 )
    {
        $split[$i] = preg_replace("/'.*?'/","'newparam'",$chunk);
    }
}

echo implode($split);

output:

// delete_me('First');
delete_me('newparam');
/* delete_me('Third'); */
delete_me('newparam'); // Some comment behind a command.
/* Tiny bit of comment */ delete_me('newparam');

The trick here is that the pattern supplied to preg_split matches the comment blocks, so you get an array of even/odd pieces of code/comment.

caveat This will of course break when you would put /* in a string literal.