正则表达式匹配（评论除外）

Question

I'm trying to find all occurrences of some code unless that code is preceded by a comment.

Here's an example of what I want to find:

$page_content .= '<meta http-equiv="refresh"

or

$page_content .= 'Some other text here</p><meta http-equiv="refresh"

With or without preceding white space. Here's what I want to ignore

//$page_content .= '<meta http-equiv="refresh"

again with or without preceding white space.

That way I can be sure that my code base never contains this code unless it's in a comment or set up an automatic alert if it is found without getting false alerts for when its commented out (ignore multi-line comments for now).

I've tried using look behind

(?<!\/\/).*<meta http-equiv="refresh"

but I've not had much luck as this still matches every occurrence, commented or not.

One more thing: It would be great if it was in one regex rather in a loop of code so that I can search in Notepad++ or other editor that supports reg exp searches. (Its amazing how differently one question can be read/understood. I'd thought I'd been pretty clear but from the variety of completely valid answers its clear that I could have included a lot more detail :-)

Answer 1

Just remove the comment before checking for the string

while ( <$fh> ) {

    s|//.*||;

    if ( /<meta http-equiv="refresh"/ ) {
        ...;
    }
}

Answer 2

For the input specified in question :

//$page_content .= '<meta http-equiv="refresh"

This will do the thing:

use strict;

use warnings;


open my $fh, "<", "my_path\\data.txt";

while ( my $line = <$fh>) {
    if ( $line =~ /^(?!\/\/).*?<meta http-equiv=\"refresh\"/){
        print $line;
    }
}

If you have more spaces or other indent operators, use a look-behind operator: use strict;

use warnings;


open my $fh, "<", "c:\\users\\uidp7702\\desktop\\data.txt";

while ( my $line = <$fh>) {
    if ( $line =~ /(?<!\/\/)\$page_content\s.=\s\'.*?<meta http-equiv=\"refresh\"/){
        print $line;
    }
}