Question

First question from a long time user.

I’m writing a Perl script that will go through a number of HTML files, search them line-by-line for instances of “color:” or “background-color:” (the CSS tags) and print the entire line when it comes across one of these instances. This is fairly straightforward.

Now I’ll admit I’m still a beginning programmer, so this next part may be extremely obvious, but that’s why I came here :).

What I want it to do is when it finds an instance of “color:” or “background-color:” I want it to trace back and find the name of the element, and print that as well. For example:

If my document contained the following CSS:

.css_class {
    font-size: 18px;
    font-weight: bold;
    color: #FFEFA1;
        font-family: Arial, Helvetica, sans-serif;
}

I would want the script to output something like:

css_class,#FFEFA1

Ideally it would output this as a text file.

I would greatly appreciate any advice that could be given to me regarding this!

Here is my script in full thus far:

$color = "color:";


open (FILE, "index.html");  
@document = `<FILE>`;  
close (FILE);  

foreach $line (@document){  
    if($line =~ /$color/){  
        print $line;  
    }  
}   

Answer 1

Since you asked for advice (and this isn’t a coding service) I’ll offer just that.

Always use strictures and warnings:

use strict;
use warnings;

Always check the return value of open calls:

open(FILE, 'filename') or die "Can't read file 'filename' [$!]\n";

Use the three-arg form of open and lexical filehandles instead of globs:

open(my $fh, '<', 'filename') or die "Can't read file 'filename' [$!]\n";

Don’t slurp when line-by-line processing will do:

while (my $line = <$fh>) {
    # do something with $line
}

Use backreferences to retrieve data from regex matches:

if ($line =~ /color *: *(#[0-9a-fA-F]{6})/) {
    # color value is in $1
}

Save the class name in a temporary variable so that you have it when you match a color:

if ($line =~ /^.(\w+) *\{/) {
    $class = $1;
}