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Dust-Me CSV to CSS with Rake

Posted by Sandro Paganotti in Ruby on Rails - comments are closed

Have you ever tried Dust-Me Selectors ? It is a Firefox Add-On that parse your CSS file against the pages of your website and return a list of unused selectors.

The problem is that this add-on has only a CSV export feature which let you save the list of unused selectors in a plain file. Next you have to manually find each line in you CSS file and delete it (ARGH!).

I’ve wrote a rake task to fix this problem; you can call it with the command:

rake eraser:css FILENAME="path/to/exported/csv/file.csv" 

and it create a new CSS file (named “mod_” + original_file_name) containing only the used selectors!

Here is the task code, it is still in beta but seems working well, anyway check the css generated code before use.

namespace :eraser do

  task :css => :environment do

    tmp_cols = File.open(ENV["FILENAME"],"r"){|f| f.collect{|e| e.split(",")}}
    cols = Array.new(tmp_cols[0].length)
    tmp_cols.each do |e|
      cols.each_index do |i|
        cols[i] = Array.new if cols[i].nil?
        cols[i] << e[i].to_s
      end
    end 

    cols.each_index do |index|
      cols[index][0] =~ Regexp.new("\\/([^\\?\\/]+)(\\?|$)")
      filename = $1
      cols[index][0] = filename
      cols[index][1] = File.open(File.join(RAILS_ROOT,"public","stylesheets",filename), "r"){ |file| file.collect{|e| e}.join("\n")}
    end

    cols.each do |lines|
      lines.each do |l|
        if (not l.strip.blank?) and (not (l == lines[1] or l == lines[0]))
          puts "Deleting: " + l
          rexp =  Regexp.new("^(.*)#{l},*(.*" +"\\{[^\\}]*\\})")
          lines[1] =~ rexp
          before = $1.to_s
          after = $2.to_s
          if before.strip.blank? and (after.split("{"))[0].to_s.strip.blank?
            lines[1].sub!(rexp,"")
          else
            lines[1].sub!(rexp,before+after).sub!(/, *\{/,"{")
          end
        end
      end
    end

    puts "creating modded file" 
    cols.each do |e|
      File.open(File.join(RAILS_ROOT,"public","stylesheets","mod_"+e[0]), "w") do |f|
        f.write(e[1])
      end
    end

  end
end

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