class Sass::Plugin::Compiler

def on_file_changed(individual_files, modified, added, removed)
  recompile_required = false
  modified.uniq.each do |f|
    next unless watched_file?(f)
    recompile_required = true
    run_template_modified(relative_to_pwd(f))
  end
  added.uniq.each do |f|
    next unless watched_file?(f)
    recompile_required = true
    run_template_created(relative_to_pwd(f))
  end
  removed.uniq.each do |f|
    next unless watched_file?(f)
    run_template_deleted(relative_to_pwd(f))
    if (files = individual_files.find {|(source, _, _)| File.expand_path(source) == f})
      recompile_required = true
      # This was a file we were watching explicitly and compiling to a particular location.
      # Delete the corresponding file.
      try_delete_css files[1]
    else
      next unless watched_file?(f)
      recompile_required = true
      # Look for the sass directory that contained the sass file
      # And try to remove the css file that corresponds to it
      template_location_array.each do |(sass_dir, css_dir)|
        sass_dir = File.expand_path(sass_dir)
        next unless child_of_directory?(sass_dir, f)
        remainder = f[(sass_dir.size + 1)..-1]
        try_delete_css(css_filename(remainder, css_dir))
        break
      end
    end
  end
  return unless recompile_required
  # In case a file we're watching is removed and then recreated we
  # prune out the non-existant files here.
  watched_files_remaining = individual_files.select {|(source, _, _)| File.exist?(source)}
  update_stylesheets(watched_files_remaining)
end