Multiple filters support for layouts.

[0x1eef]

Hello !

I would like to first say, thank you for all your work on nanoc. I love it ! This issue is a feature request (maybe it's already possible, but I couldn't figure out how).

I would like to apply multiple filters to a layout - at the moment I could only figure out how to apply one filter (eg erb). The reason is that I would like to run the erb filter, followed by a custom filter that minifies the result of the erb filter.

The solution I came up with is this - but it is less than ideal because it implies using erb all the time, and I didn't see an easy way to avoid that.

Gist:

# lib/filters/minify_filter.rb
class MinifyFilter < Nanoc::Filters::ERB
  identifier :minify_erb
  type :text

  def run(content, params={})
    content = super(content, params)
    file = tmp_write(content)
    run_minify(file.path)
    File.read(file.path).tap { file.tap(&:unlink).close }
  end

  private

  def run_minify(path)
    system "minify", path, "--type", "html", "-o", path
  end

  def content_dir
    source = config[:data_sources].find { _1[:type] == "filesystem" }
    source[:content_dir] || File.join(Dir.getwd, "content")
  end

  def tmp_write(content)
    file = Tempfile.new('minify')
    file.write(content)
    file.tap(&:flush)
  end
end


# Rules
layout '**/*', :minify_erb