A nanoc filter for stripping blank lines.

strip_blank_lines.rb

module Nanoc::Filters

    class StripBlankLines < Nanoc::Filter

        identifier :strip_blank_lines

        def run(content, params={})
            count_pre = 0
            content.split("\n").each do |line|
                line << "\n"
            
                line.match('<pre>')  { |m| count_pre +=1 }
                line.match('</pre>') { |m| count_pre -=1 }
            
                line.match('<code>')  { |m| count_pre +=1 }
                line.match('</code>') { |m| count_pre -=1 }
            
                # if we're inside any number of <pre> blocks, skip the reduction            
                if 0 == count_pre
                    line.gsub!(/^\s*$/,'')  # zap empty lines
                end
            end.join('')
        end

    end

end