less_converter.rb

module Jekyll
  # https://gist.github.com/jasongraham/639920
  # Compiled LESS CSS into CSS. You must specify an empty YAML front matter
  # at the beginning of the file.
  # .less -> .css
  class LessConverter < Converter
    safe true
    priority :low
    pygments_prefix "\n"
    pygments_suffix "\n"
 
    def setup
      return if @setup
      require 'less'
      @setup = true
    rescue LoadError
      STDERR.puts 'You are missing a library required for less. Please run:'
      STDERR.puts '  $ [sudo] gem install less'
      raise FatalException.new("Missing dependency: less")
    end
 
    def matches(ext)
      ext =~ /less/i
    end
 
    def output_ext(ext)
      ".css"
    end
 
    def convert(content)
      setup
      begin
        parser = Less::Parser.new()
        return parser.parse(content).to_css
      rescue => e
        puts "Less Exception: #{e.message}"
        raise e
      end
    end
  end
end