Jekyll plugin to compile *.less to *.css by using Less.js

less_css_js.rb

require 'open3'

module LessCssJS
  class LessCssGenerator < Jekyll::Generator
    def generate(site)
      site.static_files.clone.each { |f|
        if f.kind_of?(Jekyll::StaticFile) and File.extname(f.path) == '.less'
          css = LessCssFile.new(site, f)
          site.static_files.delete(f)
          site.static_files << css
        end
      }
    end
  end

  class LessCssFile < Jekyll::StaticFile
    def initialize(site, sfile)
      dir = File.dirname(sfile.path).sub(site.source, '')
      name = File.basename(sfile.path)
      super(site, site.source, dir, name)
    end

    def destination(dest)
      return File.join(dest, @dir, @name.sub(/less$/, 'css'))
    end

    def write(dest)
      dest_path = destination(dest)

      #return false if File.exist?(dest_path) and !modified?
      @@mtimes[path] = mtime

      FileUtils.mkdir_p(File.dirname(dest_path))

      # Determine include path.
      includes = [ '_lesscss' ]
      if RUBY_PLATFORM =~ /(mswin|mingw|cygwin|bccwin)/
        ipath = includes.join(';')
      else
        ipath = includes.join(':')
      end

      # Execute lessc command.
      cmd = "lessc --no-color --include-path=#{ipath} #{path} #{dest_path}"
      out, err, status = Open3.capture3(cmd);
      if status.exitstatus != 0
        raise "Lesscss failed.\n#{err}"
      end

      return true
    end
  end
end