Jekyll navigation generator for bootstrap

_generate_navigation.rb

# Auto-generates navigation -- bootstrap based
# <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
#      <ul class="nav navbar-nav">
#        {% generate_navigation %}
#      </ul>
#    </div><!-- /.navbar-collapse -->
# based on https://gist.github.com/jamtur01/2759606

require 'pathname'

module Jekyll
  class Page
    def source_path
      File.join(@dir, @name).sub(%r{^/*},'')
    end
    def parent
      @dir.sub(%r{^/*},'')
    end
  end
  class IncludeListingTag < Liquid::Tag
    def initialize(tag_name, markup, tokens)
      super
    end

    def add_item(page)
      if page.index?
        title = page.parent
      else
        title = page.basename
      end

      # Try to read title from source file
      source_file = File.join(@source,page.source_path)
      if File.exists?(source_file)
        content = File.read(source_file)

        if content =~ /^(---\s*\n.*?\n?)^(---\s*$\n?)/m
          content = $POSTMATCH
          begin
            data = YAML.load($1)
          rescue => e
            puts "YAML Exception reading #{name}: #{e.message}"
          end
        end

        if data['title']
          title = data['title']
        end
      else
        puts "File not found: #{source_file}"
      end
      s = "<li><a href=\"#{page.permalink}\">#{title}</a></li>"
    end

    def render(context)
      site = context.registers[:site]
      @source = site.source
      site_pages = context.environments.first['site']['pages']
      html = "<li class='dropdown'>"
      list = Hash.new { |h,k| h[k] = [] }
      site_pages.each do |page|
        next if page.index?
        if ['css', ''].include?(page.parent)
          html += "<li><a href=\"#{page.permalink}\">#{page['title']}</a></li>"
        else
          list[page.parent.gsub('_', ' ').capitalize] << self.add_item(page) 
        end
      end

      list = list.sort
      list.each { |header, subs|
        html += "<li class='dropdown'><a href='#' class='dropdown-toggle' data-toggle='dropdown' role='button' aria-expanded='false'>#{header} <span class='caret'></span></a>"
        html += "<ul class='dropdown-menu' role='menu'>"
        subs.each { |sub| html += sub }
        html += "</ul></li>"
      }
      html += "</ul>"

      html
    end
  end
end

Liquid::Template.register_tag('generate_navigation', Jekyll::IncludeListingTag)