Jekyll SVG icons and sprite

icons.rb

module Jekyll
  module Tags

    class IconTag < Liquid::Tag

      def initialize(tag_name, markup, tokens)
        @markup = markup
        super
      end

      def render(context)

        # Gather settings
        site = context.registers[:site]
        markup = Liquid::Template.parse(@markup).render(context)

        # Extract icon name
        @dir = File.expand_path(site.config["icons_dir"]).freeze
        @name = markup.match(/(?<=['"])[\w\-]+(?=['"]\s+)/)
        @icon = "#{@name}.svg"

        # Attributes object reference
        attributes = {}
        markup.scan(Liquid::TagAttributes) do |key, value|
          attributes[key] = value
        end

        # Class attribute
        @class = attributes["class"]

        unless @class.nil?
          svg_class = @class.gsub!(/\A["']|["']\Z/, "")
          svg_class = "#{svg_class}"
        end

        @role = attributes["role"]

        unless @role.nil?
          svg_role = @role.gsub!(/\A["']|["']\Z/, "")
          svg_role = "role=\"#{svg_role}\""
        else
          svg_label = "role=\"img\""
        end

        @sprite = File.join(@input, @icon)

        if @icon === "sprite.svg"

          svg_dir = File.join(@output, "sprite.svg")
          svg_tag = File.read(svg_dir, site.file_read_opts)

        elsif File.exists?(@sprites)

          svg_tag = "<svg role=\"img\" #{svg_label} class\=\""
          svg_tag += svg_class ? "#{svg_class}\">" : "icon-#{@name} \">"
          svg_tag += "<use xlink:href\=\"\##{@name}\"></use>"
          svg_tag += "</svg>"

        elsif File.exists?(@inline)

          svg_dir = File.join(@output, "inline", @icon)
          svg_tag = File.read(svg_dir, site.file_read_opts)
          svg_tag = svg_tag.gsub!(/<svg/, "<svg #{svg_role} class=\"icon-#{@name}\"")

          unless svg_class.nil?
            if svg_tag.match(/class\=/)
              svg_tag = svg_tag.gsub!(/class\="[^"]+\"/, "class\=\"#{svg_class}")
            else
              svg_tag = svg_tag.gsub!(/<svg/, "<svg class\=\"#{svg_class}\"")
            end
          end

        end

        svg_tag

      end

    end
  end
end

Liquid::Template.register_tag("icon", Jekyll::Tags::IconTag)