Convert liquid-style tags for Mac symbols into HTML entities

macsymbols.rb

class String
  def replace_with_entity
    case self.downcase
    when /apple/
      ""
    when /(comm(and)?|cmd|clover)/
      "⌘"
    when /(cont(rol)?|ctl|ctrl)/
      "⌃"
    when /(opt(ion)?|alt)/
      "⌥"
    when /shift/
      "⇧"
    when /tab/
      "⇥"
    when /caps(lock)?/
      "⇪"
    when /eject/
      "⏏"
    when /return/
      "⏎"
    when /enter/
      "⌤"
    when /(del(ete)?|back(space)?)/
      "⌫"
    when /fwddel(ete)?/
      "⌦"
    when /(esc(ape)?)/
      "⎋"
    when /right/
      "→"
    when /left/
      "←"
    when /up/
      "↑"
    when /down/
      "↓"
    when /pgup/
      "⇞"
    when /pgdn/
      "⇟"
    when /home/
      "↖"
    when /end/
      "↘"
    when /clear/
      "⌧"
    when /gear/
      "⚙"
    else
      "{{#{self}}}"
    end
  end

  def render
    # Replace {{insertions}}
    self.gsub(/\{\{(.*?)\}\}/) {|mtch|
      m = Regexp.last_match
      m[1].strip.replace_with_entity
    }
  end
end