html_builder.cr

class HtmlBuilder
  def initialize
    @str = StringBuilder.new
  end

  def build
    self.yield
    @str.to_s
  end

  macro self.tag(name)
    "
    def #{name}
      @str << \"<#{name}>\"
      self.yield
      @str << \"</#{name}>\"
    end
    "
  end

  tag :html
  tag :head
  tag :body
  tag :title
  tag :b

  def title(title)
    title do
      text(title)
    end
  end

  def text(text)
    @str << text
  end
end

str = HtmlBuilder.new.build do
  html do
    head do
      title "Crystal Programming Language"
    end
    body do
      b { text "Crystal rocks!" }
    end
  end
end

puts str