An attempt at Slim/Haml helpers for handlebars

index.html.slim

= handlebars_template_named "edit-field" do
  = hb %{ if isEditing } do
    = hb %{ view BD.TextField valueBinding="value" }
    = hb_else
    = hb %{ if value } do
      = hbb %{ value }
      = hb_else
      span.no-name empty

/ Outputs 
  <script type="text/x-handlebars" data-template-name="edit-field>
    {{#if isEditing}}
      {{view BD.TextField valueBinding="value"}}
    {{else}}
      {{#if value}}
        {{{value}}}
      {{else}}
        <span class="no-name">empty</span>
      {{/if}}
    {{/if}}
  </script>

sliml_helper.rb

module SlimlHelper

  # e.g. hb 'view bindAttr src="test.html" classBinding="isPriority"'
  #      produces:
  #      {{view bindAttr src="test.html" classBinding="isPriority"'}}
  #
  #      hb 'view' do
  #        p Hello
  #     
  #      produces:
  #      {{#view}}<p>Hello</p>{{/view}}
  def hb(hbstring, &block)
    hb_priv(hbstring, true, &block)
  end

  # same as above, but with {{{ instead of {{
  def hbb(hbstring, &block)
    hb_priv(hbstring, false, &block)
  end

  def hb_else
    "{{else}}"
  end

  # usage: hb_link('Click Here', 'action "edit" on="click"')
  def hb_link(content, hb)
    result = '<a href="#" {{' + hb + '}}>' + content + '</a>'
    result.html_safe
  end

  def handlebars_template(&block)
    content_tag :script, type: "text/x-handlebars" do
      capture(&block)
    end
  end

  def handlebars_template_named(name, &block)
    content_tag :script, type: "text/x-handlebars", "data-template-name" => name do
      capture(&block)
    end
  end

  private 

  def hb_priv(hbstring, escape, &block)
    hbstring.strip!
    first_tag = hbstring.split.first
    hbstring.prepend('#') if block_given? # view vs. #view

    open  = escape ? "{{" : "{{{"
    close = escape ? "}}" : "}}}"
    
    output = "#{open}#{hbstring}#{close}"

    if block_given?
      output << capture(&block)
      output << "#{open}/#{first_tag}#{close}"
    end
    output.html_safe
  end

end