Class: DomTemplate

Inherits:
Object show all
Includes:
CommentSearchers
Defined in:
lib/volt/page/targets/dom_template.rb

Overview

A dom template is used to optimize going from a template name to dom nodes and bindings. It stores a copy of the template’s parsed dom nodes, then when a new instance is requested, it updates the dom markers (comments) for new binding numbers and returns a cloneNode’d version of the dom nodes and the bindings.

Instance Method Summary collapse

Methods included from CommentSearchers

#build_from_html, #find_by_comment

Constructor Details

#initialize(page, template_name) ⇒ DomTemplate

Returns a new instance of DomTemplate.



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# File 'lib/volt/page/targets/dom_template.rb', line 11

def initialize(page, template_name)
  template = page.templates[template_name]

  if template
    html = template['html']
    @bindings = template['bindings']
  else
    html = "<div>-- &lt; missing template #{template_name.inspect.gsub('<', '&lt;').gsub('>', '&gt;')} &gt; --</div>"
    @bindings = {}
  end

  @nodes = build_from_html(html)

  track_binding_anchors
end

Instance Method Details

#make_new ⇒ Object

Returns the dom nodes and bindings



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# File 'lib/volt/page/targets/dom_template.rb', line 28

def make_new
  bindings = update_binding_anchors!

  new_nodes = `self.nodes.cloneNode(true)`

  return [new_nodes, bindings]
end

#track_binding_anchors ⇒ Object

Finds each of the binding anchors in the temp dom, then stores a reference to them so they can be quickly updated without using xpath to find them again.



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# File 'lib/volt/page/targets/dom_template.rb', line 39

def track_binding_anchors
  @binding_anchors = {}

  # Loop through the bindings, find in nodes.
  @bindings.each_pair do |name,binding|
    if name.is_a?(String)
      # Find the dom node for an attribute anchor
      node = nil
      %x{
        node = self.nodes.querySelector('#' + name);
      }
      @binding_anchors[name] = node
    else
      # Find the dom node for a comment anchor
      start_comment = find_by_comment("$#{name}", @nodes)
      end_comment = find_by_comment("$/#{name}", @nodes)

      @binding_anchors[name] = [start_comment, end_comment]
    end
  end
end

#update_binding_anchors! ⇒ Object

Takes the binding_anchors and updates them with new numbers (comments and id’s) then returns the bindings updated to the new numbers.



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# File 'lib/volt/page/targets/dom_template.rb', line 63

def update_binding_anchors!
  new_bindings = {}

  @binding_anchors.each_pair do |name, anchors|
    new_name = @@binding_number
    @@binding_number += 1

    if name.is_a?(String)
      if name[0..1] == 'id'
        # A generated id
        # update the id
        `anchors.setAttribute('id', 'id' + new_name);`

        new_bindings["id#{new_name}"] = @bindings[name]
      else
        # Assume a fixed id, should not be updated
        # TODO: Might want to check the page to see if a node
        # with this id already exists and raise if it does.

        # Copy from existing binding
        new_bindings[name] = @bindings[name]
      end
    else
      start_comment, end_comment = anchors

      %x{
        start_comment.textContent = " $" + new_name + " ";
        end_comment.textContent = " $/" + new_name + " ";
      }

      new_bindings[new_name] = @bindings[name]
    end
  end

  return new_bindings
end