Class: Volt::EachBinding

Inherits:
BaseBinding show all
Defined in:
lib/volt/page/bindings/each_binding.rb

Instance Attribute Summary

Attributes inherited from BaseBinding

#binding_name, #context, #target

Instance Method Summary collapse

Methods inherited from BaseBinding

#dom_section, #remove_anchors

Constructor Details

#initialize(page, target, context, binding_name, getter, variable_name, index_name, template_name) ⇒ EachBinding

Returns a new instance of EachBinding.



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# File 'lib/volt/page/bindings/each_binding.rb', line 5

def initialize(page, target, context, binding_name, getter, variable_name, index_name, template_name)
  super(page, target, context, binding_name)

  @item_name     = variable_name
  @index_name    = index_name
  @template_name = template_name

  @templates = []

  @getter      = getter

  # Listen for changes
  @computation = -> { reload }.watch!
end

Instance Method Details

#current_values(values) ⇒ Object 



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# File 'lib/volt/page/bindings/each_binding.rb', line 131

def current_values(values)
  return [] if values.is_a?(Model) || values.is_a?(Exception)
  values = values.attributes if values.respond_to?(:attributes)

  values
end

#item_added(position) ⇒ Object 



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# File 'lib/volt/page/bindings/each_binding.rb', line 70

def item_added(position)
  binding_name     = @@binding_number
  @@binding_number += 1

  if position >= @templates.size
    # Setup new bindings in the spot we want to insert the item
    dom_section.insert_anchor_before_end(binding_name)
  else
    # Insert the item before an existing item
    dom_section.insert_anchor_before(binding_name, @templates[position].binding_name)
  end

  # TODORW: :parent => @value may change
  item_context                           = SubContext.new({ _index_value: position, parent: @value }, @context)
  item_context.locals[@item_name.to_sym] = proc { @value[item_context.locals[:_index_value]] }

  position_dependency                    = Dependency.new
  item_context.locals[:_index_dependency] = position_dependency

  # Get and set index
  item_context.locals[:_index=]           = proc do |val|
    position_dependency.changed!
    item_context.locals[:_index_value] = val
  end


  # Get and set value
  value_dependency                    = Dependency.new
  item_context.locals["_#{@item_name.to_s}_dependency".to_sym] = value_dependency

  item_context.locals["#{@item_name.to_s}=".to_sym] = proc do |val|
    value_dependency.changed!
    @value[item_context.locals[:_index_value]] = val
  end

  # If the user provides an each_with_index, we can assign the lookup for the index
  # variable here.
  if @index_name
    item_context.locals[@index_name.to_sym] = proc do
      position_dependency.depend
      item_context.locals[:_index_value]
    end
  end

  item_template = TemplateRenderer.new(@page, @target, item_context, binding_name, @template_name)
  @templates.insert(position, item_template)

  update_indexes_after(position)
end

#item_removed(position) ⇒ Object 



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# File 'lib/volt/page/bindings/each_binding.rb', line 57

def item_removed(position)
  # Remove dependency
  @templates[position].context.locals[:_index_dependency].remove
  @templates[position].context.locals["_#{@item_name.to_s}_dependency".to_sym].remove

  @templates[position].remove_anchors
  @templates[position].remove
  @templates.delete_at(position)

  # Removed at the position, update context for every item after this position
  update_indexes_after(position)
end

#reload ⇒ Object

When a changed event happens, we update to the new size.



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# File 'lib/volt/page/bindings/each_binding.rb', line 21

def reload
  begin
    value = @context.instance_eval(&@getter)
  rescue => e
    Volt.logger.error("EachBinding Error: #{e.inspect}")
    value = []
  end

  # Since we're checking things like size, we don't want this to be re-triggered on a
  # size change, so we run without tracking.
  Computation.run_without_tracking do
    # Adjust to the new size
    values = current_values(value)

    @value = values

    remove_listeners

    if @value.respond_to?(:on)
      @added_listener   = @value.on('added') { |position| item_added(position) }
      @removed_listener = @value.on('removed') { |position| item_removed(position) }
    end

    templates_size = @templates.size
    values_size    = values.size

    # Start over, re-create all nodes
    (templates_size - 1).downto(0) do |index|
      item_removed(index)
    end
    0.upto(values_size - 1) do |index|
      item_added(index)
    end
  end
end

#remove ⇒ Object

When this each_binding is removed, cleanup.



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# File 'lib/volt/page/bindings/each_binding.rb', line 150

def remove
  @computation.stop
  @computation = nil

  # Clear value
  @value       = []

  @getter = nil

  remove_listeners

  if @templates
    template_count = @templates.size
    template_count.times do |index|
      item_removed(template_count - index - 1)
    end
    # @templates.compact.each(&:remove)
    @templates = nil
  end

  super
end

#remove_listeners ⇒ Object 



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# File 'lib/volt/page/bindings/each_binding.rb', line 138

def remove_listeners
  if @added_listener
    @added_listener.remove
    @added_listener = nil
  end
  if @removed_listener
    @removed_listener.remove
    @removed_listener = nil
  end
end

#update_indexes_after(start_index) ⇒ Object

When items are added or removed in the middle of the list, we need to update each templates index value.



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# File 'lib/volt/page/bindings/each_binding.rb', line 122

def update_indexes_after(start_index)
  size = @templates.size
  if size > 0
    start_index.upto(size - 1) do |index|
      @templates[index].context.locals[:_index=].call(index)
    end
  end
end