Class: ReactiveManager

Inherits:
Object show all
Includes:
Events
Defined in:
lib/volt/reactive/reactive_value.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Events

#event_chain, #has_listeners?, #listeners, #on, #remove_listener, #trigger!, #trigger_by_scope!, #trigger_for_methods!

Constructor Details

#initialize(reactive_value, getter, setter = nil, scope = nil) ⇒ ReactiveManager

When created, ReactiveValue’s get a getter (a proc)



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# File 'lib/volt/reactive/reactive_value.rb', line 199

def initialize(reactive_value, getter, setter=nil, scope=nil)
  @reactive_value = reactive_value
  @getter = getter
  @setter = setter
  @scope = scope

  @parents = []
end

Instance Attribute Details

#parents ⇒ Object (readonly)

Returns the value of attribute parents.



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# File 'lib/volt/reactive/reactive_value.rb', line 196

def parents
  @parents
end

#scope ⇒ Object (readonly)

Returns the value of attribute scope.



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# File 'lib/volt/reactive/reactive_value.rb', line 196

def scope
  @scope
end

Instance Method Details

#add_parent!(parent) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 406

def add_parent!(parent)
  @parents << parent
  event_chain.add_object(parent)
end

#check_tag(method_name, tag_name, current_obj) ⇒ Object

Method calls can be tagged so the reactive value knows how to handle them. This lets you check the state of the tags.



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# File 'lib/volt/reactive/reactive_value.rb', line 333

def check_tag(method_name, tag_name, current_obj)
  if current_obj.respond_to?(:reactive_method_tag)
    tag = current_obj.reactive_method_tag(method_name, tag_name)

    unless tag
      # Get the tag from the all methods if its not directly specified
      tag = current_obj.reactive_method_tag(:__all_methods, tag_name)
    end

    # Evaluate now if its a proc
    tag = tag.call(method_name) if tag.class == ::Proc

    return tag
  end

  return nil
end

#cur(shallow = false, ignore_cache = false) ⇒ Object

Fetch the current value



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# File 'lib/volt/reactive/reactive_value.rb', line 241

def cur(shallow=false, ignore_cache=false)
  # Use cache if it is cached
  if @cur_cache && !shallow && !ignore_cache
    # We might be caching another reactive value, so we just set
    # it as the result and let it get unwrapped.
    result = @cur_cache
  else
    if @getter.class == ::Proc
      # Get the current value, capture any errors
      begin
        result = @getter.call
      rescue => e
        result = e
      end
    else
      # getter is just an object, return it
      result = @getter
    end
  end

  if !shallow && result.reactive?
    # Unwrap any stored reactive values
    result = result.cur
  end

  return result
end

#cur=(val) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 306

def cur=(val)
  if @setter
    @setter.call(val)
    # update_followers
  elsif @scope == nil
    @getter = val
    @setter = nil

    # update_followers
    trigger!('changed')
  else
    raise "Value can not be updated"
  end

end

#deep_cur ⇒ Object

Returns a copy of the object with where all ReactiveValue’s are replaced with their current value. NOTE: Classes need to implement their own deep_cur method for this to work, it works out of the box with arrays and hashes.



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# File 'lib/volt/reactive/reactive_value.rb', line 326

def deep_cur
  self.cur.deep_cur
end

#event_added(event, scope, first, first_for_event) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 225

def event_added(event, scope, first, first_for_event)
  # When the first event is registered, we need to start listening on our current object
  # for it to publish events.

  update_followers if first
end

#event_removed(event, last, last_for_event) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 232

def event_removed(event, last, last_for_event)
  # If no one is listening on the reactive value, then we don't need to listen on our
  # current object for events, because no one cares.

  remove_followers if last
end

#inspect ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 216

def inspect
  "@<#{self.class.to_s}:#{object_id} #{cur.inspect}>"
end

#reactive? ⇒ Boolean

Returns:



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# File 'lib/volt/reactive/reactive_value.rb', line 212

def reactive?
  true
end

#reactive_object_id ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 220

def reactive_object_id
  @reactive_object_id ||= rand(100000)
end

#reactive_value ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 208

def reactive_value
  @reactive_value
end

#remove_followers ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 294

def remove_followers
  # Remove from previous
  if @cur_cache
    @cur_cache = nil
  end

  if @cur_cache_chain_listener
    @cur_cache_chain_listener.remove
    @cur_cache_chain_listener = nil
  end
end

#remove_parent!(parent) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 411

def remove_parent!(parent)
  @parents.delete(parent)
  event_chain.remove_object(parent)
end

#set_scope(new_scope) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 423

def set_scope(new_scope)
  dup.scope!(new_scope)
end

#set_scope!(new_scope) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 417

def set_scope!(new_scope)
  @scope = new_scope

  self
end

#setter!(setter = nil, &block) ⇒ Object

Sets the setter



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# File 'lib/volt/reactive/reactive_value.rb', line 428

def setter!(setter=nil, &block)
  @setter = setter || block
end

#unwrap_if_pass_reactive(args, method_name, current_obj) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 351

def unwrap_if_pass_reactive(args, method_name, current_obj)
  # Check to see if the method we're calling wants to receive reactive values.
  pass_reactive = check_tag(method_name, :pass_reactive, current_obj)

  # Unwrap arguments if the method doesn't want reactive values
  return pass_reactive ? args : args.map{|v| v.cur }
end

#update_followers ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 270

def update_followers
  return if @setting_up
  if has_listeners?
    current_obj = cur(true, true)
    should_attach = current_obj.respond_to?(:on)

    if should_attach
      if !@cur_cache || current_obj.object_id != @cur_cache.object_id
        remove_followers

        @setting_up = true
        @cur_cache_chain_listener = self.event_chain.add_object(current_obj)
        @setting_up = nil
      end
    else
      remove_followers
    end

    # Store current if we have listeners
    @cur_cache = current_obj
  end

end

#with(*args, &block) ⇒ Object

With returns a new reactive value dependent on any arguments passed in. If a block is passed in, the getter is the block its self, which will be passed the .cur and the .cur of any reactive arguments.



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# File 'lib/volt/reactive/reactive_value.rb', line 362

def with(*args, &block)
  return with_and_options(args, &block)
end

#with_and_options(args, &block) ⇒ Object 



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# File 'lib/volt/reactive/reactive_value.rb', line 366

def with_and_options(args, &block)
  getter = @getter
  setter = @setter
  scope = @scope

  if block
    # If a block was passed in, the getter now becomes a proc that calls
    # the passed in block with the right arguments.
    getter = ::Proc.new do
      # TODO: Calling cur every time
      current_val = self.cur

      if current_val.is_a?(Exception)
        current_val
      else
        block.call(current_val, args)
      end
    end

    # TODO: Make this work with custom setters
    setter = nil

    # Scope also gets set to nil, because now we should always retrigger this
    # method because we don't know enough about what methods its calling.
    scope = nil
  end

  new_val = ReactiveValue.new(getter, setter, scope)

  # Add the ReactiveValue we're building from
  new_val.reactive_manager.add_parent!(self)

  # Add any reactive arguments as parents
  args.select(&:reactive?).each do |arg|
    new_val.reactive_manager.add_parent!(arg.reactive_manager)
  end

  return new_val
end