Class: MotionWiretap::Wiretap

Inherits:
Object
  • Object
show all
Defined in:
lib/motion-wiretap/all/wiretap.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Wiretap

Returns a new instance of Wiretap.



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# File 'lib/motion-wiretap/all/wiretap.rb', line 15

def initialize(&block)
  @is_torn_down = false
  @is_completed = false
  @is_error = false
  @queue = nil
  @value = nil

  @listener_handlers = []
  @completion_handlers = []
  @error_handlers = []

  listen &block if block
end

Instance Attribute Details

#value ⇒ Object (readonly)

wiretaps have an intrinsic “current value”



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# File 'lib/motion-wiretap/all/wiretap.rb', line 13

def value
  @value
end

Instance Method Details

#and_then(wiretap = nil, &block) ⇒ Object

called when no more values are expected



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# File 'lib/motion-wiretap/all/wiretap.rb', line 101

def and_then(wiretap=nil, &block)
  raise "Block or Wiretap is expected in #{self.class.name}##{__method__}" unless block || wiretap
  raise "Only Block *or* Wiretap is expected in #{self.class.name}##{__method__}" if block && wiretap
  @completion_handlers << (block ? block.weak! : wiretap)
  if @is_completed
    trigger_completed_on(block || wiretap)
  end
  return self
end

#cancel! ⇒ Object

this is the preferred way to turn off a wiretap; child classes override ‘teardown`, which is only ever called once.



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# File 'lib/motion-wiretap/all/wiretap.rb', line 36

def cancel!
  return if @is_torn_down
  @is_torn_down = true
  teardown
end

#combine(&block) ⇒ Object

Returns a Wiretap that combines all the values into one value (the values are all passed in at the same time)

Examples:

wiretap.combine do |one, two|
  one ? two : nil
end



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# File 'lib/motion-wiretap/all/wiretap.rb', line 188

def combine(&block)
  return WiretapCombiner.new(self, block)
end

#dealloc ⇒ Object 



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# File 'lib/motion-wiretap/all/wiretap.rb', line 29

def dealloc
  self.cancel!
  super
end

#enqueue(&block) ⇒ Object

send a block to the GCD queue



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# File 'lib/motion-wiretap/all/wiretap.rb', line 54

def enqueue(&block)
  if @queue
    @queue.async(&block)
  else
    block.call
  end
end

#filter(&block) ⇒ Object

Returns a Wiretap that will only be called if the &condition block returns true



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# File 'lib/motion-wiretap/all/wiretap.rb', line 178

def filter(&block)
  return WiretapFilter.new(self, block)
end

#listen(wiretap = nil, &block) ⇒ Object

called when the value changes



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# File 'lib/motion-wiretap/all/wiretap.rb', line 67

def listen(wiretap=nil, &block)
  raise "Block or Wiretap is expected in #{self.class.name}##{__method__}" unless block || wiretap
  raise "Only Block *or* Wiretap is expected in #{self.class.name}##{__method__}" if block && wiretap
  @listener_handlers << (block ? block.weak! : wiretap)
  self
end

#map(&block) ⇒ Object

Returns a Wiretap that passes each value through the provided block

Examples:

wiretap.map do |item|
  item.to_s
end



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# File 'lib/motion-wiretap/all/wiretap.rb', line 208

def map(&block)
  return WiretapMapper.new(self, block)
end

#on_error(wiretap = nil, &block) ⇒ Object

called when an error occurs, and no more values are expected



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# File 'lib/motion-wiretap/all/wiretap.rb', line 135

def on_error(wiretap=nil, &block)
  raise "Block or Wiretap is expected in #{self.class.name}##{__method__}" unless block || wiretap
  raise "Only Block *or* Wiretap is expected in #{self.class.name}##{__method__}" if block && wiretap
  @error_handlers << (block ? block.weak! : wiretap)
  if @is_error
    trigger_error_on(block || wiretap, @is_error)
  end
  return self
end

#queue(queue) ⇒ Object

specify the GCD queue that the listeners should be run on



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# File 'lib/motion-wiretap/all/wiretap.rb', line 48

def queue(queue)
  @queue = queue
  return self
end

#reduce(memo = nil, &block) ⇒ Object

Returns a Wiretap that passes each value through the block, and also the previous return value (memo).

Examples:

# returns the total of all the prices
wiretap.reduce(0) do |memo, item|
  memo + item.price
end



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# File 'lib/motion-wiretap/all/wiretap.rb', line 199

def reduce(memo=nil, &block)
  return WiretapReducer.new(self, memo, block)
end

#teardown ⇒ Object

Overridden by subclasses to turn off observation, unregister notifications, etc.



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# File 'lib/motion-wiretap/all/wiretap.rb', line 44

def teardown
end

#trigger_changed(*values) ⇒ Object 



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# File 'lib/motion-wiretap/all/wiretap.rb', line 74

def trigger_changed(*values)
  return if @is_torn_down || @is_completed || @is_error
  if values.length == 1
    @value = values.first
  else
    @value = values
  end

  @listener_handlers.each do |block_or_wiretap|
    trigger_changed_on(block_or_wiretap, values)
  end

  return self
end

#trigger_changed_on(block_or_wiretap, values) ⇒ Object

Sends the block or wiretap a changed signal



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# File 'lib/motion-wiretap/all/wiretap.rb', line 90

def trigger_changed_on(block_or_wiretap, values)
  if block_or_wiretap.is_a? Wiretap
    block_or_wiretap.trigger_changed(*values)
  else
    enqueue do
      block_or_wiretap.call(*values)
    end
  end
end

#trigger_completed ⇒ Object 



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# File 'lib/motion-wiretap/all/wiretap.rb', line 111

def trigger_completed
  return if @is_torn_down || @is_completed || @is_error
  @is_completed = true

  @completion_handlers.each do |block_or_wiretap|
    trigger_completed_on(block_or_wiretap)
  end

  cancel!
  return self
end

#trigger_completed_on(block_or_wiretap) ⇒ Object

Sends the block or wiretap a completed signal



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# File 'lib/motion-wiretap/all/wiretap.rb', line 124

def trigger_completed_on(block_or_wiretap)
  if block_or_wiretap.is_a? Wiretap
    block_or_wiretap.trigger_completed
  else
    enqueue do
      block_or_wiretap.call
    end
  end
end

#trigger_error(error = SINGLETON) ⇒ Object 



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# File 'lib/motion-wiretap/all/wiretap.rb', line 145

def trigger_error(error=SINGLETON)
  return if @is_torn_down || @is_completed || @is_error
  raise "You must pass a truthy value to `trigger_error()`" unless error

  # convert SINGLETON to a default error value
  error = true if error == SINGLETON
  @is_error = error

  @error_handlers.each do |block_or_wiretap|
    trigger_error_on(block_or_wiretap, error)
  end

  cancel!
  return self
end

#trigger_error_on(block_or_wiretap, error) ⇒ Object

Sends the block or wiretap an error value



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# File 'lib/motion-wiretap/all/wiretap.rb', line 162

def trigger_error_on(block_or_wiretap, error)
  if block_or_wiretap.is_a? Wiretap
    block_or_wiretap.trigger_error(error)
  else
    enqueue do
      block_or_wiretap.call(error)
    end
  end
end