Class: Computation

Inherits:
Object show all
Defined in:
lib/volt/reactive/computation.rb

Constant Summary collapse

@@current = 
nil
@@flush_queue = 
[]

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(computation) ⇒ Computation

Returns a new instance of Computation.



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# File 'lib/volt/reactive/computation.rb', line 14

def initialize(computation)
  @computation = computation
  @invalidations = []
end

Class Method Details

.current ⇒ Object 



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# File 'lib/volt/reactive/computation.rb', line 10

def self.current
  @@current
end

.current=(val) ⇒ Object 



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# File 'lib/volt/reactive/computation.rb', line 6

def self.current=(val)
  @@current = val
end

.flush! ⇒ Object 



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# File 'lib/volt/reactive/computation.rb', line 98

def self.flush!
  raise "Can't flush while in a flush" if @flushing

  @flushing = true
  # clear any timers
  @timer = nil

  computations = @@flush_queue
  @@flush_queue = []

  computations.each do |computation|
    computation.compute!
  end

  @flushing = false
end

.queue_flush! ⇒ Object 



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# File 'lib/volt/reactive/computation.rb', line 115

def self.queue_flush!
  if !@timer
    # Flush once everything else has finished running
    @timer = `setImmediate(function() { self['$flush!'](); });`
  end
end

.run_without_tracking ⇒ Object 



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# File 'lib/volt/reactive/computation.rb', line 88

def self.run_without_tracking
  previous = Computation.current
  Computation.current = nil
  return_value = yield
  Computation.current = previous

  return return_value
end

Instance Method Details

#compute! ⇒ Object

Runs the computation



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# File 'lib/volt/reactive/computation.rb', line 20

def compute!
  @invalidated = false

  unless @stopped

    @computing = true
    run_in do
      @computation.call
    end
    @computing = false
  end
end

#invalidate! ⇒ Object

Calling invalidate removes the computation from all of its dependencies. This keeps its dependencies from invalidating it again.



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# File 'lib/volt/reactive/computation.rb', line 48

def invalidate!
  unless @invalidated
    @invalidated = true

    if !@stopped && !@computing
      @@flush_queue << self

      # If we are in the browser, we queue a flush for the next tick
      if Volt.in_browser?
        self.class.queue_flush!
      end
    end

    invalidations = @invalidations
    @invalidations = []

    invalidations.each do |invalidation|
      invalidation.call
    end
  end
end

#on_invalidate(&callback) ⇒ Object 



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# File 'lib/volt/reactive/computation.rb', line 33

def on_invalidate(&callback)
  if @invalidated
    # Call invalidate now, since its already invalidated
    Computation.run_without_tracking do
      callback.call
    end
  else
    # Store the invalidation
    @invalidations << callback
  end
end

#run_in ⇒ Object

Runs in this computation as the current computation, returns the computation



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# File 'lib/volt/reactive/computation.rb', line 79

def run_in
  previous = Computation.current
  Computation.current = self
  yield
  Computation.current = previous

  return self
end

#stop ⇒ Object

Stop re-run of the computations



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# File 'lib/volt/reactive/computation.rb', line 71

def stop
  unless @stopped
    @stopped = true
    invalidate!
  end
end