Class: Reacto::Operations::Diff

Inherits:
Object
  • Object
show all
Defined in:
lib/reacto/operations/diff.rb

Constant Summary collapse

DEFAULT_FN = 
-> (a, b) { [a, b] }

Instance Method Summary collapse

Constructor Details

#initialize(fn = DEFAULT_FN, initial = NO_VALUE) ⇒ Diff

Returns a new instance of Diff.



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# File 'lib/reacto/operations/diff.rb', line 9

def initialize(fn = DEFAULT_FN, initial = NO_VALUE)
  @fn = fn
  @prev = initial
end

Instance Method Details

#call(tracker) ⇒ Object 



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# File 'lib/reacto/operations/diff.rb', line 14

def call(tracker)
  value = lambda do |v|
    if @prev == NO_VALUE
      @prev = v
      return
    end

    current = @fn.call(@prev, v)
    @prev = v

    tracker.on_value(current)
  end


  Subscriptions::OperationSubscription.new(
    tracker,
    value: value
  )
end