Class: Promise

Inherits:
Object show all
Defined in:
opal/stdlib/promise.rb

Direct Known Subclasses

Trace, When

Defined Under Namespace

Classes: Trace, When

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(success = nil, failure = nil) ⇒ Promise

Returns a new instance of Promise



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# File 'opal/stdlib/promise.rb', line 16

def initialize(success = nil, failure = nil)
  @success = success
  @failure = failure

  @realized  = nil
  @exception = false
  @value     = nil
  @error     = nil
  @delayed   = nil

  @prev = nil
  @next = nil
end

Instance Attribute Details

#error ⇒ Object (readonly)

Returns the value of attribute error



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# File 'opal/stdlib/promise.rb', line 14

def error
  @error
end

#next ⇒ Object (readonly)

Returns the value of attribute next



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# File 'opal/stdlib/promise.rb', line 14

def next
  @next
end

#prev ⇒ Object (readonly)

Returns the value of attribute prev



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# File 'opal/stdlib/promise.rb', line 14

def prev
  @prev
end

#value ⇒ Object (readonly)

Returns the value of attribute value



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# File 'opal/stdlib/promise.rb', line 14

def value
  @value
end

Class Method Details

.error(value) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 6

def self.error(value)
  new.reject(value)
end

.value(value) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 2

def self.value(value)
  new.resolve(value)
end

.when(*promises) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 10

def self.when(*promises)
  When.new(promises)
end

Instance Method Details

#<<(promise) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 57

def <<(promise)
  @prev = promise

  self
end

#>>(promise) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 63

def >>(promise)
  @next = promise

  if exception?
    promise.reject(@delayed)
  elsif resolved?
    promise.resolve(@delayed || value)
  elsif rejected? && (!@failure || Promise === (@delayed || @error))
    promise.reject(@delayed || error)
  end

  self
end

#^(promise) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 50

def ^(promise)
  promise << self
  self    >> promise

  promise
end

#act? ⇒ Boolean

Returns:



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# File 'opal/stdlib/promise.rb', line 30

def act?
  @success != nil
end

#always(&block) ⇒ Object Also known as: finally, ensure 



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# File 'opal/stdlib/promise.rb', line 170

def always(&block)
  self ^ Promise.new(block, block)
end

#exception!(error) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 151

def exception!(error)
  @exception = true

  reject!(error)
end

#exception? ⇒ Boolean

Returns:



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# File 'opal/stdlib/promise.rb', line 34

def exception?
  @exception
end

#fail(&block) ⇒ Object Also known as: rescue, catch 



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# File 'opal/stdlib/promise.rb', line 163

def fail(&block)
  self ^ Promise.new(nil, block)
end

#inspect ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 181

def inspect
  result = "#<#{self.class}(#{object_id})"

  if @next
    result += " >> #{@next.inspect}"
  end

  if realized?
    result += ": #{(@value || @error).inspect}>"
  else
    result += ">"
  end

  result
end

#realized? ⇒ Boolean

Returns:



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# File 'opal/stdlib/promise.rb', line 38

def realized?
  @realized != nil
end

#reject(value = nil) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 112

def reject(value = nil)
  if realized?
    raise ArgumentError, 'the promise has already been realized'
  end

  if Promise === value
    value << @prev

    return value ^ self
  end

  @realized = :reject
  @error    = value

  begin
    if @failure
      value = @failure.call(value)

      if Promise === value
        reject!(value)
      end
    else
      reject!(value)
    end
  rescue Exception => e
    exception!(e)
  end

  self
end

#reject!(value) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 143

def reject!(value)
  if @next
    @next.reject(value)
  else
    @delayed = value
  end
end

#rejected? ⇒ Boolean

Returns:



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# File 'opal/stdlib/promise.rb', line 46

def rejected?
  @realized == :reject
end

#resolve(value = nil) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 77

def resolve(value = nil)
  if realized?
    raise ArgumentError, 'the promise has already been realized'
  end

  if Promise === value
    value << @prev

    return value ^ self
  end

  @realized = :resolve
  @value    = value

  begin
    if @success
      value = @success.call(value)
    end

    resolve!(value)
  rescue Exception => e
    exception!(e)
  end

  self
end

#resolve!(value) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 104

def resolve!(value)
  if @next
    @next.resolve(value)
  else
    @delayed = value
  end
end

#resolved? ⇒ Boolean

Returns:



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# File 'opal/stdlib/promise.rb', line 42

def resolved?
  @realized == :resolve
end

#then(&block) ⇒ Object Also known as: do 



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# File 'opal/stdlib/promise.rb', line 157

def then(&block)
  self ^ Promise.new(block)
end

#trace(&block) ⇒ Object 



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# File 'opal/stdlib/promise.rb', line 177

def trace(&block)
  self ^ Trace.new(block)
end