60 lines
1.5 KiB
Ruby
60 lines
1.5 KiB
Ruby
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module Virtual
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# A slot is a slot in an object. It is the storage location for a value.
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# (Remember, values are typed)
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# From a memory perspective a slot is an index into an array (the object)
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# But we are not modelling the array here, but the index into it.
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# Four known objects exist and those correspond to subclasses:
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# - the message that has been received: MessageSlot
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# - the frame of the method that is executing (local variables): FrameSlot
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# - self as an object: SelfSlot
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# - a message that will be sent, NewMessageSlot
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# additionally frame, self and return are slots in Message and NewMessage
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# Slot has a lot of small subclasses
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# Names for the slots avoid indexes
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class Slot < Object
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MESSAGE_REGISTER = :r0
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SELF_REGISTER = :r1
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FRAME_REGISTER = :r2
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NEW_MESSAGE_REGISTER = :r3
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MESSAGE_CALLER = 0
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MESSAGE_RETURN_ADDRESS = 1
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MESSAGE_EXCEPTION_ADDRESS = 2
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MESSAGE_SELF = 3
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MESSAGE_NAME = 4
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MESSAGE_RETURN_VALUE = 5
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MESSAGE_FRAME = 6
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MESSAGE_PAYLOAD = 7
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attr_accessor :index , :type , :value
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private #abstract base class
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def initialize index , type , value
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@index = index
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@type = type
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@value = value
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end
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end
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class FrameSlot < Slot
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def initialize index , type = Mystery, value = nil
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super
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end
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end
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class SelfSlot < Slot
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def initialize index , type = Mystery, value = nil
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super
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end
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end
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end
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require_relative "message_slot"
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require_relative "new_message_slot"
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