47 lines
1.4 KiB
Ruby
47 lines
1.4 KiB
Ruby
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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# The mapping into arrays is a straightforward matter, but happens in the
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# next level down, the register machine.
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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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# the name of the object of a slot is a symbol that represents what the class name describes
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# ie it is one of :message , :self , :frame , :new_message
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# one of the objects the machine works on.
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def object_name
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raise "abstract called #{self}"
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end
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attr_accessor :type , :value
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def to_s
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"#{self.class.name}.new(#{type}, #{value})"
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end
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private #abstract base class
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def initialize type , value
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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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end
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require_relative "message_slot"
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require_relative "self_slot"
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require_relative "frame_slot"
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require_relative "new_message_slot"
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