111 lines
4.1 KiB
Ruby
111 lines
4.1 KiB
Ruby
module Mom
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# A SlotDefinition defines a slot. A bit like a variable name but for objects.
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#
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# PS: for the interested: A "developement" of Smalltalk was the
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# prototype based language (read: JavaScript equivalent)
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# called Self https://en.wikipedia.org/wiki/Self_(programming_language)
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#
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# SlotDefinitions are the instance names of objects. But since the language is dynamic
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# what is it that we can say about instance names at runtime?
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# Start with a known object like the Message (in register one), we know all it's
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# variables. But there is a Message in there, and for that we know the instances
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# too. And off course for _all_ objects we know where the type is.
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#
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# The definiion is an array of symbols that we can resolve to SlotLoad
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# Instructions. Or in the case of constants to ConstantLoad
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#
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class SlotDefinition
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attr_reader :known_object , :slots
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# is an array of symbols, that specifies the first the object, and then the Slot.
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# The first element is either a known type name (Capitalized symbol of the class name) ,
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# or the symbol :message
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# And subsequent symbols must be instance variables on the previous type.
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# Examples: [:message , :receiver] or [:Space , :next_message]
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def initialize( object , slots)
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raise "No slots #{object}" unless slots
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slots = [slots] unless slots.is_a?(Array)
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@known_object , @slots = object , slots
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raise "Not known #{slots}" unless object
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end
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def to_s
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names = [known_name] + @slots
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"[#{names.join(', ')}]"
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end
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def known_name
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case known_object
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when Constant , Parfait::Object
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known_object.class.short_name
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when Risc::Label
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known_object.to_s
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when Symbol
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known_object
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else
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"unknown"
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end
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end
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# load the slots into a register
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# the code is added to compiler
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# the register returned
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def to_register(compiler, source)
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if known_object.respond_to?(:ct_type)
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type = known_object.ct_type
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elsif(known_object.respond_to?(:get_type))
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type = known_object.get_type
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else
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type = :Object
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end
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right = compiler.use_reg( type )
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case known_object
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when Constant
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parfait = known_object.to_parfait(compiler)
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const = Risc.load_constant(source, parfait , right)
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compiler.add_code const
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if slots.length == 1
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raise "only type allowed for constants, not #{slots[0]}" unless slots[0] == :type
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compiler.add_code Risc::SlotToReg.new( source , right , Parfait::TYPE_INDEX, right)
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end
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raise "Can't have slots into Constants #{slots}" if slots.length > 1
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when Parfait::Object , Risc::Label
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const = const = Risc.load_constant(source, known_object , right)
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compiler.add_code const
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if slots.length > 0
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# desctructively replace the existing value to be loaded if more slots
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compiler.add_code Risc.slot_to_reg( source , right ,slots[0], right)
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end
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when Symbol
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return sym_to_risc(compiler , source)
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else
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raise "We have a #{self} #{known_object}"
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end
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if slots.length > 1
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# desctructively replace the existing value to be loaded if more slots
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index = Risc.resolve_to_index(slots[0] , slots[1] ,compiler)
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compiler.add_code Risc::SlotToReg.new( source , right ,index, right)
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if slots.length > 2
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raise "3 slots only for type #{slots}" unless slots[2] == :type
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compiler.add_code Risc::SlotToReg.new( source , right , Parfait::TYPE_INDEX, right)
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end
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end
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return const.register
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end
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# resolve the slots one by one to slot_to_reg instructions using the
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# type information inferred from their names / type hierachy
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def sym_to_risc(compiler , source)
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slots = @slots.dup
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raise "Not Message #{@known_object}" unless @known_object == :message
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left = Risc.message_reg
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left = left.resolve_and_add( slots.shift , compiler)
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reg = compiler.current.register
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while( !slots.empty? )
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left = left.resolve_and_add( slots.shift , compiler)
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end
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return reg
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end
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end
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end
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