106 lines
3.0 KiB
Ruby
106 lines
3.0 KiB
Ruby
# An Object is really a hash like structure. It is dynamic and
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# you want to store values by name (instance variable names).
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#
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# One could (like mri), store the names in each object, but that is wasteful
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# Instead we store only the values, and access them by index.
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# The Layout allows the mapping of names to index.
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# The Layout of an object describes the memory layout of the object
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# The Layout is a simple list of the names of instance variables.
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#
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# As every object has a Layout to describe it, the name "layout" is the
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# first name in the list for every Layout.
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# But as we want every Object to have a class, the Layout carries that class.
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# So the layout of layout has an entry "object_class"
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# But Objects must also be able to carry methods themselves (ruby calls singleton_methods)
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# and those too are stored in the Layout (both layout and class include behaviour)
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# In other words, the Layout is a list of names that describe
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# the values stored in an actual object.
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# The object is an List of values of length n and
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# the Layout is an List of names of length n , plus class reference and methods reference
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# Together they turn the object into a hash like structure
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module Parfait
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class Layout < Object
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attribute :object_class
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include Behaviour
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include Indexed
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self.offset(3)
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def initialize( object_class )
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super()
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add_instance_variable :layout ,:Layout
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self.object_class = object_class
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end
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def == other
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self.object_id == other.object_id
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end
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# add the name of an instance variable
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# The index will be returned and can subsequently be searched with index_of
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# The index of the name is the index of the data in the object
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#
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# TODO , later we would need to COPY the layout to keep the old constant
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# but now we are concerned with booting, ie getting a working structure
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def add_instance_variable name , type
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raise "Name shouldn't be nil" unless name
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raise "Type shouldn't be nil" unless type
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self.push(name)
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self.push(type)
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self.get_length
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end
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def instance_names
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names = List.new
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name = true
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each do |item|
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names.push(item) if name
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name = ! name
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end
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names
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end
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def instance_length
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(self.get_length / 2).to_i # to_i for opal
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end
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alias :super_index :index_of
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def index_of(name)
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raise "Use variable_index instead"
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end
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# index of the variable when using get_internal_word
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# (get_internal_word is 1 based and 1 is always the layout)
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def variable_index name
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has = super_index(name)
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return nil unless has
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raise "internal error #{name}:#{has}" if has < 1
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(1 + has / 2).to_i # to_i for opal
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end
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def type_at index
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type_index = index * 2
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get(type_index)
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end
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def inspect
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"Layout[#{super}]"
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end
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def sof_reference_name
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"#{self.object_class.name}_Layout"
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end
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alias :name :sof_reference_name
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def super_class_name
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nil # stop resolve recursing up metaclasses
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end
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end
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end
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