269 lines
8.1 KiB
Ruby
269 lines
8.1 KiB
Ruby
module Parfait
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# 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 in both time and space.
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# Instead we store only the values, and access them by index.
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# The Type allows the mapping of names to index.
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# The Type of an object describes the memory layout of the object. In a c analogy, it is the
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# information defined in a struct.
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# The Type is a list of the names of instance variables, and their value types (int etc).
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#
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# Every object has a Type to describe it, so it's *first* instance variable is **always**
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# "type". This means the name "type" is the first name in the list
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# for every Type instance.
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# But, as we want every Object to have a class, the Type carries that class.
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# So the type of type 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 Type (both type and class include behaviour)
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# The object is an List of values of length n
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# The Type is a list of n names and n types that describe the values stored in an actual object.
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# Together they turn the object into a hash like structure
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# For types to be a useful concept, they have to be unique and immutable. Any "change", like adding
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# a name/type pair, will result in a new instance.
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# The Type class carries a hash of types of the systems, which is used to ensure that
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# there is only one instance of every type. Hash and equality are defined on type
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# for this to work.
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class Type < Object
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attr_reader :object_class , :names , :types , :methods
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def self.for_hash( object_class , hash)
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hash = {type: object_class.name }.merge(hash) unless hash[:type]
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new_type = Type.new( object_class , hash)
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Parfait.object_space.add_type(new_type)
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end
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def initialize( object_class , hash )
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super()
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set_object_class( object_class)
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init_lists( hash )
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end
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# this part of the init is seperate because at boot time we can not use normal new
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# new is overloaded to grab the type from space, and before boot, that is not set up
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def init_lists(hash)
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@methods = nil
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@names = List.new
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@types = List.new
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raise "No type Type in #{hash}" unless hash[:type]
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private_add_instance_variable(:type , hash[:type]) #first
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hash.each do |name , type|
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private_add_instance_variable(name , type) unless name == :type
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end
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end
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def to_s
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"#{@object_class.name}-#{@names.inspect}"
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end
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def method_names
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names = List.new
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return names unless @methods
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@methods.each_method do |method|
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names.push method.name
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end
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names
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end
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def create_method( method_name , arguments , frame)
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raise "create_method #{method_name}.#{method_name.class}" unless method_name.is_a?(Symbol)
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#puts "Self: #{self.class} clazz: #{clazz.name}"
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raise "frame must be a type, not:#{frame}" unless frame.is_a?(Type)
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found = get_method( method_name )
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if found
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#puts "redefining method #{method_name}" #TODO, this surely must get more complicated
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raise "attempt to redifine method for different type " unless self == found.self_type
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found.init(arguments , frame)
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return found
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else
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add_method CallableMethod.new( self , method_name , arguments , frame )
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end
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end
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def add_method( method )
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raise "not a method #{method.class} #{method.inspect}" unless method.is_a? CallableMethod
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raise "syserr #{method.name.class}" unless method.name.is_a? Symbol
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if self.is_a?(Class) and (method.self_type != self)
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raise "Adding to wrong class, should be #{method.for_class}"
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end
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if get_method( method.name )
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remove_method(method.name)
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end
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method.set_next( @methods )
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@methods = method
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#puts "#{self.name} add #{method.name}"
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method
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end
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def remove_method( method_name )
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raise "No such method #{method_name} in #{self.name}" unless @methods
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if( @methods.name == method_name)
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@methods = @methods.next
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return true
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end
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method = @methods
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while(method && method.next)
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if( method.next.name == method_name)
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method.set_next( method.next.next )
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return true
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else
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method = method.next
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end
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end
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raise "No such method #{method_name} in #{self.name}"
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end
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def get_method( fname )
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raise "get_method #{fname}.#{fname.class}" unless fname.is_a?(Symbol)
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return nil unless @methods
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@methods.each_method do |m|
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return m if(m.name == fname )
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end
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nil
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end
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# resolve according to normal oo logic, ie look up in superclass if not present
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# NOTE: this will probably not work in future as the code for the superclass
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# method, being bound to t adifferent type, will assume that types (not the run-time
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# actual types) layout. Either need to enforce some c++ style upwards compatibility (buuh)
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# or copy the methods and recompile them for the actual type. (maybe still later dynamically)
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# But for now we walk up, as it should really just be to object
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def resolve_method( fname )
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method = get_method(fname)
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return method if method
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sup = object_class.super_class
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return nil unless sup
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return nil if object_class.name == :Object
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sup.instance_type.resolve_method(fname)
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end
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def methods_length
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return 0 unless @methods
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len = 0
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@methods.each_method { len += 1}
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return len
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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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# Type objects are immutable, so a new object is returned
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# As types are also unique, two same adds will result in identical results
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def add_instance_variable( name , type )
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raise "No nil name" unless name
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raise "No nil type" unless type
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hash = to_hash
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hash[name] = type
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return Type.for_hash( @object_class , hash)
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end
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def set_object_class(oc)
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raise "object class should be a class, not #{oc.class}" unless oc.is_a?(Class)
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@object_class = oc
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end
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def instance_length
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@names.get_length()
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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 0 based and 0 is always the type)
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def variable_index( name )
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has = @names.index_of(name)
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return nil unless has
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raise "internal error #{name}:#{has}" if has < 0
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has
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end
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def get_length()
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@names.get_length()
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end
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def name_at( index )
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raise "No names #{index}" unless @names
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@names.get(index)
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end
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def type_at( index )
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@types.get(index)
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end
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def inspect
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"Type[#{names.inspect}]"
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end
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def rxf_reference_name
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"#{@object_class.name}_Type"
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end
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alias :name :rxf_reference_name
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def each
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index = 0
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while( index < get_length() )
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yield( name_at(index) , type_at(index) )
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index += 1
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end
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end
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def each_method(&block)
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return unless @methods
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@methods.each_method(&block)
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end
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def to_hash
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hash = {}
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each do |name , type|
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raise "Name nil #{type}" unless name
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raise "Type nil #{name}" unless type
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hash[name] = type
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end
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hash
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end
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def hash
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index = 1
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hash_code = Type.str_hash( @object_class.name )
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each do |name , type|
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item_hash = Type.str_hash(name) + Type.str_hash(type)
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hash_code += item_hash + (item_hash / 256 ) * index
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index += 1
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end
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hash_code % (2 ** 62)
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end
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def self.str_hash(str)
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if RUBY_ENGINE == 'opal'
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hash = 5381
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str.to_s.each_char do |c|
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hash = ((hash << 5) + hash) + c.to_i; # hash * 33 + c without getting bignums
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end
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hash % (2 ** 51)
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else
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str.hash
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end
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end
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private
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def private_add_instance_variable( name , type)
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raise "Name shouldn't be nil" unless name
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raise "Value Type shouldn't be nil" unless type
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@names.push(name)
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@types.push(type)
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end
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end
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end
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