fix the if test by naming branch and label and stitching them in constructor
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@ -1,28 +1,31 @@
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module Ast
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class IfExpression < Expression
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# attr_reader :cond, :if_true, :if_false
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@@counter = 0 #naming the braches by counting mainly to get them back together in testing
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def compile frame , method
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is = cond.compile(frame , method)
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# is.is_false(frame,method)
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# TODO should/will use different branches for different conditions.
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branch = Virtual::ImplicitBranch.new
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branch_name = "if_merge_#{@@counter}".to_sym
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@@counter += 1
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branch = Virtual::ImplicitBranch.new branch_name
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method.add branch
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last = is
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if_true.each do |part|
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last = part.compile(frame,method )
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raise part.inspect if last.nil?
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end
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label = Virtual::Label.new
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method.add label
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merge = Virtual::Label.new(branch_name)
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method.add merge
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branch.swap
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method.current = branch
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if_false.each do |part|
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last = part.compile(frame,method )
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raise part.inspect if last.nil?
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end
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method.add label
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method.add merge
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branch.swap
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method.current = label
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method.current = merge
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#TODO should return the union of the true and false types
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last
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end
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@ -20,6 +20,17 @@ module Virtual
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end
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end
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module Named
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def initialize name , nex = nil
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super(nex)
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@name = name
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end
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attr_reader :name
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def attributes
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[:name ] + super
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end
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end
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# the first instruction we need is to stop. Off course in a real machine this would be a syscall, but that is just
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# an implementation (in a programm it would be a function). But in a virtual machine, not only do we need this instruction,
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# it is indeed the first instruction as just this instruction is the smallest possible programm for the machine.
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@ -33,6 +44,7 @@ module Virtual
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#resolves to nothing, but allows forward definition
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class Label < Instruction
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include Named
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end
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# the next instruction represents the true branch and the other is the .... other
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@ -40,13 +52,27 @@ module Virtual
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# this is an abstract base class (though no measures are taken to prevent instantiation) and derived
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# class names indicate the actual test
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class Branch < Instruction
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def initialize nex = nil , other = nil
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def initialize name , nex = nil , other = nil
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super(nex)
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@next = nex
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@other = other
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if other
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label = self.next
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while label
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break if label.is_a?(Label) and label.name == name
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label = label.next
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end
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before_label = self.other
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while before_label.next
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break if before_label.next.is_a?(Label) and before_label.next.name == name
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before_label = before_label.next
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end
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before_label.next = label
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end
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end
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attr_reader :other
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attr_reader :other , :name
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def attributes
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[:other] + super
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[:name , :next , :other]
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end
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# so code can be "poured in" in the same way as normal, we swap the braches around in after the true condition
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# and swap them back after
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@ -64,14 +90,7 @@ module Virtual
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# A note: future branch conditions include OverflowBranch and other non-c
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class FrameGet < Instruction
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def initialize name , nex = nil
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super(nex)
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@name = name
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end
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attr_reader :name
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def attributes
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[:name ] + super
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end
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include Named
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end
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class FrameSend < Instruction
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@ -110,13 +129,6 @@ module Virtual
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end
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class ObjectGet < Instruction
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def initialize name , nex = nil
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super(nex)
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@name = name
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end
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attr_reader :name
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def attributes
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[:name] + super
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end
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include Named
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end
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end
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@ -54,7 +54,7 @@ def ofthen(n)
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end
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end
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HERE
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@output = nil
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@output = [Virtual::MethodDefinition.new(:ofthen,[Virtual::Argument.new(:n,Virtual::Mystery.new())],Virtual::SelfReference.new(nil),Virtual::Local.new(:maybenot,Virtual::IntegerConstant.new(667)),Virtual::MethodEnter.new(Virtual::ImplicitBranch.new(nil,Virtual::FrameSet.new(:isit,Virtual::IntegerConstant.new(42),Virtual::Label.new(:if_merge_0,nil)),Virtual::FrameSet.new(:maybenot,Virtual::IntegerConstant.new(667),Virtual::Label.new(:if_merge_0,nil)))))]
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check
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end
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