From 7534626d873128dc7312f04b27506ed52b308712 Mon Sep 17 00:00:00 2001
From: Torsten Ruger <torsten@villataika.fi>
Date: Wed, 16 Jul 2014 21:16:08 +0300
Subject: [PATCH] fix the if test by naming branch and label and stitching them
 in constructor

---
 lib/ast/if_expression.rb     | 13 ++++++----
 lib/virtual/instruction.rb   | 50 ++++++++++++++++++++++--------------
 test/virtual/test_methods.rb |  2 +-
 3 files changed, 40 insertions(+), 25 deletions(-)

diff --git a/lib/ast/if_expression.rb b/lib/ast/if_expression.rb
index f5df7ced..d58b397c 100644
--- a/lib/ast/if_expression.rb
+++ b/lib/ast/if_expression.rb
@@ -1,28 +1,31 @@
 module Ast
   class IfExpression < Expression
 #    attr_reader  :cond, :if_true, :if_false
+    @@counter = 0   #naming the braches by counting mainly to get them back together in testing
     def compile frame , method
       is = cond.compile(frame , method)
       #      is.is_false(frame,method)
       # TODO should/will use different branches for different conditions. 
-      branch = Virtual::ImplicitBranch.new
+      branch_name = "if_merge_#{@@counter}".to_sym
+      @@counter += 1
+      branch = Virtual::ImplicitBranch.new branch_name
       method.add branch
       last = is
       if_true.each do |part|
         last = part.compile(frame,method )
         raise part.inspect if last.nil?
       end
-      label = Virtual::Label.new
-      method.add label
+      merge = Virtual::Label.new(branch_name)
+      method.add merge
       branch.swap
       method.current = branch
       if_false.each do |part|
         last = part.compile(frame,method )
         raise part.inspect if last.nil?
       end
-      method.add label
+      method.add merge
       branch.swap
-      method.current = label
+      method.current = merge
       #TODO should return the union of the true and false types
       last
     end
diff --git a/lib/virtual/instruction.rb b/lib/virtual/instruction.rb
index 2a5efd82..bd9c4615 100644
--- a/lib/virtual/instruction.rb
+++ b/lib/virtual/instruction.rb
@@ -20,6 +20,17 @@ module Virtual
     end
   end
 
+  module Named
+    def initialize name , nex = nil
+      super(nex)
+      @name = name
+    end
+    attr_reader :name
+    def attributes
+      [:name ] + super
+    end
+  end
+
   # the first instruction we need is to stop. Off course in a real machine this would be a syscall, but that is just 
   # an implementation (in a programm it would be a function). But in a virtual machine, not only do we need this instruction,
   # it is indeed the first instruction as just this instruction is the smallest possible programm for the machine.
@@ -33,6 +44,7 @@ module Virtual
 
   #resolves to nothing, but allows forward definition
   class Label < Instruction
+    include Named
   end
 
   # the next instruction represents the true branch and the other is the .... other
@@ -40,13 +52,27 @@ module Virtual
   # this is an abstract base class (though no measures are taken to prevent instantiation) and derived
   # class names indicate the actual test
   class Branch < Instruction
-    def initialize nex = nil , other = nil
+    def initialize name , nex = nil , other = nil
       super(nex)
+      @next = nex
       @other = other
+      if other
+        label = self.next
+        while label
+          break if label.is_a?(Label) and label.name == name
+          label = label.next
+        end
+        before_label = self.other
+        while before_label.next
+          break if before_label.next.is_a?(Label) and before_label.next.name == name
+          before_label = before_label.next
+        end
+        before_label.next = label
+      end
     end
-    attr_reader :other
+    attr_reader :other , :name
     def attributes
-      [:other] + super
+      [:name , :next , :other]
     end
     # so code can be "poured in" in the same way as normal, we swap the braches around in after the true condition
     # and swap them back after
@@ -64,14 +90,7 @@ module Virtual
 
   # A note: future branch conditions include OverflowBranch and other non-c 
   class FrameGet < Instruction
-    def initialize name , nex = nil
-      super(nex)
-      @name = name
-    end
-    attr_reader :name
-    def attributes
-      [:name ] + super
-    end
+    include Named
   end
 
   class FrameSend < Instruction
@@ -110,13 +129,6 @@ module Virtual
   end
 
   class ObjectGet < Instruction
-    def initialize name , nex = nil
-      super(nex)
-      @name = name
-    end
-    attr_reader :name
-    def attributes
-      [:name] + super
-    end
+    include Named
   end
 end
diff --git a/test/virtual/test_methods.rb b/test/virtual/test_methods.rb
index 4c2f9cf6..be13db31 100644
--- a/test/virtual/test_methods.rb
+++ b/test/virtual/test_methods.rb
@@ -54,7 +54,7 @@ def ofthen(n)
   end
 end
 HERE
-      @output = nil
+      @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)))))]
       check
   end