work on branches

the concept is different in bosl, move appropriate to virtual

lib/bosl/compiler/if_expression.rb

@@ -12,11 +12,10 @@ module Bosl
       true_block =  @method.source.new_block "if_true"     # second, linked in after current, before merge
       false_block = @method.source.new_block "if_false"    # directly next in order, ie if we don't jump we land here
 
-
-      is = process(condition )
+      is = process(condition)
       # TODO should/will use different branches for different conditions.
       # just a scetch : cond_val = cond_val.is_true?(method) unless cond_val.is_a? BranchCondition
-      @method.source.add_code Virtual::IsTrueBranch.new( true_block )
+      @method.source.add_code Register::IsZeroBranch.new( condition , true_block )
 
       # compile the true block (as we think of it first, even it is second in sequential order)
       @method.source.current true_block
@@ -26,7 +25,7 @@ module Bosl
       # compile the false block
       @method.source.current false_block
       last = process_all(if_false).last if if_false
-      @method.source.add_code Virtual::UnconditionalBranch.new( merge_block )
+      @method.source.add_code Register::AlwaysBranch.new(expression, merge_block )
 
       #puts "compiled if: end"
       @method.source.current merge_block

lib/bosl/compiler/while_expression.rb

@@ -14,12 +14,12 @@ module Bosl
 
       cond = process(condition)
 
-      @method.source.add_code Virtual::IsTrueBranch.new(merge)
+      @method.source.add_code Register::IsZeroBranch.new(condition,merge)
 
       last = process_all(expressions).last
 
       # unconditionally branch to the start
-      @method.source.add_code Virtual::UnconditionalBranch.new(start)
+      @method.source.add_code Register::AlwaysBranch.new(expression,start)
 
       # continue execution / compiling at the merge block
       @method.source.current merge

lib/register/instructions/branch.rb

@@ -13,7 +13,19 @@ module Register
     def to_s
       "Branch: #{block.name}"
     end
+    alias :inspect :to_s 
+  end
 
+  class IsZeroBranch < Branch
+  end
+
+  class IsNegativeBranch < Branch
+  end
+
+  class IsPositiveBranch < Branch
+  end
+
+  class AlwaysBranch < Branch
   end
 
 end

lib/virtual/instruction.rb

@@ -13,7 +13,6 @@ module Virtual
 
 end
 
-require_relative "instructions/branch"
 require_relative "instructions/halt"
 require_relative "instructions/instance_get"
 require_relative "instructions/method_call"

lib/virtual/instructions/branch.rb

@@ -1,14 +0,0 @@
-module Virtual
-
-
-  # a branch must branch to a block. This is an abstract class, names indicate the actual test
-  class Branch < Instruction
-    def initialize to
-      @to = to
-    end
-    attr_reader :to
-  end
-end
-
-require_relative "is_true_branch"
-require_relative "unconditional_branch"

lib/virtual/instructions/is_true_branch.rb

@@ -1,8 +0,0 @@
-module Virtual
-
-  # implicit means there is no explcit test involved.
-  # normal ruby rules are false and nil are false, EVERYTHING else is true (and that includes 0)
-  class IsTrueBranch < Branch
-  end
-
-end

lib/virtual/instructions/unconditional_branch.rb

@@ -1,6 +0,0 @@
-module Virtual
-
-  class UnconditionalBranch < Branch
-  end
-
-end