change operators to symbols

lib/risc/instructions/operator_instruction.rb

@@ -1,9 +1,17 @@
 module Risc
 
+  # Destructive operator instructions on the two registers given
+  #
+  # left = left OP right
+  #
+  # With OP being the normal logical and mathematical operations provided by
+  # cpus. Ie  "+" , "-", ">>", "<<", "*", "&", "|"
+  #
   class OperatorInstruction < Instruction
-    def initialize source , operator , left , right
+    def initialize( source , operator , left , right )
       super(source)
       @operator = operator
+      raise "unsuported operator :#{operator}:" unless [:+, :-, :>>, :<<, :*, :&, :|, :==].include?(operator)
       @left = left
       @right = right
     end
@@ -14,8 +22,8 @@ module Risc
     end
 
   end
-  def self.op source , operator , left , right
-    OperatorInstruction.new source , operator , left , right
+  def self.op( source , operator , left , right )
+    OperatorInstruction.new( source , operator , left , right )
   end
 
 end