add branches to builder

lib/risc/builder.rb

@@ -32,6 +32,16 @@ module Risc
       reg
     end
 
+    def if_zero( label )
+      add Risc::IsZero.new("jump if zero" , label)
+    end
+    def if_not_zero( label )
+      add Risc::IsNotZero.new("jump if not zero" , label)
+    end
+    def branch( label )
+      add Risc::Branch.new("jump to" , label)
+    end
+
     # build code using dsl (see __init__ or MessageSetup for examples)
     # names (that ruby would resolve to a variable/method) are converted
     # to registers. << means assignment and [] is supported both on

lib/risc/builtin/word.rb

@@ -70,11 +70,11 @@ module Risc
             space << space[:nil_object]
 
             add Risc.op(source + "if method is nil", :- , space , typed_method )
-            add Risc::IsZero.new(source + "jump if nil" , exit_label)
+            if_zero exit_label
 
             name << typed_method[:name]
             add Risc.op(source + " compare name with me", :- , name , word )
-            add Risc::IsNotZero.new(source + "jump if not same" , false_label)
+            if_not_zero false_label
 
             typed_method << typed_method[:binary]
             message[:return_value] << typed_method
@@ -83,7 +83,7 @@ module Risc
 
             add false_label
             typed_method << typed_method[:next_method]
-            add Risc::Branch.new(source + "back to while", while_start_label)
+            branch  while_start_label
 
             add exit_label
           end