ridiculously easy to implement the if now

lib/arm/arm_machine.rb

@@ -14,6 +14,10 @@ module Arm
       block <<  cmp( left ,  right )
       Vm::BranchCondition.new :le
     end
+    def integer_less_than block ,  left , right
+      block <<  cmp( left ,  right )
+      Vm::BranchCondition.new :lt
+    end
     def integer_greater_than block ,  left , right
       block <<  cmp( left ,  right )
       Vm::BranchCondition.new :gt

lib/ast/if_expression.rb

@@ -11,5 +11,31 @@ module Ast
     def attributes
       [:cond, :if_true, :if_false]
     end
+    def compile context , into
+      false_block = into.new_block "#{into.name}_else"
+      merge_block = false_block.new_block "#{into.name}_if_merge"
+
+      cond_val = cond.compile(context , into)
+      puts "compiled if condition #{cond_val.inspect}"
+      into.b false_block , condition_code: cond_val.not_operator
+            
+      last = nil
+      if_true.each do |part|
+        last = part.compile(context , into )
+        puts "compiled in if true #{last.inspect}"
+      end
+      
+      into.b merge_block
+
+      if_false.each do |part|
+        last = part.compile(context , false_block )
+        puts "compiled in if false #{last.inspect}"
+      end
+      
+      puts "compile if end"
+      into.insert_at merge_block
+
+      return last
+    end
   end
 end

lib/ast/operator_expressions.rb

@@ -37,6 +37,8 @@ module Ast
       case operator
       when ">"
         code = l_val.greater_than into , r_val
+      when "<"
+        code = l_val.less_than into , r_val
       when "+"
         res = context.function.new_local
         into.res = l_val + r_val

lib/vm/values.rb

@@ -38,6 +38,8 @@ module Vm
         :gt
       when :gt
         :le
+      when :lt
+        :ge
       else
         raise "no implemented #{@operator}"
       end
@@ -96,6 +98,9 @@ module Vm
     def greater_than block , right
       RegisterMachine.instance.integer_greater_than block , self , right
     end
+    def less_than block , right
+      RegisterMachine.instance.integer_less_than block , self , right
+    end
     def == other
       code = class_for(CompareInstruction).new(self , other , opcode: :cmp)
     end