module Bosl
  Compiler.class_eval do
#    operator attr_reader  :operator, :left, :right
    def on_operator expression
      operator , left , right = *expression
      Virtual::Return.new(:int)
    end

    def on_assign expression
      name , value = *expression
      name = name.to_a.first
      v = process(value)
      index = method.has_local( name )
      if(index)
        method.source.add_code Virtual::Set.new(Virtual::FrameSlot.new(:int,index ) , v )
      else
        index = method.has_arg( name )
        if(index)
          method.source.add_code Virtual::Set.new(Virtual::ArgSlot.new(:int,index ) , v )
        else
          raise "must define variable #{name} before using it in #{@method.inspect}"
        end
      end
    end

  end
end