module Temple
  module Filters
    class MultiFlattener
      def initialize(options = {})
        @options = {}
      end

      def compile(exp)
        exp.first == :multi ? on_multi(*exp[1..-1]) : exp
      end
      
      def on_multi(*exps)
        # If the multi contains a single element, just return the element
        return compile(exps.first) if exps.length == 1
        result = [:multi]
        
        exps.each do |exp|
          exp = compile(exp)
          if exp.first == :multi
            result.concat(exp[1..-1])
          else
            result << exp
          end
        end
        
        result
      end
    end
  end
end