case class UDFunctionCallExpr(nameAsParsed: String, fnQName: RefQName, args: List[Expression],
resultType: NodeInfo.Kind, argsTypes: List[NodeInfo.Kind], constructor: List[CompiledDPath] => RecipeOp)
	extends FunctionCallBase(nameAsParsed, fnQName, args) {

	lazy val argsToArgType = (args zip argsTypes).toMap
	override lazy val inherentType = resultType

	override def targetTypeForSubexpression(childExpr: Expression): NodeInfo.Kind = {
		argsToArgType.get(childExpr) match {
			case Some(argType) => argType
			case None => {
				Assert.invariantFailed("subexpression %s is not an argument.".format(subexp))
			}
		}
	}
	override lazy val compiledDPath = {
		val recipes = args.map { _.compiledDPath }
		val res = new CompiledDPath(constructor(recipes) +: conversions)
		res
	}
}

case class UDFunctionCall(recipes: List[CompiledDPath], functionClassObject: Object, udfEvaluate: Method)
	extends FNArgsList(recipes) {

	override def computeValues(values: List[Any], dstate: DState) = {
		val res = udfEvaluate.invoke(functionClassObject, values: _*) //might need to explicitly cast values to type Object before hand
		res
	}
}