bsloane1650 commented on a change in pull request #273: WIP: Add User Defined
Functions Capability
URL: https://github.com/apache/incubator-daffodil/pull/273#discussion_r331645724
##########
File path:
daffodil-core/src/main/scala/org/apache/daffodil/dpath/Expression.scala
##########
@@ -1870,6 +1871,47 @@ case class FunctionCallExpression(functionQNameString:
String, expressions: List
case (RefQName(_, "unsignedByte", XSD), args) =>
XSConverterExpr(functionQNameString, functionQName, args,
NodeInfo.UnsignedByte)
+ case (RefQName(Some(_), _, _), args) => {
+ val namespace = functionQName.namespace.toString()
+ val fName = functionQName.local
+
+ lazy val udfservice = {
+ val a = UDFService
+ a.warnings.map { w => SDW(WarnID.UserDefinedFunction, w) }
+ val allErrors = a.errors.mkString("\n\n")
+ SDE(s"Function unknown: fname[${fName}]
fnamespace[${namespace}].\n$allErrors")
+ a
+ }
+
+ val fcObject = udfservice.udfs.lookupFunctionClass(namespace, fName)
+
+ if (fcObject == null) {
+ SDE("Function not found: fname[%s] fnamespace[%s]. Currently
registered UDFs:\n%s", fName, namespace, udfservice.allFunctionClasses)
+ }
+
+ val fcClassType = fcObject.getClass
+
+ val paramTypesReturnTypeTuple: Array[(Array[Class[_]], Class[_])] =
fcClassType.getMethods.collect {
+ case p if p.getName == "evaluate" => (p.getParameterTypes,
p.getReturnType)
+ }
+
+ if (paramTypesReturnTypeTuple.isEmpty) {
+ SDE("Missing evaluate method for function provided: name[%s]
namespace[%s]", fName, namespace)
+ }
+
+ if (paramTypesReturnTypeTuple.length > 1) {
+ SDE("Only one evaluate method allowed per function class: name[%s]
namespace[%s]", fName, namespace)
+ }
+
+ val paramTypes: Array[Class[_]] = paramTypesReturnTypeTuple.head._1
+ val retType: Class[_] = paramTypesReturnTypeTuple.head._2
+
Review comment:
I could imagine people using UDFs as an alternative to DFDL variables.
Depending on how the user's enviroment is set up, they might find it easier to
supply "variables" through there own infrastructure, and use UDFs to provide
them to Daffodil. I could also imagine them doing more questionable things,
such as implementing a "getParseTimestamp" function.
Not to mention all the crazy things that code/schema generators might want
to spit out.
Ultimately, I don't see any principled reason not to allow this. At most, we
should emit a warning if we really think we want to call attention to people
doing this.
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