Add exceptionOccurred method to InfosetOutputter

daffodil-core/src/test/scala/org/apache/daffodil/core/api/TestMetadataWalking.scala

@@ -30,6 +30,7 @@ import org.apache.daffodil.runtime1.api.InfosetItem
 import org.apache.daffodil.runtime1.api.InfosetSimpleElement
 import org.apache.daffodil.runtime1.api.MetadataHandler
 import org.apache.daffodil.runtime1.api.SimpleElementMetadata
+import org.apache.daffodil.runtime1.infoset.ExceptionOccurredMixin
 import org.apache.daffodil.runtime1.infoset.InfosetOutputter
 import org.apache.daffodil.runtime1.infoset.InfosetOutputterImpl
 import org.apache.daffodil.runtime1.processors.DataProcessor
@@ -72,7 +73,7 @@ class TestMetadataWalking {
     override def endComplexElementMetadata(m: ComplexElementMetadata): Unit = buf += m
   }
 
-  class GatherData extends InfosetOutputterImpl with InfosetOutputter {
+  class GatherData extends InfosetOutputterImpl with InfosetOutputter with ExceptionOccurredMixin {
 
     private val buf = new ArrayBuffer[InfosetItem]
 

daffodil-japi/src/main/scala/org/apache/daffodil/japi/infoset/Infoset.scala

@@ -470,4 +470,5 @@ abstract class InfosetOutputterProxy extends InfosetOutputter {
   override def endComplex(diComplex: InfosetComplexElement): Unit = infosetOutputter.endComplex(diComplex)
   override def startArray(diArray: InfosetArray): Unit = infosetOutputter.startArray(diArray)
   override def endArray(diArray: InfosetArray): Unit = infosetOutputter.endArray(diArray)
+  override def exceptionOccurred(e: Exception): Unit = infosetOutputter.exceptionOccurred(e)
 }

daffodil-japi/src/test/java/org/apache/daffodil/example/TestInfosetOutputter.java

@@ -91,4 +91,9 @@ public void startArray(InfosetArray diArray) {
     @Override
     public void endArray(InfosetArray diArray) {
     }
+
+    @Override
+    public void exceptionOccurred(Exception e) {
+        // do nothing
+    }
 }

daffodil-runtime1/src/main/scala/org/apache/daffodil/runtime1/infoset/InfosetOutputter.scala

@@ -120,6 +120,18 @@ trait InfosetOutputter extends BlobMethodsMixin {
   def endArray(diArray: InfosetArray): Unit
 
   def getStatus(): Status
+
+  /**
+   * Override this to be fed any exceptions thrown by the start/end methods of this class.
+   * This is mostly to facilitate users debugging their code that uses the API.
+   *
+   * This saves the user of the API from having to wrap try/catch around their
+   * start/end method bodies.
+   *
+   * @param e the exception thrown by one of the other methods.
+   */
+  def exceptionOccurred(e: Exception): Unit
+
 }
 
 /**
@@ -185,3 +197,10 @@ object Status extends Enumeration {
   type Status = Value
   val DONE, READY, VISITING = Value
 }
+
+trait ExceptionOccurredMixin {
+  def exceptionOccurred(e: Exception): Unit = {
+    val ex = e // because sometimes the debugger won't show the exception
+    ex.getCause() // good place for a breakpoint
+  }
+}

daffodil-runtime1/src/main/scala/org/apache/daffodil/runtime1/infoset/InfosetWalker.scala

@@ -453,6 +453,7 @@ class InfosetWalker private (
       outputterFunc
     } catch {
       case e: Exception => {
+        outputter.exceptionOccurred(e) // debugging hook for the user.
         val cause = e.getCause
         val msg = if (cause == null) e.toString else cause.toString
         context.SDE("Failed to %s: %s", desc, msg)

daffodil-runtime1/src/main/scala/org/apache/daffodil/runtime1/infoset/JsonInfosetOutputter.scala

@@ -29,6 +29,7 @@ import java.nio.charset.StandardCharsets
 
 class JsonInfosetOutputter private (writer: java.io.Writer, pretty: Boolean)
   extends InfosetOutputterImpl
+  with ExceptionOccurredMixin
   with Indentable {
 
   def this(os: java.io.OutputStream, pretty: Boolean) = {

daffodil-runtime1/src/main/scala/org/apache/daffodil/runtime1/infoset/NullInfosetOutputter.scala

@@ -24,7 +24,8 @@ import org.apache.daffodil.runtime1.api.InfosetSimpleElement
 /**
  * Ignores all infoset events, outputting nothing
  */
-class NullInfosetOutputter() extends InfosetOutputterImpl {
+class NullInfosetOutputter() extends InfosetOutputterImpl
+with ExceptionOccurredMixin {
 
   override def reset(): Unit = {}
 

daffodil-runtime1/src/main/scala/org/apache/daffodil/runtime1/infoset/TeeInfosetOutputter.scala

@@ -30,7 +30,8 @@ import org.apache.daffodil.runtime1.api.InfosetSimpleElement
  *
  *    InfosetOutputters to send all events
  */
-class TeeInfosetOutputter(outputters: InfosetOutputter*) extends InfosetOutputterImpl {
+class TeeInfosetOutputter(outputters: InfosetOutputter*) extends InfosetOutputterImpl
+with ExceptionOccurredMixin {
 
   override def reset(): Unit = {
     outputters.foreach { _.reset() }

daffodil-runtime1/src/main/scala/org/apache/daffodil/runtime1/infoset/XMLInfosetOutputterMixin.scala

@@ -21,7 +21,7 @@ import org.apache.daffodil.lib.equality._
 import org.apache.daffodil.lib.util.Maybe
 import org.apache.daffodil.lib.xml.XMLUtils
 
-trait XMLInfosetOutputterMixin {
+trait XMLInfosetOutputterMixin extends ExceptionOccurredMixin {
 
   def remapped(dataValueAsString: String) =
     XMLUtils.remapXMLIllegalCharactersToPUA(dataValueAsString)
@@ -58,5 +58,4 @@ trait XMLInfosetOutputterMixin {
       }
     res
   }
-
 }

daffodil-sapi/src/main/scala/org/apache/daffodil/sapi/infoset/Infoset.scala

@@ -459,4 +459,5 @@ abstract class InfosetInputterProxy extends InfosetInputter {
   override def endComplex(diComplex: InfosetComplexElement): Unit = infosetOutputter.endComplex(diComplex)
   override def startArray(diArray: InfosetArray): Unit = infosetOutputter.startArray(diArray)
   override def endArray(diArray: InfosetArray): Unit = infosetOutputter.endArray(diArray)
+  override def exceptionOccurred(e: Exception): Unit = infosetOutputter.exceptionOccurred(e)
 }

daffodil-sapi/src/test/scala/org/apache/daffodil/example/TestInfosetInputterOutputter.scala

@@ -139,4 +139,6 @@ case class TestInfosetOutputter() extends InfosetOutputter {
   override def startArray(diArray: InfosetArray): Unit = {}
 
   override def endArray(diArray: InfosetArray): Unit = {}
+
+  override def exceptionOccurred(e: Exception): Unit = {}
 }