olabusayoT commented on a change in pull request #436: URL: https://github.com/apache/incubator-daffodil/pull/436#discussion_r511948390
########## File path: daffodil-runtime1/src/main/scala/org/apache/daffodil/processors/DaffodilUnparseContentHandler.scala ########## @@ -0,0 +1,309 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.daffodil.processors + +import scala.util.Try +import scala.xml.NamespaceBinding + +import javax.xml.XMLConstants +import org.apache.daffodil.api.DFDL +import org.apache.daffodil.api.DFDL.DaffodilUnhandledSAXException +import org.apache.daffodil.api.DFDL.DaffodilUnparseErrorSAXException +import org.apache.daffodil.infoset.IllegalContentWhereEventExpected +import org.apache.daffodil.infoset.InfosetInputterEventType.EndDocument +import org.apache.daffodil.infoset.InfosetInputterEventType.EndElement +import org.apache.daffodil.infoset.InfosetInputterEventType.StartDocument +import org.apache.daffodil.infoset.InfosetInputterEventType.StartElement +import org.apache.daffodil.infoset.SAXInfosetInputter +import org.apache.daffodil.util.MStackOf +import org.apache.daffodil.util.Maybe.Nope +import org.apache.daffodil.util.Maybe.One +import org.apache.daffodil.util.Misc +import org.xml.sax.Attributes +import org.xml.sax.Locator + +/** + * DaffodilUnparseContentHandler produces InfosetEvent objects for the SAXInfosetInputter to + * consume and convert to a event that the Dataprocessor unparse can use. The infosetEvent object + * is built from information that is passed to the ContentHandler from an XMLReader parser. In + * order to receive the uri and prefix information from the XMLReader, the following features + * must be set to true on whatever XMLReader is used: http://xml.org/sax/features/namespaces and + * http://xml.org/sax/features/namespace-prefixes + * + * This class, together with the SAXInfosetInputter, uses coroutines to ensure that only one event, + * at a time, is passed between the two classes. The following is the general process: + * + * - an external call is made to parse an XML Documents + * - this class receives a StartDocument call, which is the first infosetEvent that is sent to + * the SAXInfosetInputter. That event is put on the inputter's queue, this thread is paused, and + * that inputter's thread is run + * - when the SAXInfosetInputter is done processing an event and is ready for a new event, it + * sends the completed event via the coroutine system, and loads it on the contentHandler's + * queue, which restarts this thread and pauses that one. In the expected case, the events will + * contain no new information, until the unparse is completed. + * - this process continues until the EndDocument method is called. Once that infosetEvent is + * sent to the inputter, it signals the end of events coming from the contentHandler. This + * ends the unparseProcess and returns the event with the unparseResult and/or any error + * information + * + * @param dp dataprocessor object that will be used to call the parse + * @param output outputChannel of choice where the unparsed data is stored + */ +class DaffodilUnparseContentHandler( + dp: DFDL.DataProcessor, + output: DFDL.Output) + extends DFDL.DaffodilUnparseContentHandler { + private lazy val inputter = new SAXInfosetInputter(this, dp, output) + private var unparseResult: DFDL.UnparseResult = _ + private lazy val infosetEvent: DFDL.SaxInfosetEvent = new DFDL.SaxInfosetEvent + private lazy val characterData = new StringBuilder + private var prefixMapping: NamespaceBinding = _ + private lazy val prefixMappingTrackingStack = new MStackOf[NamespaceBinding] + private var contentHandlerPrefixMappingUsed = false + + /** + * returns null in the case of an DaffodilUnhandledSAXException + */ + def getUnparseResult: DFDL.UnparseResult = unparseResult + + def enableInputterResolutionOfRelativeInfosetBlobURIs(): Unit = inputter.enableResolutionOfRelativeInfosetBlobURIs() + + override def setDocumentLocator(locator: Locator): Unit = { + // do nothing + } + + override def startDocument(): Unit = { + infosetEvent.eventType = One(StartDocument) + sendToInputter() + } + + override def endDocument(): Unit = { + infosetEvent.eventType = One(EndDocument) + sendToInputter() + } + + override def startPrefixMapping(prefix: String, uri: String): Unit = { + contentHandlerPrefixMappingUsed = true + val pre = if (prefix == "") null else prefix + prefixMapping = NamespaceBinding(pre, uri, prefixMapping) + } + + /** + * XMLReader does not guarantee the order of the prefixes called for this function, but it does + * guarantee that this method is called after its corresponding endElement, which means we can + * can just take off the top mappings, because the element that might have cared about the order + * is already done using the prefixMappings + */ + override def endPrefixMapping(prefix: String): Unit = { + prefixMapping = if (prefixMapping == null) prefixMapping else prefixMapping.parent + } + + /** + * Uses Attributes, which is passed in to the startElement callback, to extract prefix mappings and + * populate the global prefixMapping + */ + def mapPrefixMappingFromAttributesImpl(atts:Attributes): Unit = { + var i = 0 + while (i < atts.getLength) { + val qName = atts.getQName(i) + if (qName.startsWith("xmlns")) { + val uri = atts.getValue(i) + val prefix = if(qName.contains(":")) { + val pref = qName.split(":").last + pref + } else { + null // NamespaceBinding does not allow blanks so return null instead + } + prefixMapping = NamespaceBinding(prefix, uri, prefixMapping) + } + i += 1 + } + } + + override def startElement(uri: String, localName: String, qName: String, atts: Attributes): Unit = { + // we need to check if the characters data is all whitespace, if it is we drop the whitespace + // data, if it is not, it is an error as starting a new element with actual characterData means + // we haven't hit an endElement yet, which means we're in a complexElement and a complexElement + // cannot have character content + if (characterData.nonEmpty && !Misc.isAllWhitespace(characterData)) { + throw new IllegalContentWhereEventExpected("Non-whitespace characters in complex " + + "Element: " + characterData.toString + ) + } else { + // reset since it was whitespace only + characterData.setLength(0) + } + + if (!contentHandlerPrefixMappingUsed) { + // always pushes but doesn't always add a mapping since atts can be empty + prefixMappingTrackingStack.push(prefixMapping) + mapPrefixMappingFromAttributesImpl(atts) + } + + if (!infosetEvent.isEmpty && infosetEvent.localName.isDefined) { + // we started another element while we were in the process of building a startElement + // this means the first element was complex and we are ready for the inputter queue + sendToInputter() + } + // use Attributes to determine xsi:nil value + val nilIn = atts.getIndex(XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI, "nil") + infosetEvent.nilValue = if (nilIn >= 0) { + val nilValue = atts.getValue(nilIn) + One(nilValue) + } else { + Nope + } + // set localName and namespaceURI + lazy val qNameArr = qName.split(":") + infosetEvent.localName = + if (localName.nonEmpty) { + One(localName) + } else if (qNameArr.length > 1) { + One(qNameArr.last) + } else if (qNameArr.nonEmpty) { + One(qNameArr.head) + } else { Review comment: Ah you're right, it was a left over from when I was using options, I was returning either lift(1) or lift(0) then since the former case represented when there was a prefix and a localName and the latter, when there is only a localName, but it can be simplified to .nonEmpty and .last ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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