jw3 commented on a change in pull request #452: URL: https://github.com/apache/incubator-daffodil/pull/452#discussion_r528904422
########## File path: daffodil-schematron/src/main/scala/org/apache/daffodil/validation/Schematron.scala ########## @@ -0,0 +1,90 @@ +/* + * 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.validation + +import java.io.InputStream +import java.io.StringWriter + +import javax.xml.parsers.ParserConfigurationException +import javax.xml.parsers.SAXParserFactory +import javax.xml.transform.Source +import javax.xml.transform.Templates +import javax.xml.transform.TransformerFactory +import javax.xml.transform.URIResolver +import javax.xml.transform.dom.DOMResult +import javax.xml.transform.dom.DOMSource +import javax.xml.transform.sax.SAXSource +import javax.xml.transform.stream.StreamResult +import javax.xml.transform.stream.StreamSource +import org.apache.daffodil.api.ValidatorInitializationException +import org.xml.sax.InputSource +import org.xml.sax.SAXException +import org.xml.sax.XMLReader + + +/** + * Schematron engine implementation + */ +object Schematron { + val templatesRootDir = "iso-schematron-xslt2" + private val templatesPipeline = Array("iso_dsdl_include.xsl", + "iso_abstract_expand.xsl", + "iso_svrl_for_xslt2.xsl") + + def fromRules(rules: Templates) = new Schematron(xmlReader.get(), rules) + + def templatesFor(sch: InputStream, tf: TransformerFactory): Templates = tf.newTemplates( + templatesPipeline.foldLeft(new StreamSource(sch): Source) { + (source, template) => + val xsl = getClass.getClassLoader.getResourceAsStream(s"$templatesRootDir/$template") + val result: DOMResult = new DOMResult + tf.newTransformer(new StreamSource(xsl)).transform(source, result) + new DOMSource(result.getNode) + } + ) + + def isoTemplateResolver(child: Option[URIResolver]) = new ClassPathUriResolver(Schematron.templatesRootDir, child) + + // reduce overhead by caching the xml reader, but the SAXParser class is not thread safe so use a thread local + private val xmlReader = new ThreadLocal[XMLReader] { + override def initialValue(): XMLReader = { + val fac = SAXParserFactory.newInstance + try { + fac.setFeature(javax.xml.XMLConstants.FEATURE_SECURE_PROCESSING, true) + fac.setFeature("http://xml.org/sax/features/external-general-entities";, false) + fac.setFeature("http://xml.org/sax/features/external-parameter-entities";, false) + fac.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd";, false) + } catch { + case ex@(_: ParserConfigurationException | _: SAXException) => + throw ValidatorInitializationException(s"Error setting feature on parser: ${ex.getMessage}") + } + fac.setValidating(false) + fac.newSAXParser.getXMLReader + } + } +} + +final class Schematron private(reader: XMLReader, templates: Templates) { + private lazy val transformer = templates.newTransformer + + def validate(is: InputStream): String = { + val writer = new StringWriter + transformer.transform(new SAXSource(reader, new InputSource(is)), new StreamResult(writer)) Review comment: :+1: ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
