Do rough DOM processor refactoring

This is necessary before metadata support is added.

Relates to MID-6337

infra/prism-impl/src/main/java/com/evolveum/midpoint/prism/impl/lex/dom/DomIterativeReader.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2020 Evolveum and contributors
+ *
+ * This work is dual-licensed under the Apache License 2.0
+ * and European Union Public License. See LICENSE file for details.
+ */
+
+package com.evolveum.midpoint.prism.impl.lex.dom;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.HashMap;
+import java.util.Map;
+import javax.xml.namespace.QName;
+import javax.xml.stream.XMLInputFactory;
+import javax.xml.stream.XMLStreamConstants;
+import javax.xml.stream.XMLStreamException;
+import javax.xml.stream.XMLStreamReader;
+
+import com.evolveum.midpoint.prism.schema.SchemaRegistry;
+
+import org.apache.commons.io.IOUtils;
+import org.codehaus.staxmate.dom.DOMConverter;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+
+import com.evolveum.midpoint.prism.ParserSource;
+import com.evolveum.midpoint.prism.impl.lex.LexicalProcessor;
+import com.evolveum.midpoint.prism.impl.xnode.RootXNodeImpl;
+import com.evolveum.midpoint.util.DOMUtil;
+import com.evolveum.midpoint.util.QNameUtil;
+import com.evolveum.midpoint.util.exception.SchemaException;
+import com.evolveum.midpoint.util.exception.SystemException;
+
+/**
+ *
+ */
+class DomIterativeReader {
+
+    private final ParserSource source;
+    private final LexicalProcessor.RootXNodeHandler handler;
+    private final SchemaRegistry schemaRegistry;
+
+    DomIterativeReader(ParserSource source, LexicalProcessor.RootXNodeHandler handler, SchemaRegistry schemaRegistry) {
+        this.source = source;
+        this.handler = handler;
+        this.schemaRegistry = schemaRegistry;
+    }
+
+    // code taken from Validator class
+    public void readObjectsIteratively() throws SchemaException, IOException {
+        InputStream is = source.getInputStream();
+        XMLStreamReader stream = null;
+        try {
+            stream = getXMLInputFactory().createXMLStreamReader(is);
+
+            int eventType = stream.nextTag();
+            if (eventType != XMLStreamConstants.START_ELEMENT) {
+                throw new SystemException("StAX Malfunction?");
+            }
+            DOMConverter domConverter = new DOMConverter();
+            Map<String, String> rootNamespaceDeclarations = new HashMap<>();
+
+            QName objectsMarker = schemaRegistry.getPrismContext().getObjectsElementName();
+            if (objectsMarker != null && !QNameUtil.match(stream.getName(), objectsMarker)) {
+                readSingleObjectIteratively(stream, rootNamespaceDeclarations, domConverter, handler);
+            }
+            for (int i = 0; i < stream.getNamespaceCount(); i++) {
+                rootNamespaceDeclarations.put(stream.getNamespacePrefix(i), stream.getNamespaceURI(i));
+            }
+            while (stream.hasNext()) {
+                eventType = stream.next();
+                if (eventType == XMLStreamConstants.START_ELEMENT) {
+                    if (!readSingleObjectIteratively(stream, rootNamespaceDeclarations, domConverter, handler)) {
+                        return;
+                    }
+                }
+            }
+        } catch (XMLStreamException ex) {
+            String lineInfo = stream != null
+                    ? " on line " + stream.getLocation().getLineNumber()
+                    : "";
+            throw new SchemaException(
+                    "Exception while parsing XML" + lineInfo + ": " + ex.getMessage(), ex);
+        } finally {
+            if (source.closeStreamAfterParsing()) {
+                IOUtils.closeQuietly(is);
+            }
+        }
+
+    }
+
+    private boolean readSingleObjectIteratively(
+            XMLStreamReader stream, Map<String, String> rootNamespaceDeclarations,
+            DOMConverter domConverter, LexicalProcessor.RootXNodeHandler handler)
+            throws XMLStreamException, SchemaException {
+        Document objectDoc = domConverter.buildDocument(stream);
+        Element objectElement = DOMUtil.getFirstChildElement(objectDoc);
+        DOMUtil.setNamespaceDeclarations(objectElement, rootNamespaceDeclarations);
+        RootXNodeImpl rootNode = new DomReader(objectElement, schemaRegistry).read();
+        return handler.handleData(rootNode);
+    }
+
+    private XMLInputFactory getXMLInputFactory() {
+        XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance();
+        xmlInputFactory.setProperty(XMLInputFactory.SUPPORT_DTD, false);
+        xmlInputFactory.setProperty("javax.xml.stream.isSupportingExternalEntities", false);
+        // TODO: cache? static? prism context?
+        return xmlInputFactory;
+    }
+}