/*
* eXist Open Source Native XML Database
* Copyright (C) 2012 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* $Id$
*/
package org.exist.contentextraction;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.exist.dom.memtree.DocumentBuilderReceiver;
import org.exist.dom.memtree.MemTreeBuilder;
import org.exist.dom.memtree.NodeImpl;
import org.exist.dom.INodeHandle;
import org.exist.dom.QName;
import org.exist.storage.NodePath;
import org.exist.util.serializer.AttrList;
import org.exist.util.serializer.Receiver;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.FunctionReference;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.ValueSequence;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
/**
* @author Dulip Withanage <dulip.withanage@gmail.com>
* @author Dannes Wessels <dannes@exist-db.org>
*
* @version 1.1
*/
public class ContentReceiver implements Receiver {
private final static Logger LOG = LogManager.getLogger(ContentReceiver.class);
private final ValueSequence result = new ValueSequence();
private final FunctionReference ref;
private final NodePath currentElementPath = new NodePath();
private final NodePath[] paths;
private DocumentBuilderReceiver docBuilderReceiver = null;
private NodePath startElementPath = null;
private Sequence userData = null;
private Sequence prevReturnData = Sequence.EMPTY_SEQUENCE;
private final XQueryContext context;
private boolean sendDataToCB = false;
/**
* Receiver constructor
*
* @param context The XQuery context
* @param paths Paths that must be extracted from the TIKA XHTML document
* @param ref Reference to callback function
* @param userData Additional user supplied datas
*/
public ContentReceiver(XQueryContext context, NodePath[] paths, FunctionReference ref, Sequence userData) {
this.context = context;
this.paths = paths;
this.ref = ref;
this.userData = userData;
}
/**
* Get the result of the content extraction
*
* @return
*/
public Sequence getResult() {
return result;
}
/**
* Check if content of current (node) path should be retrieved.
*
* @param path Xpath to current node
*
* @return TRUE if path is in to-be-retrieved paths
*/
private boolean matches(NodePath path) {
for (NodePath p : paths) {
if (p.match(path)) {
return true;
}
}
return false;
}
@Override
public void startDocument() throws SAXException {
}
@Override
public void endDocument() throws SAXException {
}
@Override
public void startPrefixMapping(String prefix, String namespaceURI) throws SAXException {
}
@Override
public void endPrefixMapping(String prefix) throws SAXException {
}
@Override
public void startElement(QName qname, AttrList attribs) throws SAXException {
// Calculate path to current element
currentElementPath.addComponent(qname);
// Current path matches wanted path
if ( matches(currentElementPath) ){
if(sendDataToCB) {
// Data is already sent to callback, ignore
} else {
// New element match, new data
// Save reference to current path
startElementPath = new NodePath(currentElementPath);
// Store old fragment in stack
context.pushDocumentContext();
// Create new receiver
MemTreeBuilder memBuilder = context.getDocumentBuilder();
docBuilderReceiver = new DocumentBuilderReceiver(memBuilder);
// Switch on retrievel
sendDataToCB=true;
}
}
if(sendDataToCB){
docBuilderReceiver.startElement(qname, attribs);
}
}
@Override
public void endElement(QName qname) throws SAXException {
// Send end element to result
if(sendDataToCB){
docBuilderReceiver.endElement(qname);
}
// If path was to be matched path
if (sendDataToCB && currentElementPath.match(startElementPath)) {
// flush the collected data
sendDataToCallback();
// get back from stack
context.popDocumentContext();
// Switch off retrieval
sendDataToCB=false;
docBuilderReceiver = null;
}
// calculate new path
currentElementPath.removeLastComponent();
}
@Override
public void characters(CharSequence seq) throws SAXException {
if (sendDataToCB) {
docBuilderReceiver.characters(seq);
}
}
@Override
public void attribute(QName qname, String value) throws SAXException {
if (sendDataToCB) {
docBuilderReceiver.attribute(qname, value);
}
}
@Override
public void comment(char[] ch, int start, int length) throws SAXException {
}
@Override
public void cdataSection(char[] ch, int start, int len) throws SAXException {
}
@Override
public void processingInstruction(String target, String data) throws SAXException {
}
@Override
public void documentType(String name, String publicId, String systemId) throws SAXException {
}
@Override
public void highlightText(CharSequence seq) throws SAXException {
}
@Override
public void setCurrentNode(INodeHandle node) {
}
/**
* Does not return anything.
*
* @return NULL
*/
@Override
public Document getDocument() {
return null;
}
/**
* Send data to callback handler
*/
private void sendDataToCallback() {
// Retrieve result as document
Document doc = docBuilderReceiver.getDocument();
// Get the root
NodeImpl root = (NodeImpl) doc.getDocumentElement();
// Construct parameters
Sequence[] params = new Sequence[3];
params[0] = root;
params[1] = userData;
params[2] = prevReturnData;
try {
// Send data to callback function
Sequence ret = ref.evalFunction(null, null, params);
prevReturnData = ret;
result.addAll(ret);
} catch (XPathException e) {
LOG.warn(e.getMessage(), e);
}
}
}