com.topologi.diffx.Extension Maven / Gradle / Ivy
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package com.topologi.diffx;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Hashtable;
import java.util.Map;
import javax.xml.parsers.ParserConfigurationException;
import org.docx4j.XmlUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import com.topologi.diffx.algorithm.DiffXAlgorithm;
import com.topologi.diffx.algorithm.GuanoAlgorithm;
import com.topologi.diffx.config.DiffXConfig;
import com.topologi.diffx.config.TextGranularity;
import com.topologi.diffx.config.WhiteSpaceProcessing;
import com.topologi.diffx.format.SafeXMLFormatter;
import com.topologi.diffx.load.DOMRecorder;
import com.topologi.diffx.sequence.EventSequence;
import com.topologi.diffx.sequence.SequenceSlicer;
/**
* To use Diff-X as an XSLT extension.
*
* In Saxon, declare the namespace as:
*
{@code
*
* }
*
* Diff-X can be called within XSLT with:
*
{@code
*
*
* Note: the method signatures requires DOM arguments, include the Saxon-DOM jar
* on your classpath to use this extension function with Saxon.
*
* @author Christophe Lauret
* @version 18 May 2010
*/
public final class Extension {
/**
* Maps the DOM builder factory to use with the given DOM package.
*
* This is because some XSLT processors will only accept certain types DOM objects.
*/
private static final Map BUILDERS = new Hashtable();
static {
// BUILDERS.put("net.sf.saxon.dom", "net.sf.saxon.dom.DocumentBuilderFactoryImpl");
}
/**
* Compares the two specified Nodes and returns the diff as a node.
*
* Only the first node in the node list is sequenced.
*
* @param xml1 The first XML node to compare.
* @param xml2 The second XML node to compare.
* @param whitespace The white space processing (a valid {@link WhiteSpaceProcessing} value).
* @param granularity The text granularity (a valid {@link TextGranularity} value).
*
* @throws DiffXException Should a Diff-X exception occur.
* @throws IOException Should an I/O exception occur.
*/
public static Node diff(Node xml1, Node xml2, String whitespace, String granularity)
throws DiffXException, IOException {
// Get the config
DiffXConfig config = toConfig(whitespace, granularity);
// Get Sequences
DOMRecorder loader = new DOMRecorder();
loader.setConfig(config);
EventSequence seq1 = loader.process(xml1);
EventSequence seq2 = loader.process(xml2);
if (seq1.size() == 0 && seq1.size() == 0) return null;
// Start comparing
StringWriter out = new StringWriter();
diff(seq1, seq2, out, config);
// Return a node
try {
String factory = getFactoryClass(xml1, xml2);
Node node = toNode(out.toString(), config, factory);
return node;
} catch (Exception ex) {
throw new DiffXException("Could not generate Node from Diff-X result", ex);
}
}
// private helpers ------------------------------------------------------------------------------
/**
* Compares the two specified xml files and prints the diff onto the given writer.
*
* @param seq1 The first XML reader to compare.
* @param seq2 The first XML reader to compare.
* @param out Where the output goes.
* @param config The DiffX configuration to use.
*
* @throws DiffXException Should a Diff-X exception occur.
* @throws IOException Should an I/O exception occur.
*/
private static void diff(EventSequence seq1, EventSequence seq2, Writer out, DiffXConfig config)
throws DiffXException, IOException {
SafeXMLFormatter formatter = new SafeXMLFormatter(out);
formatter.declarePrefixMapping(seq1.getPrefixMapping());
formatter.declarePrefixMapping(seq2.getPrefixMapping());
if (config != null) {
formatter.setConfig(config);
}
SequenceSlicer slicer = new SequenceSlicer(seq1, seq2);
slicer.slice();
slicer.formatStart(formatter);
DiffXAlgorithm df = new GuanoAlgorithm(seq1, seq2);
df.process(formatter);
slicer.formatEnd(formatter);
}
/**
* Returns the Diff-X config for the specified argument as String.
*
* @param whitespace A valid white space processing value.
* @param granularity A valid text granularity value.
*
* @return the Diff-X config for the specified arguments as String.
*/
private static DiffXConfig toConfig(String whitespace, String granularity) {
WhiteSpaceProcessing ws = WhiteSpaceProcessing.valueOf(whitespace);
TextGranularity tg = TextGranularity.valueOf(granularity);
return new DiffXConfig(ws, tg);
}
/**
* Returns a node for the specified string value.
*
* @param xml The XML to parse.
* @param config The DiffX configuration to use.
* @param factory The class name of the DOM builder factory.
*
* @return the corresponding document node.
*/
private static Node toNode(String xml, DiffXConfig config, String factory) throws IOException, ParserConfigurationException, SAXException {
// DocumentBuilderFactory dbFactory = factory == null ? DocumentBuilderFactory.newInstance()
// : DocumentBuilderFactory.newInstance(factory, Extension.class.getClassLoader());
// Avoid build error - see https://code.google.com/p/wo-diffx/issues/detail?id=7
Document document = XmlUtils.getNewDocumentBuilder().parse(new InputSource(new StringReader(xml)));
return document.getDocumentElement();
}
/**
* Returns the factory class to use based on the given NodeLists.
*
* @param xml1 the first node list.
* @param xml2 the second node list.
*/
private static String getFactoryClass(Node xml1, Node xml2) {
Package pkg = xml1 != null? xml1.getClass().getPackage()
: xml2 != null? xml2.getClass().getPackage()
: null;
return BUILDERS.get(pkg.getName());
}
}