XmlDocumentComparator.java

/*
 * Copyright 2007 - 2017 the original author or authors.
 *
 * Licensed 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 net.sf.jailer;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Compares XML-documents.
 *  
 * @author Ralf Wisser
 */
public class XmlDocumentComparator {

	/**
	 * Checks whether all information in a xml-document
	 * can also be found in another document.
	 * 
	 * @param part first xml-document
	 * @param doc second xml-document
	 * @return <code>true</code> iff all information in <code>part</code> 
	 *         can also be found in <code>doc</code>
	 */
	static public boolean contains(Document part, Document doc) {
		Collection<Element> remainingLeafs = new ArrayList<Element>();
		boolean c = contains(part.getDocumentElement(), doc.getDocumentElement(), remainingLeafs);
		dumpLeafs("remaining leafs", remainingLeafs);
		return c;
	}
	
	/**
	 * Checks whether all information in a xml-document
	 * can also be found in another document and vice versa.
	 * 
	 * @param a first xml-document
	 * @param b second xml-document
	 * @return <code>true</code> iff all information in <code>a</code> 
	 *         can also be found in <code>b</code> and vice versa
	 */
	static public boolean equals(Document a, Document b) {
		Collection<Element> remainingLeafsA = new ArrayList<Element>();
		Collection<Element> remainingLeafsB = new ArrayList<Element>();
		boolean c = contains(a.getDocumentElement(), b.getDocumentElement(), remainingLeafsA)
			&& contains(b.getDocumentElement(), a.getDocumentElement(), remainingLeafsB);
		dumpLeafs("remaining leafs", remainingLeafsA);
		dumpLeafs("remaining leafs", remainingLeafsB);
		return c;
	}
	
	/**
	 * Parses a XML-file.
	 * 
	 * @param xmlFile the XML file
	 * @return the DOM-tree
	 */
	public static Document parseXmlDocument(File xmlFile) throws ParserConfigurationException, FileNotFoundException, SAXException, IOException {
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		factory.setNamespaceAware(true);
		DocumentBuilder builder = factory.newDocumentBuilder();
		Document document = builder.parse(new InputSource(new FileReader(xmlFile)));
		return document;
	}
	
	/**
	 * Checks whether all information in a xml-element-tree
	 * can also be found in another tree.
	 * 
	 * @param part first xml-element-tree
	 * @param doc second xml-element-tree
	 * @param remainingLeafs collection to put in all leafs from part which cannot be found in doc
	 * @return <code>true</code> iff all information in <code>part</code> 
	 *         can also be found in <code>doc</code>
	 */
	static public boolean contains(Element part, Element doc, Collection<Element> remainingLeafs) {
		if (!part.getTagName().equals(doc.getTagName())) {
			remainingLeafs.addAll(leafs(part));
			return false;
		}
		if (part.getChildNodes().getLength() == 0) {
			String partText = part.getTextContent() == null? "" : part.getTextContent().trim();
			String docText = doc.getTextContent() == null? "" : doc.getTextContent().trim();
			if (!partText.equals(docText)) {
				remainingLeafs.add(part);
				return false;
			}
		}
		// TODO: check attributes too
		
		boolean docContainsPart = true;
		for (int i = 0; i < part.getChildNodes().getLength(); ++i) {
			if (!(part.getChildNodes().item(i) instanceof Element)) continue; 
			Element partChild = (Element) part.getChildNodes().item(i);
			
			// search child in doc, child-order is not relevant
			Collection<Element> remainingLeafsOfAllChildren = null;
			boolean partChildFoundInDoc = false;
			for (int j = 0; j < doc.getChildNodes().getLength(); ++j) {
				if (!(doc.getChildNodes().item(j) instanceof Element)) continue; 
				Element docChild = (Element) doc.getChildNodes().item(j);
				Collection<Element> remainingLeafsOfChild = new ArrayList<Element>();
				if (contains(partChild, docChild, remainingLeafsOfChild)) {
					partChildFoundInDoc = true;
					break;
				}
				if (remainingLeafsOfAllChildren == null) {
					remainingLeafsOfAllChildren = remainingLeafsOfChild;
				} else {
					remainingLeafsOfAllChildren.retainAll(remainingLeafsOfChild);
				}
			}
			if (!partChildFoundInDoc) {
				if (remainingLeafsOfAllChildren != null) {
					remainingLeafs.addAll(remainingLeafsOfAllChildren);
				} else {
					System.out.print("");
				}
				docContainsPart = false;
			}
		}
		return docContainsPart;
	}

	/**
	 * Collects all leafs of a element-tree.
	 * 
	 * @param root the root of the tree
	 * @return all leafs of the element-tree
	 */
	private static Collection<Element> leafs(Element root) {
		Collection<Element> leafs = new ArrayList<Element>();
		boolean isLeaf = true;
		for (int i = 0; i < root.getChildNodes().getLength(); ++i) {
			if (root.getChildNodes().item(i) instanceof Element) {
				Element child = (Element) root.getChildNodes().item(i);
				leafs.addAll(leafs(child));
				isLeaf = false;
			}
		}
		if (isLeaf) {
			leafs.add(root);
		}
		return leafs;
	}
	
	/**
	 * Dumps a set of leafs.
	 * 
	 * @param title the title
	 * @param leafs the set of leafs
	 */
	private static void dumpLeafs(String title, Collection<Element> leafs) {
		if (leafs.isEmpty()) {
			return;
		}
		System.out.println(title + ":");
		for (Iterator<Element> i = leafs.iterator(); i.hasNext(); ) {
			Element e = i.next();
			String path = "";
			for (Node n = e; n != null; n = n.getParentNode()) {
				path = n.getNodeName() + "/" + path;
			}
			System.out.println(path + ":" + e.getTextContent());
		}
	}
}