DocumentHelper.java

/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j;

import java.io.StringReader;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import org.dom4j.io.SAXReader;
import org.dom4j.rule.Pattern;

import org.jaxen.VariableContext;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * <code>DocumentHelper</code> is a collection of helper methods for using
 * DOM4J.
 *
 * @author <a href="mailto:jstrachan@apache.org">James Strachan </a>
 * @version $Revision: 1.26 $
 */
@SuppressWarnings("unused")
public final class DocumentHelper {
    private DocumentHelper() {
    }

    private static DocumentFactory getDocumentFactory() {
        return DocumentFactory.getInstance();
    }

    // Static helper methods
    public static Document createDocument() {
        return getDocumentFactory().createDocument();
    }

    public static Document createDocument(Element rootElement) {
        return getDocumentFactory().createDocument(rootElement);
    }

    public static Element createElement(QName qname) {
        return getDocumentFactory().createElement(qname);
    }

    public static Element createElement(String name) {
        return getDocumentFactory().createElement(name);
    }

    public static Attribute createAttribute(Element owner, QName qname,
            String value) {
        return getDocumentFactory().createAttribute(owner, qname, value);
    }

    public static Attribute createAttribute(Element owner, String name,
            String value) {
        return getDocumentFactory().createAttribute(owner, name, value);
    }

    public static CDATA createCDATA(String text) {
        return DocumentFactory.getInstance().createCDATA(text);
    }

    public static Comment createComment(String text) {
        return DocumentFactory.getInstance().createComment(text);
    }

    public static Text createText(String text) {
        return DocumentFactory.getInstance().createText(text);
    }

    public static Entity createEntity(String name, String text) {
        return DocumentFactory.getInstance().createEntity(name, text);
    }

    public static Namespace createNamespace(String prefix, String uri) {
        return DocumentFactory.getInstance().createNamespace(prefix, uri);
    }

    public static ProcessingInstruction createProcessingInstruction(String pi,
            String d) {
        return getDocumentFactory().createProcessingInstruction(pi, d);
    }

    public static ProcessingInstruction createProcessingInstruction(String pi,
            Map<String, String> data) {
        return getDocumentFactory().createProcessingInstruction(pi, data);
    }

    public static QName createQName(String localName, Namespace namespace) {
        return getDocumentFactory().createQName(localName, namespace);
    }

    public static QName createQName(String localName) {
        return getDocumentFactory().createQName(localName);
    }

    /**
     * <p>
     * <code>createXPath</code> parses an XPath expression and creates a new
     * XPath <code>XPath</code> instance using the singleton {@link
     * DocumentFactory}.
     * </p>
     * 
     * @param xpathExpression
     *            is the XPath expression to create
     * 
     * @return a new <code>XPath</code> instance
     * 
     * @throws InvalidXPathException
     *             if the XPath expression is invalid
     */
    public static XPath createXPath(String xpathExpression)
            throws InvalidXPathException {
        return getDocumentFactory().createXPath(xpathExpression);
    }

    /**
     * <p>
     * <code>createXPath</code> parses an XPath expression and creates a new
     * XPath <code>XPath</code> instance using the singleton {@link
     * DocumentFactory}.
     * </p>
     * 
     * @param xpathExpression
     *            is the XPath expression to create
     * @param context
     *            is the variable context to use when evaluating the XPath
     * 
     * @return a new <code>XPath</code> instance
     * 
     * @throws InvalidXPathException
     *             if the XPath expression is invalid
     */
    public static XPath createXPath(String xpathExpression,
            VariableContext context) throws InvalidXPathException {
        return getDocumentFactory().createXPath(xpathExpression, context);
    }

    /**
     * <p>
     * <code>createXPathFilter</code> parses a NodeFilter from the given XPath
     * filter expression using the singleton {@link DocumentFactory}. XPath
     * filter expressions occur within XPath expressions such as
     * <code>self::node()[ filterExpression ]</code>
     * </p>
     * 
     * @param xpathFilterExpression
     *            is the XPath filter expression to create
     * 
     * @return a new <code>NodeFilter</code> instance
     */
    public static NodeFilter createXPathFilter(String xpathFilterExpression) {
        return getDocumentFactory().createXPathFilter(xpathFilterExpression);
    }

    /**
     * <p>
     * <code>createPattern</code> parses the given XPath expression to create
     * an XSLT style {@link Pattern}instance which can then be used in an XSLT
     * processing model.
     * </p>
     * 
     * @param xpathPattern
     *            is the XPath pattern expression to create
     * 
     * @return a new <code>Pattern</code> instance
     */
    public static Pattern createPattern(String xpathPattern) {
        return getDocumentFactory().createPattern(xpathPattern);
    }

    /**
     * <p>
     * <code>selectNodes</code> performs the given XPath expression on the
     * {@link List}of {@link Node}instances appending all the results together
     * into a single list.
     * </p>
     * 
     * @param xpathFilterExpression
     *            is the XPath filter expression to evaluate
     * @param nodes
     *            is the list of nodes on which to evalute the XPath
     * 
     * @return the results of all the XPath evaluations as a single list
     */
    public static List<Node> selectNodes(String xpathFilterExpression, List<Node> nodes) {
        XPath xpath = createXPath(xpathFilterExpression);

        return xpath.selectNodes(nodes);
    }

    /**
     * <p>
     * <code>selectNodes</code> performs the given XPath expression on the
     * {@link List}of {@link Node}instances appending all the results together
     * into a single list.
     * </p>
     * 
     * @param xpathFilterExpression
     *            is the XPath filter expression to evaluate
     * @param node
     *            is the Node on which to evalute the XPath
     * 
     * @return the results of all the XPath evaluations as a single list
     */
    public static List<Node> selectNodes(String xpathFilterExpression, Node node) {
        XPath xpath = createXPath(xpathFilterExpression);

        return xpath.selectNodes(node);
    }

    /**
     * <p>
     * <code>sort</code> sorts the given List of Nodes using an XPath
     * expression as a {@link java.util.Comparator}.
     * </p>
     * 
     * @param list
     *            is the list of Nodes to sort
     * @param xpathExpression
     *            is the XPath expression used for comparison
     */
    public static void sort(List<Node> list, String xpathExpression) {
        XPath xpath = createXPath(xpathExpression);
        xpath.sort(list);
    }

    /**
     * <p>
     * <code>sort</code> sorts the given List of Nodes using an XPath
     * expression as a {@link java.util.Comparator}and optionally removing
     * duplicates.
     * </p>
     * 
     * @param list
     *            is the list of Nodes to sort
     * @param expression
     *            is the XPath expression used for comparison
     * @param distinct
     *            if true then duplicate values (using the sortXPath for
     *            comparisions) will be removed from the List
     */
    public static void sort(List<Node> list, String expression, boolean distinct) {
        XPath xpath = createXPath(expression);
        xpath.sort(list, distinct);
    }

    /**
     * <p>
     * <code>parseText</code> parses the given text as an XML document and
     * returns the newly created Document.
     * </p>
     *
     * Loading external DTD and entities is disabled (if it is possible) for security reasons.
     * 
     * @param text
     *            the XML text to be parsed
     * 
     * @return a newly parsed Document
     * 
     * @throws DocumentException
     *             if the document could not be parsed
     */
    public static Document parseText(String text) throws DocumentException {
        SAXReader reader = new SAXReader();
        try {
            reader.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
            reader.setFeature("http://xml.org/sax/features/external-general-entities", false);
            reader.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
        } catch (SAXException e) {
            //Parse with external resources downloading allowed.
        }

        String encoding = getEncoding(text);

        InputSource source = new InputSource(new StringReader(text));
        source.setEncoding(encoding);

        Document result = reader.read(source);

        // if the XML parser doesn't provide a way to retrieve the encoding,
        // specify it manually
        if (result.getXMLEncoding() == null) {
            result.setXMLEncoding(encoding);
        }

        return result;
    }

    private static String getEncoding(String text) {
        String result = null;

        String xml = text.trim();

        if (xml.startsWith("<?xml")) {
            int end = xml.indexOf("?>");
            String sub = xml.substring(0, end);
            StringTokenizer tokens = new StringTokenizer(sub, " =\"\'");

            while (tokens.hasMoreTokens()) {
                String token = tokens.nextToken();

                if ("encoding".equals(token)) {
                    if (tokens.hasMoreTokens()) {
                        result = tokens.nextToken();
                    }

                    break;
                }
            }
        }

        return result;
    }

    /**
     * <p>
     * makeElement
     * </p>
     * a helper method which navigates from the given Document or Element node
     * to some Element using the path expression, creating any necessary
     * elements along the way. For example the path <code>a/b/c</code> would
     * get the first child &lt;a&gt; element, which would be created if it did
     * not exist, then the next child &lt;b&gt; and so on until finally a
     * &lt;c&gt; element is returned.
     * 
     * @param source
     *            is the Element or Document to start navigating from
     * @param path
     *            is a simple path expression, seperated by '/' which denotes
     *            the path from the source to the resulting element such as
     *            a/b/c
     * 
     * @return the first Element on the given path which either already existed
     *         on the path or were created by this method.
     */
    public static Element makeElement(Branch source, String path) {
        StringTokenizer tokens = new StringTokenizer(path, "/");
        Element parent;

        if (source instanceof Document) {
            Document document = (Document) source;
            parent = document.getRootElement();

            // lets throw a NoSuchElementException
            // if we are given an empty path
            String name = tokens.nextToken();

            if (parent == null) {
                parent = document.addElement(name);
            }
        } else {
            parent = (Element) source;
        }

        Element element = null;

        while (tokens.hasMoreTokens()) {
            String name = tokens.nextToken();

            if (name.indexOf(':') > 0) {
                element = parent.element(parent.getQName(name));
            } else {
                element = parent.element(name);
            }

            if (element == null) {
                element = parent.addElement(name);
            }

            parent = element;
        }

        return element;
    }
}

/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived
 * from this Software without prior written permission of MetaStuff, Ltd. For
 * written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may
 * "DOM4J" appear in their names without prior written permission of MetaStuff,
 * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */