/*

 * Copyright 2000-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.xml.transform;

import java.util.Properties;

/**

 * An instance of this abstract class can transform a

 * source tree into a result tree.

 *

 * <p>An instance of this class can be obtained with the

 * {@link TransformerFactory#newTransformer TransformerFactory.newTransformer}

 * method. This instance may then be used to process XML from a

 * variety of sources and write the transformation output to a

 * variety of sinks.</p>

 *

 * <p>An object of this class may not be used in multiple threads

 * running concurrently.  Different Transformers may be used

 * concurrently by different threads.</p>

 *

 * <p>A <code>Transformer</code> may be used multiple times.  Parameters and

 * output properties are preserved across transformations.</p>

 *

 * @author <a href="Jeff.Suttor@Sun.com">Jeff Suttor</a>

 */

public abstract class Transformer {

    /**

     * Default constructor is protected on purpose.

     */

    protected Transformer() { }

        /**

         * <p>Reset this <code>Transformer</code> to its original configuration.</p>

         *

         * <p><code>Transformer</code> is reset to the same state as when it was created with

         * {@link TransformerFactory#newTransformer()},

         * {@link TransformerFactory#newTransformer(Source source)} or

         * {@link Templates#newTransformer()}.

         * <code>reset()</code> is designed to allow the reuse of existing <code>Transformer</code>s

         * thus saving resources associated with the creation of new <code>Transformer</code>s.</p>

         *

         * <p>The reset <code>Transformer</code> is not guaranteed to have the same {@link URIResolver}

         * or {@link ErrorListener} <code>Object</code>s, e.g. {@link Object#equals(Object obj)}.

         * It is guaranteed to have a functionally equal <code>URIResolver</code>

         * and <code>ErrorListener</code>.</p>

     *

     * @throws UnsupportedOperationException When implementation does not

     *   override this method.

         *

         * @since 1.5

         */

        public void reset() {

                // implementors should override this method

                throw new UnsupportedOperationException(

                        "This Transformer, \"" + this.getClass().getName() + "\", does not support the reset functionality."

                        + "  Specification \"" + this.getClass().getPackage().getSpecificationTitle() + "\""

                        + " version \"" + this.getClass().getPackage().getSpecificationVersion() + "\""

                        );

        }

    /**

     * <p>Transform the XML <code>Source</code> to a <code>Result</code>.

     * Specific transformation behavior is determined by the settings of the

     * <code>TransformerFactory</code> in effect when the

     * <code>Transformer</code> was instantiated and any modifications made to

     * the <code>Transformer</code> instance.</p>

     *

     * <p>An empty <code>Source</code> is represented as an empty document

     * as constructed by {@link javax.xml.parsers.DocumentBuilder#newDocument()}.

     * The result of transforming an empty <code>Source</code> depends on

     * the transformation behavior; it is not always an empty

     * <code>Result</code>.</p>

     *

     * @param xmlSource The XML input to transform.

     * @param outputTarget The <code>Result</code> of transforming the

     *   <code>xmlSource</code>.

     *

     * @throws TransformerException If an unrecoverable error occurs

     *   during the course of the transformation.

     */

    public abstract void transform(Source xmlSource, Result outputTarget)

        throws TransformerException;

    /**

     * Add a parameter for the transformation.

     *

     * <p>Pass a qualified name as a two-part string, the namespace URI

     * enclosed in curly braces ({}), followed by the local name. If the

     * name has a null URL, the String only contain the local name. An

     * application can safely check for a non-null URI by testing to see if the

     * first character of the name is a '{' character.</p>

     * <p>For example, if a URI and local name were obtained from an element

     * defined with <xyz:foo

     * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/>,

     * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".

     * Note that no prefix is used.</p>

     *

     * @param name The name of the parameter, which may begin with a

     * namespace URI in curly braces ({}).

     * @param value The value object.  This can be any valid Java object. It is

     * up to the processor to provide the proper object coersion or to simply

     * pass the object on for use in an extension.

     *

     * @throws NullPointerException If value is null.

     */

     public abstract void setParameter(String name, Object value);

    /**

     * Get a parameter that was explicitly set with setParameter.

     *

     * <p>This method does not return a default parameter value, which

     * cannot be determined until the node context is evaluated during

     * the transformation process.

     *

     * @param name of <code>Object</code> to get

     *

     * @return A parameter that has been set with setParameter.

     */

    public abstract Object getParameter(String name);

    /**

     * <p>Set a list of parameters.</p>

     *

     * <p>Note that the list of parameters is specified as a

     * <code>Properties</code> <code>Object</code> which limits the parameter

     * values to <code>String</code>s.  Multiple calls to

     * {@link #setParameter(String name, Object value)} should be used when the

     * desired values are non-<code>String</code> <code>Object</code>s.

     * The parameter names should conform as specified in

     * {@link #setParameter(String name, Object value)}.

     * An <code>IllegalArgumentException</code> is thrown if any names do not

     * conform.</p>

     *

     * <p>New parameters in the list are added to any existing parameters.

     * If the name of a new parameter is equal to the name of an existing

     * parameter as determined by {@link java.lang.Object#equals(Object obj)},

     *  the existing parameter is set to the new value.</p>

     *

     * @param params Parameters to set.

     *

     * @throws IllegalArgumentException If any parameter names do not conform

     *   to the naming rules.

     */

    /**

     * Clear all parameters set with setParameter.

     */

    public abstract void clearParameters();

    /**

     * Set an object that will be used to resolve URIs used in

     * document().

     *

     * <p>If the resolver argument is null, the URIResolver value will

     * be cleared and the transformer will no longer have a resolver.</p>

     *

     * @param resolver An object that implements the URIResolver interface,

     * or null.

     */

    public abstract void setURIResolver(URIResolver resolver);

    /**

     * Get an object that will be used to resolve URIs used in

     * document().

     *

     * @return An object that implements the URIResolver interface,

     * or null.

     */

    public abstract URIResolver getURIResolver();

    /**

     * Set the output properties for the transformation.  These

     * properties will override properties set in the Templates

     * with xsl:output.

     *

     * <p>If argument to this function is null, any properties

     * previously set are removed, and the value will revert to the value

     * defined in the templates object.</p>

     *

     * <p>Pass a qualified property key name as a two-part string, the namespace

     * URI enclosed in curly braces ({}), followed by the local name. If the

     * name has a null URL, the String only contain the local name. An

     * application can safely check for a non-null URI by testing to see if the

     * first character of the name is a '{' character.</p>

     * <p>For example, if a URI and local name were obtained from an element

     * defined with <xyz:foo

     * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/>,

     * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".

     * Note that no prefix is used.</p>

     * An <code>IllegalArgumentException</code> is thrown  if any of the

     * argument keys are not recognized and are not namespace qualified.

     *

     * @param oformat A set of output properties that will be

     *   used to override any of the same properties in affect

     *   for the transformation.

     *

     * @throws IllegalArgumentException When keys are not recognized and

     *   are not namespace qualified.

     *

     * @see javax.xml.transform.OutputKeys

     * @see java.util.Properties

     *

     */

    public abstract void setOutputProperties(Properties oformat);

    /**

     * <p>Get a copy of the output properties for the transformation.</p>

     *

     * <p>The properties returned should contain properties set by the user,

     * and properties set by the stylesheet, and these properties

     * are "defaulted" by default properties specified by

     * <a href="http://www.w3.org/TR/xslt#output">section 16 of the

     * XSL Transformations (XSLT) W3C Recommendation</a>.  The properties that

     * were specifically set by the user or the stylesheet should be in the base

     * Properties list, while the XSLT default properties that were not

     * specifically set should be the default Properties list.  Thus,

     * getOutputProperties().getProperty(String key) will obtain any

     * property in that was set by {@link #setOutputProperty},

     * {@link #setOutputProperties}, in the stylesheet, <em>or</em> the default

     * properties, while

     * getOutputProperties().get(String key) will only retrieve properties

     * that were explicitly set by {@link #setOutputProperty},

     * {@link #setOutputProperties}, or in the stylesheet.</p>

     *

     * <p>Note that mutation of the Properties object returned will not

     * effect the properties that the transformer contains.</p>

     *

     * <p>If any of the argument keys are not recognized and are not

     * namespace qualified, the property will be ignored and not returned.

     * In other words the behaviour is not orthogonal with

     * {@link #setOutputProperties setOutputProperties}.</p>

     *

     * @return A copy of the set of output properties in effect for

     *   the next transformation.

     *

     * @see javax.xml.transform.OutputKeys

     * @see java.util.Properties

     * @see <a href="http://www.w3.org/TR/xslt#output">

     *   XSL Transformations (XSLT) Version 1.0</a>

     */

    public abstract Properties getOutputProperties();

    /**

     * Set an output property that will be in effect for the

     * transformation.

     *

     * <p>Pass a qualified property name as a two-part string, the namespace URI

     * enclosed in curly braces ({}), followed by the local name. If the

     * name has a null URL, the String only contain the local name. An

     * application can safely check for a non-null URI by testing to see if the

     * first character of the name is a '{' character.</p>

     * <p>For example, if a URI and local name were obtained from an element

     * defined with <xyz:foo

     * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/>,

     * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".

     * Note that no prefix is used.</p>

     *

     * <p>The Properties object that was passed to {@link #setOutputProperties}

     * won't be effected by calling this method.</p>

     *

     * @param name A non-null String that specifies an output

     * property name, which may be namespace qualified.

     * @param value The non-null string value of the output property.

     *

     * @throws IllegalArgumentException If the property is not supported, and is

     * not qualified with a namespace.

     *

     * @see javax.xml.transform.OutputKeys

     */

    public abstract void setOutputProperty(String name, String value)

        throws IllegalArgumentException;

    /**

     * <p>Get an output property that is in effect for the transformer.</p>

     *

     * <p>If a property has been set using {@link #setOutputProperty},

     * that value will be returned. Otherwise, if a property is explicitly

     * specified in the stylesheet, that value will be returned. If

     * the value of the property has been defaulted, that is, if no

     * value has been set explicitly either with {@link #setOutputProperty} or

     * in the stylesheet, the result may vary depending on

     * implementation and input stylesheet.</p>

     *

     * @param name A non-null String that specifies an output

     * property name, which may be namespace qualified.

     *

     * @return The string value of the output property, or null

     * if no property was found.

     *

     * @throws IllegalArgumentException If the property is not supported.

     *

     * @see javax.xml.transform.OutputKeys

     */

    public abstract String getOutputProperty(String name)

        throws IllegalArgumentException;

    /**

     * Set the error event listener in effect for the transformation.

     *

     * @param listener The new error listener.

     *

     * @throws IllegalArgumentException if listener is null.

     */

    public abstract void setErrorListener(ErrorListener listener)

        throws IllegalArgumentException;

    /**

     * Get the error event handler in effect for the transformation.

     * Implementations must provide a default error listener.

     *

     * @return The current error handler, which should never be null.

     */

    public abstract ErrorListener getErrorListener();

}