/*
 * $Id: FONode.java,v 1.34 2003/03/05 21:48:02 jeremias Exp $
 * ============================================================================
 *                    The Apache Software License, Version 1.1
 * ============================================================================
 *
 * Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 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 end-user documentation included with the redistribution, if any, must
 *    include the following acknowledgment: "This product includes software
 *    developed by the Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself, if
 *    and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "FOP" and "Apache Software Foundation" must not be used to
 *    endorse or promote products derived from this software without prior
 *    written permission. For written permission, please contact
 *    apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache", nor may
 *    "Apache" appear in their name, without prior written permission of the
 *    Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``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 THE
 * APACHE SOFTWARE FOUNDATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLU-
 * DING, 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.
 * ============================================================================
 *
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Apache Software Foundation and was originally created by
 * James Tauber <jtauber@jtauber.com>. For more information on the Apache
 * Software Foundation, please see <http://www.apache.org/>.
 */
package org.apache.fop.fo;

// Java
import java.util.ListIterator;

// XML
import org.xml.sax.Attributes;
import org.xml.sax.Locator;

// Avalon
import org.apache.avalon.framework.logger.Logger;

// FOP
import org.apache.fop.apps.FOPException;
import org.apache.fop.util.CharUtilities;
import org.apache.fop.apps.FOUserAgent;

/**
 * base class for nodes in the XML tree
 *
 */
public abstract class FONode {
    /** Parent FO node */
    protected FONode parent;
    /** Name of the node */
    protected String name;

    /**
     * Main constructor.
     * @param parent parent of this node
     */
    protected FONode(FONode parent) {
        this.parent = parent;
    }

    /**
     * Sets the name of the node.
     * @param str the name
     */
    public void setName(String str) {
        name = str;
    }

    /**
     * Sets the name of the node.
     * @param str the name
     */
    public void setLocation(Locator locator) {
        // do nothing by default
    }
    
    /**
     * Returns the logger for the node.
     * @return the logger
     */
    public Logger getLogger() {
        return getFOTreeControl().getLogger();
    }

    /**
     * Returns the user agent for the node.
     * @return FOUserAgent
     */
    public FOUserAgent getUserAgent() {
        return getFOTreeControl().getUserAgent();
    }

    /**
     * Do something with the attributes for this element
     * @param attlist Collection of attributes passed to us from the parser.
     * @throws FOPException for errors or inconsistencies in the attributes
     */
    public void handleAttrs(Attributes attlist) throws FOPException {
    }

    /**
     * Returns the name of the object
     * @return the name of this object
     */
    public String getName() {
        return this.name;
    }

    /**
     * Adds characters (does nothing here)
     * @param data text
     * @param start start position
     * @param length length of the text
     * @param locator location in fo source file. 
     */
    protected void addCharacters(char data[], int start, int length,
                                 Locator locator) {
        // ignore
    }

    /**
     *
     */
    protected void start() {
        // do nothing by default
    }

    /**
     *
     */
    protected void end() {
        // do nothing by default
    }

    /**
     * @param child child node to be added to the children of this node
     */
    protected void addChild(FONode child) {
    }

    /**
     * @return the parent node of this node
     */
    public FONode getParent() {
        return this.parent;
    }

    /**
     * Return an iterator over all the children of this FObj.
     * @return A ListIterator.
     */
    public ListIterator getChildren() {
        return null;
    }

    /**
     * Return an iterator over the object's children starting
     * at the pased node.
     * @param childNode First node in the iterator
     * @return A ListIterator or null if childNode isn't a child of
     * this FObj.
     */
    public ListIterator getChildren(FONode childNode) {
        return null;
    }

    /**
     * @return an iterator for the characters in this node
     */
    public CharIterator charIterator() {
        return new OneCharIterator(CharUtilities.CODE_EOT);
    }

    /**
     * This is a quick check to see if it is a marker.
     * This is needed since there is no other quick way of checking
     * for a marker and not adding to the child list.
     *
     * @return true if this is a marker
     */
    protected boolean isMarker() {
        return false;
    }

    /**
     * Recursively goes up the FOTree hierarchy until the FONode is found,
     * which returns the parent Document.
     * @return the Document object that is the parent of this node.
     */
    public FOTreeControl getFOTreeControl() {
        return parent.getFOTreeControl();
    }

    /**
     * This is a hook for an FOTreeVisitor subclass to be able to access
     * this object.
     * @param fotv the FOTreeVisitor subclass that can access this object.
     * @see org.apache.fop.fo.FOTreeVisitor
     */
    public void acceptVisitor(FOTreeVisitor fotv) {
        fotv.serveFONode(this);
    }

}