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/* StdXMLBuilder.java                                              NanoXML/Java

 *

 * $Revision: 1.1 $

 * $Date: 2006/06/14 07:29:07 $

 * $Name:  $

 *

 * This file is part of NanoXML 2 for Java.

 * Copyright (C) 2001 Marc De Scheemaecker, All Rights Reserved.

 *

 * This software is provided 'as-is', without any express or implied warranty.

 * In no event will the authors be held liable for any damages arising from the

 * use of this software.

 *

 * Permission is granted to anyone to use this software for any purpose,

 * including commercial applications, and to alter it and redistribute it

 * freely, subject to the following restrictions:

 *

 *  1. The origin of this software must not be misrepresented; you must not

 *     claim that you wrote the original software. If you use this software in

 *     a product, an acknowledgment in the product documentation would be

 *     appreciated but is not required.

 *

 *  2. Altered source versions must be plainly marked as such, and must not be

 *     misrepresented as being the original software.

 *

 *  3. This notice may not be removed or altered from any source distribution.

 */

package net.n3.nanoxml;

import java.io.Reader;

import java.util.Stack;

/**

 * StdXMLBuilder is a concrete implementation of IXMLBuilder which creates a

 * tree of XMLElement from an XML data source.

 *

 * @see net.n3.nanoxml.XMLElement

 *

 * @author Marc De Scheemaecker

 * @version $Name:  $, $Revision: 1.1 $

 */

public class StdXMLBuilder

    implements IXMLBuilder

{

    /**

     * This stack contains the current element and its parents.

     */

    private Stack stack;

    /**

     * The root element of the parsed XML tree.

     */

    private XMLElement root;

    /**

     * Creates the builder.

     */

    public StdXMLBuilder()

    {

        this.stack = null;

        this.root = null;

    }

    /**

     * Cleans up the object when it's destroyed.

     */

    protected void finalize()

        throws Throwable

    {

        this.root = null;

        this.stack.clear();

        this.stack = null;

        super.finalize();

    }

    /**

     * This method is called before the parser starts processing its input.

     *

     * @param systemID the system ID of the XML data source

     * @param lineNr   the line on which the parsing starts

     */

    public void startBuilding(String systemID,

                              int    lineNr)

    {

        this.stack = new Stack();

        this.root = null;

    }

    /**

     * This method is called when a processing instruction is encountered.

     * PIs with target "xml" are handled by the parser.

     *

     * @param target the PI target

     * @param reader to read the data from the PI

     */

    public void newProcessingInstruction(String target,

                                         Reader reader)

    {

        // nothing to do

    }

    /**

     * This method is called when a new XML element is encountered.

     *

     * @see #endElement

     *

     * @param name       the name of the element

     * @param nsPrefix   the prefix used to identify the namespace

     * @param nsSystemID the system ID associated with the namespace

     * @param systemID   the system ID of the XML data source

     * @param lineNr     the line in the source where the element starts

     */

    public void startElement(String name,

                             String nsPrefix,

                             String nsSystemID,

                             String systemID,

                             int    lineNr)

    {

        XMLElement elt = new XMLElement(name, systemID, lineNr);

        if (this.stack.empty()) {

            this.root = elt;

        } else {

            XMLElement top = (XMLElement) this.stack.peek();

            top.addChild(elt);

        }

        this.stack.push(elt);

    }

    /**

     * This method is called when the attributes of an XML element have been

     * processed.

     *

     * @see #startElement

     * @see #addAttribute

     *

     * @param name       the name of the element

     * @param nsPrefix   the prefix used to identify the namespace

     * @param nsSystemID the system ID associated with the namespace

     */

    public void elementAttributesProcessed(String name,

                                           String nsPrefix,

                                           String nsSystemID)

    {

        // nothing to do

    }

    /**

     * This method is called when the end of an XML elemnt is encountered.

     *

     * @see #startElement

     *

     * @param name       the name of the element

     * @param nsPrefix   the prefix used to identify the namespace

     * @param nsSystemID the system ID associated with the namespace

     */

    public void endElement(String name,

                           String nsPrefix,

                           String nsSystemID)

    {

        XMLElement elt = (XMLElement) this.stack.pop();

        if (elt.getChildrenCount() == 1) {

            XMLElement child = elt.getChildAtIndex(0);

            if (child.getName() == null) {

                elt.setContent(child.getContent());

                elt.removeChildAtIndex(0);

            }

        }

    }

    /**

     * This method is called when a new attribute of an XML element is 

     * encountered.

     *

     * @param key        the key (name) of the attribute

     * @param nsPrefix   the prefix used to identify the namespace

     * @param nsSystemID the system ID associated with the namespace

     * @param value      the value of the attribute

     * @param type       the type of the attribute ("CDATA" if unknown)

     *

     * @throws java.lang.Exception

     *     If an exception occurred while processing the event.

     */

    public void addAttribute(String key,

                             String nsPrefix,

                             String nsSystemID,

                             String value,

                             String type)

        throws Exception

    {

        XMLElement top = (XMLElement) this.stack.peek();

        if (top.hasAttribute(key)) {

            throw new XMLParseException(top.getSystemID(),

                                        top.getLineNr(),

                                        "Duplicate attribute: " + key);

        }

        top.setAttribute(key, value);

    }

    /**

     * This method is called when a PCDATA element is encountered. A Java 

     * reader is supplied from which you can read the data. The reader will

     * only read the data of the element. You don't need to check for

     * boundaries. If you don't read the full element, the rest of the data 

     * is skipped. You also don't have to care about entities; they are 

     * resolved by the parser.

     *

     * @param reader   the Java reader from which you can retrieve the data

     * @param systemID the system ID of the XML data source

     * @param lineNr   the line in the source where the element starts

     *

     * @throws java.lang.Exception

     *     If an exception occurred while processing the event.

     */

    public void addPCData(Reader reader,

                          String systemID,

                          int    lineNr)

        throws Exception

    {

        int bufSize = 2048;

        int sizeRead = 0;

        StringBuffer str = new StringBuffer(bufSize);

        char[] buf = new char[bufSize];

        for (;;) {

            if (sizeRead >= bufSize) {

                bufSize *= 2;

                str.ensureCapacity(bufSize);

            }

            int size = reader.read(buf);

            if (size < 0) {

                break;

            }

            str.append(buf, 0, size);

            sizeRead += size;

        }

        XMLElement elt = new XMLElement(null, systemID, lineNr);

        elt.setContent(str.toString());

        if (! this.stack.empty()) {

            XMLElement top = (XMLElement) this.stack.peek();

            top.addChild(elt);

        }

    }

    /**

     * Returns the result of the building process. This method is called just

     * before the parse() method of IXMLParser returns.

     *

     * @see net.n3.nanoxml.IXMLParser#parse

     *

     * @return the result of the building process.

     */

    public Object getResult()

    {

        return this.root;

    }

}