/*
 * Copyright 2002,2004 The Apache Software Foundation.
 *
 * 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 org.apache.commons.jelly.util;

import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;

/**
 * Ensures that only one start and end document event is passed onto the underlying
 * ContentHandler. This object can only be used once and then discarded.
 *
 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
 */
public class SafeContentHandler implements ContentHandler {
    private ContentHandler handler;
    private boolean documentStarted;
    private boolean documentEnded;

    public SafeContentHandler(ContentHandler handler) {
        this.handler = handler;
    }

    /**
     * @throws org.xml.sax.SAXException
     */
    public void startDocument() throws SAXException {
        if (! documentStarted) {
            handler.startDocument();
            documentStarted = true;
        }
    }

    /**
     * @throws org.xml.sax.SAXException
     */
    public void endDocument() throws SAXException {
        if (! documentEnded) {
            handler.endDocument();
            documentEnded = true;
        }
    }

    /**
     * @param arg0
     * @param arg1
     * @param arg2
     * @throws org.xml.sax.SAXException
     */
    public void characters(char[] arg0, int arg1, int arg2)
        throws SAXException {
        handler.characters(arg0, arg1, arg2);
    }

    /**
     * @param arg0
     * @param arg1
     * @param arg2
     * @throws org.xml.sax.SAXException
     */
    public void endElement(String arg0, String arg1, String arg2)
        throws SAXException {
        handler.endElement(arg0, arg1, arg2);
    }

    /**
     * @param arg0
     * @throws org.xml.sax.SAXException
     */
    public void endPrefixMapping(String arg0) throws SAXException {
        handler.endPrefixMapping(arg0);
    }

    /**
     * @param arg0
     * @param arg1
     * @param arg2
     * @throws org.xml.sax.SAXException
     */
    public void ignorableWhitespace(char[] arg0, int arg1, int arg2)
        throws SAXException {
        handler.ignorableWhitespace(arg0, arg1, arg2);
    }

    /**
     * @param arg0
     * @param arg1
     * @throws org.xml.sax.SAXException
     */
    public void processingInstruction(String arg0, String arg1)
        throws SAXException {
        handler.processingInstruction(arg0, arg1);
    }

    /**
     * @param arg0
     */
    public void setDocumentLocator(Locator arg0) {
        handler.setDocumentLocator(arg0);
    }

    /**
     * @param arg0
     * @throws org.xml.sax.SAXException
     */
    public void skippedEntity(String arg0) throws SAXException {
        handler.skippedEntity(arg0);
    }

    /**
     * @param arg0
     * @param arg1
     * @param arg2
     * @param arg3
     * @throws org.xml.sax.SAXException
     */
    public void startElement(
        String arg0,
        String arg1,
        String arg2,
        Attributes arg3)
        throws SAXException {
        handler.startElement(arg0, arg1, arg2, arg3);
    }

    /**
     * @param arg0
     * @param arg1
     * @throws org.xml.sax.SAXException
     */
    public void startPrefixMapping(String arg0, String arg1)
        throws SAXException {
        handler.startPrefixMapping(arg0, arg1);
    }
}