/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 xni;

import org.apache.xerces.xni.Augmentations;
import org.apache.xerces.xni.NamespaceContext;
import org.apache.xerces.xni.QName;
import org.apache.xerces.xni.XMLAttributes;
import org.apache.xerces.xni.XMLDocumentHandler;
import org.apache.xerces.xni.XMLLocator;
import org.apache.xerces.xni.XMLResourceIdentifier;
import org.apache.xerces.xni.XMLString;
import org.apache.xerces.xni.XNIException;
import org.apache.xerces.xni.parser.XMLDocumentSource;

/**
 * This sample demonstrates how to implement a simple pass-through
 * filter for the document "streaming" information set using XNI.
 * This filter could be used in a pipeline of XNI parser components
 * that communicate document events.
 * <p>
 * <strong>Note:</strong> This sample does not contain a 
 * <code>main</code> method and cannot be run. It is only for
 * demonstration purposes.
 *
 * @author Andy Clark, IBM
 *
 * @version $Id$
 */
public class PassThroughFilter
    implements XMLDocumentHandler {
    
    //
    // Data
    //
    
    /** The document handler. */
    protected XMLDocumentHandler fDocumentHandler;

    /** The document source */
    protected XMLDocumentSource fDocumentSource;
    
    //
    // Public methods
    //
   
    /** 
     * Sets the document handler. 
     *
     * @param handler The new document handler.
     */
    public void setDocumentHandler(XMLDocumentHandler handler) {
        fDocumentHandler = handler;
    } // setDocumentHandler(XMLDocumentHandler)
    
    //
    // XMLDocumentHandler methods
    //
    
    /**
     * The start of the document.
     *
     * @param locator  The document locator, or null if the document
     *                 location cannot be reported during the parsing 
     *                 of this document. However, it is <em>strongly</em>
     *                 recommended that a locator be supplied that can 
     *                 at least report the system identifier of the
     *                 document.
     * @param encoding The auto-detected IANA encoding name of the entity
     *                 stream. This value will be null in those situations
     *                 where the entity encoding is not auto-detected (e.g.
     *                 internal entities or a document entity that is
     *                 parsed from a java.io.Reader).
     *     
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void startDocument(XMLLocator locator, String encoding, 
                              NamespaceContext namespaceContext, Augmentations augs)
        throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.startDocument(locator, encoding, namespaceContext, augs);
	    }
    } // startDocument(XMLLocator,String)
    
    /**
     * Notifies of the presence of an XMLDecl line in the document. If
     * present, this method will be called immediately following the
     * startDocument call.
     * 
     * @param version    The XML version.
     * @param encoding   The IANA encoding name of the document, or null if
     *                   not specified.
     * @param standalone The standalone value, or null if not specified.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void xmlDecl(String version, String encoding, 
                        String standalone, Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.xmlDecl(version, encoding, standalone, augs);
	    }
    } // xmlDecl(String,String,String
    
    /**
     * Notifies of the presence of the DOCTYPE line in the document.
     * 
     * @param rootElement The name of the root element.
     * @param publicId    The public identifier if an external DTD or null
     *                    if the external DTD is specified using SYSTEM.
     * @param systemId    The system identifier if an external DTD, null
     *                    otherwise.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void doctypeDecl(String rootElement, String publicId, 
                            String systemId, Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.doctypeDecl(rootElement, publicId, systemId, augs);
        }
    } // doctypeDecl(String,String,String)
    
    /**
     * A comment.
     * 
     * @param text The text in the comment.
     *
     * @throws XNIException Thrown by application to signal an error.
     */
    public void comment(XMLString text, Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.comment(text, augs);
        }
    } // comment(XMLString)
    
    /**
     * A processing instruction. Processing instructions consist of a
     * target name and, optionally, text data. The data is only meaningful
     * to the application.
     * <p>
     * Typically, a processing instruction's data will contain a series
     * of pseudo-attributes. These pseudo-attributes follow the form of
     * element attributes but are <strong>not</strong> parsed or presented
     * to the application as anything other than text. The application is
     * responsible for parsing the data.
     * 
     * @param target The target.
     * @param data   The data or null if none specified.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void processingInstruction(String target, XMLString data, Augmentations augs)
        throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.processingInstruction(target, data, augs);
        }
    } // processingInstruction(String,XMLString)
    
    /**
     * The start of an element.
     * 
     * @param element    The name of the element.
     * @param attributes The element attributes.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void startElement(QName element, XMLAttributes attributes, Augmentations augs)
        throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.startElement(element, attributes, augs);
        }
    } // startElement(QName,XMLAttributes)
    
    /**
     * An empty element.
     * 
     * @param element    The name of the element.
     * @param attributes The element attributes.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void emptyElement(QName element, XMLAttributes attributes, Augmentations augs)
        throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.emptyElement(element, attributes, augs);
        }
    } // emptyElement(QName,XMLAttributes)
    
    /**
     * The end of an element.
     * 
     * @param element The name of the element.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void endElement(QName element, Augmentations augs)
        throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.endElement(element, augs);
        }
    } // endElement(QName)
    
    /**
     * This method notifies the start of an entity.
     * <p>
     * <strong>Note:</strong> This method is not called for entity references
     * appearing as part of attribute values.
     * 
     * @param name     The name of the entity.
     * @param publicId The public identifier of the entity if the entity
     *                 is external, null otherwise.
     * @param systemId The system identifier of the entity if the entity
     *                 is external, null otherwise.
     * @param baseSystemId The base system identifier of the entity if
     *                     the entity is external, null otherwise.
     * @param encoding The auto-detected IANA encoding name of the entity
     *                 stream. This value will be null in those situations
     *                 where the entity encoding is not auto-detected (e.g.
     *                 internal entities or a document entity that is
     *                 parsed from a java.io.Reader).
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void startGeneralEntity(String name, 
                                   XMLResourceIdentifier identifier, 
                                   String encoding, Augmentations augs) 
        throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.startGeneralEntity(name, identifier, encoding, augs);
        }
    } // startGeneralEntity(String,XMLResourceIdentifier,String,Augmentations)
    
    /**
     * Notifies of the presence of a TextDecl line in an entity. If present,
     * this method will be called immediately following the startEntity call.
     * <p>
     * <strong>Note:</strong> This method will never be called for the
     * document entity; it is only called for external general entities
     * referenced in document content.
     * <p>
     * <strong>Note:</strong> This method is not called for entity references
     * appearing as part of attribute values.
     * 
     * @param version  The XML version, or null if not specified.
     * @param encoding The IANA encoding name of the entity.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void textDecl(String version, String encoding, Augmentations augs)
        throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.textDecl(version, encoding, augs);
        }
    } // textDecl(String,String)
    
    /**
     * This method notifies the end of an entity.
     * <p>
     * <strong>Note:</strong> This method is not called for entity references
     * appearing as part of attribute values.
     * 
     * @param name The name of the entity.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void endGeneralEntity(String name, Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.endGeneralEntity(name, augs);
        }
    } // endGeneralEntity(String,Augmentations)
    
    /**
     * Character content.
     * 
     * @param text The content.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void characters(XMLString text, Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.characters(text, augs);
        }
    } // characters(XMLString)
    
    /**
     * Ignorable whitespace. For this method to be called, the document
     * source must have some way of determining that the text containing
     * only whitespace characters should be considered ignorable. For
     * example, the validator can determine if a length of whitespace
     * characters in the document are ignorable based on the element
     * content model.
     * 
     * @param text The ignorable whitespace.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void ignorableWhitespace(XMLString text, Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.ignorableWhitespace(text, augs);
        }
    } // ignorableWhitespace(XMLString)
    
    /** 
     * The start of a CDATA section. 
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void startCDATA(Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.startCDATA(augs);
        }
    } // startCDATA()
    
    /**
     * The end of a CDATA section. 
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void endCDATA(Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.endCDATA(augs);
        }
    } // endCDATA()
    
    /**
     * The end of the document.
     *
     * @throws XNIException Thrown by handler to signal an error.
     */
    public void endDocument(Augmentations augs) throws XNIException {
        if (fDocumentHandler != null) {
            fDocumentHandler.endDocument(augs);
        }
    } // endDocument()


    /** Sets the document source. */
    public void setDocumentSource(XMLDocumentSource source){
        fDocumentSource = source;    
    }


    /** Returns the document source. */
    public XMLDocumentSource getDocumentSource(){
        return fDocumentSource;
    }
    
} // class PassThroughFilter