/*

 * 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.xml.sax;

import java.io.IOException;

import java.io.Reader;

import java.io.InputStream;

/**

 * A single input source for an XML entity.

 *

 * <p>This class allows a SAX application to encapsulate information

 * about an input source in a single object, which may include

 * a public identifier, a system identifier, a byte stream (possibly

 * with a specified encoding), and/or a character stream.</p>

 *

 * <p>There are two places that the application can deliver an

 * input source to the parser: as the argument to the Parser.parse

 * method, or as the return value of the EntityResolver.resolveEntity

 * method.</p>

 *

 * <p>The SAX parser will use the InputSource object to determine how

 * to read XML input.  If there is a character stream available, the

 * parser will read that stream directly, disregarding any text

 * encoding declaration found in that stream.

 * If there is no character stream, but there is

 * a byte stream, the parser will use that byte stream, using the

 * encoding specified in the InputSource or else (if no encoding is

 * specified) autodetecting the character encoding using an algorithm

 * such as the one in the XML specification.  If neither a character

 * stream nor a

 * byte stream is available, the parser will attempt to open a URI

 * connection to the resource identified by the system

 * identifier.</p>

 *

 * <p>An InputSource object belongs to the application: the SAX parser

 * shall never modify it in any way (it may modify a copy if

 * necessary).  However, standard processing of both byte and

 * character streams is to close them on as part of end-of-parse cleanup,

 * so applications should not attempt to re-use such streams after they

 * have been handed to a parser.  </p>

 *

 * @since 1.4, SAX 1.0

 * @author David Megginson

 * @see org.xml.sax.XMLReader#parse(org.xml.sax.InputSource)

 * @see org.xml.sax.EntityResolver#resolveEntity

 * @see java.io.InputStream

 * @see java.io.Reader

 */

public class InputSource {

    /**

     * Zero-argument default constructor.

     *

     * @see #setPublicId

     * @see #setSystemId

     * @see #setByteStream

     * @see #setCharacterStream

     * @see #setEncoding

     */

    public InputSource ()

    {

    }

    /**

     * Create a new input source with a system identifier.

     *

     * <p>Applications may use setPublicId to include a

     * public identifier as well, or setEncoding to specify

     * the character encoding, if known.</p>

     *

     * <p>If the system identifier is a URL, it must be fully

     * resolved (it may not be a relative URL).</p>

     *

     * @param systemId The system identifier (URI).

     * @see #setPublicId

     * @see #setSystemId

     * @see #setByteStream

     * @see #setEncoding

     * @see #setCharacterStream

     */

    public InputSource (String systemId)

    {

        setSystemId(systemId);

    }

    /**

     * Create a new input source with a byte stream.

     *

     * <p>Application writers should use setSystemId() to provide a base

     * for resolving relative URIs, may use setPublicId to include a

     * public identifier, and may use setEncoding to specify the object's

     * character encoding.</p>

     *

     * @param byteStream The raw byte stream containing the document.

     * @see #setPublicId

     * @see #setSystemId

     * @see #setEncoding

     * @see #setByteStream

     * @see #setCharacterStream

     */

    public InputSource (InputStream byteStream)

    {

        setByteStream(byteStream);

    }

    /**

     * Create a new input source with a character stream.

     *

     * <p>Application writers should use setSystemId() to provide a base

     * for resolving relative URIs, and may use setPublicId to include a

     * public identifier.</p>

     *

     * <p>The character stream shall not include a byte order mark.</p>

     *

     * @see #setPublicId

     * @see #setSystemId

     * @see #setByteStream

     * @see #setCharacterStream

     */

    public InputSource (Reader characterStream)

    {

        setCharacterStream(characterStream);

    }

    /**

     * Set the public identifier for this input source.

     *

     * <p>The public identifier is always optional: if the application

     * writer includes one, it will be provided as part of the

     * location information.</p>

     *

     * @param publicId The public identifier as a string.

     * @see #getPublicId

     * @see org.xml.sax.Locator#getPublicId

     * @see org.xml.sax.SAXParseException#getPublicId

     */

    public void setPublicId (String publicId)

    {

        this.publicId = publicId;

    }

    /**

     * Get the public identifier for this input source.

     *

     * @return The public identifier, or null if none was supplied.

     * @see #setPublicId

     */

    public String getPublicId ()

    {

        return publicId;

    }

    /**

     * Set the system identifier for this input source.

     *

     * <p>The system identifier is optional if there is a byte stream

     * or a character stream, but it is still useful to provide one,

     * since the application can use it to resolve relative URIs

     * and can include it in error messages and warnings (the parser

     * will attempt to open a connection to the URI only if

     * there is no byte stream or character stream specified).</p>

     *

     * <p>If the application knows the character encoding of the

     * object pointed to by the system identifier, it can register

     * the encoding using the setEncoding method.</p>

     *

     * <p>If the system identifier is a URL, it must be fully

     * resolved (it may not be a relative URL).</p>

     *

     * @param systemId The system identifier as a string.

     * @see #setEncoding

     * @see #getSystemId

     * @see org.xml.sax.Locator#getSystemId

     * @see org.xml.sax.SAXParseException#getSystemId

     */

    public void setSystemId (String systemId)

    {

        this.systemId = systemId;

    }

    /**

     * Get the system identifier for this input source.

     *

     * <p>The getEncoding method will return the character encoding

     * of the object pointed to, or null if unknown.</p>

     *

     * <p>If the system ID is a URL, it will be fully resolved.</p>

     *

     * @return The system identifier, or null if none was supplied.

     * @see #setSystemId

     * @see #getEncoding

     */

    public String getSystemId ()

    {

        return systemId;

    }

    /**

     * Set the byte stream for this input source.

     *

     * <p>The SAX parser will ignore this if there is also a character

     * stream specified, but it will use a byte stream in preference

     * to opening a URI connection itself.</p>

     *

     * <p>If the application knows the character encoding of the

     * byte stream, it should set it with the setEncoding method.</p>

     *

     * @param byteStream A byte stream containing an XML document or

     *        other entity.

     * @see #setEncoding

     * @see #getByteStream

     * @see #getEncoding

     * @see java.io.InputStream

     */

    public void setByteStream (InputStream byteStream)

    {

        this.byteStream = byteStream;

    }

    /**

     * Get the byte stream for this input source.

     *

     * <p>The getEncoding method will return the character

     * encoding for this byte stream, or null if unknown.</p>

     *

     * @return The byte stream, or null if none was supplied.

     * @see #getEncoding

     * @see #setByteStream

     */

    public InputStream getByteStream ()

    {

        return byteStream;

    }

    /**

     * Set the character encoding, if known.

     *

     * <p>The encoding must be a string acceptable for an

     * XML encoding declaration (see section 4.3.3 of the XML 1.0

     * recommendation).</p>

     *

     * <p>This method has no effect when the application provides a

     * character stream.</p>

     *

     * @param encoding A string describing the character encoding.

     * @see #setSystemId

     * @see #setByteStream

     * @see #getEncoding

     */

    public void setEncoding (String encoding)

    {

        this.encoding = encoding;

    }

    /**

     * Get the character encoding for a byte stream or URI.

     * This value will be ignored when the application provides a

     * character stream.

     *

     * @return The encoding, or null if none was supplied.

     * @see #setByteStream

     * @see #getSystemId

     * @see #getByteStream

     */

    public String getEncoding ()

    {

        return encoding;

    }

    /**

     * Set the character stream for this input source.

     *

     * <p>If there is a character stream specified, the SAX parser

     * will ignore any byte stream and will not attempt to open

     * a URI connection to the system identifier.</p>

     *

     * @param characterStream The character stream containing the

     *        XML document or other entity.

     * @see #getCharacterStream

     * @see java.io.Reader

     */

    public void setCharacterStream (Reader characterStream)

    {

        this.characterStream = characterStream;

    }

    /**

     * Get the character stream for this input source.

     *

     * @return The character stream, or null if none was supplied.

     * @see #setCharacterStream

     */

    public Reader getCharacterStream ()

    {

        return characterStream;

    }

    /**

     * Indicates whether the {@code InputSource} object is empty. Empty is

     * defined as follows:

     * <ul>

     * <li>All of the input sources, including the public identifier, system

     * identifier, byte stream, and character stream, are {@code null}.

     * </li>

     * <li>The public identifier and system identifier are  {@code null}, and

     * byte and character stream are either  {@code null} or contain no byte

     * or character.

     * <p>

     * Note that this method will reset the byte stream if it is provided, or

     * the character stream if the byte stream is not provided.

     * </li>

     * </ul>

     * <p>

     * In case of error while checking the byte or character stream, the method

     * will return false to allow the XML processor to handle the error.

     *

     * @return true if the {@code InputSource} object is empty, false otherwise

     */

    public boolean isEmpty() {

        return (publicId == null && systemId == null && isStreamEmpty());

    }

    private boolean isStreamEmpty() {

        boolean empty = true;

        try {

            if (byteStream != null) {

                byteStream.reset();

                int bytesRead = byteStream.available();

                if (bytesRead > 0) {

                    return false;

                }

            }

            if (characterStream != null) {

                characterStream.reset();

                int c = characterStream.read();

                characterStream.reset();

                if (c != -1) {

                    return false;

                }

            }

        } catch (IOException ex) {

            //in case of error, return false

            return false;

        }

        return empty;

    }

    ////////////////////////////////////////////////////////////////////

    // Internal state.

    ////////////////////////////////////////////////////////////////////

    private String publicId;

    private String systemId;

    private InputStream byteStream;

    private String encoding;

    private Reader characterStream;

}

// end of InputSource.java