itextpdf-master/itext/src/main/java/com/itextpdf/text/io/RandomAccessSource.java
/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2022 iText Group NV
 * Authors: Kevin Day, Bruno Lowagie, et al.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS.
 *
 * This program 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 Affero General License for more
 * details. You should have received a copy of the GNU Affero General License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA, 02110-1301 USA, or download the license from the following URL:
 * http://itextpdf.com/terms-of-use/
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General License.
 *
 * In accordance with Section 7(b) of the GNU Affero General License, a covered
 * work must retain the producer line in every PDF that is created or
 * manipulated using iText.
 *
 * You can be released from the requirements of the license by purchasing a
 * commercial license. Buying such a license is mandatory as soon as you develop
 * commercial activities involving the iText software without disclosing the
 * source code of your own applications. These activities include: offering paid
 * services to customers as an ASP, serving PDFs on the fly in a web
 * application, shipping iText with a closed source product.
 *
 * For more information, please contact iText Software Corp. at this address:
 * sales@itextpdf.com
 */
package com.itextpdf.text.io;

import java.io.IOException;

/**
 * Represents an abstract source that bytes can be read from.  This class forms the foundation for all byte input in iText. 
 * Implementations do not keep track of a current 'position', but rather provide absolute get methods.  Tracking position
 * should be handled in classes that use RandomAccessSource internally (via composition).
 * @since 5.3.5
 */
public interface RandomAccessSource {
	/**
	 * Gets a byte at the specified position
	 * @param position
	 * @return the byte, or -1 if EOF is reached
	 */
	public int get(long position) throws IOException;
	
	/**
	 * Gets an array at the specified position.  If the number of bytes requested cannot be read, the bytes that can be
	 * read will be placed in bytes and the number actually read will be returned.
	 * @param position the position in the RandomAccessSource to read from
	 * @param bytes output buffer
	 * @param off offset into the output buffer where results will be placed
	 * @param len the number of bytes to read
	 * @return the number of bytes actually read, or -1 if the file is at EOF
	 */
	public int get(long position, byte bytes[], int off, int len) throws IOException;
	
	/**
	 * @return the length of this source
	 */
	public long length();
	
	/**
	 * Closes this source.  The underlying data structure or source (if any) will also be closed
	 * @throws IOException
	 */
	public void close() throws IOException;
	
}
