org.verapdf.as.io.ASInputStream Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of parser Show documentation

veraPDF tools for parsing, modifying and creating PDF documents.

There is a newer version: 1.26.1

/**
 * This file is part of veraPDF Parser, a module of the veraPDF project.
 * Copyright (c) 2015, veraPDF Consortium 
 * All rights reserved.
 *
 * veraPDF Parser is free software: you can redistribute it and/or modify
 * it under the terms of either:
 *
 * The GNU General public license GPLv3+.
 * You should have received a copy of the GNU General Public License
 * along with veraPDF Parser as the LICENSE.GPL file in the root of the source
 * tree.  If not, see http://www.gnu.org/licenses/ or
 * https://www.gnu.org/licenses/gpl-3.0.en.html.
 *
 * The Mozilla Public License MPLv2+.
 * You should have received a copy of the Mozilla Public License along with
 * veraPDF Parser as the LICENSE.MPL file in the root of the source tree.
 * If a copy of the MPL was not distributed with this file, you can obtain one at
 * http://mozilla.org/MPL/2.0/.
 */
package org.verapdf.as.io;

import org.verapdf.tools.IntReference;

import java.io.IOException;
import java.io.InputStream;

/**
 * Base class for stream hierarchy. Has methods for resource management.
 * Please don't forget to close all the opened streams.
 *
 * @author Timur Kamalov
 */
public abstract class ASInputStream extends InputStream {

	protected boolean isClosed = false;
	protected boolean isSourceClosed = false;

	protected IntReference resourceUsers = new IntReference(1);

	public abstract int read() throws IOException;

	public abstract int read(byte[] buffer, int size) throws IOException;

	public abstract int skip(int size) throws IOException;

	@Override
	public void close() throws IOException {
		if (!isClosed) {
			isClosed = true;
			if (!this.resourceUsers.equals(0)) {
				this.resourceUsers.decrement();
			}
		}
		if (this.resourceUsers.equals(0)) {
			closeResource();
		}
	}

	@Override
	public abstract void reset() throws IOException;

	/**
	 * Closes stream resource. There is a difference between closing stream and
	 * closing it's resource. Several streams may have the same resource (e. g.
	 * the same file stream) and resource should be closed only after all
	 * streams using it are closed.
	 */
	public abstract void closeResource() throws IOException;

	/**
	 * Method increments number of resource users.
	 *
	 * {@see closeResource}
	 */
	public abstract void incrementResourceUsers();

	/**
	 * Method decrements number of resource users.
	 *
	 * {@see closeResource}
	 */
	public abstract void decrementResourceUsers();

	/**
	 * Creates copy of stream. The two streams can be closed separately.
	 */
	public static ASInputStream createStreamFromStream(ASInputStream stream) {
		return new ASInputStreamWrapper(stream);
	}
}