de.intarsys.pdf.st.STXRefEntry Maven / Gradle / Ivy

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/*
 * Copyright (c) 2007, intarsys consulting GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * - Neither the name of intarsys nor the names of its contributors may be used
 *   to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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package de.intarsys.pdf.st;

import java.io.IOException;

import de.intarsys.pdf.cos.COSObject;
import de.intarsys.pdf.crypt.ISystemSecurityHandler;
import de.intarsys.pdf.parser.COSLoadException;

/**
 * Abstract superclass for a XRef entry.
 * 
 * The XRef entry describes an object slot in a XRef. The entry consists of an
 * offset in the file, a generation number and a token indicating if this entry
 * is free.
 */
public abstract class STXRefEntry implements Comparable {

	private final int objectNumber;

	private final short generationNumber;

	protected STXRefEntry(int objectNumber, int generationNumber) {
		this.objectNumber = objectNumber;
		this.generationNumber = (short) generationNumber;
	}

	public abstract void accept(IXRefEntryVisitor visitor)
			throws XRefEntryVisitorException;

	public int compareTo(Object obj) {
		if (obj instanceof STXRefEntry) {
			return (getObjectNumber() - ((STXRefEntry) obj).getObjectNumber());
		}
		return -1;
	}

	public abstract STXRefEntry copy();

	public abstract STXRefEntryOccupied fill(int pos);

	public abstract long getColumn1();

	public abstract int getColumn2();

	public int getGenerationNumber() {
		return generationNumber & 0xffff;
	}

	public int getObjectNumber() {
		return objectNumber;
	}

	abstract public boolean isFree();

	public abstract COSObject load(STDocument doc,
			ISystemSecurityHandler securityHandler) throws IOException,
			COSLoadException;

	@Override
	public String toString() {
		return getObjectNumber() + " " + getGenerationNumber() + " R"; //$NON-NLS-1$ //$NON-NLS-2$
	}

	abstract protected void unlink();
}