de.intarsys.pdf.st.STXRefSubsection 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
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package de.intarsys.pdf.st;

import java.util.ArrayList;
import java.util.List;

/**
 * A XRef subsection in a PDF document.
 * 
 * A XRef section consists of at least one subsection. The subsections describe
 * the objects that have changed with regard to the previous document version.
 * 
 * Each subsection contains entries for a contiguous range of objects. The
 * serialized form starts with 2 number, the object number of the first entry
 * and the number of entries. Following this there is one line for each entry in
 * the form
 * 
 * In Use entry: 
 * offset[10] " " generation[5] " " n eol[2]
 * 
 * 
 * Free entry: 
 * next free[10] " " generation[5] " " f eol[2]
 * 
 */
public class STXRefSubsection {
	private STXRefSubsection next;

	private List entries;

	private int start;

	// record size for performance sake
	private int size;

	private STXRefSection xRefSection;

	protected STXRefSubsection(int start) {
		this(null, start);
	}

	public STXRefSubsection(STXRefSection xRefSection, int start) {
		this.xRefSection = xRefSection;
		this.start = start;
		this.entries = new ArrayList();
		this.size = 0;
	}

	protected void addEntry(STXRefEntry entry) {
		int number = entry.getObjectNumber();
		if (number < getStart()) {
			throw new IllegalArgumentException("can't add object with number "
					+ number);
		}
		int end = start + size;
		if (start <= number && number < end) {
			entries.set(number - start, entry);
			return;
		}
		if (number == end) {
			// fits to end of list
			entries.add(entry);
			size++;
			checkNext();
			return;
		}
		throw new IllegalArgumentException("can't add object with number "
				+ number);
	}

	protected void checkNext() {
		if (getNext() == null) {
			return;
		}
		if (getSize() == 0) {
			start = getNext().getStart();
			mergeWithNext();
			return;
		}
		if ((start + getSize()) == getNext().getStart()) {
			mergeWithNext();
		}
	}

	protected List getEntries() {
		return entries;
	}

	protected STXRefEntry getEntry(int objectNumber) {
		return (STXRefEntry) entries.get(objectNumber - start);
	}

	protected STXRefSubsection getNext() {
		return next;
	}

	public int getSize() {
		return size;
	}

	public int getStart() {
		return start;
	}

	public int getStop() {
		return start + getSize();
	}

	protected STXRefSection getXRefSection() {
		return xRefSection;
	}

	protected boolean isInSection(int objectNumber) {
		return ((objectNumber >= start) && (objectNumber < (start + getSize())));
	}

	protected void mergeWithNext() {
		entries.addAll(getNext().getEntries());
		size = entries.size();
		setNext(getNext().getNext());
	}

	protected void setNext(STXRefSubsection next) {
		this.next = next;
	}

	protected void setXRefSection(STXRefSection xRefSection) {
		this.xRefSection = xRefSection;
	}

}