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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,
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 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
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 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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package de.intarsys.pdf.cos;

import java.util.HashSet;
import java.util.Set;

/**
 * Adapter implementation for visiting a COS object structure, including
 * indirect references.
 * 
 * Every object in the potential cyclic data structure is visited exactly once.
 * 
 */
public class COSObjectWalkerDeep extends COSObjectWalkerShallow {
	private Set visited;

	final private boolean forceSwap;

	final private boolean swapAlways;

	public COSObjectWalkerDeep() {
		this(true);
	}

	public COSObjectWalkerDeep(boolean forceSwap) {
		visited = new HashSet();
		this.forceSwap = forceSwap;
		this.swapAlways = forceSwap;
	}

	public COSObjectWalkerDeep(boolean forceSwap, boolean swapAlways) {
		visited = new HashSet();
		this.forceSwap = forceSwap;
		this.swapAlways = swapAlways;
	}

	public Set getVisited() {
		return visited;
	}

	protected void handleException(RuntimeException e)
			throws COSVisitorException {
		throw new COSVisitorException(e);
	}

	@Override
	public Object visitFromIndirectObject(COSIndirectObject io)
			throws COSVisitorException {
		if (getVisited().contains(io)) {
			return null;
		}
		getVisited().add(io);
		// descend if
		// - we should always swap
		// - we should swap and object was previously read
		// - object is swapped in
		if (swapAlways || forceSwap && !io.isInitialState() || !io.isSwapped()) {
			try {
				io.dereference().accept(this);
			} catch (RuntimeException e) {
				handleException(e);
			}
		}
		return null;
	}
}