de.intarsys.pdf.cos.COSNull 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.cos;

/**
 * The null object
 */
public class COSNull extends COSPrimitiveObject {
	public static final COSNull NULL = (COSNull) COSNull.create().beConstant();

	static public COSNull create() {
		return new COSNull();
	}

	protected COSNull() {
		super();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see de.intarsys.pdf.cos.COSObject#accept(de.intarsys.pdf.cos.ICOSObjectVisitor)
	 */
	@Override
	public java.lang.Object accept(ICOSObjectVisitor visitor)
			throws COSVisitorException {
		return visitor.visitFromNull(this);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see de.intarsys.pdf.cos.COSObject#basicToString()
	 */
	@Override
	protected String basicToString() {
		return "null"; //$NON-NLS-1$
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see de.intarsys.pdf.cos.COSObject#copyBasic(de.intarsys.pdf.cos.COSDocument)
	 */
	@Override
	protected COSObject copyBasic() {
		return new COSNull();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	@Override
	public boolean equals(Object o) {
		return o instanceof COSNull;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Object#hashCode()
	 */
	@Override
	public int hashCode() {
		// arbitrary number to avoid collisions
		return 27;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see de.intarsys.pdf.cos.COSObject#isNull()
	 */
	@Override
	public boolean isNull() {
		return true;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see de.intarsys.tools.objectsession.ISaveStateSupport#saveState()
	 */
	public Object saveState() {
		COSObject result = new COSNull();
		result.container = this.container.saveStateContainer();
		return result;
	}
}