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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.

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/*
 * #%L
 * SciJava Common shared library for SciJava software.
 * %%
 * Copyright (C) 2009 - 2017 Board of Regents of the University of
 * Wisconsin-Madison, Broad Institute of MIT and Harvard, Max Planck
 * Institute of Molecular Cell Biology and Genetics, University of
 * Konstanz, and KNIME GmbH.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. 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.
 * 
 * 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 HOLDERS 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 org.scijava.io.handle;

import java.io.IOException;
import java.util.Arrays;

import org.scijava.io.location.DummyLocation;
import org.scijava.plugin.Plugin;

/**
 * A {@link DataHandle} which reads all zeroes, and writes no actual data.
 *
 * @author Curtis Rueden
 */
@Plugin(type = DataHandle.class)
public class DummyHandle extends AbstractDataHandle {

	// -- Fields --

	private long offset;
	private long length;

	// -- DataHandle methods --

	@Override
	public boolean isReadable() {
		return true;
	}

	@Override
	public boolean isWritable() {
		return true;
	}

	@Override
	public boolean exists() {
		return true;
	}

	@Override
	public long offset() {
		return offset;
	}

	@Override
	public void seek(final long pos) {
		if (pos > length()) setLength(pos);
		offset = pos;
	}

	@Override
	public long length() {
		return length;
	}

	@Override
	public void setLength(final long length) {
		this.length = length;
	}

	// -- DataInput methods --

	@Override
	public byte readByte() throws IOException {
		final long r = available(1);
		if (r <= 0) return -1;
		offset++;
		return 0;
	}

	@Override
	public int read(final byte[] b, final int off, final int len)
		throws IOException
	{
		final int r = (int) available(len);
		offset += r;
		Arrays.fill(b, off, off + r, (byte) 0);
		return r;
	}

	// -- DataOutput methods --

	@Override
	public void write(final int v) throws IOException {
		ensureWritable(1);
		offset++;
	}

	@Override
	public void write(final byte[] b, final int off, final int len)
		throws IOException
	{
		ensureWritable(len);
		offset += len;
	}

	// -- Closeable methods --

	@Override
	public void close() {
		// NB: No action needed.
	}

	// -- Typed methods --

	@Override
	public Class getType() {
		return DummyLocation.class;
	}
}