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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 - 2016 Board of Regents of the University of
 * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
 * Institute of Molecular Cell Biology and Genetics.
 * %%
 * 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
 * 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.
 * #L%
 */

package org.scijava.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintStream;

/**
 * This class takes an {@link InputStream} and either accumulates the read bytes
 * in a {@link String} or outputs to a {@link PrintStream}.
 * 
 * Its intended use is to catch the output and error streams of {@link Process}
 * instances.
 * 
 * 
 * @author Johannes Schindelin
 */
public class ReadInto extends Thread {

	protected BufferedReader reader;
	protected PrintStream out;
	protected StringBuilder buffer = new StringBuilder();
	protected boolean done, closeOnEOF;

	/**
	 * Construct a ReadInto thread and start it right away.
	 * 
	 * @param in the stream to read
	 * @param out the stream to print to; if it is null, the {@link #toString()}
	 *          method will have the output instead
	 */
	public ReadInto(final InputStream in, final PrintStream out) {
		this(in, out, false);
	}

	/**
	 * Construct a ReadInto thread and start it right away.
	 * 
	 * @param in the stream to read
	 * @param out the stream to print to; if it is null, the {@link #toString()}
	 *          method will have the output instead
	 */
	public ReadInto(final InputStream in, final PrintStream out, final boolean closeOnEOF) {
		reader = new BufferedReader(new InputStreamReader(in));
		this.out = out;
		this.closeOnEOF = closeOnEOF;
		if (out == null && closeOnEOF) throw new IllegalArgumentException("Cannot close null output");
		start();
	}

	/**
	 * The main method.
	 * 
	 * It runs until interrupted, or until the {@link InputStream} ends, whichever
	 * comes first.
	 * 
	 */
	@Override
	public void run() {
		try {
			for (;;) {
				final String line = reader.readLine();
				if (line == null) break;
				if (out != null) out.println(line);
				else buffer.append(line).append("\n");
				if (done) break;
				Thread.sleep(0);
			}
		}
		catch (final InterruptedException e) { /* just stop */}
		catch (final IOException e) { /* just stop */}
		if (closeOnEOF) {
			out.close();
		}
		try {
			reader.close();
		}
		catch (final IOException e) { /* just stop */ }
	}

	@Override
	public void interrupt() {
		try {
			done();
		} catch (IOException e) { /* just stop */ }
		super.interrupt();
	}

	public void done() throws IOException {
		if (done) return;
		done = true;
		reader.close();
	}

	/**
	 * Return the output as a {@link String} unless a {@link PrintStream} was
	 * specified in the constructor.
	 */
	@Override
	public String toString() {
		if (out != null) return "ReadInto " + out;
		return buffer.toString();
	}
}