GnuplotPipe.java

/*
 * Copyright (c) 2013, SRI International
 * All rights reserved.
 * Licensed under the The BSD 3-Clause License;
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 * 
 * http://opensource.org/licenses/BSD-3-Clause
 * 
 * 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 the aic-util 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 HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.sri.ai.util.gnuplot;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import com.google.common.annotations.Beta;
import com.sri.ai.util.Util;

/**
 * A class for opening a pipe to gnuplot.
 * It requires gnuplot to be installed, with its directory in the PATH.
 * 
 * @author braz
 */
@Beta
public class GnuplotPipe extends BufferedOutputStream {
	public GnuplotPipe(boolean persist) {
		super(getGnuplotOutputStream(persist));
	}

	private static OutputStream getGnuplotOutputStream(boolean persist) {
		String persistFlag = persist? " -persist" : " ";
		Process process = null;
		try {
			String executableName = System.getProperty("os.name").contains("Windows")? "pgnuplot.exe" : "gnuplot";
			process = Runtime.getRuntime().exec(executableName + persistFlag);
		} catch (IOException e) {
			Util.fatalError("Could not launch gnuplot", e);
		}
		return process.getOutputStream();
	}

	/**
	 * Sends a command to gnuplot through the pipe.
	 * 
	 * @param command
	 *            the command to send.
	 * @throws IOException
	 *             if the command fails.
	 */
	public void send(String command) throws IOException {
		write((command + "\n").getBytes());
		flush();
	}
}