//tabstop=4
//*****************************************************************************/
// Project: jpl
//
// File:    $Id$
// Date:    $Date$
// Author:  Fred Dushin <fadushin@syr.edu>
//          
//
// Description:
//    
//
// -------------------------------------------------------------------------
// Copyright (c) 1998 Fred Dushin
//                    All rights reserved.
// 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Library Public License for more details.
//*****************************************************************************/
package jpl;

import jpl.fli.Prolog;


//----------------------------------------------------------------------/
// JPL
/**
 * The JPL class contains initialization and termination methods for 
 * the High-Level interface.  The Prolog engine must be initialized 
 * before any queries are made.
 * 
 * <hr><i>
 * Copyright (C) 1998  Fred Dushin<p>
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.<p>
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library Public License for more details.<p>
 * </i><hr>
 * @author  Fred Dushin <fadushin@syr.edu>
 * @version $Revision$
 */
// Implementation notes:  
// 
//----------------------------------------------------------------------/
public class JPL
{
	protected static final boolean DEBUG = false;
	private static boolean  _initialized = false;
	
	//------------------------------------------------------------------/
	// init
	/**
	 * Initializes the Prolog engine, using the String argument
	 * parameters passed.  For parameter options, consult your local
	 * Prolog documentation.  The parameter values are passed directly
	 * to initialization routines for the Prolog environment.<p>
	 * 
	 * This method must be called before making any queries.
	 * 
	 * @param   argv   Initialization parameter list
	 */
	// Implementation notes:  
	// 
	//------------------------------------------------------------------/
	public static void
	init( java.lang.String argv[] )
	{
		if ( !_initialized ){
			Prolog.initialise( argv.length, argv );
			_initialized = true;
		}
	}
	
	//------------------------------------------------------------------/
	// init
	/**
	 * Default initializor.  Starts the engine with pl, the default
	 * Prolog command, with the initial goal to be "true" (eliminates
	 * that initial message).
	 */
	// Implementation notes:  
	// 
	//------------------------------------------------------------------/
	public static void
	init()
	{
		java.lang.String argv[] = { "pl", "-g", "true" };
		init( argv );
	}
	
	//------------------------------------------------------------------/
	// halt
	/**
	 * Terminates the Prolog session.<p>
	 * 
	 * <b>Note.</b>  This method calls the FLI halt() method with a
	 * status of 0, but the halt method currently is a no-op in SWI.
	 */
	// Implementation notes:  
	// 
	//------------------------------------------------------------------/
	public static void
	halt()
	{
		Prolog.halt( 0 );
	}
	
	
	// a static reference to the current Version
	private static final Version version_ = new Version();
	
	//------------------------------------------------------------------/
	// version
	/**
	 * @return the running version of JPL.
	 */
	// Implementation notes:  
	// 
	//------------------------------------------------------------------/
	public static Version
	version()
	{
		return version_;
	}
	
	//------------------------------------------------------------------/
	// version_string
	/**
	 * @return the running version (in String form) of JPL.
	 */
	// Implementation notes:  
	// 
	//------------------------------------------------------------------/
	public static java.lang.String
	version_string()
	{
		return 
			"JPL " +
			version_.major + "." +
			version_.minor + "." +
			version_.patch + "-" +
			version_.status;
	}
	
	public static void
	main( java.lang.String argv[] )
	{
		System.out.println( version_string() );
	}
}

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