cours0708/workspace/Palindrome/iutsud/Assertion.java

/* 
 * Copyright (C) 1997 Roger Whitney <whitney@cs.sdsu.edu>
 *
 * This file is part of the San Diego State University Java Library.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


package iutsud ;


/**
 * Cette classe imite la macro  ASSERT de C/C++. 
 * Elle permet de s'assurer qu'une condition est v<EFBFBD>rifi<EFBFBD>e
 * avant de poursuivre l'ex<EFBFBD>cution.<p>
 * Elle a trois m<EFBFBD>thodes
 * statiques : <code>pre</code>, <code>post</code> et <code>invariant</code> 
 * Ces m<EFBFBD>thodes sont identiques. Chaque m<EFBFBD>thode arr<EFBFBD>te l'ex<EFBFBD>cution du
 * programme en levant une exception si son argument est faux. <p>
 * Un exemple d'utilisation d'assertion est :
 * <pre>
 *		<code>Assertion.pre( (mois == 1 ) && ( jour <= 31 ));</code>
 * </pre>
 * Ceci v<EFBFBD>rifie que la condition est vrai <EFBFBD> ce stade de l'ex<EFBFBD>cution.
 * Si elle n'est pas v<EFBFBD>rifi<EFBFBD>e, une exception de type 
 * 		<code>Assertion.PreConditionException</code>,  
 * 		<code>Assertion.PostConditionException</code>
 *		ou  <code>Assertion.InvariantException</code> 
 * est lev<EFBFBD>e.
 * Ces exceptions d<EFBFBD>rivent de <code>RuntimeException</code>
 * et arr<EFBFBD>tent l'ex<EFBFBD>cution du programme en affichant
 * l'<EFBFBD>tat de la pile d'ex<EFBFBD>cution. <P>
 * Cette classe provient de la classe <code>sdsu.io.Assert</code> de l'universit<EFBFBD>
 *	de San Diego (<a href="http://www.eli.sdsu.edu/java-SDSU">http://www.eli.sdsu.edu/java-SDSU</a>).
 * <p>Les modifications sont mineures :
 * <li> d<EFBFBD>finition et utilisation d'exceptions internes <EFBFBD> la classe
 * <li> suppression de la m<EFBFBD>thode <code>condition</code>
 * <li> m<EFBFBD>thode <code>classInvariant</code> renomm<EFBFBD>e <code>invariant</code>
 * <li> classe <code>Assert</code> renomm<EFBFBD>e <code>Assertion</code>
 */
 /*
 * <p> This class is modeled after the ASSERT macro in C/C++. The class 
 * has three static methods. 
 * The methods are identical. Each method will throw an exception if
 * is argument is false. A sample use of the assert is:
 * <pre>
 *		Assert.pre( (X > 5 ) && ( Z <= 10 ));
 * </pre>
 * This asserts that the condition should be true at this point.
 * If it is not an exception will be thrown. So the program can
 * assume that the condition is true after the above assert. <P>
 * In C/C++ ASSERT is defined as a macro. Thus the macro can be 
 * turned off with a compile switch. This allows the code to contain
 * ASSERTS with out any runtime cost. There is no way in Java to
 * completely eliminate the cost of the Assert calls. Hopefully
 * future compilers will be smart enough to use tricks with 
 * classpaths and two versions of this class to "turn off" the
 * Assert calls in productin code without modifing the program
 * source.<P>
 * See <I>Writing Solid Code</I> by Steve Maguire, pp 13-44
 * or <I>Object-Oriented Software Construction</I> by 
 * Bertrand Meyer, pp 111 - 163 for the use and importance
 * of Assert.
 *
 * @see sdsu.test.AssertException
 * @version 1.0 30 December 1997 
 * @author Roger Whitney 
 * (<a href=mailto:whitney@cs.sdsu.edu>whitney@cs.sdsu.edu</a>)
 */
 
public abstract class Assertion
	{
	
	private Assertion()
	{
		super() ;
	}
	
//    /* main de test

	private static void main(String args[]) {

	while (true) {
	
		System.out.print( "Print a Boolean ");
		boolean b = Console.readBoolean() ;
		pre(b) ;
		post(b) ;
		invariant(b) ;
		}
	}
//	*/

	/**
	 *	Exception lev<EFBFBD>e lorsqu'une pr<EFBFBD>condition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 */
 
	public static class PreConditionException extends RuntimeException	
	{
		public PreConditionException(String message)
		{
			super(message) ;
		}
	}	// end class PreConditionException

	/**
	 *	Exception lev<EFBFBD>e lorsqu'une postcondition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 */
	 
	public static class PostConditionException extends RuntimeException	
	{
		public PostConditionException(String message)
		{
			super(message) ;
		}
	}	// end class PostConditionException
	
	/**
	 *	Exception lev<EFBFBD>e lorsqu'un invariant n'est pas v<EFBFBD>rifi<EFBFBD>e
	 */
	 
	public static class InvariantException extends RuntimeException	
	{
		public InvariantException(String message)
		{
			super(message) ;
		}
	}	// end class InvariantException
	
	/**
	 *	Arr<EFBFBD>te l'ex<EFBFBD>cution du programme si la condition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 *  en levant l'exception <code>PreConditionException</code>
	 *	@param	cond	la condition <EFBFBD> v<EFBFBD>rifier
	 */
	 	 
	public static void pre( boolean cond )
		{
		 if ( !cond )
		 	throw new PreConditionException( "Pr<EFBFBD>condition non v<>rifi<66>e" );
		}
	/**
	 *	Arr<EFBFBD>te l'ex<EFBFBD>cution du programme si la condition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 *  en levant l'exception <code>PreConditionException</code> 
	 *  avec le message pass<EFBFBD> en param<EFBFBD>tre
	 *	@param	cond	la condition <EFBFBD> v<EFBFBD>rifier
	 *	@param	message	message <EFBFBD> afficher
	 */
	 	 
	public static void pre( boolean cond , String message )
		{
		 if ( !cond )
		 	throw new PreConditionException( message );
		}
		
	/**
	 *	Arr<EFBFBD>te l'ex<EFBFBD>cution du programme si la condition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 *  en levant l'exception <code>PostConditionException</code>
	 *	@param	cond	la condition <EFBFBD> v<EFBFBD>rifier
	 */

	public static void post( boolean cond )
		{
		 if ( !cond )
		 	throw new PostConditionException( "Postcondition non v<>rifi<66>e" );
		}
		
	/**
	 *	Arr<EFBFBD>te l'ex<EFBFBD>cution du programme si la condition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 *  en levant l'exception <code>PostConditionException</code>
	 *  avec le message pass<EFBFBD> en param<EFBFBD>tre
	 *	@param	cond	la condition <EFBFBD> v<EFBFBD>rifier
	 *	@param	message	message <EFBFBD> afficher
	 */
	 	 
	public static void post( boolean cond , String message)
		{
		 if ( !cond )
		 	throw new PostConditionException( message );
		}
		
	/**
	 *	Arr<EFBFBD>te l'ex<EFBFBD>cution du programme si la condition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 *  en levant l'exception <code>InvariantException</code>
	 *	@param	cond	la condition <EFBFBD> v<EFBFBD>rifier
	 */

	public static void invariant( boolean cond )
		{
		 if ( !cond )
		 	throw new InvariantException( "Invariant non v<>rifi<66>" );
		}
	/**
	 *	Arr<EFBFBD>te l'ex<EFBFBD>cution du programme si la condition n'est pas v<EFBFBD>rifi<EFBFBD>e
	 *  en levant l'exception <code>InvariantException</code>
	 *  avec le message pass<EFBFBD> en param<EFBFBD>tre
	 *	@param	cond	la condition <EFBFBD> v<EFBFBD>rifier
	 *	@param	message	message <EFBFBD> afficher
	 */
	 	 
	public static void invariant( boolean cond , String message )
		{
		 if ( !cond )
		 	throw new InvariantException( message );
		}

	}