package	corejava;

/**
   A class for assertion checking

   @version 1.00 10 Oct	1998
   @author Cay Horstmann
*/

public class Assertion
{
   /**
      Check an assertion
      @param b the condition to	check
      @param s a string	describing the check
      @throws Assertion.Failure	if condition not true
   */

   public static void check(boolean b, String s)
   {  if (doCheck && !b)
	 throw new Failure(s);
   }

   /**
      Check an assertion
      @param b the condition to	check
      @throws Assertion.Failure	if condition not true
   */

   public static void check(boolean b)
   {  if (doCheck && !b)
	 throw new Failure();
   }

   /**
      Check an assertion
      @param obj an object to check
      @param s a string	describing the check
      @throws Assertion.Failure	if object is null
   */

   public static void check(Object obj,	String s)
   {  if (doCheck && obj == null)
	 throw new Failure(s);
   }

   /**
      Check an assertion
      @param obj an object to check
      @throws Assertion.Failure	if object is null
   */

   public static void check(Object obj)
   {  if (doCheck && obj == null)
	 throw new Failure();
   }

   /**
      Check an assertion
      @param x a number
      @param s a string	describing the check
      @throws Assertion.Failure	if number is 0
   */

   public static void check(double x, String s)
   {  if (doCheck && x == 0)
	 throw new Failure(s);
   }

   /**
      Check an assertion
      @param x a number
      @throws Assertion.Failure	if number is 0
   */

   public static void check(double x)
   {  if (doCheck && x == 0)
	 throw new Failure();
   }

   /**
      Check an assertion
      @param x a number
      @param s a string	describing the check
      @throws Assertion.Failure	if number is 0
   */

   public static void check(long x, String s)
   {  if (doCheck && x == 0)
	 throw new Failure(s);
   }

   /**
      Check an assertion
      @param x a number
      @throws Assertion.Failure	if number is 0
   */

   public static void check(long x)
   {  if (doCheck && x == 0)
	 throw new Failure();
   }

   /**
      Turn checking on or off
      @param c true to turn checking on, false to turn checking	off
   */

   public static void setCheck(boolean c)
   {  doCheck =	c;
   }

   private static boolean doCheck = true;

   /**
      test stub
   */

   public static void main(String[] args)
   {  Assertion.check(args);
      Assertion.check(args.length, "No command line arguments");
   }

   /**
      A	class for reporting assertion failures
   */

   public static class Failure extends RuntimeException
   {  public Failure()
      {	 super("Assertion failed");
      }

      /**
	 @param	gripe a	description of the reason for the failure
      */
      public Failure(String gripe)
      {	 super(gripe);
      }
   }
}