/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package net.sourceforge.phpdt.internal.core;

/* This class is not intended to be instantiated. */
public final class Assert {

	private Assert() {
		// cannot be instantiated
	}

	/**
	 * Asserts that an argument is legal. If the given boolean is not
	 * <code>true</code>, an <code>IllegalArgumentException</code> is
	 * thrown.
	 * 
	 * @param expression
	 *            the outcode of the check
	 * @return <code>true</code> if the check passes (does not return if the
	 *         check fails)
	 * @exception IllegalArgumentException
	 *                if the legality test failed
	 */
	public static boolean isLegal(boolean expression) {
		return isLegal(expression, ""); //$NON-NLS-1$
	}

	/**
	 * Asserts that an argument is legal. If the given boolean is not
	 * <code>true</code>, an <code>IllegalArgumentException</code> is
	 * thrown. The given message is included in that exception, to aid
	 * debugging.
	 * 
	 * @param expression
	 *            the outcode of the check
	 * @param message
	 *            the message to include in the exception
	 * @return <code>true</code> if the check passes (does not return if the
	 *         check fails)
	 * @exception IllegalArgumentException
	 *                if the legality test failed
	 */
	public static boolean isLegal(boolean expression, String message) {
		if (!expression)
			throw new IllegalArgumentException(message);
		return expression;
	}

	/**
	 * Asserts that the given object is not <code>null</code>. If this is not
	 * the case, some kind of unchecked exception is thrown.
	 * 
	 * @param object
	 *            the value to test
	 * @exception IllegalArgumentException
	 *                if the object is <code>null</code>
	 */
	public static void isNotNull(Object object) {
		isNotNull(object, ""); //$NON-NLS-1$
	}

	/**
	 * Asserts that the given object is not <code>null</code>. If this is not
	 * the case, some kind of unchecked exception is thrown. The given message
	 * is included in that exception, to aid debugging.
	 * 
	 * @param object
	 *            the value to test
	 * @param message
	 *            the message to include in the exception
	 * @exception IllegalArgumentException
	 *                if the object is <code>null</code>
	 */
	public static void isNotNull(Object object, String message) {
		if (object == null)
			throw new AssertionFailedException("null argument; " + message); //$NON-NLS-1$
	}

	/**
	 * Asserts that the given boolean is <code>true</code>. If this is not
	 * the case, some kind of unchecked exception is thrown.
	 * 
	 * @param expression
	 *            the outcode of the check
	 * @return <code>true</code> if the check passes (does not return if the
	 *         check fails)
	 */
	public static boolean isTrue(boolean expression) {
		return isTrue(expression, ""); //$NON-NLS-1$
	}

	/**
	 * Asserts that the given boolean is <code>true</code>. If this is not
	 * the case, some kind of unchecked exception is thrown. The given message
	 * is included in that exception, to aid debugging.
	 * 
	 * @param expression
	 *            the outcode of the check
	 * @param message
	 *            the message to include in the exception
	 * @return <code>true</code> if the check passes (does not return if the
	 *         check fails)
	 */
	public static boolean isTrue(boolean expression, String message) {
		if (!expression)
			throw new AssertionFailedException("Assertion failed; " + message); //$NON-NLS-1$
		return expression;
	}

	public static class AssertionFailedException extends RuntimeException {
		public AssertionFailedException(String detail) {
			super(detail);
		}
	}
}
