/*******************************************************************************
 * 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 Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: IBM Corporation - initial API and implementation
 ******************************************************************************/
package org.erlide.jinterface.backend.util;

/* 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(final 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(final boolean expression, final 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(final 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(final Object object, final 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(final 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(final boolean expression, final String message) {
		if (!expression) {
			throw new AssertionFailedException("Assertion failed; " + message); //$NON-NLS-1$
		}
		return expression;
	}

	public static class AssertionFailedException extends RuntimeException {

		private static final long serialVersionUID = 1L;

		public AssertionFailedException(final String detail) {
			super(detail);
		}
	}
}
