package org.eclipse.core.internal.runtime;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */

/**
 * <code>Assert</code> is useful for for embedding runtime sanity checks
 * in code.
 * The predicate methods all test a condition and throw some
 * type of unchecked exception if the condition does not hold.
 * <p>
 * Assertion failure exceptions, like most runtime exceptions, are
 * thrown when something is misbehaving. Assertion failures are invariably
 * unspecified behavior; consequently, clients should never rely on
 * these being thrown (and certainly should not being catching them
 * specifically).
 * </p>
 */
public final class Assert {
/* This class is not intended to be instantiated. */
private Assert() {
}
/** 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, "");
}
/** 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, "");
}
/** 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);
}
/** 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, "");
}
/** 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);
	return expression;
}
}