Assert


1   /*******************************************************************************
2    * Copyright (c) 2000, 2005 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    * 
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.core.internal.utils;
12  
13  import org.eclipse.osgi.util.NLS;
14  
15  /**
16   * <code>Assert</code> is useful for for embedding runtime sanity checks
17   * in code.
18   * The predicate methods all test a condition and throw some
19   * type of unchecked exception if the condition does not hold.
20   * <p>
21   * Assertion failure exceptions, like most runtime exceptions, are
22   * thrown when something is misbehaving. Assertion failures are invariably
23   * unspecified behavior; consequently, clients should never rely on
24   * these being thrown (and certainly should not being catching them
25   * specifically).
26   * </p>
27   */
28  public final class Assert {
29      /* This class is not intended to be instantiated. */
30      private Assert() {
31          // not allowed
32      }
33  
34      /** Asserts that an argument is legal. If the given boolean is
35       * not <code>true</code>, an <code>IllegalArgumentException</code>
36       * is thrown.
37       *
38       * @param expression the outcode of the check
39       * @return <code>true</code> if the check passes (does not return
40       *    if the check fails)
41       * @exception IllegalArgumentException if the legality test failed
42       */
43      public static boolean isLegal(boolean expression) {
44          return isLegal(expression, ""); //$NON-NLS-1$
45      }
46  
47      /** Asserts that an argument is legal. If the given boolean is
48       * not <code>true</code>, an <code>IllegalArgumentException</code>
49       * is thrown.
50       * The given message is included in that exception, to aid debugging.
51       *
52       * @param expression the outcode of the check
53       * @param message the message to include in the exception
54       * @return <code>true</code> if the check passes (does not return
55       *    if the check fails)
56       * @exception IllegalArgumentException if the legality test failed
57       */
58      public static boolean isLegal(boolean expression, String   message) {
59          if (!expression)
60              throw new IllegalArgumentException  (message);
61          return expression;
62      }
63  
64      /** Asserts that the given object is not <code>null</code>. If this
65       * is not the case, some kind of unchecked exception is thrown.
66       * 
67       * @param object the value to test
68       * @exception IllegalArgumentException if the object is <code>null</code>
69       */
70      public static void isNotNull(Object   object) {
71          isNotNull(object, ""); //$NON-NLS-1$
72      }
73  
74      /** Asserts that the given object is not <code>null</code>. If this
75       * is not the case, some kind of unchecked exception is thrown.
76       * The given message is included in that exception, to aid debugging.
77       *
78       * @param object the value to test
79       * @param message the message to include in the exception
80       * @exception IllegalArgumentException if the object is <code>null</code>
81       */
82      public static void isNotNull(Object   object, String   message) {
83          if (object == null)
84              throw new AssertionFailedException(NLS.bind(Messages.utils_null, message));
85      }
86  
87      /** Asserts that the given boolean is <code>true</code>. If this
88       * is not the case, some kind of unchecked exception is thrown.
89       *
90       * @param expression the outcode of the check
91       * @return <code>true</code> if the check passes (does not return
92       *    if the check fails)
93       */
94      public static boolean isTrue(boolean expression) {
95          return isTrue(expression, ""); //$NON-NLS-1$
96      }
97  
98      /** Asserts that the given boolean is <code>true</code>. If this
99       * is not the case, some kind of unchecked exception is thrown.
100      * The given message is included in that exception, to aid debugging.
101      *
102      * @param expression the outcode of the check
103      * @param message the message to include in the exception
104      * @return <code>true</code> if the check passes (does not return
105      *    if the check fails)
106      */
107     public static boolean isTrue(boolean expression, String   message) {
108         if (!expression)
109             throw new AssertionFailedException(NLS.bind(Messages.utils_failed, message));
110         return expression;
111     }
112 }
113
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