KeyStroke


1   /*******************************************************************************
2    * Copyright (c) 2004, 2006 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  
12  package org.eclipse.jface.bindings.keys;
13  
14  import java.util.StringTokenizer  ;
15  
16  import org.eclipse.jface.bindings.Trigger;
17  import org.eclipse.jface.bindings.keys.formatting.KeyFormatterFactory;
18  import org.eclipse.jface.util.Util;
19  
20  /**
21   * <p>
22   * A <code>KeyStroke</code> is defined as an optional set of modifier keys
23   * followed optionally by a natural key. A <code>KeyStroke</code> is said to
24   * be complete if it contains a natural key. A natural key is any Unicode
25   * character (e.g., "backspace", etc.), any character belonging to a natural
26   * language (e.g., "A", "1", "[", etc.), or any special control character
27   * specific to computers (e.g., "F10", "PageUp", etc.).
28   * </p>
29   * <p>
30   * All <code>KeyStroke</code> objects have a formal string representation
31   * available via the <code>toString()</code> method. There are a number of
32   * methods to get instances of <code>KeyStroke</code> objects, including one
33   * which can parse this formal string representation.
34   * </p>
35   * <p>
36   * All <code>KeyStroke</code> objects, via the <code>format()</code> method,
37   * provide a version of their formal string representation translated by
38   * platform and locale, suitable for display to a user.
39   * </p>
40   * <p>
41   * <code>KeyStroke</code> objects are immutable. Clients are not permitted to
42   * extend this class.
43   * </p>
44   * 
45   * @since 3.1
46   */
47  public final class KeyStroke extends Trigger implements Comparable   {
48  
49      /**
50       * The delimiter between multiple keys in a single key strokes -- expressed
51       * in the formal key stroke grammar. This is not to be displayed to the
52       * user. It is only intended as an internal representation.
53       */
54      public static final String   KEY_DELIMITER = "\u002B"; //$NON-NLS-1$
55  
56      /**
57       * The set of delimiters for <code>Key</code> objects allowed during
58       * parsing of the formal string representation.
59       */
60      public static final String   KEY_DELIMITERS = KEY_DELIMITER;
61  
62      /**
63       * The representation for no key.
64       */
65      public static final int NO_KEY = 0;
66  
67      /**
68       * Creates an instance of <code>KeyStroke</code> given a natural key.
69       * 
70       * @param naturalKey
71       *            the natural key. The format of this integer is defined by
72       *            whichever widget toolkit you are using; <code>NO_KEY</code>
73       *            always means no natural key.
74       * @return a key stroke. This key stroke will have no modifier keys.
75       *         Guaranteed not to be <code>null</code>.
76       * @see SWTKeySupport
77       */
78      public static final KeyStroke getInstance(final int naturalKey) {
79          return new KeyStroke(NO_KEY, naturalKey);
80      }
81  
82      /**
83       * Creates an instance of <code>KeyStroke</code> given a set of modifier keys
84       * and a natural key.
85       * 
86       * @param modifierKeys
87       *            the modifier keys. The format of this integer is defined by
88       *            whichever widget toolkit you are using; <code>NO_KEY</code>
89       *            always means no modifier keys.
90       * @param naturalKey
91       *            the natural key. The format of this integer is defined by
92       *            whichever widget toolkit you are using; <code>NO_KEY</code>
93       *            always means no natural key.
94       * @return a key stroke. Guaranteed not to be <code>null</code>.
95       * @see SWTKeySupport
96       */
97      public static final KeyStroke getInstance(final int modifierKeys,
98              final int naturalKey) {
99          return new KeyStroke(modifierKeys, naturalKey);
100     }
101 
102     /**
103      * Creates an instance of <code>KeyStroke</code> by parsing a given a formal
104      * string representation.
105      * 
106      * @param string
107      *            the formal string representation to parse.
108      * @return a key stroke. Guaranteed not to be <code>null</code>.
109      * @throws ParseException
110      *             if the given formal string representation could not be parsed
111      *             to a valid key stroke.
112      */
113     public static final KeyStroke getInstance(final String   string)
114             throws ParseException {
115         if (string == null) {
116             throw new NullPointerException  ("Cannot parse a null string"); //$NON-NLS-1$
117         }
118 
119         final IKeyLookup lookup = KeyLookupFactory.getDefault();
120         int modifierKeys = NO_KEY;
121         int naturalKey = NO_KEY;
122         final StringTokenizer   stringTokenizer = new StringTokenizer  (string,
123                 KEY_DELIMITERS, true);
124         int i = 0;
125 
126         while (stringTokenizer.hasMoreTokens()) {
127             String   token = stringTokenizer.nextToken();
128 
129             if (i % 2 == 0) {
130                 if (stringTokenizer.hasMoreTokens()) {
131                     token = token.toUpperCase();
132                     final int modifierKey = lookup.formalModifierLookup(token);
133                     if (modifierKey == NO_KEY) {
134                         throw new ParseException(
135                                 "Cannot create key stroke with duplicate or non-existent modifier key: " //$NON-NLS-1$
136                                         + token);
137                     }
138 
139                     modifierKeys |= modifierKey;
140 
141                 } else if (token.length() == 1) {
142                     naturalKey = token.charAt(0);
143 
144                 } else {
145                     token = token.toUpperCase();
146                     naturalKey = lookup.formalKeyLookup(token);
147                 }
148             }
149 
150             i++;
151         }
152 
153         return new KeyStroke(modifierKeys, naturalKey);
154     }
155 
156     /**
157      * An integer representation of the modifier keys; <code>NO_KEY</code>
158      * means that there is no modifier key.
159      */
160     private final int modifierKeys;
161 
162     /**
163      * The natural key for this key stroke. This value is <code>NO_KEY</code>
164      * if the key stroke is incomplete (i.e., has no natural key).
165      */
166     private final int naturalKey;
167 
168     /**
169      * Constructs an instance of <code>KeyStroke</code> given a set of
170      * modifier keys and a natural key.
171      * 
172      * @param modifierKeys
173      *            the modifier keys. The format of this integer is defined by
174      *            whichever widget toolkit you are using; <code>NO_KEY</code>
175      *            always means no modifier keys.
176      * @param naturalKey
177      *            the natural key. The format of this integer is defined by
178      *            whichever widget toolkit you are using; <code>NO_KEY</code>
179      *            always means no natural key.
180      * @see SWTKeySupport
181      */
182     private KeyStroke(final int modifierKeys, final int naturalKey) {
183         this.modifierKeys = modifierKeys;
184         this.naturalKey = naturalKey;
185     }
186 
187     /*
188      * (non-Javadoc)
189      * 
190      * @see java.lang.Comparable#compareTo(java.lang.Object)
191      */
192     public final int compareTo(final Object   object) {
193         final KeyStroke keyStroke = (KeyStroke) object;
194         int compareTo = Util.compare(modifierKeys, keyStroke.modifierKeys);
195 
196         if (compareTo == 0) {
197             compareTo = Util.compare(naturalKey, keyStroke.naturalKey);
198         }
199 
200         return compareTo;
201     }
202 
203     /*
204      * (non-Javadoc)
205      * 
206      * @see java.lang.Object#equals(java.lang.Object)
207      */
208     public final boolean equals(final Object   object) {
209         if (!(object instanceof KeyStroke)) {
210             return false;
211         }
212 
213         final KeyStroke keyStroke = (KeyStroke) object;
214         if (modifierKeys != keyStroke.modifierKeys) {
215             return false;
216         }
217 
218         return (naturalKey == keyStroke.naturalKey);
219     }
220 
221     /**
222      * Formats this key stroke into the current default look.
223      * 
224      * @return A string representation for this key stroke using the default
225      *         look; never <code>null</code>.
226      */
227     public final String   format() {
228         return KeyFormatterFactory.getDefault().format(this);
229     }
230 
231     /**
232      * Returns the modifier keys for this key stroke.
233      * 
234      * @return the bit mask of modifier keys; <code>NO_KEY</code> means that
235      *         there is no modifier key.
236      */
237     public final int getModifierKeys() {
238         return modifierKeys;
239     }
240 
241     /**
242      * Returns the natural key for this key stroke.
243      * 
244      * @return The natural key for this key stroke. This value is
245      *         <code>NO_KEY</code> if the key stroke is incomplete (i.e., has
246      *         no natural key).
247      */
248     public final int getNaturalKey() {
249         return naturalKey;
250     }
251 
252     /*
253      * (non-Javadoc)
254      * 
255      * @see java.lang.Object#hashCode()
256      */
257     public final int hashCode() {
258         return modifierKeys << 4 + naturalKey;
259     }
260 
261     /**
262      * Returns whether or not this key stroke is complete. Key strokes are
263      * complete iff they have a natural key which is not <code>NO_KEY</code>.
264      * 
265      * @return <code>true</code>, iff the key stroke is complete.
266      */
267     public final boolean isComplete() {
268         return (naturalKey != NO_KEY);
269     }
270 
271     /**
272      * Returns the formal string representation for this key stroke.
273      * 
274      * @return The formal string representation for this key stroke. Guaranteed
275      *         not to be <code>null</code>.
276      * @see java.lang.Object#toString()
277      */
278     public final String   toString() {
279         return KeyFormatterFactory.getFormalKeyFormatter().format(this);
280     }
281 }
282
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