1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.inputmethod.keyboard.internal;
18 
19 import com.android.inputmethod.keyboard.Key;
20 
21 import java.util.HashMap;
22 
23 import javax.annotation.Nonnull;
24 
25 public abstract class UniqueKeysCache {
setEnabled(boolean enabled)26     public abstract void setEnabled(boolean enabled);
clear()27     public abstract void clear();
getUniqueKey(@onnull Key key)28     public abstract @Nonnull Key getUniqueKey(@Nonnull Key key);
29 
30     @Nonnull
31     public static final UniqueKeysCache NO_CACHE = new UniqueKeysCache() {
32         @Override
33         public void setEnabled(boolean enabled) {}
34 
35         @Override
36         public void clear() {}
37 
38         @Override
39         public Key getUniqueKey(Key key) { return key; }
40     };
41 
42     @Nonnull
newInstance()43     public static UniqueKeysCache newInstance() {
44         return new UniqueKeysCacheImpl();
45     }
46 
47     private static final class UniqueKeysCacheImpl extends UniqueKeysCache {
48         private final HashMap<Key, Key> mCache;
49 
50         private boolean mEnabled;
51 
UniqueKeysCacheImpl()52         UniqueKeysCacheImpl() {
53             mCache = new HashMap<>();
54         }
55 
56         @Override
setEnabled(final boolean enabled)57         public void setEnabled(final boolean enabled) {
58             mEnabled = enabled;
59         }
60 
61         @Override
clear()62         public void clear() {
63             mCache.clear();
64         }
65 
66         @Override
getUniqueKey(final Key key)67         public Key getUniqueKey(final Key key) {
68             if (!mEnabled) {
69                 return key;
70             }
71             final Key existingKey = mCache.get(key);
72             if (existingKey != null) {
73                 // Reuse the existing object that equals to "key" without adding "key" to
74                 // the cache.
75                 return existingKey;
76             }
77             mCache.put(key, key);
78             return key;
79         }
80     }
81 }
82