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
17package com.android.inputmethod.keyboard.internal;
18
19import com.android.inputmethod.keyboard.Key;
20
21import java.util.HashMap;
22
23import javax.annotation.Nonnull;
24
25public abstract class UniqueKeysCache {
26    public abstract void setEnabled(boolean enabled);
27    public abstract void clear();
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
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
52        UniqueKeysCacheImpl() {
53            mCache = new HashMap<>();
54        }
55
56        @Override
57        public void setEnabled(final boolean enabled) {
58            mEnabled = enabled;
59        }
60
61        @Override
62        public void clear() {
63            mCache.clear();
64        }
65
66        @Override
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