1 /*
2  * Copyright (C) 2013 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 #ifndef ANDROID_HWUI_TINYHASHMAP_H
18 #define ANDROID_HWUI_TINYHASHMAP_H
19 
20 #include <utils/BasicHashtable.h>
21 
22 namespace android {
23 namespace uirenderer {
24 
25 /**
26  * A very simple hash map that doesn't allow duplicate keys, overwriting the older entry.
27  */
28 template <typename TKey, typename TValue>
29 class TinyHashMap {
30 public:
31     typedef key_value_pair_t<TKey, TValue> TEntry;
32 
33     /**
34      * Puts an entry in the hash, removing any existing entry with the same key
35      */
put(TKey key,TValue value)36     void put(TKey key, TValue value) {
37         hash_t hash = android::hash_type(key);
38 
39         ssize_t index = mTable.find(-1, hash, key);
40         if (index != -1) {
41             mTable.removeAt(index);
42         }
43 
44         TEntry initEntry(key, value);
45         mTable.add(hash, initEntry);
46     }
47 
48     /**
49      * Return true if key is in the map, in which case stores the value in the output ref
50      */
get(TKey key,TValue & outValue)51     bool get(TKey key, TValue& outValue) {
52         hash_t hash = android::hash_type(key);
53         ssize_t index = mTable.find(-1, hash, key);
54         if (index == -1) {
55             return false;
56         }
57         outValue = mTable.entryAt(index).value;
58         return true;
59     }
60 
clear()61     void clear() { mTable.clear(); }
62 
63 private:
64     BasicHashtable<TKey, TEntry> mTable;
65 };
66 
67 }; // namespace uirenderer
68 }; // namespace android
69 
70 #endif // ANDROID_HWUI_TINYHASHMAP_H
71