TinyHashMap.h revision 527a3aace1dd72432c2e0472a570e030ad04bf16 
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
22namespace android {
23namespace uirenderer {
24
25/**
26 * A very simple hash map that doesn't allow duplicate keys, overwriting the older entry.
27 *
28 * Currently, expects simple keys that are handled by hash_t()
29 */
30template <typename TKey, typename TValue>
31class TinyHashMap {
32public:
33    typedef key_value_pair_t<TKey, TValue> TEntry;
34
35    /**
36     * Puts an entry in the hash, removing any existing entry with the same key
37     */
38    void put(TKey key, TValue value) {
39        hash_t hash = hash_t(key);
40
41        ssize_t index = mTable.find(-1, hash, key);
42        if (index != -1) {
43            mTable.removeAt(index);
44        }
45
46        TEntry initEntry(key, value);
47        mTable.add(hash, initEntry);
48    }
49
50    /**
51     * Return true if key is in the map, in which case stores the value in the output ref
52     */
53    bool get(TKey key, TValue& outValue) {
54        hash_t hash = hash_t(key);
55        ssize_t index = mTable.find(-1, hash, key);
56        if (index == -1) {
57            return false;
58        }
59        outValue = mTable.entryAt(index).value;
60        return true;
61    }
62
63    void clear() { mTable.clear(); }
64
65private:
66    BasicHashtable<TKey, TEntry> mTable;
67};
68
69}; // namespace uirenderer
70}; // namespace android
71
72#endif // ANDROID_HWUI_TINYHASHMAP_H
73