1/*
2 * Copyright 2009, 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 SkTRegistry_DEFINED
18#define SkTRegistry_DEFINED
19
20#include "SkTypes.h"
21
22/** Template class that registers itself (in the constructor) into a linked-list
23    and provides a function-pointer. This can be used to auto-register a set of
24    services, e.g. a set of image codecs.
25 */
26template <typename T, typename P> class SkTRegistry : SkNoncopyable {
27public:
28    typedef T (*Factory)(P);
29
30    SkTRegistry(Factory fact) {
31#ifdef ANDROID
32        // work-around for double-initialization bug
33        {
34            SkTRegistry* reg = gHead;
35            while (reg) {
36                if (reg == this) {
37                    return;
38                }
39                reg = reg->fChain;
40            }
41        }
42#endif
43        fFact = fact;
44        fChain = gHead;
45        gHead = this;
46    }
47
48    static const SkTRegistry* Head() { return gHead; }
49
50    const SkTRegistry* next() const { return fChain; }
51    Factory factory() const { return fFact; }
52
53private:
54    Factory      fFact;
55    SkTRegistry* fChain;
56
57    static SkTRegistry* gHead;
58};
59
60// The caller still needs to declare an instance of this somewhere
61template <typename T, typename P> SkTRegistry<T, P>* SkTRegistry<T, P>::gHead;
62
63#endif
64