1/*
2 * Copyright (C) 2010 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef APIClient_h
27#define APIClient_h
28
29#include <algorithm>
30#include <array>
31#include <tuple>
32
33namespace API {
34
35template<typename ClientInterface> struct ClientTraits;
36
37template<typename ClientInterface> class Client {
38 typedef typename ClientTraits<ClientInterface>::Versions ClientVersions;
39 static const int latestClientVersion = std::tuple_size<ClientVersions>::value - 1;
40 typedef typename std::tuple_element<latestClientVersion, ClientVersions>::type LatestClientInterface;
41
42 // Helper class that can return an std::array of element sizes in a tuple.
43 template<typename> struct InterfaceSizes;
44 template<typename... Interfaces> struct InterfaceSizes<std::tuple<Interfaces...>> {
45 static std::array<size_t, sizeof...(Interfaces)> sizes()
46 {
47 return { { sizeof(Interfaces)... } };
48 }
49 };
50
51public:
52 Client()
53 {
54#if !ASSERT_DISABLED
55 auto interfaceSizes = InterfaceSizes<ClientVersions>::sizes();
56 ASSERT(std::is_sorted(interfaceSizes.begin(), interfaceSizes.end()));
57#endif
58
59 initialize(nullptr);
60 }
61
62 void initialize(const ClientInterface* client)
63 {
64 if (client && client->version == latestClientVersion) {
65 m_client = *reinterpret_cast<const LatestClientInterface*>(client);
66 return;
67 }
68
69 memset(&m_client, 0, sizeof(m_client));
70
71 if (client && client->version < latestClientVersion) {
72 auto interfaceSizes = InterfaceSizes<ClientVersions>::sizes();
73
74 memcpy(&m_client, client, interfaceSizes[client->version]);
75 }
76 }
77
78 const LatestClientInterface& client() const { return m_client; }
79
80protected:
81 LatestClientInterface m_client;
82};
83
84} // namespace API
85
86#endif // APIClient_h
87