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 32namespace API { 33 34template<typename ClientInterface> struct ClientTraits; 35 36template<typename ClientInterface> class Client { 37 typedef typename ClientTraits<ClientInterface>::Versions ClientVersions; 38 static const int latestClientVersion = std::tuple_size<ClientVersions>::value - 1; 39 typedef typename std::tuple_element<latestClientVersion, ClientVersions>::type LatestClientInterface; 40 41 // Helper class that can return an std::array of element sizes in a tuple. 42 template<typename> struct InterfaceSizes; 43 template<typename... Interfaces> struct InterfaceSizes<std::tuple<Interfaces...>> { 44 static std::array<size_t, sizeof...(Interfaces)> sizes() 45 { 46 return { { sizeof(Interfaces)... } }; 47 } 48 }; 49 50public: 51 Client() 52 { 53#if !ASSERT_DISABLED 54 auto interfaceSizes = InterfaceSizes<ClientVersions>::sizes(); 55 ASSERT(std::is_sorted(interfaceSizes.begin(), interfaceSizes.end())); 56#endif 57 58 initialize(nullptr); 59 } 60 61 void initialize(const ClientInterface* client) 62 { 63 if (client && client->version == latestClientVersion) { 64 m_client = *reinterpret_cast<const LatestClientInterface*>(client); 65 return; 66 } 67 68 memset(&m_client, 0, sizeof(m_client)); 69 70 if (client && client->version < latestClientVersion) { 71 auto interfaceSizes = InterfaceSizes<ClientVersions>::sizes(); 72 73 memcpy(&m_client, client, interfaceSizes[client->version]); 74 } 75 } 76 77 const LatestClientInterface& client() const { return m_client; } 78 79protected: 80 LatestClientInterface m_client; 81}; 82 83} // namespace API 84 85#endif // APIClient_h 86