1221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org/* 2221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. 3221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org * 4221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org * Use of this source code is governed by a BSD-style license 5221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org * that can be found in the LICENSE file in the root of the source 6221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org * tree. An additional intellectual property rights grant can be found 7221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org * in the file PATENTS. All contributing project authors may 8221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org * be found in the AUTHORS file in the root of the source tree. 9221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org */ 10221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 11221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// Borrowed from Chromium's src/base/template_util.h. 12221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 13221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TEMPLATE_UTIL_H_ 14221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TEMPLATE_UTIL_H_ 15221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 16bcf0a1019f34cac346bd8349c2206f9d06adbe4epbos@webrtc.org#include <stddef.h> // For size_t. 17221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 18221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgnamespace webrtc { 19221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 20221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// Template definitions from tr1. 21221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 22221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate<class T, T v> 23221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgstruct integral_constant { 24221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org static const T value = v; 25221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org typedef T value_type; 26221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org typedef integral_constant<T, v> type; 27221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org}; 28221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 29221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T, T v> const T integral_constant<T, v>::value; 30221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 31221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtypedef integral_constant<bool, true> true_type; 32221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtypedef integral_constant<bool, false> false_type; 33221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 34221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T> struct is_pointer : false_type {}; 35221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T> struct is_pointer<T*> : true_type {}; 36221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 37221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T, class U> struct is_same : public false_type {}; 38221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T> struct is_same<T, T> : true_type {}; 39221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 40221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate<class> struct is_array : public false_type {}; 41221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate<class T, size_t n> struct is_array<T[n]> : public true_type {}; 42221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate<class T> struct is_array<T[]> : public true_type {}; 43221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 44221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T> struct is_non_const_reference : false_type {}; 45221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T> struct is_non_const_reference<T&> : true_type {}; 46221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T> struct is_non_const_reference<const T&> : false_type {}; 47221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 48221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <class T> struct is_void : false_type {}; 49221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <> struct is_void<void> : true_type {}; 50221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 51221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgnamespace internal { 52221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 53221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// Types YesType and NoType are guaranteed such that sizeof(YesType) < 54221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// sizeof(NoType). 55221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtypedef char YesType; 56221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 57221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgstruct NoType { 58221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org YesType dummy[2]; 59221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org}; 60221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 61221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// This class is an implementation detail for is_convertible, and you 62221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// don't need to know how it works to use is_convertible. For those 63221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// who care: we declare two different functions, one whose argument is 64221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// of type To and one with a variadic argument list. We give them 65221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// return types of different size, so we can use sizeof to trick the 66221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// compiler into telling us which function it would have chosen if we 67221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// had called it with an argument of type From. See Alexandrescu's 68221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// _Modern C++ Design_ for more details on this sort of trick. 69221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 70221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgstruct ConvertHelper { 71221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org template <typename To> 72221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org static YesType Test(To); 73221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 74221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org template <typename To> 75221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org static NoType Test(...); 76221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 77221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org template <typename From> 78221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org static From& Create(); 79221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org}; 80221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 81221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// Used to determine if a type is a struct/union/class. Inspired by Boost's 82221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// is_class type_trait implementation. 83221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgstruct IsClassHelper { 84221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org template <typename C> 85221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org static YesType Test(void(C::*)(void)); 86221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 87221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org template <typename C> 88221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org static NoType Test(...); 89221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org}; 90221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 91221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org} // namespace internal 92221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 93221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// Inherits from true_type if From is convertible to To, false_type otherwise. 94221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// 95221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// Note that if the type is convertible, this will be a true_type REGARDLESS 96221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org// of whether or not the conversion would emit a warning. 97221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <typename From, typename To> 98221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgstruct is_convertible 99221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org : integral_constant<bool, 100221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org sizeof(internal::ConvertHelper::Test<To>( 101221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org internal::ConvertHelper::Create<From>())) == 102221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org sizeof(internal::YesType)> { 103221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org}; 104221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 105221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgtemplate <typename T> 106221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.orgstruct is_class 107221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org : integral_constant<bool, 108221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org sizeof(internal::IsClassHelper::Test<T>(0)) == 109221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org sizeof(internal::YesType)> { 110221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org}; 111221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 112221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org} // namespace webrtc 113221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org 114221798a7c4ad83ba7fb8b3ae39b99d44278bbe5aandrew@webrtc.org#endif // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TEMPLATE_UTIL_H_ 115