147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org/* 247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org * Copyright 2011 The WebRTC Project Authors. All rights reserved. 347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org * 447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org * Use of this source code is governed by a BSD-style license 547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org * that can be found in the LICENSE file in the root of the source 647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org * tree. An additional intellectual property rights grant can be found 747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org * in the file PATENTS. All contributing project authors may 847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org * be found in the AUTHORS file in the root of the source tree. 947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org */ 1047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 1147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org#ifndef WEBRTC_BASE_TEMPLATE_UTIL_H_ 1247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org#define WEBRTC_BASE_TEMPLATE_UTIL_H_ 1347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 1447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org#include <stddef.h> // For size_t. 1547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 1647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgnamespace rtc { 1747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 1847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// template definitions from tr1 1947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 2047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate<class T, T v> 2147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgstruct integral_constant { 2247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org static const T value = v; 2347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org typedef T value_type; 2447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org typedef integral_constant<T, v> type; 2547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org}; 2647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 2747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T, T v> const T integral_constant<T, v>::value; 2847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 2947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtypedef integral_constant<bool, true> true_type; 3047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtypedef integral_constant<bool, false> false_type; 3147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 3247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T> struct is_pointer : false_type {}; 3347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T> struct is_pointer<T*> : true_type {}; 3447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 3547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T, class U> struct is_same : public false_type {}; 3647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T> struct is_same<T,T> : true_type {}; 3747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 3847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate<class> struct is_array : public false_type {}; 3947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate<class T, size_t n> struct is_array<T[n]> : public true_type {}; 4047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate<class T> struct is_array<T[]> : public true_type {}; 4147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 4247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T> struct is_non_const_reference : false_type {}; 4347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T> struct is_non_const_reference<T&> : true_type {}; 4447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T> struct is_non_const_reference<const T&> : false_type {}; 4547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 4647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <class T> struct is_void : false_type {}; 4747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <> struct is_void<void> : true_type {}; 4847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 4947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgnamespace internal { 5047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 5147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// Types YesType and NoType are guaranteed such that sizeof(YesType) < 5247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// sizeof(NoType). 5347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtypedef char YesType; 5447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 5547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgstruct NoType { 5647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org YesType dummy[2]; 5747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org}; 5847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 5947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// This class is an implementation detail for is_convertible, and you 6047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// don't need to know how it works to use is_convertible. For those 6147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// who care: we declare two different functions, one whose argument is 6247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// of type To and one with a variadic argument list. We give them 6347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// return types of different size, so we can use sizeof to trick the 6447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// compiler into telling us which function it would have chosen if we 6547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// had called it with an argument of type From. See Alexandrescu's 6647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// _Modern C++ Design_ for more details on this sort of trick. 6747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 6847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgstruct ConvertHelper { 6947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org template <typename To> 7047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org static YesType Test(To); 7147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 7247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org template <typename To> 7347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org static NoType Test(...); 7447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 7547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org template <typename From> 7647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org static From& Create(); 7747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org}; 7847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 7947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// Used to determine if a type is a struct/union/class. Inspired by Boost's 8047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// is_class type_trait implementation. 8147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgstruct IsClassHelper { 8247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org template <typename C> 8347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org static YesType Test(void(C::*)(void)); 8447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 8547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org template <typename C> 8647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org static NoType Test(...); 8747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org}; 8847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 8947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org} // namespace internal 9047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 9147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// Inherits from true_type if From is convertible to To, false_type otherwise. 9247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// 9347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// Note that if the type is convertible, this will be a true_type REGARDLESS 9447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org// of whether or not the conversion would emit a warning. 9547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <typename From, typename To> 9647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgstruct is_convertible 9747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org : integral_constant<bool, 9847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org sizeof(internal::ConvertHelper::Test<To>( 9947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org internal::ConvertHelper::Create<From>())) == 10047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org sizeof(internal::YesType)> { 10147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org}; 10247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 10347be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgtemplate <typename T> 10447be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.orgstruct is_class 10547be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org : integral_constant<bool, 10647be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org sizeof(internal::IsClassHelper::Test<T>(0)) == 10747be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org sizeof(internal::YesType)> { 10847be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org}; 10947be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 11047be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org} // namespace rtc 11147be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org 11247be73b8629244d6bb63a28198f97f040ce53d21henrike@webrtc.org#endif // WEBRTC_BASE_TEMPLATE_UTIL_H_ 113