OLD | NEW |
| (Empty) |
1 /* | |
2 * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved. | |
3 * Copyright (C) 2009, 2010 Google Inc. All rights reserved. | |
4 * | |
5 * This library is free software; you can redistribute it and/or | |
6 * modify it under the terms of the GNU Library General Public | |
7 * License as published by the Free Software Foundation; either | |
8 * version 2 of the License, or (at your option) any later version. | |
9 * | |
10 * This library is distributed in the hope that it will be useful, | |
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 * Library General Public License for more details. | |
14 * | |
15 * You should have received a copy of the GNU Library General Public License | |
16 * along with this library; see the file COPYING.LIB. If not, write to | |
17 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, | |
18 * Boston, MA 02110-1301, USA. | |
19 * | |
20 */ | |
21 | |
22 #ifndef TypeTraits_h | |
23 #define TypeTraits_h | |
24 | |
25 #include <wtf/Platform.h> | |
26 | |
27 #if (defined(__GLIBCXX__) && (__GLIBCXX__ >= 20070724) && defined(__GXX_EXPERIME
NTAL_CXX0X__)) || (defined(_MSC_VER) && (_MSC_VER >= 1600)) | |
28 #include <type_traits> | |
29 #if defined(__GLIBCXX__) && (__GLIBCXX__ >= 20070724) && defined(__GXX_EXPERIMEN
TAL_CXX0X__) | |
30 #include <tr1/memory> | |
31 #endif | |
32 #endif | |
33 | |
34 namespace WTF { | |
35 | |
36 // The following are provided in this file: | |
37 // | |
38 // Conditional<Predicate, If, Then>::Type | |
39 // | |
40 // IsInteger<T>::value | |
41 // IsPod<T>::value, see the definition for a note about its limitations | |
42 // IsConvertibleToInteger<T>::value | |
43 // | |
44 // IsArray<T>::value | |
45 // | |
46 // IsSameType<T, U>::value | |
47 // | |
48 // RemovePointer<T>::Type | |
49 // RemoveReference<T>::Type | |
50 // RemoveConst<T>::Type | |
51 // RemoveVolatile<T>::Type | |
52 // RemoveConstVolatile<T>::Type | |
53 // RemoveExtent<T>::Type | |
54 // | |
55 // DecayArray<T>::Type | |
56 // | |
57 // COMPILE_ASSERT's in TypeTraits.cpp illustrate their usage and what they
do. | |
58 | |
59 template <bool Predicate, class If, class Then> struct Conditional { typede
f If Type; }; | |
60 template <class If, class Then> struct Conditional<false, If, Then> { typede
f Then Type; }; | |
61 | |
62 template<typename T> struct IsInteger { static const bool value =
false; }; | |
63 template<> struct IsInteger<bool> { static const bool value =
true; }; | |
64 template<> struct IsInteger<char> { static const bool value =
true; }; | |
65 template<> struct IsInteger<signed char> { static const bool value =
true; }; | |
66 template<> struct IsInteger<unsigned char> { static const bool value =
true; }; | |
67 template<> struct IsInteger<short> { static const bool value =
true; }; | |
68 template<> struct IsInteger<unsigned short> { static const bool value =
true; }; | |
69 template<> struct IsInteger<int> { static const bool value =
true; }; | |
70 template<> struct IsInteger<unsigned int> { static const bool value =
true; }; | |
71 template<> struct IsInteger<long> { static const bool value =
true; }; | |
72 template<> struct IsInteger<unsigned long> { static const bool value =
true; }; | |
73 template<> struct IsInteger<long long> { static const bool value =
true; }; | |
74 template<> struct IsInteger<unsigned long long> { static const bool value =
true; }; | |
75 #if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED) | |
76 template<> struct IsInteger<wchar_t> { static const bool value =
true; }; | |
77 #endif | |
78 | |
79 template<typename T> struct IsFloatingPoint { static const bool value =
false; }; | |
80 template<> struct IsFloatingPoint<float> { static const bool value =
true; }; | |
81 template<> struct IsFloatingPoint<double> { static const bool value =
true; }; | |
82 template<> struct IsFloatingPoint<long double> { static const bool value =
true; }; | |
83 | |
84 template<typename T> struct IsArithmetic { static const bool value = IsI
nteger<T>::value || IsFloatingPoint<T>::value; }; | |
85 | |
86 // IsPod is misnamed as it doesn't cover all plain old data (pod) types. | |
87 // Specifically, it doesn't allow for enums or for structs. | |
88 template <typename T> struct IsPod { static const bool value = IsA
rithmetic<T>::value; }; | |
89 template <typename P> struct IsPod<P*> { static const bool value = tru
e; }; | |
90 | |
91 template<typename T> class IsConvertibleToInteger { | |
92 // Avoid "possible loss of data" warning when using Microsoft's C++ comp
iler | |
93 // by not converting int's to doubles. | |
94 template<bool performCheck, typename U> class IsConvertibleToDouble; | |
95 template<typename U> class IsConvertibleToDouble<false, U> { | |
96 public: | |
97 static const bool value = false; | |
98 }; | |
99 | |
100 template<typename U> class IsConvertibleToDouble<true, U> { | |
101 typedef char YesType; | |
102 struct NoType { | |
103 char padding[8]; | |
104 }; | |
105 | |
106 static YesType floatCheck(long double); | |
107 static NoType floatCheck(...); | |
108 static T& t; | |
109 public: | |
110 static const bool value = sizeof(floatCheck(t)) == sizeof(YesType); | |
111 }; | |
112 | |
113 public: | |
114 static const bool value = IsInteger<T>::value || IsConvertibleToDouble<!
IsInteger<T>::value, T>::value; | |
115 }; | |
116 | |
117 | |
118 template <class T> struct IsArray { | |
119 static const bool value = false; | |
120 }; | |
121 | |
122 template <class T> struct IsArray<T[]> { | |
123 static const bool value = true; | |
124 }; | |
125 | |
126 template <class T, size_t N> struct IsArray<T[N]> { | |
127 static const bool value = true; | |
128 }; | |
129 | |
130 | |
131 template <typename T, typename U> struct IsSameType { | |
132 static const bool value = false; | |
133 }; | |
134 | |
135 template <typename T> struct IsSameType<T, T> { | |
136 static const bool value = true; | |
137 }; | |
138 | |
139 template <typename T, typename U> class IsSubclass { | |
140 typedef char YesType; | |
141 struct NoType { | |
142 char padding[8]; | |
143 }; | |
144 | |
145 static YesType subclassCheck(U*); | |
146 static NoType subclassCheck(...); | |
147 static T* t; | |
148 public: | |
149 static const bool value = sizeof(subclassCheck(t)) == sizeof(YesType); | |
150 }; | |
151 | |
152 template <typename T, template<class V> class U> class IsSubclassOfTemplate
{ | |
153 typedef char YesType; | |
154 struct NoType { | |
155 char padding[8]; | |
156 }; | |
157 | |
158 template<typename W> static YesType subclassCheck(U<W>*); | |
159 static NoType subclassCheck(...); | |
160 static T* t; | |
161 public: | |
162 static const bool value = sizeof(subclassCheck(t)) == sizeof(YesType); | |
163 }; | |
164 | |
165 template <typename T, template <class V> class OuterTemplate> struct RemoveT
emplate { | |
166 typedef T Type; | |
167 }; | |
168 | |
169 template <typename T, template <class V> class OuterTemplate> struct RemoveT
emplate<OuterTemplate<T>, OuterTemplate> { | |
170 typedef T Type; | |
171 }; | |
172 | |
173 template <typename T> struct RemoveConst { | |
174 typedef T Type; | |
175 }; | |
176 | |
177 template <typename T> struct RemoveConst<const T> { | |
178 typedef T Type; | |
179 }; | |
180 | |
181 template <typename T> struct RemoveVolatile { | |
182 typedef T Type; | |
183 }; | |
184 | |
185 template <typename T> struct RemoveVolatile<volatile T> { | |
186 typedef T Type; | |
187 }; | |
188 | |
189 template <typename T> struct RemoveConstVolatile { | |
190 typedef typename RemoveVolatile<typename RemoveConst<T>::Type>::Type Typ
e; | |
191 }; | |
192 | |
193 template <typename T> struct RemovePointer { | |
194 typedef T Type; | |
195 }; | |
196 | |
197 template <typename T> struct RemovePointer<T*> { | |
198 typedef T Type; | |
199 }; | |
200 | |
201 template <typename T> struct RemoveReference { | |
202 typedef T Type; | |
203 }; | |
204 | |
205 template <typename T> struct RemoveReference<T&> { | |
206 typedef T Type; | |
207 }; | |
208 | |
209 template <typename T> struct RemoveExtent { | |
210 typedef T Type; | |
211 }; | |
212 | |
213 template <typename T> struct RemoveExtent<T[]> { | |
214 typedef T Type; | |
215 }; | |
216 | |
217 template <typename T, size_t N> struct RemoveExtent<T[N]> { | |
218 typedef T Type; | |
219 }; | |
220 | |
221 template <class T> struct DecayArray { | |
222 typedef typename RemoveReference<T>::Type U; | |
223 public: | |
224 typedef typename Conditional< | |
225 IsArray<U>::value, | |
226 typename RemoveExtent<U>::Type*, | |
227 typename RemoveConstVolatile<U>::Type | |
228 >::Type Type; | |
229 }; | |
230 | |
231 #if COMPILER(CLANG) || GCC_VERSION_AT_LEAST(4, 6, 0) || (defined(_MSC_VER) && (_
MSC_VER >= 1400) && (_MSC_VER < 1600) && !defined(__INTEL_COMPILER)) | |
232 // VC8 (VS2005) and later has __has_trivial_constructor and __has_trivial_de
structor, | |
233 // but the implementation returns false for built-in types. We add the extra
IsPod condition to | |
234 // work around this. | |
235 template <typename T> struct HasTrivialConstructor { | |
236 static const bool value = __has_trivial_constructor(T) || IsPod<RemoveCo
nstVolatile<T> >::value; | |
237 }; | |
238 template <typename T> struct HasTrivialDestructor { | |
239 static const bool value = __has_trivial_destructor(T) || IsPod<RemoveCon
stVolatile<T> >::value; | |
240 }; | |
241 #elif (defined(__GLIBCXX__) && (__GLIBCXX__ >= 20070724) && defined(__GXX_EXPERI
MENTAL_CXX0X__)) || (defined(_MSC_VER) && (_MSC_VER >= 1600)) | |
242 // GCC's libstdc++ 20070724 and later supports C++ TR1 type_traits in the st
d namespace. | |
243 // VC10 (VS2010) and later support C++ TR1 type_traits in the std::tr1 names
pace. | |
244 template<typename T> struct HasTrivialConstructor : public std::tr1::has_tri
vial_constructor<T> { }; | |
245 template<typename T> struct HasTrivialDestructor : public std::tr1::has_triv
ial_destructor<T> { }; | |
246 #else | |
247 // For compilers that don't support detection of trivial constructors and de
structors in classes, | |
248 // we use a template that returns true for any POD type that IsPod can detec
t (see IsPod caveats above), | |
249 // but false for all other types (which includes all classes). This will giv
e false negatives, which can hurt | |
250 // performance, but avoids false positives, which would result in incorrect
behavior. | |
251 template <typename T> struct HasTrivialConstructor { | |
252 static const bool value = IsPod<RemoveConstVolatile<T> >::value; | |
253 }; | |
254 template <typename T> struct HasTrivialDestructor { | |
255 static const bool value = IsPod<RemoveConstVolatile<T> >::value; | |
256 }; | |
257 #endif | |
258 | |
259 } // namespace WTF | |
260 | |
261 #endif // TypeTraits_h | |
OLD | NEW |