1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Template-based metaprogramming and type-testing facilities. */
#ifndef mozilla_TypeTraits_h
#define mozilla_TypeTraits_h
#include "mozilla/Types.h"
/*
* These traits are approximate copies of the traits and semantics from C++11's
* <type_traits> header. Don't add traits not in that header! When all
* platforms provide that header, we can convert all users and remove this one.
*/
#include <wchar.h>
namespace mozilla {
/* Forward declarations. */
template<typename> struct RemoveCV;
template<typename> struct AddRvalueReference;
/* 20.2.4 Function template declval [declval] */
/**
* DeclVal simplifies the definition of expressions which occur as unevaluated
* operands. It converts T to a reference type, making it possible to use in
* decltype expressions even if T does not have a default constructor, e.g.:
* decltype(DeclVal<TWithNoDefaultConstructor>().foo())
*/
template<typename T>
typename AddRvalueReference<T>::Type DeclVal();
/* 20.9.3 Helper classes [meta.help] */
/**
* Helper class used as a base for various type traits, exposed publicly
* because <type_traits> exposes it as well.
*/
template<typename T, T Value>
struct IntegralConstant
{
static const T value = Value;
typedef T ValueType;
typedef IntegralConstant<T, Value> Type;
};
/** Convenient aliases. */
typedef IntegralConstant<bool, true> TrueType;
typedef IntegralConstant<bool, false> FalseType;
/* 20.9.4 Unary type traits [meta.unary] */
/* 20.9.4.1 Primary type categories [meta.unary.cat] */
namespace detail {
template<typename T>
struct IsVoidHelper : FalseType {};
template<>
struct IsVoidHelper<void> : TrueType {};
} // namespace detail
/**
* IsVoid determines whether a type is void.
*
* mozilla::IsVoid<int>::value is false;
* mozilla::IsVoid<void>::value is true;
* mozilla::IsVoid<void*>::value is false;
* mozilla::IsVoid<volatile void>::value is true.
*/
template<typename T>
struct IsVoid : detail::IsVoidHelper<typename RemoveCV<T>::Type> {};
namespace detail {
template <typename T>
struct IsIntegralHelper : FalseType {};
template<> struct IsIntegralHelper<char> : TrueType {};
template<> struct IsIntegralHelper<signed char> : TrueType {};
template<> struct IsIntegralHelper<unsigned char> : TrueType {};
template<> struct IsIntegralHelper<short> : TrueType {};
template<> struct IsIntegralHelper<unsigned short> : TrueType {};
template<> struct IsIntegralHelper<int> : TrueType {};
template<> struct IsIntegralHelper<unsigned int> : TrueType {};
template<> struct IsIntegralHelper<long> : TrueType {};
template<> struct IsIntegralHelper<unsigned long> : TrueType {};
template<> struct IsIntegralHelper<long long> : TrueType {};
template<> struct IsIntegralHelper<unsigned long long> : TrueType {};
template<> struct IsIntegralHelper<bool> : TrueType {};
template<> struct IsIntegralHelper<wchar_t> : TrueType {};
#ifdef MOZ_CHAR16_IS_NOT_WCHAR
template<> struct IsIntegralHelper<char16_t> : TrueType {};
#endif
} /* namespace detail */
/**
* IsIntegral determines whether a type is an integral type.
*
* mozilla::IsIntegral<int>::value is true;
* mozilla::IsIntegral<unsigned short>::value is true;
* mozilla::IsIntegral<const long>::value is true;
* mozilla::IsIntegral<int*>::value is false;
* mozilla::IsIntegral<double>::value is false;
*
* Note that the behavior of IsIntegral on char16_t and char32_t is
* unspecified.
*/
template<typename T>
struct IsIntegral : detail::IsIntegralHelper<typename RemoveCV<T>::Type>
{};
template<typename T, typename U>
struct IsSame;
namespace detail {
template<typename T>
struct IsFloatingPointHelper
: IntegralConstant<bool,
IsSame<T, float>::value ||
IsSame<T, double>::value ||
IsSame<T, long double>::value>
{};
} // namespace detail
/**
* IsFloatingPoint determines whether a type is a floating point type (float,
* double, long double).
*
* mozilla::IsFloatingPoint<int>::value is false;
* mozilla::IsFloatingPoint<const float>::value is true;
* mozilla::IsFloatingPoint<long double>::value is true;
* mozilla::IsFloatingPoint<double*>::value is false.
*/
template<typename T>
struct IsFloatingPoint
: detail::IsFloatingPointHelper<typename RemoveCV<T>::Type>
{};
namespace detail {
template<typename T>
struct IsArrayHelper : FalseType {};
template<typename T, decltype(sizeof(1)) N>
struct IsArrayHelper<T[N]> : TrueType {};
template<typename T>
struct IsArrayHelper<T[]> : TrueType {};
} // namespace detail
/**
* IsArray determines whether a type is an array type, of known or unknown
* length.
*
* mozilla::IsArray<int>::value is false;
* mozilla::IsArray<int[]>::value is true;
* mozilla::IsArray<int[5]>::value is true.
*/
template<typename T>
struct IsArray : detail::IsArrayHelper<typename RemoveCV<T>::Type>
{};
namespace detail {
template<typename T>
struct IsFunPtr;
template<typename>
struct IsFunPtr
: public FalseType
{};
template<typename Result, typename... ArgTypes>
struct IsFunPtr<Result(*)(ArgTypes...)>
: public TrueType
{};
}; // namespace detail
/**
* IsFunction determines whether a type is a function type. Function pointers
* don't qualify here--only the type of an actual function symbol. We do not
* correctly handle varags function types because of a bug in MSVC.
*
* Given the function:
* void f(int) {}
*
* mozilla::IsFunction<void(int)> is true;
* mozilla::IsFunction<void(*)(int)> is false;
* mozilla::IsFunction<decltype(f)> is true.
*/
template<typename T>
struct IsFunction
: public detail::IsFunPtr<typename RemoveCV<T>::Type *>
{};
namespace detail {
template<typename T>
struct IsPointerHelper : FalseType {};
template<typename T>
struct IsPointerHelper<T*> : TrueType {};
} // namespace detail
/**
* IsPointer determines whether a type is a possibly-CV-qualified pointer type
* (but not a pointer-to-member type).
*
* mozilla::IsPointer<struct S*>::value is true;
* mozilla::IsPointer<int*>::value is true;
* mozilla::IsPointer<int**>::value is true;
* mozilla::IsPointer<const int*>::value is true;
* mozilla::IsPointer<int* const>::value is true;
* mozilla::IsPointer<int* volatile>::value is true;
* mozilla::IsPointer<void (*)(void)>::value is true;
* mozilla::IsPointer<int>::value is false;
* mozilla::IsPointer<struct S>::value is false.
* mozilla::IsPointer<int(struct S::*)>::value is false
*/
template<typename T>
struct IsPointer : detail::IsPointerHelper<typename RemoveCV<T>::Type>
{};
/**
* IsLvalueReference determines whether a type is an lvalue reference.
*
* mozilla::IsLvalueReference<struct S*>::value is false;
* mozilla::IsLvalueReference<int**>::value is false;
* mozilla::IsLvalueReference<void (*)(void)>::value is false;
* mozilla::IsLvalueReference<int>::value is false;
* mozilla::IsLvalueReference<struct S>::value is false;
* mozilla::IsLvalueReference<struct S*&>::value is true;
* mozilla::IsLvalueReference<struct S&&>::value is false.
*/
template<typename T>
struct IsLvalueReference : FalseType {};
template<typename T>
struct IsLvalueReference<T&> : TrueType {};
/**
* IsRvalueReference determines whether a type is an rvalue reference.
*
* mozilla::IsRvalueReference<struct S*>::value is false;
* mozilla::IsRvalueReference<int**>::value is false;
* mozilla::IsRvalueReference<void (*)(void)>::value is false;
* mozilla::IsRvalueReference<int>::value is false;
* mozilla::IsRvalueReference<struct S>::value is false;
* mozilla::IsRvalueReference<struct S*&>::value is false;
* mozilla::IsRvalueReference<struct S&&>::value is true.
*/
template<typename T>
struct IsRvalueReference : FalseType {};
template<typename T>
struct IsRvalueReference<T&&> : TrueType {};
namespace detail {
// __is_enum is a supported extension across all of our supported compilers.
template<typename T>
struct IsEnumHelper
: IntegralConstant<bool, __is_enum(T)>
{};
} // namespace detail
/**
* IsEnum determines whether a type is an enum type.
*
* mozilla::IsEnum<enum S>::value is true;
* mozilla::IsEnum<enum S*>::value is false;
* mozilla::IsEnum<int>::value is false;
*/
template<typename T>
struct IsEnum
: detail::IsEnumHelper<typename RemoveCV<T>::Type>
{};
namespace detail {
// __is_class is a supported extension across all of our supported compilers:
// http://llvm.org/releases/3.0/docs/ClangReleaseNotes.html
// http://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Type-Traits.html#Type-Traits
// http://msdn.microsoft.com/en-us/library/ms177194%28v=vs.100%29.aspx
template<typename T>
struct IsClassHelper
: IntegralConstant<bool, __is_class(T)>
{};
} // namespace detail
/**
* IsClass determines whether a type is a class type (but not a union).
*
* struct S {};
* union U {};
* mozilla::IsClass<int>::value is false;
* mozilla::IsClass<const S>::value is true;
* mozilla::IsClass<U>::value is false;
*/
template<typename T>
struct IsClass
: detail::IsClassHelper<typename RemoveCV<T>::Type>
{};
/* 20.9.4.2 Composite type traits [meta.unary.comp] */
/**
* IsReference determines whether a type is an lvalue or rvalue reference.
*
* mozilla::IsReference<struct S*>::value is false;
* mozilla::IsReference<int**>::value is false;
* mozilla::IsReference<int&>::value is true;
* mozilla::IsReference<void (*)(void)>::value is false;
* mozilla::IsReference<const int&>::value is true;
* mozilla::IsReference<int>::value is false;
* mozilla::IsReference<struct S>::value is false;
* mozilla::IsReference<struct S&>::value is true;
* mozilla::IsReference<struct S*&>::value is true;
* mozilla::IsReference<struct S&&>::value is true.
*/
template<typename T>
struct IsReference
: IntegralConstant<bool,
IsLvalueReference<T>::value || IsRvalueReference<T>::value>
{};
/**
* IsArithmetic determines whether a type is arithmetic. A type is arithmetic
* iff it is an integral type or a floating point type.
*
* mozilla::IsArithmetic<int>::value is true;
* mozilla::IsArithmetic<double>::value is true;
* mozilla::IsArithmetic<long double*>::value is false.
*/
template<typename T>
struct IsArithmetic
: IntegralConstant<bool, IsIntegral<T>::value || IsFloatingPoint<T>::value>
{};
/* 20.9.4.3 Type properties [meta.unary.prop] */
/**
* IsConst determines whether a type is const or not.
*
* mozilla::IsConst<int>::value is false;
* mozilla::IsConst<void* const>::value is true;
* mozilla::IsConst<const char*>::value is false.
*/
template<typename T>
struct IsConst : FalseType {};
template<typename T>
struct IsConst<const T> : TrueType {};
/**
* IsVolatile determines whether a type is volatile or not.
*
* mozilla::IsVolatile<int>::value is false;
* mozilla::IsVolatile<void* volatile>::value is true;
* mozilla::IsVolatile<volatile char*>::value is false.
*/
template<typename T>
struct IsVolatile : FalseType {};
template<typename T>
struct IsVolatile<volatile T> : TrueType {};
/**
* Traits class for identifying POD types. Until C++11 there's no automatic
* way to detect PODs, so for the moment this is done manually. Users may
* define specializations of this class that inherit from mozilla::TrueType and
* mozilla::FalseType (or equivalently mozilla::IntegralConstant<bool, true or
* false>, or conveniently from mozilla::IsPod for composite types) as needed to
* ensure correct IsPod behavior.
*/
template<typename T>
struct IsPod : public FalseType {};
template<> struct IsPod<char> : TrueType {};
template<> struct IsPod<signed char> : TrueType {};
template<> struct IsPod<unsigned char> : TrueType {};
template<> struct IsPod<short> : TrueType {};
template<> struct IsPod<unsigned short> : TrueType {};
template<> struct IsPod<int> : TrueType {};
template<> struct IsPod<unsigned int> : TrueType {};
template<> struct IsPod<long> : TrueType {};
template<> struct IsPod<unsigned long> : TrueType {};
template<> struct IsPod<long long> : TrueType {};
template<> struct IsPod<unsigned long long> : TrueType {};
template<> struct IsPod<bool> : TrueType {};
template<> struct IsPod<float> : TrueType {};
template<> struct IsPod<double> : TrueType {};
template<> struct IsPod<wchar_t> : TrueType {};
#ifdef MOZ_CHAR16_IS_NOT_WCHAR
template<> struct IsPod<char16_t> : TrueType {};
#endif
template<typename T> struct IsPod<T*> : TrueType {};
namespace detail {
// __is_empty is a supported extension across all of our supported compilers:
// http://llvm.org/releases/3.0/docs/ClangReleaseNotes.html
// http://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Type-Traits.html#Type-Traits
// http://msdn.microsoft.com/en-us/library/ms177194%28v=vs.100%29.aspx
template<typename T>
struct IsEmptyHelper
: IntegralConstant<bool, IsClass<T>::value && __is_empty(T)>
{};
} // namespace detail
/**
* IsEmpty determines whether a type is a class (but not a union) that is empty.
*
* A class is empty iff it and all its base classes have no non-static data
* members (except bit-fields of length 0) and no virtual member functions, and
* no base class is empty or a virtual base class.
*
* Intuitively, empty classes don't have any data that has to be stored in
* instances of those classes. (The size of the class must still be non-zero,
* because distinct array elements of any type must have different addresses.
* However, if the Empty Base Optimization is implemented by the compiler [most
* compilers implement it, and in certain cases C++11 requires it], the size of
* a class inheriting from an empty |Base| class need not be inflated by
* |sizeof(Base)|.) And intuitively, non-empty classes have data members and/or
* vtable pointers that must be stored in each instance for proper behavior.
*
* static_assert(!mozilla::IsEmpty<int>::value, "not a class => not empty");
* union U1 { int x; };
* static_assert(!mozilla::IsEmpty<U1>::value, "not a class => not empty");
* struct E1 {};
* struct E2 { int : 0 };
* struct E3 : E1 {};
* struct E4 : E2 {};
* static_assert(mozilla::IsEmpty<E1>::value &&
* mozilla::IsEmpty<E2>::value &&
* mozilla::IsEmpty<E3>::value &&
* mozilla::IsEmpty<E4>::value,
* "all empty");
* union U2 { E1 e1; };
* static_assert(!mozilla::IsEmpty<U2>::value, "not a class => not empty");
* struct NE1 { int x; };
* struct NE2 : virtual E1 {};
* struct NE3 : E2 { virtual ~NE3() {} };
* struct NE4 { virtual void f() {} };
* static_assert(!mozilla::IsEmpty<NE1>::value &&
* !mozilla::IsEmpty<NE2>::value &&
* !mozilla::IsEmpty<NE3>::value &&
* !mozilla::IsEmpty<NE4>::value,
* "all empty");
*/
template<typename T>
struct IsEmpty : detail::IsEmptyHelper<typename RemoveCV<T>::Type>
{};
namespace detail {
template<typename T,
bool = IsFloatingPoint<T>::value,
bool = IsIntegral<T>::value,
typename NoCV = typename RemoveCV<T>::Type>
struct IsSignedHelper;
// Floating point is signed.
template<typename T, typename NoCV>
struct IsSignedHelper<T, true, false, NoCV> : TrueType {};
// Integral is conditionally signed.
template<typename T, typename NoCV>
struct IsSignedHelper<T, false, true, NoCV>
: IntegralConstant<bool, bool(NoCV(-1) < NoCV(1))>
{};
// Non-floating point, non-integral is not signed.
template<typename T, typename NoCV>
struct IsSignedHelper<T, false, false, NoCV> : FalseType {};
} // namespace detail
/**
* IsSigned determines whether a type is a signed arithmetic type. |char| is
* considered a signed type if it has the same representation as |signed char|.
*
* mozilla::IsSigned<int>::value is true;
* mozilla::IsSigned<const unsigned int>::value is false;
* mozilla::IsSigned<unsigned char>::value is false;
* mozilla::IsSigned<float>::value is true.
*/
template<typename T>
struct IsSigned : detail::IsSignedHelper<T> {};
namespace detail {
template<typename T,
bool = IsFloatingPoint<T>::value,
bool = IsIntegral<T>::value,
typename NoCV = typename RemoveCV<T>::Type>
struct IsUnsignedHelper;
// Floating point is not unsigned.
template<typename T, typename NoCV>
struct IsUnsignedHelper<T, true, false, NoCV> : FalseType {};
// Integral is conditionally unsigned.
template<typename T, typename NoCV>
struct IsUnsignedHelper<T, false, true, NoCV>
: IntegralConstant<bool,
(IsSame<NoCV, bool>::value || bool(NoCV(1) < NoCV(-1)))>
{};
// Non-floating point, non-integral is not unsigned.
template<typename T, typename NoCV>
struct IsUnsignedHelper<T, false, false, NoCV> : FalseType {};
} // namespace detail
/**
* IsUnsigned determines whether a type is an unsigned arithmetic type.
*
* mozilla::IsUnsigned<int>::value is false;
* mozilla::IsUnsigned<const unsigned int>::value is true;
* mozilla::IsUnsigned<unsigned char>::value is true;
* mozilla::IsUnsigned<float>::value is false.
*/
template<typename T>
struct IsUnsigned : detail::IsUnsignedHelper<T> {};
/* 20.9.5 Type property queries [meta.unary.prop.query] */
/* 20.9.6 Relationships between types [meta.rel] */
/**
* IsSame tests whether two types are the same type.
*
* mozilla::IsSame<int, int>::value is true;
* mozilla::IsSame<int*, int*>::value is true;
* mozilla::IsSame<int, unsigned int>::value is false;
* mozilla::IsSame<void, void>::value is true;
* mozilla::IsSame<const int, int>::value is false;
* mozilla::IsSame<struct S, struct S>::value is true.
*/
template<typename T, typename U>
struct IsSame : FalseType {};
template<typename T>
struct IsSame<T, T> : TrueType {};
namespace detail {
#if defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER)
template<class Base, class Derived>
struct BaseOfTester : IntegralConstant<bool, __is_base_of(Base, Derived)> {};
#else
// The trickery used to implement IsBaseOf here makes it possible to use it for
// the cases of private and multiple inheritance. This code was inspired by the
// sample code here:
//
// http://stackoverflow.com/questions/2910979/how-is-base-of-works
template<class Base, class Derived>
struct BaseOfHelper
{
public:
operator Base*() const;
operator Derived*();
};
template<class Base, class Derived>
struct BaseOfTester
{
private:
template<class T>
static char test(Derived*, T);
static int test(Base*, int);
public:
static const bool value =
sizeof(test(BaseOfHelper<Base, Derived>(), int())) == sizeof(char);
};
template<class Base, class Derived>
struct BaseOfTester<Base, const Derived>
{
private:
template<class T>
static char test(Derived*, T);
static int test(Base*, int);
public:
static const bool value =
sizeof(test(BaseOfHelper<Base, Derived>(), int())) == sizeof(char);
};
template<class Base, class Derived>
struct BaseOfTester<Base&, Derived&> : FalseType {};
template<class Type>
struct BaseOfTester<Type, Type> : TrueType {};
template<class Type>
struct BaseOfTester<Type, const Type> : TrueType {};
#endif
} /* namespace detail */
/*
* IsBaseOf allows to know whether a given class is derived from another.
*
* Consider the following class definitions:
*
* class A {};
* class B : public A {};
* class C {};
*
* mozilla::IsBaseOf<A, B>::value is true;
* mozilla::IsBaseOf<A, C>::value is false;
*/
template<class Base, class Derived>
struct IsBaseOf
: IntegralConstant<bool, detail::BaseOfTester<Base, Derived>::value>
{};
namespace detail {
// This belongs inside ConvertibleTester, but it's pulled out to
// work around a bug in the compiler used for hazard builds.
template <typename To>
static void ConvertibleTestHelper(To);
template<typename From, typename To>
struct ConvertibleTester
{
private:
template<typename From1, typename To1,
typename = decltype(ConvertibleTestHelper<To1>(DeclVal<From>()))>
static char test(int);
template<typename From1, typename To1>
static int test(...);
public:
static const bool value =
sizeof(test<From, To>(0)) == sizeof(char);
};
} // namespace detail
/**
* IsConvertible determines whether a value of type From will implicitly convert
* to a value of type To. For example:
*
* struct A {};
* struct B : public A {};
* struct C {};
*
* mozilla::IsConvertible<A, A>::value is true;
* mozilla::IsConvertible<A*, A*>::value is true;
* mozilla::IsConvertible<B, A>::value is true;
* mozilla::IsConvertible<B*, A*>::value is true;
* mozilla::IsConvertible<C, A>::value is false;
* mozilla::IsConvertible<A, C>::value is false;
* mozilla::IsConvertible<A*, C*>::value is false;
* mozilla::IsConvertible<C*, A*>::value is false.
*
* For obscure reasons, you can't use IsConvertible when the types being tested
* are related through private inheritance, and you'll get a compile error if
* you try. Just don't do it!
*
* Note - we need special handling for void, which ConvertibleTester doesn't
* handle. The void handling here doesn't handle const/volatile void correctly,
* which could be easily fixed if the need arises.
*/
template<typename From, typename To>
struct IsConvertible
: IntegralConstant<bool, detail::ConvertibleTester<From, To>::value>
{};
template<typename B>
struct IsConvertible<void, B>
: IntegralConstant<bool, IsVoid<B>::value>
{};
template<typename A>
struct IsConvertible<A, void>
: IntegralConstant<bool, IsVoid<A>::value>
{};
template<>
struct IsConvertible<void, void>
: TrueType
{};
/* 20.9.7 Transformations between types [meta.trans] */
/* 20.9.7.1 Const-volatile modifications [meta.trans.cv] */
/**
* RemoveConst removes top-level const qualifications on a type.
*
* mozilla::RemoveConst<int>::Type is int;
* mozilla::RemoveConst<const int>::Type is int;
* mozilla::RemoveConst<const int*>::Type is const int*;
* mozilla::RemoveConst<int* const>::Type is int*.
*/
template<typename T>
struct RemoveConst
{
typedef T Type;
};
template<typename T>
struct RemoveConst<const T>
{
typedef T Type;
};
/**
* RemoveVolatile removes top-level volatile qualifications on a type.
*
* mozilla::RemoveVolatile<int>::Type is int;
* mozilla::RemoveVolatile<volatile int>::Type is int;
* mozilla::RemoveVolatile<volatile int*>::Type is volatile int*;
* mozilla::RemoveVolatile<int* volatile>::Type is int*.
*/
template<typename T>
struct RemoveVolatile
{
typedef T Type;
};
template<typename T>
struct RemoveVolatile<volatile T>
{
typedef T Type;
};
/**
* RemoveCV removes top-level const and volatile qualifications on a type.
*
* mozilla::RemoveCV<int>::Type is int;
* mozilla::RemoveCV<const int>::Type is int;
* mozilla::RemoveCV<volatile int>::Type is int;
* mozilla::RemoveCV<int* const volatile>::Type is int*.
*/
template<typename T>
struct RemoveCV
{
typedef typename RemoveConst<typename RemoveVolatile<T>::Type>::Type Type;
};
/* 20.9.7.2 Reference modifications [meta.trans.ref] */
/**
* Converts reference types to the underlying types.
*
* mozilla::RemoveReference<T>::Type is T;
* mozilla::RemoveReference<T&>::Type is T;
* mozilla::RemoveReference<T&&>::Type is T;
*/
template<typename T>
struct RemoveReference
{
typedef T Type;
};
template<typename T>
struct RemoveReference<T&>
{
typedef T Type;
};
template<typename T>
struct RemoveReference<T&&>
{
typedef T Type;
};
template<bool Condition, typename A, typename B>
struct Conditional;
namespace detail {
enum Voidness { TIsVoid, TIsNotVoid };
template<typename T, Voidness V = IsVoid<T>::value ? TIsVoid : TIsNotVoid>
struct AddLvalueReferenceHelper;
template<typename T>
struct AddLvalueReferenceHelper<T, TIsVoid>
{
typedef void Type;
};
template<typename T>
struct AddLvalueReferenceHelper<T, TIsNotVoid>
{
typedef T& Type;
};
} // namespace detail
/**
* AddLvalueReference adds an lvalue & reference to T if one isn't already
* present. (Note: adding an lvalue reference to an rvalue && reference in
* essence replaces the && with a &&, per C+11 reference collapsing rules. For
* example, int&& would become int&.)
*
* The final computed type will only *not* be an lvalue reference if T is void.
*
* mozilla::AddLvalueReference<int>::Type is int&;
* mozilla::AddLvalueRference<volatile int&>::Type is volatile int&;
* mozilla::AddLvalueReference<void*>::Type is void*&;
* mozilla::AddLvalueReference<void>::Type is void;
* mozilla::AddLvalueReference<struct S&&>::Type is struct S&.
*/
template<typename T>
struct AddLvalueReference
: detail::AddLvalueReferenceHelper<T>
{};
namespace detail {
template<typename T, Voidness V = IsVoid<T>::value ? TIsVoid : TIsNotVoid>
struct AddRvalueReferenceHelper;
template<typename T>
struct AddRvalueReferenceHelper<T, TIsVoid>
{
typedef void Type;
};
template<typename T>
struct AddRvalueReferenceHelper<T, TIsNotVoid>
{
typedef T&& Type;
};
} // namespace detail
/**
* AddRvalueReference adds an rvalue && reference to T if one isn't already
* present. (Note: adding an rvalue reference to an lvalue & reference in
* essence keeps the &, per C+11 reference collapsing rules. For example,
* int& would remain int&.)
*
* The final computed type will only *not* be a reference if T is void.
*
* mozilla::AddRvalueReference<int>::Type is int&&;
* mozilla::AddRvalueRference<volatile int&>::Type is volatile int&;
* mozilla::AddRvalueRference<const int&&>::Type is const int&&;
* mozilla::AddRvalueReference<void*>::Type is void*&&;
* mozilla::AddRvalueReference<void>::Type is void;
* mozilla::AddRvalueReference<struct S&>::Type is struct S&.
*/
template<typename T>
struct AddRvalueReference
: detail::AddRvalueReferenceHelper<T>
{};
/* 20.9.7.3 Sign modifications [meta.trans.sign] */
template<bool B, typename T = void>
struct EnableIf;
namespace detail {
template<bool MakeConst, typename T>
struct WithC : Conditional<MakeConst, const T, T>
{};
template<bool MakeVolatile, typename T>
struct WithV : Conditional<MakeVolatile, volatile T, T>
{};
template<bool MakeConst, bool MakeVolatile, typename T>
struct WithCV : WithC<MakeConst, typename WithV<MakeVolatile, T>::Type>
{};
template<typename T>
struct CorrespondingSigned;
template<>
struct CorrespondingSigned<char> { typedef signed char Type; };
template<>
struct CorrespondingSigned<unsigned char> { typedef signed char Type; };
template<>
struct CorrespondingSigned<unsigned short> { typedef short Type; };
template<>
struct CorrespondingSigned<unsigned int> { typedef int Type; };
template<>
struct CorrespondingSigned<unsigned long> { typedef long Type; };
template<>
struct CorrespondingSigned<unsigned long long> { typedef long long Type; };
template<typename T,
typename CVRemoved = typename RemoveCV<T>::Type,
bool IsSignedIntegerType = IsSigned<CVRemoved>::value &&
!IsSame<char, CVRemoved>::value>
struct MakeSigned;
template<typename T, typename CVRemoved>
struct MakeSigned<T, CVRemoved, true>
{
typedef T Type;
};
template<typename T, typename CVRemoved>
struct MakeSigned<T, CVRemoved, false>
: WithCV<IsConst<T>::value, IsVolatile<T>::value,
typename CorrespondingSigned<CVRemoved>::Type>
{};
} // namespace detail
/**
* MakeSigned produces the corresponding signed integer type for a given
* integral type T, with the const/volatile qualifiers of T. T must be a
* possibly-const/volatile-qualified integral type that isn't bool.
*
* If T is already a signed integer type (not including char!), then T is
* produced.
*
* Otherwise, if T is an unsigned integer type, the signed variety of T, with
* T's const/volatile qualifiers, is produced.
*
* Otherwise, the integral type of the same size as T, with the lowest rank,
* with T's const/volatile qualifiers, is produced. (This basically only acts
* to produce signed char when T = char.)
*
* mozilla::MakeSigned<unsigned long>::Type is signed long;
* mozilla::MakeSigned<volatile int>::Type is volatile int;
* mozilla::MakeSigned<const unsigned short>::Type is const signed short;
* mozilla::MakeSigned<const char>::Type is const signed char;
* mozilla::MakeSigned<bool> is an error;
* mozilla::MakeSigned<void*> is an error.
*/
template<typename T>
struct MakeSigned
: EnableIf<IsIntegral<T>::value &&
!IsSame<bool, typename RemoveCV<T>::Type>::value,
typename detail::MakeSigned<T>
>::Type
{};
namespace detail {
template<typename T>
struct CorrespondingUnsigned;
template<>
struct CorrespondingUnsigned<char> { typedef unsigned char Type; };
template<>
struct CorrespondingUnsigned<signed char> { typedef unsigned char Type; };
template<>
struct CorrespondingUnsigned<short> { typedef unsigned short Type; };
template<>
struct CorrespondingUnsigned<int> { typedef unsigned int Type; };
template<>
struct CorrespondingUnsigned<long> { typedef unsigned long Type; };
template<>
struct CorrespondingUnsigned<long long> { typedef unsigned long long Type; };
template<typename T,
typename CVRemoved = typename RemoveCV<T>::Type,
bool IsUnsignedIntegerType = IsUnsigned<CVRemoved>::value &&
!IsSame<char, CVRemoved>::value>
struct MakeUnsigned;
template<typename T, typename CVRemoved>
struct MakeUnsigned<T, CVRemoved, true>
{
typedef T Type;
};
template<typename T, typename CVRemoved>
struct MakeUnsigned<T, CVRemoved, false>
: WithCV<IsConst<T>::value, IsVolatile<T>::value,
typename CorrespondingUnsigned<CVRemoved>::Type>
{};
} // namespace detail
/**
* MakeUnsigned produces the corresponding unsigned integer type for a given
* integral type T, with the const/volatile qualifiers of T. T must be a
* possibly-const/volatile-qualified integral type that isn't bool.
*
* If T is already an unsigned integer type (not including char!), then T is
* produced.
*
* Otherwise, if T is an signed integer type, the unsigned variety of T, with
* T's const/volatile qualifiers, is produced.
*
* Otherwise, the unsigned integral type of the same size as T, with the lowest
* rank, with T's const/volatile qualifiers, is produced. (This basically only
* acts to produce unsigned char when T = char.)
*
* mozilla::MakeUnsigned<signed long>::Type is unsigned long;
* mozilla::MakeUnsigned<volatile unsigned int>::Type is volatile unsigned int;
* mozilla::MakeUnsigned<const signed short>::Type is const unsigned short;
* mozilla::MakeUnsigned<const char>::Type is const unsigned char;
* mozilla::MakeUnsigned<bool> is an error;
* mozilla::MakeUnsigned<void*> is an error.
*/
template<typename T>
struct MakeUnsigned
: EnableIf<IsIntegral<T>::value &&
!IsSame<bool, typename RemoveCV<T>::Type>::value,
typename detail::MakeUnsigned<T>
>::Type
{};
/* 20.9.7.4 Array modifications [meta.trans.arr] */
/**
* RemoveExtent produces either the type of the elements of the array T, or T
* itself.
*
* mozilla::RemoveExtent<int>::Type is int;
* mozilla::RemoveExtent<const int[]>::Type is const int;
* mozilla::RemoveExtent<volatile int[5]>::Type is volatile int;
* mozilla::RemoveExtent<long[][17]>::Type is long[17].
*/
template<typename T>
struct RemoveExtent
{
typedef T Type;
};
template<typename T>
struct RemoveExtent<T[]>
{
typedef T Type;
};
template<typename T, decltype(sizeof(1)) N>
struct RemoveExtent<T[N]>
{
typedef T Type;
};
/* 20.9.7.5 Pointer modifications [meta.trans.ptr] */
namespace detail {
template<typename T, typename CVRemoved>
struct RemovePointerHelper
{
typedef T Type;
};
template<typename T, typename Pointee>
struct RemovePointerHelper<T, Pointee*>
{
typedef Pointee Type;
};
} // namespace detail
/**
* Produces the pointed-to type if a pointer is provided, else returns the input
* type. Note that this does not dereference pointer-to-member pointers.
*
* struct S { bool m; void f(); };
* mozilla::RemovePointer<int>::Type is int;
* mozilla::RemovePointer<int*>::Type is int;
* mozilla::RemovePointer<int* const>::Type is int;
* mozilla::RemovePointer<int* volatile>::Type is int;
* mozilla::RemovePointer<const long*>::Type is const long;
* mozilla::RemovePointer<void* const>::Type is void;
* mozilla::RemovePointer<void (S::*)()>::Type is void (S::*)();
* mozilla::RemovePointer<void (*)()>::Type is void();
* mozilla::RemovePointer<bool S::*>::Type is bool S::*.
*/
template<typename T>
struct RemovePointer
: detail::RemovePointerHelper<T, typename RemoveCV<T>::Type>
{};
/**
* Converts T& to T*. Otherwise returns T* given T. Note that C++17 wants
* std::add_pointer to work differently for function types. We don't implement
* that behavior here.
*
* mozilla::AddPointer<int> is int*;
* mozilla::AddPointer<int*> is int**;
* mozilla::AddPointer<int&> is int*;
* mozilla::AddPointer<int* const> is int** const.
*/
template<typename T>
struct AddPointer
{
typedef typename RemoveReference<T>::Type* Type;
};
/* 20.9.7.6 Other transformations [meta.trans.other] */
/**
* EnableIf is a struct containing a typedef of T if and only if B is true.
*
* mozilla::EnableIf<true, int>::Type is int;
* mozilla::EnableIf<false, int>::Type is a compile-time error.
*
* Use this template to implement SFINAE-style (Substitution Failure Is not An
* Error) requirements. For example, you might use it to impose a restriction
* on a template parameter:
*
* template<typename T>
* class PodVector // vector optimized to store POD (memcpy-able) types
* {
* EnableIf<IsPod<T>::value, T>::Type* vector;
* size_t length;
* ...
* };
*/
template<bool B, typename T>
struct EnableIf
{};
template<typename T>
struct EnableIf<true, T>
{
typedef T Type;
};
/**
* Conditional selects a class between two, depending on a given boolean value.
*
* mozilla::Conditional<true, A, B>::Type is A;
* mozilla::Conditional<false, A, B>::Type is B;
*/
template<bool Condition, typename A, typename B>
struct Conditional
{
typedef A Type;
};
template<class A, class B>
struct Conditional<false, A, B>
{
typedef B Type;
};
namespace detail {
template<typename U,
bool IsArray = IsArray<U>::value,
bool IsFunction = IsFunction<U>::value>
struct DecaySelector;
template<typename U>
struct DecaySelector<U, false, false>
{
typedef typename RemoveCV<U>::Type Type;
};
template<typename U>
struct DecaySelector<U, true, false>
{
typedef typename RemoveExtent<U>::Type* Type;
};
template<typename U>
struct DecaySelector<U, false, true>
{
typedef typename AddPointer<U>::Type Type;
};
}; // namespace detail
/**
* Strips const/volatile off a type and decays it from an lvalue to an
* rvalue. So function types are converted to function pointers, arrays to
* pointers, and references are removed.
*
* mozilla::Decay<int>::Type is int
* mozilla::Decay<int&>::Type is int
* mozilla::Decay<int&&>::Type is int
* mozilla::Decay<const int&>::Type is int
* mozilla::Decay<int[2]>::Type is int*
* mozilla::Decay<int(int)>::Type is int(*)(int)
*/
template<typename T>
class Decay
: public detail::DecaySelector<typename RemoveReference<T>::Type>
{
};
} /* namespace mozilla */
#endif /* mozilla_TypeTraits_h */
|