/usr/include/llvm-4.0/llvm/ADT/BitmaskEnum.h is in llvm-4.0-dev 1:4.0.1-10.
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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 | //===-- llvm/ADT/BitmaskEnum.h ----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_BITMASKENUM_H
#define LLVM_ADT_BITMASKENUM_H
#include <cassert>
#include <type_traits>
#include <utility>
#include "llvm/Support/MathExtras.h"
/// LLVM_MARK_AS_BITMASK_ENUM lets you opt in an individual enum type so you can
/// perform bitwise operations on it without putting static_cast everywhere.
///
/// \code
/// enum MyEnum {
/// E1 = 1, E2 = 2, E3 = 4, E4 = 8,
/// LLVM_MARK_AS_BITMASK_ENUM(/* LargestValue = */ E4)
/// };
///
/// void Foo() {
/// MyEnum A = (E1 | E2) & E3 ^ ~E4; // Look, ma: No static_cast!
/// }
/// \endcode
///
/// Normally when you do a bitwise operation on an enum value, you get back an
/// instance of the underlying type (e.g. int). But using this macro, bitwise
/// ops on your enum will return you back instances of the enum. This is
/// particularly useful for enums which represent a combination of flags.
///
/// The parameter to LLVM_MARK_AS_BITMASK_ENUM should be the largest individual
/// value in your enum.
///
/// All of the enum's values must be non-negative.
#define LLVM_MARK_AS_BITMASK_ENUM(LargestValue) \
LLVM_BITMASK_LARGEST_ENUMERATOR = LargestValue
/// LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE() pulls the operator overloads used
/// by LLVM_MARK_AS_BITMASK_ENUM into the current namespace.
///
/// Suppose you have an enum foo::bar::MyEnum. Before using
/// LLVM_MARK_AS_BITMASK_ENUM on MyEnum, you must put
/// LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE() somewhere inside namespace foo or
/// namespace foo::bar. This allows the relevant operator overloads to be found
/// by ADL.
///
/// You don't need to use this macro in namespace llvm; it's done at the bottom
/// of this file.
#define LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE() \
using ::llvm::BitmaskEnumDetail::operator~; \
using ::llvm::BitmaskEnumDetail::operator|; \
using ::llvm::BitmaskEnumDetail::operator&; \
using ::llvm::BitmaskEnumDetail::operator^; \
using ::llvm::BitmaskEnumDetail::operator|=; \
using ::llvm::BitmaskEnumDetail::operator&=; \
/* Force a semicolon at the end of this macro. */ \
using ::llvm::BitmaskEnumDetail::operator^=
namespace llvm {
/// Traits class to determine whether an enum has a
/// LLVM_BITMASK_LARGEST_ENUMERATOR enumerator.
template <typename E, typename Enable = void>
struct is_bitmask_enum : std::false_type {};
template <typename E>
struct is_bitmask_enum<
E, typename std::enable_if<sizeof(E::LLVM_BITMASK_LARGEST_ENUMERATOR) >=
0>::type> : std::true_type {};
namespace BitmaskEnumDetail {
/// Get a bitmask with 1s in all places up to the high-order bit of E's largest
/// value.
template <typename E> typename std::underlying_type<E>::type Mask() {
// On overflow, NextPowerOf2 returns zero with the type uint64_t, so
// subtracting 1 gives us the mask with all bits set, like we want.
return NextPowerOf2(static_cast<typename std::underlying_type<E>::type>(
E::LLVM_BITMASK_LARGEST_ENUMERATOR)) -
1;
}
/// Check that Val is in range for E, and return Val cast to E's underlying
/// type.
template <typename E> typename std::underlying_type<E>::type Underlying(E Val) {
auto U = static_cast<typename std::underlying_type<E>::type>(Val);
assert(U >= 0 && "Negative enum values are not allowed.");
assert(U <= Mask<E>() && "Enum value too large (or largest val too small?)");
return U;
}
template <typename E,
typename = typename std::enable_if<is_bitmask_enum<E>::value>::type>
E operator~(E Val) {
return static_cast<E>(~Underlying(Val) & Mask<E>());
}
template <typename E,
typename = typename std::enable_if<is_bitmask_enum<E>::value>::type>
E operator|(E LHS, E RHS) {
return static_cast<E>(Underlying(LHS) | Underlying(RHS));
}
template <typename E,
typename = typename std::enable_if<is_bitmask_enum<E>::value>::type>
E operator&(E LHS, E RHS) {
return static_cast<E>(Underlying(LHS) & Underlying(RHS));
}
template <typename E,
typename = typename std::enable_if<is_bitmask_enum<E>::value>::type>
E operator^(E LHS, E RHS) {
return static_cast<E>(Underlying(LHS) ^ Underlying(RHS));
}
// |=, &=, and ^= return a reference to LHS, to match the behavior of the
// operators on builtin types.
template <typename E,
typename = typename std::enable_if<is_bitmask_enum<E>::value>::type>
E &operator|=(E &LHS, E RHS) {
LHS = LHS | RHS;
return LHS;
}
template <typename E,
typename = typename std::enable_if<is_bitmask_enum<E>::value>::type>
E &operator&=(E &LHS, E RHS) {
LHS = LHS & RHS;
return LHS;
}
template <typename E,
typename = typename std::enable_if<is_bitmask_enum<E>::value>::type>
E &operator^=(E &LHS, E RHS) {
LHS = LHS ^ RHS;
return LHS;
}
} // namespace BitmaskEnumDetail
// Enable bitmask enums in namespace ::llvm and all nested namespaces.
LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
} // namespace llvm
#endif
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