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// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_BASE_FLAGS_H_
#define V8_BASE_FLAGS_H_
#include <cstddef>
#include "src/base/compiler-specific.h"
namespace v8 {
namespace base {
// The Flags class provides a type-safe way of storing OR-combinations of enum
// values. The Flags<T, S> class is a template class, where T is an enum type,
// and S is the underlying storage type (usually int).
//
// The traditional C++ approach for storing OR-combinations of enum values is to
// use an int or unsigned int variable. The inconvenience with this approach is
// that there's no type checking at all; any enum value can be OR'd with any
// other enum value and passed on to a function that takes an int or unsigned
// int.
template <typename T, typename S = int>
class Flags final {
public:
typedef T flag_type;
typedef S mask_type;
Flags() : mask_(0) {}
Flags(flag_type flag) // NOLINT(runtime/explicit)
: mask_(static_cast<S>(flag)) {}
explicit Flags(mask_type mask) : mask_(static_cast<S>(mask)) {}
bool operator==(flag_type flag) const {
return mask_ == static_cast<S>(flag);
}
bool operator!=(flag_type flag) const {
return mask_ != static_cast<S>(flag);
}
Flags& operator&=(const Flags& flags) {
mask_ &= flags.mask_;
return *this;
}
Flags& operator|=(const Flags& flags) {
mask_ |= flags.mask_;
return *this;
}
Flags& operator^=(const Flags& flags) {
mask_ ^= flags.mask_;
return *this;
}
Flags operator&(const Flags& flags) const { return Flags(*this) &= flags; }
Flags operator|(const Flags& flags) const { return Flags(*this) |= flags; }
Flags operator^(const Flags& flags) const { return Flags(*this) ^= flags; }
Flags& operator&=(flag_type flag) { return operator&=(Flags(flag)); }
Flags& operator|=(flag_type flag) { return operator|=(Flags(flag)); }
Flags& operator^=(flag_type flag) { return operator^=(Flags(flag)); }
Flags operator&(flag_type flag) const { return operator&(Flags(flag)); }
Flags operator|(flag_type flag) const { return operator|(Flags(flag)); }
Flags operator^(flag_type flag) const { return operator^(Flags(flag)); }
Flags operator~() const { return Flags(~mask_); }
operator mask_type() const { return mask_; }
bool operator!() const { return !mask_; }
friend size_t hash_value(const Flags& flags) { return flags.mask_; }
private:
mask_type mask_;
};
#define DEFINE_OPERATORS_FOR_FLAGS(Type) \
inline Type operator&( \
Type::flag_type lhs, \
Type::flag_type rhs)ALLOW_UNUSED_TYPE WARN_UNUSED_RESULT; \
inline Type operator&(Type::flag_type lhs, Type::flag_type rhs) { \
return Type(lhs) & rhs; \
} \
inline Type operator&(Type::flag_type lhs, \
const Type& rhs)ALLOW_UNUSED_TYPE WARN_UNUSED_RESULT; \
inline Type operator&(Type::flag_type lhs, const Type& rhs) { \
return rhs & lhs; \
} \
inline void operator&(Type::flag_type lhs, \
Type::mask_type rhs)ALLOW_UNUSED_TYPE; \
inline void operator&(Type::flag_type lhs, Type::mask_type rhs) {} \
inline Type operator|(Type::flag_type lhs, Type::flag_type rhs) \
ALLOW_UNUSED_TYPE WARN_UNUSED_RESULT; \
inline Type operator|(Type::flag_type lhs, Type::flag_type rhs) { \
return Type(lhs) | rhs; \
} \
inline Type operator|(Type::flag_type lhs, const Type& rhs) \
ALLOW_UNUSED_TYPE WARN_UNUSED_RESULT; \
inline Type operator|(Type::flag_type lhs, const Type& rhs) { \
return rhs | lhs; \
} \
inline void operator|(Type::flag_type lhs, Type::mask_type rhs) \
ALLOW_UNUSED_TYPE; \
inline void operator|(Type::flag_type lhs, Type::mask_type rhs) {} \
inline Type operator^(Type::flag_type lhs, Type::flag_type rhs) \
ALLOW_UNUSED_TYPE WARN_UNUSED_RESULT; \
inline Type operator^(Type::flag_type lhs, Type::flag_type rhs) { \
return Type(lhs) ^ rhs; \
} inline Type \
operator^(Type::flag_type lhs, const Type& rhs) \
ALLOW_UNUSED_TYPE WARN_UNUSED_RESULT; \
inline Type operator^(Type::flag_type lhs, const Type& rhs) { \
return rhs ^ lhs; \
} inline void \
operator^(Type::flag_type lhs, Type::mask_type rhs) ALLOW_UNUSED_TYPE; \
inline void operator^(Type::flag_type lhs, Type::mask_type rhs) { \
} inline Type \
operator~(Type::flag_type val)ALLOW_UNUSED_TYPE; \
inline Type operator~(Type::flag_type val) { return ~Type(val); }
} // namespace base
} // namespace v8
#endif // V8_BASE_FLAGS_H_
|
