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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_UTIL_FLAGS_H_
#define V8_UTIL_FLAGS_H_
// Origin:
// https://github.com/v8/v8/blob/1bafcc6b999b23ea1d394f5d267a08183e3c4e19/src/base/flags.h#L15-L90
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:
using flag_type = T;
using mask_type = S;
constexpr Flags() : mask_(0) {}
constexpr Flags(flag_type flag) : mask_(static_cast<S>(flag)) {}
constexpr explicit Flags(mask_type mask) : mask_(static_cast<S>(mask)) {}
constexpr bool operator==(flag_type flag) const {
return mask_ == static_cast<S>(flag);
}
constexpr 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;
}
constexpr Flags operator&(const Flags& flags) const {
return Flags(mask_ & flags.mask_);
}
constexpr Flags operator|(const Flags& flags) const {
return Flags(mask_ | flags.mask_);
}
constexpr Flags operator^(const Flags& flags) const {
return Flags(mask_ ^ flags.mask_);
}
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)); }
constexpr Flags operator&(flag_type flag) const {
return operator&(Flags(flag));
}
constexpr Flags operator|(flag_type flag) const {
return operator|(Flags(flag));
}
constexpr Flags operator^(flag_type flag) const {
return operator^(Flags(flag));
}
constexpr Flags operator~() const { return Flags(~mask_); }
constexpr operator mask_type() const { return mask_; }
constexpr bool operator!() const { return !mask_; }
Flags without(flag_type flag) { return *this & (~Flags(flag)); }
friend size_t hash_value(const Flags& flags) { return flags.mask_; }
private:
mask_type mask_;
};
} // namespace base
} // namespace v8
#endif // V8_UTIL_FLAG_H_
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