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/* -*- 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/. */
#ifndef util_EnumFlags_h
#define util_EnumFlags_h
#include "mozilla/Attributes.h"
#include <initializer_list>
#include <type_traits>
namespace js {
// Wrapper type for flags fields based on an enum type.
//
// EnumFlags does not (implicitly) convert to/from the underlying integer type.
// That can be supported for specific flags fields by deriving from this class
// and implementing an extra constructor and/or |operator FieldType|.
//
// Note: this type is similar to mfbt/EnumSet.h, but has the same size in debug
// and release builds so is more appropriate for core data structures where we
// don't want this size difference.
template <typename EnumType>
class EnumFlags {
protected:
// Use the enum's underlying type for the flags field. This makes JIT accesses
// more predictable and simplifies the implementation of this class.
static_assert(std::is_enum_v<EnumType>);
using FieldType = std::underlying_type_t<EnumType>;
static_assert(std::is_unsigned_v<FieldType>);
FieldType flags_ = 0;
explicit constexpr EnumFlags(FieldType rawFlags) : flags_(rawFlags) {}
public:
constexpr EnumFlags() = default;
constexpr MOZ_IMPLICIT EnumFlags(std::initializer_list<EnumType> list) {
for (EnumType flag : list) {
setFlag(flag);
}
}
constexpr bool hasFlag(EnumType flag) const {
return flags_ & static_cast<FieldType>(flag);
}
constexpr void setFlag(EnumType flag) {
flags_ |= static_cast<FieldType>(flag);
}
constexpr void clearFlag(EnumType flag) {
flags_ &= ~static_cast<FieldType>(flag);
}
constexpr void setFlag(EnumType flag, bool b) {
if (b) {
setFlag(flag);
} else {
clearFlag(flag);
}
}
constexpr bool isEmpty() const { return flags_ == 0; }
constexpr FieldType toRaw() const { return flags_; }
void setRaw(FieldType flag) { flags_ = flag; }
constexpr bool operator==(const EnumFlags& other) const {
return flags_ == other.flags_;
}
constexpr bool operator!=(const EnumFlags& other) const {
return flags_ != other.flags_;
}
};
} // namespace js
#endif // util_EnumFlags_h