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// Copyright 2019 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_ENUM_SET_H_
#define V8_BASE_ENUM_SET_H_
#include <ostream>
#include <type_traits>
#include "src/base/bits.h"
#include "src/base/logging.h"
namespace v8 {
namespace base {
// A poor man's version of STL's bitset: A bit set of enums E (without explicit
// values), fitting into an integral type T.
template <class E, class T = int>
class EnumSet {
static_assert(std::is_enum<E>::value, "EnumSet can only be used with enums");
public:
constexpr EnumSet() = default;
constexpr EnumSet(std::initializer_list<E> init) {
T bits = 0;
for (E e : init) bits |= Mask(e);
bits_ = bits;
}
constexpr bool empty() const { return bits_ == 0; }
constexpr bool contains(E element) const {
return (bits_ & Mask(element)) != 0;
}
constexpr bool contains_any(EnumSet set) const {
return (bits_ & set.bits_) != 0;
}
constexpr bool contains_only(E element) const {
return bits_ == Mask(element);
}
constexpr bool is_subset_of(EnumSet set) const {
return (bits_ & set.bits_) == bits_;
}
void Add(E element) { bits_ |= Mask(element); }
void Add(EnumSet set) { bits_ |= set.bits_; }
void Remove(E element) { bits_ &= ~Mask(element); }
void Remove(EnumSet set) { bits_ &= ~set.bits_; }
void RemoveAll() { bits_ = 0; }
void Intersect(EnumSet set) { bits_ &= set.bits_; }
constexpr T ToIntegral() const { return bits_; }
constexpr bool operator==(EnumSet set) const { return bits_ == set.bits_; }
constexpr bool operator!=(EnumSet set) const { return bits_ != set.bits_; }
constexpr EnumSet operator|(EnumSet set) const {
return EnumSet(bits_ | set.bits_);
}
constexpr EnumSet operator&(EnumSet set) const {
return EnumSet(bits_ & set.bits_);
}
constexpr EnumSet operator-(EnumSet set) const {
return EnumSet(bits_ & ~set.bits_);
}
EnumSet& operator|=(EnumSet set) { return *this = *this | set; }
EnumSet& operator&=(EnumSet set) { return *this = *this & set; }
EnumSet& operator-=(EnumSet set) { return *this = *this - set; }
constexpr EnumSet operator|(E element) const {
return EnumSet(bits_ | Mask(element));
}
constexpr EnumSet operator&(E element) const {
return EnumSet(bits_ & Mask(element));
}
constexpr EnumSet operator-(E element) const {
return EnumSet(bits_ & ~Mask(element));
}
EnumSet& operator|=(E element) { return *this = *this | element; }
EnumSet& operator&=(E element) { return *this = *this & element; }
EnumSet& operator-=(E element) { return *this = *this - element; }
static constexpr EnumSet FromIntegral(T bits) { return EnumSet{bits}; }
private:
explicit constexpr EnumSet(T bits) : bits_(bits) {}
static constexpr T Mask(E element) {
DCHECK_GT(sizeof(T) * 8, static_cast<size_t>(element));
return T{1} << static_cast<typename std::underlying_type<E>::type>(element);
}
T bits_ = 0;
};
template <typename E, typename T>
std::ostream& operator<<(std::ostream& os, EnumSet<E, T> set) {
os << "{";
bool first = true;
while (!set.empty()) {
if (!first) os << ", ";
first = false;
T bits = set.ToIntegral();
E element = static_cast<E>(bits::CountTrailingZerosNonZero(bits));
os << element;
set.Remove(element);
}
os << "}";
return os;
}
} // namespace base
} // namespace v8
#endif // V8_BASE_ENUM_SET_H_
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