gecko-dev/mfbt/EnumSet.h
David Major 7bdbf197ee Bug 1657455 - Give EnumSet an assignment operator r=sg
Newer clangs complain that we explicitly defined a copy constructor but not a copy assignment.

Differential Revision: https://phabricator.services.mozilla.com/D86061
2020-08-06 20:40:37 +00:00

313 lines
6.7 KiB
C++

/* -*- 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/. */
/* A set abstraction for enumeration values. */
#ifndef mozilla_EnumSet_h
#define mozilla_EnumSet_h
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include <initializer_list>
#include <type_traits>
#include <stdint.h>
namespace mozilla {
/**
* EnumSet<T, U> is a set of values defined by an enumeration. It is implemented
* using a bit mask with the size of U for each value. It works both for enum
* and enum class types.
*/
template <typename T, typename Serialized = typename std::make_unsigned<
typename std::underlying_type<T>::type>::type>
class EnumSet {
public:
typedef T valueType;
constexpr EnumSet() : mBitField(0) {}
constexpr MOZ_IMPLICIT EnumSet(T aEnum) : mBitField(bitFor(aEnum)) {}
constexpr EnumSet(T aEnum1, T aEnum2)
: mBitField(bitFor(aEnum1) | bitFor(aEnum2)) {}
constexpr EnumSet(T aEnum1, T aEnum2, T aEnum3)
: mBitField(bitFor(aEnum1) | bitFor(aEnum2) | bitFor(aEnum3)) {}
constexpr EnumSet(T aEnum1, T aEnum2, T aEnum3, T aEnum4)
: mBitField(bitFor(aEnum1) | bitFor(aEnum2) | bitFor(aEnum3) |
bitFor(aEnum4)) {}
constexpr MOZ_IMPLICIT EnumSet(std::initializer_list<T> list) : mBitField(0) {
for (auto value : list) {
(*this) += value;
}
}
#ifdef DEBUG
constexpr EnumSet(const EnumSet& aEnumSet) : mBitField(aEnumSet.mBitField) {}
constexpr EnumSet& operator=(const EnumSet& aEnumSet) {
mBitField = aEnumSet.mBitField;
incVersion();
return *this;
}
#endif
/**
* Add an element
*/
constexpr void operator+=(T aEnum) {
incVersion();
mBitField |= bitFor(aEnum);
}
/**
* Add an element
*/
constexpr EnumSet operator+(T aEnum) const {
EnumSet result(*this);
result += aEnum;
return result;
}
/**
* Union
*/
void operator+=(const EnumSet& aEnumSet) {
incVersion();
mBitField |= aEnumSet.mBitField;
}
/**
* Union
*/
EnumSet operator+(const EnumSet& aEnumSet) const {
EnumSet result(*this);
result += aEnumSet;
return result;
}
/**
* Remove an element
*/
void operator-=(T aEnum) {
incVersion();
mBitField &= ~(bitFor(aEnum));
}
/**
* Remove an element
*/
EnumSet operator-(T aEnum) const {
EnumSet result(*this);
result -= aEnum;
return result;
}
/**
* Remove a set of elements
*/
void operator-=(const EnumSet& aEnumSet) {
incVersion();
mBitField &= ~(aEnumSet.mBitField);
}
/**
* Remove a set of elements
*/
EnumSet operator-(const EnumSet& aEnumSet) const {
EnumSet result(*this);
result -= aEnumSet;
return result;
}
/**
* Clear
*/
void clear() {
incVersion();
mBitField = 0;
}
/**
* Intersection
*/
void operator&=(const EnumSet& aEnumSet) {
incVersion();
mBitField &= aEnumSet.mBitField;
}
/**
* Intersection
*/
EnumSet operator&(const EnumSet& aEnumSet) const {
EnumSet result(*this);
result &= aEnumSet;
return result;
}
/**
* Equality
*/
bool operator==(const EnumSet& aEnumSet) const {
return mBitField == aEnumSet.mBitField;
}
/**
* Equality
*/
bool operator==(T aEnum) const { return mBitField == bitFor(aEnum); }
/**
* Not equal
*/
bool operator!=(const EnumSet& aEnumSet) const {
return !operator==(aEnumSet);
}
/**
* Not equal
*/
bool operator!=(T aEnum) const { return !operator==(aEnum); }
/**
* Test is an element is contained in the set.
*/
bool contains(T aEnum) const { return mBitField & bitFor(aEnum); }
/**
* Test if a set is contained in the set.
*/
bool contains(const EnumSet& aEnumSet) const {
return (mBitField & aEnumSet.mBitField) == aEnumSet.mBitField;
}
/**
* Return the number of elements in the set.
*/
uint8_t size() const {
uint8_t count = 0;
for (Serialized bitField = mBitField; bitField; bitField >>= 1) {
if (bitField & 1) {
count++;
}
}
return count;
}
bool isEmpty() const { return mBitField == 0; }
Serialized serialize() const { return mBitField; }
void deserialize(Serialized aValue) {
incVersion();
mBitField = aValue;
}
class ConstIterator {
const EnumSet* mSet;
uint32_t mPos;
#ifdef DEBUG
uint64_t mVersion;
#endif
void checkVersion() const {
// Check that the set has not been modified while being iterated.
MOZ_ASSERT_IF(mSet, mSet->mVersion == mVersion);
}
public:
ConstIterator(const EnumSet& aSet, uint32_t aPos)
: mSet(&aSet), mPos(aPos) {
#ifdef DEBUG
mVersion = mSet->mVersion;
#endif
MOZ_ASSERT(aPos <= kMaxBits);
if (aPos != kMaxBits && !mSet->contains(T(mPos))) ++*this;
}
ConstIterator(const ConstIterator& aOther)
: mSet(aOther.mSet), mPos(aOther.mPos) {
#ifdef DEBUG
mVersion = aOther.mVersion;
checkVersion();
#endif
}
ConstIterator(ConstIterator&& aOther)
: mSet(aOther.mSet), mPos(aOther.mPos) {
#ifdef DEBUG
mVersion = aOther.mVersion;
checkVersion();
#endif
aOther.mSet = nullptr;
}
~ConstIterator() { checkVersion(); }
bool operator==(const ConstIterator& other) const {
MOZ_ASSERT(mSet == other.mSet);
checkVersion();
return mPos == other.mPos;
}
bool operator!=(const ConstIterator& other) const {
return !(*this == other);
}
T operator*() const {
MOZ_ASSERT(mSet);
MOZ_ASSERT(mPos < kMaxBits);
MOZ_ASSERT(mSet->contains(T(mPos)));
checkVersion();
return T(mPos);
}
ConstIterator& operator++() {
MOZ_ASSERT(mSet);
MOZ_ASSERT(mPos < kMaxBits);
checkVersion();
do {
mPos++;
} while (mPos < kMaxBits && !mSet->contains(T(mPos)));
return *this;
}
};
ConstIterator begin() const { return ConstIterator(*this, 0); }
ConstIterator end() const { return ConstIterator(*this, kMaxBits); }
private:
constexpr static Serialized bitFor(T aEnum) {
auto bitNumber = static_cast<Serialized>(aEnum);
MOZ_DIAGNOSTIC_ASSERT(bitNumber < kMaxBits);
return static_cast<Serialized>(Serialized{1} << bitNumber);
}
constexpr void incVersion() {
#ifdef DEBUG
mVersion++;
#endif
}
static const size_t kMaxBits = sizeof(Serialized) * 8;
Serialized mBitField;
#ifdef DEBUG
uint64_t mVersion = 0;
#endif
};
} // namespace mozilla
#endif /* mozilla_EnumSet_h_*/