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Diffstat (limited to 'mfbt/EnumSet.h')
| -rw-r--r-- | mfbt/EnumSet.h | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/mfbt/EnumSet.h b/mfbt/EnumSet.h new file mode 100644 index 0000000000..5282ab30c3 --- /dev/null +++ b/mfbt/EnumSet.h @@ -0,0 +1,344 @@ +/* -*- 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 <stdint.h> + +namespace mozilla { + +/** + * EnumSet<T> is a set of values defined by an enumeration. It is implemented + * using a 32 bit mask for each value so it will only work for enums with an int + * representation less than 32. It works both for enum and enum class types. + */ +template<typename T> +class EnumSet +{ +public: + EnumSet() + : mBitField(0) + { + initVersion(); + } + + MOZ_IMPLICIT EnumSet(T aEnum) + : mBitField(bitFor(aEnum)) + { } + + EnumSet(T aEnum1, T aEnum2) + : mBitField(bitFor(aEnum1) | + bitFor(aEnum2)) + { + initVersion(); + } + + EnumSet(T aEnum1, T aEnum2, T aEnum3) + : mBitField(bitFor(aEnum1) | + bitFor(aEnum2) | + bitFor(aEnum3)) + { + initVersion(); + } + + EnumSet(T aEnum1, T aEnum2, T aEnum3, T aEnum4) + : mBitField(bitFor(aEnum1) | + bitFor(aEnum2) | + bitFor(aEnum3) | + bitFor(aEnum4)) + { + initVersion(); + } + + MOZ_IMPLICIT EnumSet(std::initializer_list<T> list) + : mBitField(0) + { + for (auto value : list) { + (*this) += value; + } + initVersion(); + } + + EnumSet(const EnumSet& aEnumSet) + : mBitField(aEnumSet.mBitField) + { + initVersion(); + } + + /** + * Add an element + */ + void operator+=(T aEnum) + { + incVersion(); + mBitField |= bitFor(aEnum); + } + + /** + * Add an element + */ + EnumSet<T> operator+(T aEnum) const + { + EnumSet<T> result(*this); + result += aEnum; + return result; + } + + /** + * Union + */ + void operator+=(const EnumSet<T> aEnumSet) + { + incVersion(); + mBitField |= aEnumSet.mBitField; + } + + /** + * Union + */ + EnumSet<T> operator+(const EnumSet<T> aEnumSet) const + { + EnumSet<T> result(*this); + result += aEnumSet; + return result; + } + + /** + * Remove an element + */ + void operator-=(T aEnum) + { + incVersion(); + mBitField &= ~(bitFor(aEnum)); + } + + /** + * Remove an element + */ + EnumSet<T> operator-(T aEnum) const + { + EnumSet<T> result(*this); + result -= aEnum; + return result; + } + + /** + * Remove a set of elements + */ + void operator-=(const EnumSet<T> aEnumSet) + { + incVersion(); + mBitField &= ~(aEnumSet.mBitField); + } + + /** + * Remove a set of elements + */ + EnumSet<T> operator-(const EnumSet<T> aEnumSet) const + { + EnumSet<T> result(*this); + result -= aEnumSet; + return result; + } + + /** + * Clear + */ + void clear() + { + incVersion(); + mBitField = 0; + } + + /** + * Intersection + */ + void operator&=(const EnumSet<T> aEnumSet) + { + incVersion(); + mBitField &= aEnumSet.mBitField; + } + + /** + * Intersection + */ + EnumSet<T> operator&(const EnumSet<T> aEnumSet) const + { + EnumSet<T> result(*this); + result &= aEnumSet; + return result; + } + + /** + * Equality + */ + bool operator==(const EnumSet<T> aEnumSet) const + { + return mBitField == aEnumSet.mBitField; + } + + /** + * Test is an element is contained in the set. + */ + bool contains(T aEnum) const + { + return mBitField & bitFor(aEnum); + } + + /** + * Return the number of elements in the set. + */ + uint8_t size() const + { + uint8_t count = 0; + for (uint32_t bitField = mBitField; bitField; bitField >>= 1) { + if (bitField & 1) { + count++; + } + } + return count; + } + + bool isEmpty() const + { + return mBitField == 0; + } + + uint32_t serialize() const + { + return mBitField; + } + + void deserialize(uint32_t aValue) + { + incVersion(); + mBitField = aValue; + } + + class ConstIterator + { + const EnumSet<T>* mSet; + uint32_t mPos; +#ifdef DEBUG + uint64_t mVersion; +#endif + + void checkVersion() { + // Check that the set has not been modified while being iterated. + MOZ_ASSERT_IF(mSet, mSet->mVersion == mVersion); + } + + public: + ConstIterator(const EnumSet<T>& 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) { + MOZ_ASSERT(mSet == other.mSet); + checkVersion(); + return mPos == other.mPos; + } + + bool operator!=(const ConstIterator& other) { + return !(*this == other); + } + + T operator*() { + 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: + static uint32_t bitFor(T aEnum) + { + uint32_t bitNumber = (uint32_t)aEnum; + MOZ_ASSERT(bitNumber < kMaxBits); + return 1U << bitNumber; + } + + void initVersion() { +#ifdef DEBUG + mVersion = 0; +#endif + } + + void incVersion() { +#ifdef DEBUG + mVersion++; +#endif + } + + static const size_t kMaxBits = 32; + uint32_t mBitField; + +#ifdef DEBUG + uint64_t mVersion; +#endif +}; + +} // namespace mozilla + +#endif /* mozilla_EnumSet_h_*/ |