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/*
* Copyright (C) 2016-2020 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <initializer_list>
#include <iterator>
#include <type_traits>
#include <wtf/Assertions.h>
#include <wtf/EnumTraits.h>
#include <wtf/MathExtras.h>
#include <wtf/Optional.h>
#include <wtf/StdLibExtras.h>
namespace WTF {
template<typename E> class OptionSet;
template<typename T, typename E> struct OptionSetValueChecker;
template<typename T, typename E, E e, E... es>
struct OptionSetValueChecker<T, EnumValues<E, e, es...>> {
static constexpr T allValidBits()
{
return static_cast<T>(e) | OptionSetValueChecker<T, EnumValues<E, es...>>::allValidBits();
}
static constexpr bool isValidOptionSetEnum(T t)
{
return (static_cast<T>(e) == t) ? true : OptionSetValueChecker<T, EnumValues<E, es...>>::isValidOptionSetEnum(t);
}
};
template<typename T, typename E>
struct OptionSetValueChecker<T, EnumValues<E>> {
static constexpr T allValidBits()
{
return 0;
}
static constexpr bool isValidOptionSetEnum(T)
{
return false;
}
};
template<typename E, std::enable_if_t<std::is_enum<E>::value && IsTypeComplete<EnumTraits<E>>>* = nullptr>
constexpr bool isValidOptionSetEnum(E e)
{
return OptionSetValueChecker<std::underlying_type_t<E>, typename EnumTraits<E>::values>::isValidOptionSetEnum(static_cast<std::underlying_type_t<E>>(e));
}
template<typename E, std::enable_if_t<std::is_enum<E>::value && !IsTypeComplete<EnumTraits<E>>>* = nullptr>
constexpr bool isValidOptionSetEnum(E e)
{
// FIXME: Remove once all OptionSet<> enums have EnumTraits<> defined.
return hasOneBitSet(static_cast<typename OptionSet<E>::StorageType>(e));
}
template<typename E, std::enable_if_t<std::is_enum<E>::value && IsTypeComplete<EnumTraits<E>>>* = nullptr>
constexpr typename OptionSet<E>::StorageType maskRawValue(typename OptionSet<E>::StorageType rawValue)
{
auto allValidBitsValue = OptionSetValueChecker<std::underlying_type_t<E>, typename EnumTraits<E>::values>::allValidBits();
return rawValue & allValidBitsValue;
}
template<typename E, std::enable_if_t<std::is_enum<E>::value && !IsTypeComplete<EnumTraits<E>>>* = nullptr>
constexpr typename OptionSet<E>::StorageType maskRawValue(typename OptionSet<E>::StorageType rawValue)
{
// FIXME: Remove once all OptionSet<> enums have EnumTraits<> defined.
return rawValue;
}
// OptionSet is a class that represents a set of enumerators in a space-efficient manner. The enumerators
// must be powers of two greater than 0. This class is useful as a replacement for passing a bitmask of
// enumerators around.
template<typename E> class OptionSet {
WTF_MAKE_FAST_ALLOCATED;
static_assert(std::is_enum<E>::value, "T is not an enum type");
public:
using StorageType = std::make_unsigned_t<std::underlying_type_t<E>>;
template<typename StorageType> class Iterator {
WTF_MAKE_FAST_ALLOCATED;
public:
// Isolate the rightmost set bit.
E operator*() const { return static_cast<E>(m_value & -m_value); }
// Iterates from smallest to largest enum value by turning off the rightmost set bit.
Iterator& operator++()
{
m_value &= m_value - 1;
return *this;
}
Iterator& operator++(int) = delete;
bool operator==(const Iterator& other) const { return m_value == other.m_value; }
bool operator!=(const Iterator& other) const { return m_value != other.m_value; }
private:
Iterator(StorageType value) : m_value(value) { }
friend OptionSet;
StorageType m_value;
};
using iterator = Iterator<StorageType>;
static constexpr OptionSet fromRaw(StorageType rawValue)
{
return OptionSet(static_cast<E>(maskRawValue<E>(rawValue)), FromRawValue);
}
constexpr OptionSet() = default;
constexpr OptionSet(E e)
: m_storage(static_cast<StorageType>(e))
{
ASSERT(!m_storage || isValidOptionSetEnum(e));
}
constexpr OptionSet(std::initializer_list<E> initializerList)
{
for (auto& option : initializerList) {
ASSERT(isValidOptionSetEnum(option));
m_storage |= static_cast<StorageType>(option);
}
}
constexpr OptionSet(Optional<E> optional)
: m_storage(optional ? static_cast<StorageType>(*optional) : 0)
{
}
constexpr StorageType toRaw() const { return m_storage; }
constexpr bool isEmpty() const { return !m_storage; }
constexpr iterator begin() const { return m_storage; }
constexpr iterator end() const { return 0; }
constexpr explicit operator bool() { return !isEmpty(); }
constexpr bool contains(E option) const
{
return containsAny(option);
}
constexpr bool containsAny(OptionSet optionSet) const
{
return !!(*this & optionSet);
}
constexpr bool containsAll(OptionSet optionSet) const
{
return (*this & optionSet) == optionSet;
}
constexpr void add(OptionSet optionSet)
{
m_storage |= optionSet.m_storage;
}
constexpr void remove(OptionSet optionSet)
{
m_storage &= ~optionSet.m_storage;
}
constexpr bool hasExactlyOneBitSet() const
{
return m_storage && !(m_storage & (m_storage - 1));
}
constexpr Optional<E> toSingleValue() const
{
return hasExactlyOneBitSet() ? Optional<E>(static_cast<E>(m_storage)) : WTF::nullopt;
}
constexpr friend bool operator==(OptionSet lhs, OptionSet rhs)
{
return lhs.m_storage == rhs.m_storage;
}
constexpr friend bool operator!=(OptionSet lhs, OptionSet rhs)
{
return lhs.m_storage != rhs.m_storage;
}
constexpr friend OptionSet operator|(OptionSet lhs, OptionSet rhs)
{
return fromRaw(lhs.m_storage | rhs.m_storage);
}
constexpr friend OptionSet operator&(OptionSet lhs, OptionSet rhs)
{
return fromRaw(lhs.m_storage & rhs.m_storage);
}
constexpr friend OptionSet operator-(OptionSet lhs, OptionSet rhs)
{
return fromRaw(lhs.m_storage & ~rhs.m_storage);
}
constexpr friend OptionSet operator^(OptionSet lhs, OptionSet rhs)
{
return fromRaw(lhs.m_storage ^ rhs.m_storage);
}
private:
enum InitializationTag { FromRawValue };
constexpr OptionSet(E e, InitializationTag)
: m_storage(static_cast<StorageType>(e))
{
}
StorageType m_storage { 0 };
};
template<typename E>
WARN_UNUSED_RETURN constexpr bool isValidOptionSet(OptionSet<E> optionSet)
{
auto allValidBitsValue = OptionSetValueChecker<std::make_unsigned_t<std::underlying_type_t<E>>, typename EnumTraits<E>::values>::allValidBits();
return (optionSet.toRaw() | allValidBitsValue) == allValidBitsValue;
}
} // namespace WTF
using WTF::OptionSet;