#ifndef WTF_HashTraits_h
#define WTF_HashTraits_h
#include <limits>
#include <utility>
#include <wtf/HashFunctions.h>
#include <wtf/KeyValuePair.h>
#include <wtf/Optional.h>
#include <wtf/StdLibExtras.h>
namespace WTF {
class String;
template<typename T> struct HashTraits;
template<bool isInteger, typename T> struct GenericHashTraitsBase;
template<typename T> struct GenericHashTraitsBase<false, T> {
static const bool emptyValueIsZero = false;
static const bool hasIsEmptyValueFunction = false;
static const unsigned minimumTableSize = 8;
};
template<typename T> struct GenericHashTraitsBase<true, T> : GenericHashTraitsBase<false, T> {
static const bool emptyValueIsZero = true;
static void constructDeletedValue(T& slot) { slot = static_cast<T>(-1); }
static bool isDeletedValue(T value) { return value == static_cast<T>(-1); }
};
template<typename T> struct GenericHashTraits : GenericHashTraitsBase<std::is_integral<T>::value, T> {
typedef T TraitType;
typedef T EmptyValueType;
static T emptyValue() { return T(); }
template<typename U, typename V>
static void assignToEmpty(U& emptyValue, V&& value)
{
emptyValue = std::forward<V>(value);
}
typedef T PeekType;
template<typename U> static U&& peek(U&& value) { return std::forward<U>(value); }
typedef T TakeType;
template<typename U> static TakeType take(U&& value) { return std::forward<U>(value); }
};
template<typename T> struct HashTraits : GenericHashTraits<T> { };
template<typename T> struct FloatHashTraits : GenericHashTraits<T> {
static T emptyValue() { return std::numeric_limits<T>::infinity(); }
static void constructDeletedValue(T& slot) { slot = -std::numeric_limits<T>::infinity(); }
static bool isDeletedValue(T value) { return value == -std::numeric_limits<T>::infinity(); }
};
template<> struct HashTraits<float> : FloatHashTraits<float> { };
template<> struct HashTraits<double> : FloatHashTraits<double> { };
template<typename T> struct UnsignedWithZeroKeyHashTraits : GenericHashTraits<T> {
static const bool emptyValueIsZero = false;
static T emptyValue() { return std::numeric_limits<T>::max(); }
static void constructDeletedValue(T& slot) { slot = std::numeric_limits<T>::max() - 1; }
static bool isDeletedValue(T value) { return value == std::numeric_limits<T>::max() - 1; }
};
template<typename T> struct SignedWithZeroKeyHashTraits : GenericHashTraits<T> {
static const bool emptyValueIsZero = false;
static T emptyValue() { return std::numeric_limits<T>::min(); }
static void constructDeletedValue(T& slot) { slot = std::numeric_limits<T>::max(); }
static bool isDeletedValue(T value) { return value == std::numeric_limits<T>::max(); }
};
template<typename T> struct StrongEnumHashTraits : GenericHashTraits<T> {
using UnderlyingType = typename std::underlying_type<T>::type;
static const bool emptyValueIsZero = false;
static T emptyValue() { return static_cast<T>(std::numeric_limits<UnderlyingType>::max()); }
static void constructDeletedValue(T& slot) { slot = static_cast<T>(std::numeric_limits<UnderlyingType>::max() - 1); }
static bool isDeletedValue(T value) { return value == static_cast<T>(std::numeric_limits<UnderlyingType>::max() - 1); }
};
template<typename P> struct HashTraits<P*> : GenericHashTraits<P*> {
static const bool emptyValueIsZero = true;
static void constructDeletedValue(P*& slot) { slot = reinterpret_cast<P*>(-1); }
static bool isDeletedValue(P* value) { return value == reinterpret_cast<P*>(-1); }
};
template<typename T> struct SimpleClassHashTraits : GenericHashTraits<T> {
static const bool emptyValueIsZero = true;
static void constructDeletedValue(T& slot) { new (NotNull, std::addressof(slot)) T(HashTableDeletedValue); }
static bool isDeletedValue(const T& value) { return value.isHashTableDeletedValue(); }
};
template<typename T, typename Deleter> struct HashTraits<std::unique_ptr<T, Deleter>> : SimpleClassHashTraits<std::unique_ptr<T, Deleter>> {
typedef std::nullptr_t EmptyValueType;
static EmptyValueType emptyValue() { return nullptr; }
static void constructDeletedValue(std::unique_ptr<T, Deleter>& slot) { new (NotNull, std::addressof(slot)) std::unique_ptr<T, Deleter> { reinterpret_cast<T*>(-1) }; }
static bool isDeletedValue(const std::unique_ptr<T, Deleter>& value) { return value.get() == reinterpret_cast<T*>(-1); }
typedef T* PeekType;
static T* peek(const std::unique_ptr<T, Deleter>& value) { return value.get(); }
static T* peek(std::nullptr_t) { return nullptr; }
static void customDeleteBucket(std::unique_ptr<T, Deleter>& value)
{
ASSERT(!isDeletedValue(value));
T* pointer = value.release();
constructDeletedValue(value);
if (LIKELY(pointer))
Deleter()(pointer);
}
};
template<typename P> struct HashTraits<RefPtr<P>> : SimpleClassHashTraits<RefPtr<P>> {
static P* emptyValue() { return nullptr; }
typedef P* PeekType;
static PeekType peek(const RefPtr<P>& value) { return value.get(); }
static PeekType peek(P* value) { return value; }
static void customDeleteBucket(RefPtr<P>& value)
{
ASSERT(!SimpleClassHashTraits<RefPtr<P>>::isDeletedValue(value));
auto valueToBeDestroyed = WTFMove(value);
SimpleClassHashTraits<RefPtr<P>>::constructDeletedValue(value);
}
};
template<typename P> struct HashTraits<Ref<P>> : SimpleClassHashTraits<Ref<P>> {
static const bool emptyValueIsZero = true;
static Ref<P> emptyValue() { return HashTableEmptyValue; }
static const bool hasIsEmptyValueFunction = true;
static bool isEmptyValue(const Ref<P>& value) { return value.isHashTableEmptyValue(); }
static void assignToEmpty(Ref<P>& emptyValue, Ref<P>&& newValue) { ASSERT(isEmptyValue(emptyValue)); emptyValue.assignToHashTableEmptyValue(WTFMove(newValue)); }
typedef P* PeekType;
static PeekType peek(const Ref<P>& value) { return const_cast<PeekType>(value.ptrAllowingHashTableEmptyValue()); }
static PeekType peek(P* value) { return value; }
typedef std::optional<Ref<P>> TakeType;
static TakeType take(Ref<P>&& value) { return isEmptyValue(value) ? std::nullopt : std::optional<Ref<P>>(WTFMove(value)); }
};
template<> struct HashTraits<String> : SimpleClassHashTraits<String> {
static const bool hasIsEmptyValueFunction = true;
static bool isEmptyValue(const String&);
static void customDeleteBucket(String&);
};
template<typename Traits, bool hasEmptyValueFunction> struct HashTraitsEmptyValueChecker;
template<typename Traits> struct HashTraitsEmptyValueChecker<Traits, true> {
template<typename T> static bool isEmptyValue(const T& value) { return Traits::isEmptyValue(value); }
};
template<typename Traits> struct HashTraitsEmptyValueChecker<Traits, false> {
template<typename T> static bool isEmptyValue(const T& value) { return value == Traits::emptyValue(); }
};
template<typename Traits, typename T> inline bool isHashTraitsEmptyValue(const T& value)
{
return HashTraitsEmptyValueChecker<Traits, Traits::hasIsEmptyValueFunction>::isEmptyValue(value);
}
template<typename Traits, typename T>
struct HashTraitHasCustomDelete {
static T& bucketArg;
template<typename X> static std::true_type TestHasCustomDelete(X*, decltype(X::customDeleteBucket(bucketArg))* = nullptr);
static std::false_type TestHasCustomDelete(...);
typedef decltype(TestHasCustomDelete(static_cast<Traits*>(nullptr))) ResultType;
static const bool value = ResultType::value;
};
template<typename Traits, typename T>
typename std::enable_if<HashTraitHasCustomDelete<Traits, T>::value>::type
hashTraitsDeleteBucket(T& value)
{
Traits::customDeleteBucket(value);
}
template<typename Traits, typename T>
typename std::enable_if<!HashTraitHasCustomDelete<Traits, T>::value>::type
hashTraitsDeleteBucket(T& value)
{
value.~T();
Traits::constructDeletedValue(value);
}
template<typename FirstTraitsArg, typename SecondTraitsArg>
struct PairHashTraits : GenericHashTraits<std::pair<typename FirstTraitsArg::TraitType, typename SecondTraitsArg::TraitType>> {
typedef FirstTraitsArg FirstTraits;
typedef SecondTraitsArg SecondTraits;
typedef std::pair<typename FirstTraits::TraitType, typename SecondTraits::TraitType> TraitType;
typedef std::pair<typename FirstTraits::EmptyValueType, typename SecondTraits::EmptyValueType> EmptyValueType;
static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
static EmptyValueType emptyValue() { return std::make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue()); }
static const unsigned minimumTableSize = FirstTraits::minimumTableSize;
static void constructDeletedValue(TraitType& slot) { FirstTraits::constructDeletedValue(slot.first); }
static bool isDeletedValue(const TraitType& value) { return FirstTraits::isDeletedValue(value.first); }
};
template<typename First, typename Second>
struct HashTraits<std::pair<First, Second>> : public PairHashTraits<HashTraits<First>, HashTraits<Second>> { };
template<typename FirstTrait, typename... Traits>
struct TupleHashTraits : GenericHashTraits<std::tuple<typename FirstTrait::TraitType, typename Traits::TraitType...>> {
typedef std::tuple<typename FirstTrait::TraitType, typename Traits::TraitType...> TraitType;
typedef std::tuple<typename FirstTrait::EmptyValueType, typename Traits::EmptyValueType...> EmptyValueType;
template<typename BoolType>
static constexpr bool allTrue(BoolType value) { return value; }
template<typename BoolType, typename... BoolTypes>
static constexpr bool allTrue(BoolType value, BoolTypes... values) { return value && allTrue(values...); }
static const bool emptyValueIsZero = allTrue(FirstTrait::emptyValueIsZero, Traits::emptyValueIsZero...);
static EmptyValueType emptyValue() { return std::make_tuple(FirstTrait::emptyValue(), Traits::emptyValue()...); }
static const unsigned minimumTableSize = FirstTrait::minimumTableSize;
static void constructDeletedValue(TraitType& slot) { FirstTrait::constructDeletedValue(std::get<0>(slot)); }
static bool isDeletedValue(const TraitType& value) { return FirstTrait::isDeletedValue(std::get<0>(value)); }
};
template<typename... Traits>
struct HashTraits<std::tuple<Traits...>> : public TupleHashTraits<HashTraits<Traits>...> { };
template<typename KeyTraitsArg, typename ValueTraitsArg>
struct KeyValuePairHashTraits : GenericHashTraits<KeyValuePair<typename KeyTraitsArg::TraitType, typename ValueTraitsArg::TraitType>> {
typedef KeyTraitsArg KeyTraits;
typedef ValueTraitsArg ValueTraits;
typedef KeyValuePair<typename KeyTraits::TraitType, typename ValueTraits::TraitType> TraitType;
typedef KeyValuePair<typename KeyTraits::EmptyValueType, typename ValueTraits::EmptyValueType> EmptyValueType;
typedef typename ValueTraitsArg::TraitType ValueType;
static const bool emptyValueIsZero = KeyTraits::emptyValueIsZero && ValueTraits::emptyValueIsZero;
static EmptyValueType emptyValue() { return KeyValuePair<typename KeyTraits::EmptyValueType, typename ValueTraits::EmptyValueType>(KeyTraits::emptyValue(), ValueTraits::emptyValue()); }
static const unsigned minimumTableSize = KeyTraits::minimumTableSize;
static void constructDeletedValue(TraitType& slot) { KeyTraits::constructDeletedValue(slot.key); }
static bool isDeletedValue(const TraitType& value) { return KeyTraits::isDeletedValue(value.key); }
static void customDeleteBucket(TraitType& value)
{
static_assert(std::is_trivially_destructible<KeyValuePair<int, int>>::value,
"The wrapper itself has to be trivially destructible for customDeleteBucket() to make sense, since we do not destruct the wrapper itself.");
hashTraitsDeleteBucket<KeyTraits>(value.key);
value.value.~ValueType();
}
};
template<typename Key, typename Value>
struct HashTraits<KeyValuePair<Key, Value>> : public KeyValuePairHashTraits<HashTraits<Key>, HashTraits<Value>> { };
template<typename T>
struct NullableHashTraits : public HashTraits<T> {
static const bool emptyValueIsZero = false;
static T emptyValue() { return reinterpret_cast<T>(1); }
};
template<typename T>
struct CustomHashTraits : public GenericHashTraits<T> {
static const bool emptyValueIsZero = false;
static const bool hasIsEmptyValueFunction = true;
static void constructDeletedValue(T& slot)
{
new (NotNull, std::addressof(slot)) T(T::DeletedValue);
}
static bool isDeletedValue(const T& value)
{
return value.isDeletedValue();
}
static T emptyValue()
{
return T(T::EmptyValue);
}
static bool isEmptyValue(const T& value)
{
return value.isEmptyValue();
}
};
}
using WTF::HashTraits;
using WTF::KeyValuePair;
using WTF::PairHashTraits;
using WTF::NullableHashTraits;
using WTF::SimpleClassHashTraits;
#endif // WTF_HashTraits_h