mirror of
https://github.com/flutter/flutter.git
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324 lines
15 KiB
C++
324 lines
15 KiB
C++
/*
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* Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public License
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* along with this library; see the file COPYING.LIB. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*
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*/
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#ifndef SKY_ENGINE_WTF_HASHTRAITS_H_
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#define SKY_ENGINE_WTF_HASHTRAITS_H_
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#include <string.h> // For memset.
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#include <limits>
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#include <utility>
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#include "sky/engine/wtf/HashFunctions.h"
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#include "sky/engine/wtf/HashTableDeletedValueType.h"
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#include "sky/engine/wtf/StdLibExtras.h"
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#include "sky/engine/wtf/TypeTraits.h"
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namespace WTF {
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class String;
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template<typename T> class OwnPtr;
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template<typename T> class PassOwnPtr;
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template<typename T> struct HashTraits;
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template<bool isInteger, typename T> struct GenericHashTraitsBase;
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enum ShouldWeakPointersBeMarkedStrongly {
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WeakPointersActStrong,
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WeakPointersActWeak
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};
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template<typename T> struct GenericHashTraitsBase<false, T> {
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// The emptyValueIsZero flag is used to optimize allocation of empty hash tables with zeroed memory.
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static const bool emptyValueIsZero = false;
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// The hasIsEmptyValueFunction flag allows the hash table to automatically generate code to check
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// for the empty value when it can be done with the equality operator, but allows custom functions
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// for cases like String that need them.
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static const bool hasIsEmptyValueFunction = false;
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// The needsDestruction flag is used to optimize destruction and rehashing.
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static const bool needsDestruction = true;
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// The starting table size. Can be overridden when we know beforehand that
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// a hash table will have at least N entries.
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#if defined(MEMORY_SANITIZER_INITIAL_SIZE)
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static const unsigned minimumTableSize = 1;
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#else
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static const unsigned minimumTableSize = 8;
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#endif
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static const WeakHandlingFlag weakHandlingFlag = IsWeak<T>::value ? WeakHandlingInCollections : NoWeakHandlingInCollections;
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};
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// Default integer traits disallow both 0 and -1 as keys (max value instead of -1 for unsigned).
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template<typename T> struct GenericHashTraitsBase<true, T> : GenericHashTraitsBase<false, T> {
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static const bool emptyValueIsZero = true;
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static const bool needsDestruction = false;
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static void constructDeletedValue(T& slot, bool) { slot = static_cast<T>(-1); }
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static bool isDeletedValue(T value) { return value == static_cast<T>(-1); }
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};
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template<typename T> struct GenericHashTraits : GenericHashTraitsBase<IsInteger<T>::value, T> {
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typedef T TraitType;
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typedef T EmptyValueType;
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static T emptyValue() { return T(); }
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// Type for functions that do not take ownership, such as contains.
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typedef const T& PeekInType;
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typedef T* IteratorGetType;
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typedef const T* IteratorConstGetType;
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typedef T& IteratorReferenceType;
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typedef const T& IteratorConstReferenceType;
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static IteratorReferenceType getToReferenceConversion(IteratorGetType x) { return *x; }
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static IteratorConstReferenceType getToReferenceConstConversion(IteratorConstGetType x) { return *x; }
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// Type for functions that take ownership, such as add.
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// The store function either not be called or called once to store something passed in.
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// The value passed to the store function will be PassInType.
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typedef const T& PassInType;
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static void store(const T& value, T& storage) { storage = value; }
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// Type for return value of functions that transfer ownership, such as take.
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typedef T PassOutType;
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static const T& passOut(const T& value) { return value; }
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// Type for return value of functions that do not transfer ownership, such as get.
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// FIXME: We could change this type to const T& for better performance if we figured out
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// a way to handle the return value from emptyValue, which is a temporary.
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typedef T PeekOutType;
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static const T& peek(const T& value) { return value; }
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};
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template<typename T> struct HashTraits : GenericHashTraits<T> { };
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template<typename T> struct FloatHashTraits : GenericHashTraits<T> {
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static const bool needsDestruction = false;
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static T emptyValue() { return std::numeric_limits<T>::infinity(); }
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static void constructDeletedValue(T& slot, bool) { slot = -std::numeric_limits<T>::infinity(); }
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static bool isDeletedValue(T value) { return value == -std::numeric_limits<T>::infinity(); }
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};
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template<> struct HashTraits<float> : FloatHashTraits<float> { };
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template<> struct HashTraits<double> : FloatHashTraits<double> { };
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// Default unsigned traits disallow both 0 and max as keys -- use these traits to allow zero and disallow max - 1.
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template<typename T> struct UnsignedWithZeroKeyHashTraits : GenericHashTraits<T> {
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static const bool emptyValueIsZero = false;
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static const bool needsDestruction = false;
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static T emptyValue() { return std::numeric_limits<T>::max(); }
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static void constructDeletedValue(T& slot, bool) { slot = std::numeric_limits<T>::max() - 1; }
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static bool isDeletedValue(T value) { return value == std::numeric_limits<T>::max() - 1; }
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};
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template<typename P> struct HashTraits<P*> : GenericHashTraits<P*> {
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static const bool emptyValueIsZero = true;
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static const bool needsDestruction = false;
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static void constructDeletedValue(P*& slot, bool) { slot = reinterpret_cast<P*>(-1); }
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static bool isDeletedValue(P* value) { return value == reinterpret_cast<P*>(-1); }
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};
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template<typename T> struct SimpleClassHashTraits : GenericHashTraits<T> {
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static const bool emptyValueIsZero = true;
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static void constructDeletedValue(T& slot, bool) { new (NotNull, &slot) T(HashTableDeletedValue); }
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static bool isDeletedValue(const T& value) { return value.isHashTableDeletedValue(); }
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};
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template<typename P> struct HashTraits<OwnPtr<P> > : SimpleClassHashTraits<OwnPtr<P> > {
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typedef std::nullptr_t EmptyValueType;
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static EmptyValueType emptyValue() { return nullptr; }
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static const bool hasIsEmptyValueFunction = true;
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static bool isEmptyValue(const OwnPtr<P>& value) { return !value; }
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typedef typename OwnPtr<P>::PtrType PeekInType;
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typedef PassOwnPtr<P> PassInType;
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static void store(PassOwnPtr<P> value, OwnPtr<P>& storage) { storage = value; }
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typedef PassOwnPtr<P> PassOutType;
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static PassOwnPtr<P> passOut(OwnPtr<P>& value) { return value.release(); }
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static PassOwnPtr<P> passOut(std::nullptr_t) { return nullptr; }
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typedef typename OwnPtr<P>::PtrType PeekOutType;
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static PeekOutType peek(const OwnPtr<P>& value) { return value.get(); }
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static PeekOutType peek(std::nullptr_t) { return 0; }
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};
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template<typename P> struct HashTraits<RefPtr<P> > : SimpleClassHashTraits<RefPtr<P> > {
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typedef std::nullptr_t EmptyValueType;
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static EmptyValueType emptyValue() { return nullptr; }
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static const bool hasIsEmptyValueFunction = true;
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static bool isEmptyValue(const RefPtr<P>& value) { return !value; }
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typedef RefPtrValuePeeker<P> PeekInType;
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typedef RefPtr<P>* IteratorGetType;
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typedef const RefPtr<P>* IteratorConstGetType;
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typedef RefPtr<P>& IteratorReferenceType;
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typedef const RefPtr<P>& IteratorConstReferenceType;
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static IteratorReferenceType getToReferenceConversion(IteratorGetType x) { return *x; }
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static IteratorConstReferenceType getToReferenceConstConversion(IteratorConstGetType x) { return *x; }
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typedef PassRefPtr<P> PassInType;
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static void store(PassRefPtr<P> value, RefPtr<P>& storage) { storage = value; }
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typedef PassRefPtr<P> PassOutType;
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static PassOutType passOut(RefPtr<P>& value) { return value.release(); }
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static PassOutType passOut(std::nullptr_t) { return nullptr; }
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typedef P* PeekOutType;
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static PeekOutType peek(const RefPtr<P>& value) { return value.get(); }
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static PeekOutType peek(std::nullptr_t) { return 0; }
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};
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template<typename T> struct HashTraits<RawPtr<T> > : HashTraits<T*> { };
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template<> struct HashTraits<String> : SimpleClassHashTraits<String> {
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static const bool hasIsEmptyValueFunction = true;
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static bool isEmptyValue(const String&);
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};
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// This struct template is an implementation detail of the isHashTraitsEmptyValue function,
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// which selects either the emptyValue function or the isEmptyValue function to check for empty values.
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template<typename Traits, bool hasEmptyValueFunction> struct HashTraitsEmptyValueChecker;
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template<typename Traits> struct HashTraitsEmptyValueChecker<Traits, true> {
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template<typename T> static bool isEmptyValue(const T& value) { return Traits::isEmptyValue(value); }
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};
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template<typename Traits> struct HashTraitsEmptyValueChecker<Traits, false> {
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template<typename T> static bool isEmptyValue(const T& value) { return value == Traits::emptyValue(); }
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};
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template<typename Traits, typename T> inline bool isHashTraitsEmptyValue(const T& value)
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{
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return HashTraitsEmptyValueChecker<Traits, Traits::hasIsEmptyValueFunction>::isEmptyValue(value);
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}
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template<typename FirstTraitsArg, typename SecondTraitsArg>
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struct PairHashTraits : GenericHashTraits<std::pair<typename FirstTraitsArg::TraitType, typename SecondTraitsArg::TraitType> > {
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typedef FirstTraitsArg FirstTraits;
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typedef SecondTraitsArg SecondTraits;
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typedef std::pair<typename FirstTraits::TraitType, typename SecondTraits::TraitType> TraitType;
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typedef std::pair<typename FirstTraits::EmptyValueType, typename SecondTraits::EmptyValueType> EmptyValueType;
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static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
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static EmptyValueType emptyValue() { return std::make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue()); }
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static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;
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static const unsigned minimumTableSize = FirstTraits::minimumTableSize;
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static void constructDeletedValue(TraitType& slot, bool zeroValue)
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{
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FirstTraits::constructDeletedValue(slot.first, zeroValue);
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// For GC collections the memory for the backing is zeroed when it
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// is allocated, and the constructors may take advantage of that,
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// especially if a GC occurs during insertion of an entry into the
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// table. This slot is being marked deleted, but If the slot is
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// reused at a later point, the same assumptions around memory
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// zeroing must hold as they did at the initial allocation.
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// Therefore we zero the value part of the slot here for GC
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// collections.
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if (zeroValue)
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memset(reinterpret_cast<void*>(&slot.second), 0, sizeof(slot.second));
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}
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static bool isDeletedValue(const TraitType& value) { return FirstTraits::isDeletedValue(value.first); }
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};
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template<typename First, typename Second>
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struct HashTraits<std::pair<First, Second> > : public PairHashTraits<HashTraits<First>, HashTraits<Second> > { };
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template<typename KeyTypeArg, typename ValueTypeArg>
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struct KeyValuePair {
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typedef KeyTypeArg KeyType;
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KeyValuePair()
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{
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}
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KeyValuePair(const KeyTypeArg& _key, const ValueTypeArg& _value)
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: key(_key)
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, value(_value)
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{
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}
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template <typename OtherKeyType, typename OtherValueType>
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KeyValuePair(const KeyValuePair<OtherKeyType, OtherValueType>& other)
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: key(other.key)
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, value(other.value)
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{
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}
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KeyTypeArg key;
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ValueTypeArg value;
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};
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template<typename KeyTraitsArg, typename ValueTraitsArg>
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struct KeyValuePairHashTraits : GenericHashTraits<KeyValuePair<typename KeyTraitsArg::TraitType, typename ValueTraitsArg::TraitType> > {
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typedef KeyTraitsArg KeyTraits;
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typedef ValueTraitsArg ValueTraits;
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typedef KeyValuePair<typename KeyTraits::TraitType, typename ValueTraits::TraitType> TraitType;
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typedef KeyValuePair<typename KeyTraits::EmptyValueType, typename ValueTraits::EmptyValueType> EmptyValueType;
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static const bool emptyValueIsZero = KeyTraits::emptyValueIsZero && ValueTraits::emptyValueIsZero;
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static EmptyValueType emptyValue() { return KeyValuePair<typename KeyTraits::EmptyValueType, typename ValueTraits::EmptyValueType>(KeyTraits::emptyValue(), ValueTraits::emptyValue()); }
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static const bool needsDestruction = KeyTraits::needsDestruction || ValueTraits::needsDestruction;
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static const WeakHandlingFlag weakHandlingFlag = (KeyTraits::weakHandlingFlag == WeakHandlingInCollections || ValueTraits::weakHandlingFlag == WeakHandlingInCollections) ? WeakHandlingInCollections : NoWeakHandlingInCollections;
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static const unsigned minimumTableSize = KeyTraits::minimumTableSize;
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static void constructDeletedValue(TraitType& slot, bool zeroValue)
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{
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KeyTraits::constructDeletedValue(slot.key, zeroValue);
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// See similar code in this file for why we need to do this.
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if (zeroValue)
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memset(reinterpret_cast<void*>(&slot.value), 0, sizeof(slot.value));
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}
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static bool isDeletedValue(const TraitType& value) { return KeyTraits::isDeletedValue(value.key); }
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};
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template<typename Key, typename Value>
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struct HashTraits<KeyValuePair<Key, Value> > : public KeyValuePairHashTraits<HashTraits<Key>, HashTraits<Value> > { };
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template<typename T>
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struct NullableHashTraits : public HashTraits<T> {
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static const bool emptyValueIsZero = false;
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static T emptyValue() { return reinterpret_cast<T>(1); }
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};
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// This is for tracing inside collections that have special support for weak
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// pointers. The trait has a trace method which returns true if there are weak
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// pointers to things that have not (yet) been marked live. Returning true
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// indicates that the entry in the collection may yet be removed by weak
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// handling. Default implementation for non-weak types is to use the regular
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// non-weak TraceTrait. Default implementation for types with weakness is to
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// call traceInCollection on the type's trait.
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template<WeakHandlingFlag weakHandlingFlag, ShouldWeakPointersBeMarkedStrongly strongify, typename T, typename Traits>
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struct TraceInCollectionTrait;
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} // namespace WTF
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using WTF::HashTraits;
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using WTF::PairHashTraits;
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using WTF::NullableHashTraits;
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using WTF::SimpleClassHashTraits;
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#endif // SKY_ENGINE_WTF_HASHTRAITS_H_
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