/*
 * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights reserved.
 * Copyright (C) 2011, Benjamin Poulain <ikipou@gmail.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef WTF_ListHashSet_h
#define WTF_ListHashSet_h

#include "wtf/DefaultAllocator.h"
#include "wtf/HashSet.h"
#include "wtf/OwnPtr.h"
#include "wtf/PassOwnPtr.h"

namespace WTF {

    // ListHashSet: Just like HashSet, this class provides a Set
    // interface - a collection of unique objects with O(1) insertion,
    // removal and test for containership. However, it also has an
    // order - iterating it will always give back values in the order
    // in which they are added.

    // Unlike iteration of most WTF Hash data structures, iteration is
    // guaranteed safe against mutation of the ListHashSet, except for
    // removal of the item currently pointed to by a given iterator.

    template<typename Value, size_t inlineCapacity, typename HashFunctions, typename Allocator> class ListHashSet;

    template<typename Set> class ListHashSetIterator;
    template<typename Set> class ListHashSetConstIterator;
    template<typename Set> class ListHashSetReverseIterator;
    template<typename Set> class ListHashSetConstReverseIterator;

    template<typename ValueArg> class ListHashSetNodeBase;
    template<typename ValueArg, typename Allocator> class ListHashSetNode;
    template<typename ValueArg, size_t inlineCapacity> struct ListHashSetAllocator;

    template<typename HashArg> struct ListHashSetNodeHashFunctions;
    template<typename HashArg> struct ListHashSetTranslator;

    // Don't declare a destructor for HeapAllocated ListHashSet.
    template<typename Derived, typename Allocator, bool isGarbageCollected>
    class ListHashSetDestructorBase;

    template<typename Derived, typename Allocator>
    class ListHashSetDestructorBase<Derived, Allocator, true> {
    protected:
        typename Allocator::AllocatorProvider m_allocatorProvider;
    };

    template<typename Derived, typename Allocator>
    class ListHashSetDestructorBase<Derived, Allocator, false> {
    public:
        ~ListHashSetDestructorBase() { static_cast<Derived*>(this)->finalize(); }
    protected:
        typename Allocator::AllocatorProvider m_allocatorProvider;
    };

    // Note that for a ListHashSet you cannot specify the HashTraits as a
    // template argument. It uses the default hash traits for the ValueArg
    // type.
    template<typename ValueArg, size_t inlineCapacity = 256, typename HashArg = typename DefaultHash<ValueArg>::Hash, typename AllocatorArg = ListHashSetAllocator<ValueArg, inlineCapacity>> class ListHashSet
        : public ListHashSetDestructorBase<ListHashSet<ValueArg, inlineCapacity, HashArg, AllocatorArg>, AllocatorArg, AllocatorArg::isGarbageCollected> {
        typedef AllocatorArg Allocator;
        WTF_USE_ALLOCATOR(ListHashSet, Allocator);

        typedef ListHashSetNode<ValueArg, Allocator> Node;
        typedef HashTraits<Node*> NodeTraits;
        typedef ListHashSetNodeHashFunctions<HashArg> NodeHash;
        typedef ListHashSetTranslator<HashArg> BaseTranslator;

        typedef HashTable<Node*, Node*, IdentityExtractor, NodeHash, NodeTraits, NodeTraits, typename Allocator::TableAllocator> ImplType;
        typedef HashTableIterator<Node*, Node*, IdentityExtractor, NodeHash, NodeTraits, NodeTraits, typename Allocator::TableAllocator> ImplTypeIterator;
        typedef HashTableConstIterator<Node*, Node*, IdentityExtractor, NodeHash, NodeTraits, NodeTraits, typename Allocator::TableAllocator> ImplTypeConstIterator;

        typedef HashArg HashFunctions;

    public:
        typedef ValueArg ValueType;
        typedef HashTraits<ValueType> ValueTraits;
        typedef typename ValueTraits::PeekInType ValuePeekInType;
        typedef typename ValueTraits::PassInType ValuePassInType;
        typedef typename ValueTraits::PassOutType ValuePassOutType;

        typedef ListHashSetIterator<ListHashSet> iterator;
        typedef ListHashSetConstIterator<ListHashSet> const_iterator;
        friend class ListHashSetIterator<ListHashSet>;
        friend class ListHashSetConstIterator<ListHashSet>;

        typedef ListHashSetReverseIterator<ListHashSet> reverse_iterator;
        typedef ListHashSetConstReverseIterator<ListHashSet> const_reverse_iterator;
        friend class ListHashSetReverseIterator<ListHashSet>;
        friend class ListHashSetConstReverseIterator<ListHashSet>;

        template<typename ValueType> struct HashTableAddResult {
        HashTableAddResult(Node* storedValue, bool isNewEntry) : storedValue(storedValue), isNewEntry(isNewEntry) { }
            Node* storedValue;
            bool isNewEntry;
        };
        typedef HashTableAddResult<ValueType> AddResult;

        ListHashSet();
        ListHashSet(const ListHashSet&);
        ListHashSet& operator=(const ListHashSet&);
        void finalize();

        void swap(ListHashSet&);

        unsigned size() const { return m_impl.size(); }
        unsigned capacity() const { return m_impl.capacity(); }
        bool isEmpty() const { return m_impl.isEmpty(); }

        iterator begin() { return makeIterator(m_head); }
        iterator end() { return makeIterator(0); }
        const_iterator begin() const { return makeConstIterator(m_head); }
        const_iterator end() const { return makeConstIterator(0); }

        reverse_iterator rbegin() { return makeReverseIterator(m_tail); }
        reverse_iterator rend() { return makeReverseIterator(0); }
        const_reverse_iterator rbegin() const { return makeConstReverseIterator(m_tail); }
        const_reverse_iterator rend() const { return makeConstReverseIterator(0); }

        ValueType& first();
        const ValueType& first() const;
        void removeFirst();

        ValueType& last();
        const ValueType& last() const;
        void removeLast();

        iterator find(ValuePeekInType);
        const_iterator find(ValuePeekInType) const;
        bool contains(ValuePeekInType) const;

        // An alternate version of find() that finds the object by hashing and comparing
        // with some other type, to avoid the cost of type conversion.
        // The HashTranslator interface is defined in HashSet.
        template<typename HashTranslator, typename T> iterator find(const T&);
        template<typename HashTranslator, typename T> const_iterator find(const T&) const;
        template<typename HashTranslator, typename T> bool contains(const T&) const;

        // The return value of add is a pair of a pointer to the stored value,
        // and a bool that is true if an new entry was added.
        AddResult add(ValuePassInType);

        // Same as add() except that the return value is an
        // iterator. Useful in cases where it's needed to have the
        // same return value as find() and where it's not possible to
        // use a pointer to the storedValue.
        iterator addReturnIterator(ValuePassInType);

        // Add the value to the end of the collection. If the value was already in
        // the list, it is moved to the end.
        AddResult appendOrMoveToLast(ValuePassInType);

        // Add the value to the beginning of the collection. If the value was already in
        // the list, it is moved to the beginning.
        AddResult prependOrMoveToFirst(ValuePassInType);

        AddResult insertBefore(ValuePeekInType beforeValue, ValuePassInType newValue);
        AddResult insertBefore(iterator, ValuePassInType);

        void remove(ValuePeekInType value) { return remove(find(value)); }
        void remove(iterator);
        void clear();
        template<typename Collection>
        void removeAll(const Collection& other) { WTF::removeAll(*this, other); }

        ValuePassOutType take(iterator);
        ValuePassOutType take(ValuePeekInType);
        ValuePassOutType takeFirst();

        void trace(typename Allocator::Visitor*);

    private:
        void unlink(Node*);
        void unlinkAndDelete(Node*);
        void appendNode(Node*);
        void prependNode(Node*);
        void insertNodeBefore(Node* beforeNode, Node* newNode);
        void deleteAllNodes();
        Allocator* allocator() const { return this->m_allocatorProvider.get(); }
        void createAllocatorIfNeeded() { this->m_allocatorProvider.createAllocatorIfNeeded(); }
        void deallocate(Node* node) const { this->m_allocatorProvider.deallocate(node); }

        iterator makeIterator(Node* position) { return iterator(this, position); }
        const_iterator makeConstIterator(Node* position) const { return const_iterator(this, position); }
        reverse_iterator makeReverseIterator(Node* position) { return reverse_iterator(this, position); }
        const_reverse_iterator makeConstReverseIterator(Node* position) const { return const_reverse_iterator(this, position); }

        ImplType m_impl;
        Node* m_head;
        Node* m_tail;
    };

    // ListHashSetNode has this base class to hold the members because the MSVC
    // compiler otherwise gets into circular template dependencies when trying
    // to do sizeof on a node.
    template<typename ValueArg> class ListHashSetNodeBase {
    protected:
        ListHashSetNodeBase(const ValueArg& value)
            : m_value(value)
            , m_prev(0)
            , m_next(0)
#if ENABLE(ASSERT)
            , m_isAllocated(true)
#endif
        {
        }

        template <typename U>
        ListHashSetNodeBase(const U& value)
            : m_value(value)
            , m_prev(0)
            , m_next(0)
#if ENABLE(ASSERT)
            , m_isAllocated(true)
#endif
        {
        }

    public:
        ValueArg m_value;
        ListHashSetNodeBase* m_prev;
        ListHashSetNodeBase* m_next;
#if ENABLE(ASSERT)
        bool m_isAllocated;
#endif
    };

    // This allocator is only used for non-Heap ListHashSets.
    template<typename ValueArg, size_t inlineCapacity>
    struct ListHashSetAllocator : public DefaultAllocator {
        typedef DefaultAllocator TableAllocator;
        typedef ListHashSetNode<ValueArg, ListHashSetAllocator> Node;
        typedef ListHashSetNodeBase<ValueArg> NodeBase;
        class AllocatorProvider {
        public:
            void createAllocatorIfNeeded()
            {
                if (!m_allocator)
                    m_allocator = adoptPtr(new ListHashSetAllocator);
            }

            void swap(AllocatorProvider& other)
            {
                m_allocator.swap(other.m_allocator);
            }

            void deallocate(Node* node) const
            {
                ASSERT(m_allocator);
                m_allocator->deallocate(node);
            }

            ListHashSetAllocator* get() const
            {
                ASSERT(m_allocator);
                return m_allocator.get();
            }

        private:
            OwnPtr<ListHashSetAllocator> m_allocator;
        };

        ListHashSetAllocator()
            : m_freeList(pool())
            , m_isDoneWithInitialFreeList(false)
        {
            memset(m_pool.buffer, 0, sizeof(m_pool.buffer));
        }

        Node* allocateNode()
        {
            Node* result = m_freeList;

            if (!result)
                return static_cast<Node*>(fastMalloc(sizeof(NodeBase)));

            ASSERT(!result->m_isAllocated);

            Node* next = result->next();
            ASSERT(!next || !next->m_isAllocated);
            if (!next && !m_isDoneWithInitialFreeList) {
                next = result + 1;
                if (next == pastPool()) {
                    m_isDoneWithInitialFreeList = true;
                    next = 0;
                } else {
                    ASSERT(inPool(next));
                    ASSERT(!next->m_isAllocated);
                }
            }
            m_freeList = next;

            return result;
        }

        void deallocate(Node* node)
        {
            if (inPool(node)) {
#if ENABLE(ASSERT)
                node->m_isAllocated = false;
#endif
                node->m_next = m_freeList;
                m_freeList = node;
                return;
            }

            fastFree(node);
        }

        bool inPool(Node* node)
        {
            return node >= pool() && node < pastPool();
        }

        static void traceValue(typename DefaultAllocator::Visitor* visitor, Node* node) { }

    private:
        Node* pool() { return reinterpret_cast_ptr<Node*>(m_pool.buffer); }
        Node* pastPool() { return pool() + m_poolSize; }

        Node* m_freeList;
        bool m_isDoneWithInitialFreeList;
#if defined(MEMORY_SANITIZER_INITIAL_SIZE)
        // The allocation pool for nodes is one big chunk that ASAN has no
        // insight into, so it can cloak errors. Make it as small as possible
        // to force nodes to be allocated individually where ASAN can see them.
        static const size_t m_poolSize = 1;
#else
        static const size_t m_poolSize = inlineCapacity;
#endif
        AlignedBuffer<sizeof(NodeBase) * m_poolSize, WTF_ALIGN_OF(NodeBase)> m_pool;
    };

    template<typename ValueArg, typename AllocatorArg> class ListHashSetNode : public ListHashSetNodeBase<ValueArg> {
    public:
        typedef AllocatorArg NodeAllocator;
        typedef ValueArg Value;

        template <typename U>
        ListHashSetNode(U value)
            : ListHashSetNodeBase<ValueArg>(value) { }

        void* operator new(size_t, NodeAllocator* allocator)
        {
            static_assert(sizeof(ListHashSetNode) == sizeof(ListHashSetNodeBase<ValueArg>), "please add any fields to the base");
            return allocator->allocateNode();
        }

        void setWasAlreadyDestructed()
        {
            if (NodeAllocator::isGarbageCollected && HashTraits<ValueArg>::needsDestruction)
                this->m_prev = unlinkedNodePointer();
        }

        bool wasAlreadyDestructed() const
        {
            ASSERT(NodeAllocator::isGarbageCollected);
            return this->m_prev == unlinkedNodePointer();
        }

        static void finalize(void* pointer)
        {
            ASSERT(HashTraits<ValueArg>::needsDestruction); // No need to waste time calling finalize if it's not needed.
            ListHashSetNode* self = reinterpret_cast_ptr<ListHashSetNode*>(pointer);

            // Check whether this node was already destructed before being
            // unlinked from the collection.
            if (self->wasAlreadyDestructed())
                return;

            self->m_value.~ValueArg();
        }

        void destroy(NodeAllocator* allocator)
        {
            this->~ListHashSetNode();
            setWasAlreadyDestructed();
            allocator->deallocate(this);
        }

        // This is not called in normal tracing, but it is called if we find a
        // pointer to a node on the stack using conservative scanning. Since
        // the original ListHashSet may no longer exist we make sure to mark
        // the neighbours in the chain too.
        void trace(typename NodeAllocator::Visitor* visitor)
        {
            // The conservative stack scan can find nodes that have been
            // removed from the set and destructed. We don't need to trace
            // these, and it would be wrong to do so, because the class will
            // not expect the trace method to be called after the destructor.
            // It's an error to remove a node from the ListHashSet while an
            // iterator is positioned at that node, so there should be no valid
            // pointers from the stack to a destructed node.
            if (wasAlreadyDestructed())
                return;
            NodeAllocator::traceValue(visitor, this);
            visitor->mark(next());
            visitor->mark(prev());
        }

        ListHashSetNode* next() const { return reinterpret_cast<ListHashSetNode*>(this->m_next); }
        ListHashSetNode* prev() const { return reinterpret_cast<ListHashSetNode*>(this->m_prev); }

        // Don't add fields here, the ListHashSetNodeBase and this should have
        // the same size.

        static ListHashSetNode* unlinkedNodePointer() { return reinterpret_cast<ListHashSetNode*>(-1); }

        template<typename HashArg>
        friend struct ListHashSetNodeHashFunctions;
    };

    template<typename HashArg> struct ListHashSetNodeHashFunctions {
        template<typename T> static unsigned hash(const T& key) { return HashArg::hash(key->m_value); }
        template<typename T> static bool equal(const T& a, const T& b) { return HashArg::equal(a->m_value, b->m_value); }
        static const bool safeToCompareToEmptyOrDeleted = false;
    };

    template<typename Set> class ListHashSetIterator {
    private:
        typedef typename Set::const_iterator const_iterator;
        typedef typename Set::Node Node;
        typedef typename Set::ValueType ValueType;
        typedef ValueType& ReferenceType;
        typedef ValueType* PointerType;

        ListHashSetIterator(const Set* set, Node* position) : m_iterator(set, position) { }

    public:
        ListHashSetIterator() { }

        // default copy, assignment and destructor are OK

        PointerType get() const { return const_cast<PointerType>(m_iterator.get()); }
        ReferenceType operator*() const { return *get(); }
        PointerType operator->() const { return get(); }

        ListHashSetIterator& operator++() { ++m_iterator; return *this; }
        ListHashSetIterator& operator--() { --m_iterator; return *this; }

        // Postfix ++ and -- intentionally omitted.

        // Comparison.
        bool operator==(const ListHashSetIterator& other) const { return m_iterator == other.m_iterator; }
        bool operator!=(const ListHashSetIterator& other) const { return m_iterator != other.m_iterator; }

        operator const_iterator() const { return m_iterator; }

    private:
        Node* node() { return m_iterator.node(); }

        const_iterator m_iterator;

        template<typename T, size_t inlineCapacity, typename U, typename V>
        friend class ListHashSet;
    };

    template<typename Set>
    class ListHashSetConstIterator {
    private:
        typedef typename Set::const_iterator const_iterator;
        typedef typename Set::Node Node;
        typedef typename Set::ValueType ValueType;
        typedef const ValueType& ReferenceType;
        typedef const ValueType* PointerType;

        friend class ListHashSetIterator<Set>;

        ListHashSetConstIterator(const Set* set, Node* position)
            : m_set(set)
            , m_position(position)
        {
        }

    public:
        ListHashSetConstIterator()
        {
        }

        PointerType get() const
        {
            return &m_position->m_value;
        }
        ReferenceType operator*() const { return *get(); }
        PointerType operator->() const { return get(); }

        ListHashSetConstIterator& operator++()
        {
            ASSERT(m_position != 0);
            m_position = m_position->next();
            return *this;
        }

        ListHashSetConstIterator& operator--()
        {
            ASSERT(m_position != m_set->m_head);
            if (!m_position)
                m_position = m_set->m_tail;
            else
                m_position = m_position->prev();
            return *this;
        }

        // Postfix ++ and -- intentionally omitted.

        // Comparison.
        bool operator==(const ListHashSetConstIterator& other) const
        {
            return m_position == other.m_position;
        }
        bool operator!=(const ListHashSetConstIterator& other) const
        {
            return m_position != other.m_position;
        }

    private:
        Node* node() { return m_position; }

        const Set* m_set;
        Node* m_position;

        template<typename T, size_t inlineCapacity, typename U, typename V>
        friend class ListHashSet;
    };

    template<typename Set>
    class ListHashSetReverseIterator {
    private:
        typedef typename Set::const_reverse_iterator const_reverse_iterator;
        typedef typename Set::Node Node;
        typedef typename Set::ValueType ValueType;
        typedef ValueType& ReferenceType;
        typedef ValueType* PointerType;

        ListHashSetReverseIterator(const Set* set, Node* position) : m_iterator(set, position) { }

    public:
        ListHashSetReverseIterator() { }

        // default copy, assignment and destructor are OK

        PointerType get() const { return const_cast<PointerType>(m_iterator.get()); }
        ReferenceType operator*() const { return *get(); }
        PointerType operator->() const { return get(); }

        ListHashSetReverseIterator& operator++() { ++m_iterator; return *this; }
        ListHashSetReverseIterator& operator--() { --m_iterator; return *this; }

        // Postfix ++ and -- intentionally omitted.

        // Comparison.
        bool operator==(const ListHashSetReverseIterator& other) const { return m_iterator == other.m_iterator; }
        bool operator!=(const ListHashSetReverseIterator& other) const { return m_iterator != other.m_iterator; }

        operator const_reverse_iterator() const { return m_iterator; }

    private:
        Node* node() { return m_iterator.node(); }

        const_reverse_iterator m_iterator;

        template<typename T, size_t inlineCapacity, typename U, typename V>
        friend class ListHashSet;
    };

    template<typename Set> class ListHashSetConstReverseIterator {
    private:
        typedef typename Set::reverse_iterator reverse_iterator;
        typedef typename Set::Node Node;
        typedef typename Set::ValueType ValueType;
        typedef const ValueType& ReferenceType;
        typedef const ValueType* PointerType;

        friend class ListHashSetReverseIterator<Set>;

        ListHashSetConstReverseIterator(const Set* set, Node* position)
            : m_set(set)
            , m_position(position)
        {
        }

    public:
        ListHashSetConstReverseIterator()
        {
        }

        PointerType get() const
        {
            return &m_position->m_value;
        }
        ReferenceType operator*() const { return *get(); }
        PointerType operator->() const { return get(); }

        ListHashSetConstReverseIterator& operator++()
        {
            ASSERT(m_position != 0);
            m_position = m_position->prev();
            return *this;
        }

        ListHashSetConstReverseIterator& operator--()
        {
            ASSERT(m_position != m_set->m_tail);
            if (!m_position)
                m_position = m_set->m_head;
            else
                m_position = m_position->next();
            return *this;
        }

        // Postfix ++ and -- intentionally omitted.

        // Comparison.
        bool operator==(const ListHashSetConstReverseIterator& other) const
        {
            return m_position == other.m_position;
        }
        bool operator!=(const ListHashSetConstReverseIterator& other) const
        {
            return m_position != other.m_position;
        }

    private:
        Node* node() { return m_position; }

        const Set* m_set;
        Node* m_position;

        template<typename T, size_t inlineCapacity, typename U, typename V>
        friend class ListHashSet;
    };

    template<typename HashFunctions>
    struct ListHashSetTranslator {
        template<typename T> static unsigned hash(const T& key) { return HashFunctions::hash(key); }
        template<typename T, typename U> static bool equal(const T& a, const U& b) { return HashFunctions::equal(a->m_value, b); }
        template<typename T, typename U, typename V> static void translate(T*& location, const U& key, const V& allocator)
        {
            location = new (const_cast<V*>(&allocator)) T(key);
        }
    };

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline ListHashSet<T, inlineCapacity, U, V>::ListHashSet()
        : m_head(0)
        , m_tail(0)
    {
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline ListHashSet<T, inlineCapacity, U, V>::ListHashSet(const ListHashSet& other)
        : m_head(0)
        , m_tail(0)
    {
        const_iterator end = other.end();
        for (const_iterator it = other.begin(); it != end; ++it)
            add(*it);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline ListHashSet<T, inlineCapacity, U, V>& ListHashSet<T, inlineCapacity, U, V>::operator=(const ListHashSet& other)
    {
        ListHashSet tmp(other);
        swap(tmp);
        return *this;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline void ListHashSet<T, inlineCapacity, U, V>::swap(ListHashSet& other)
    {
        m_impl.swap(other.m_impl);
        std::swap(m_head, other.m_head);
        std::swap(m_tail, other.m_tail);
        this->m_allocatorProvider.swap(other.m_allocatorProvider);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline void ListHashSet<T, inlineCapacity, U, V>::finalize()
    {
        static_assert(!Allocator::isGarbageCollected, "heap allocated ListHashSet should never call finalize()");
        deleteAllNodes();
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline T& ListHashSet<T, inlineCapacity, U, V>::first()
    {
        ASSERT(!isEmpty());
        return m_head->m_value;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline void ListHashSet<T, inlineCapacity, U, V>::removeFirst()
    {
        ASSERT(!isEmpty());
        m_impl.remove(m_head);
        unlinkAndDelete(m_head);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline const T& ListHashSet<T, inlineCapacity, U, V>::first() const
    {
        ASSERT(!isEmpty());
        return m_head->m_value;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline T& ListHashSet<T, inlineCapacity, U, V>::last()
    {
        ASSERT(!isEmpty());
        return m_tail->m_value;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline const T& ListHashSet<T, inlineCapacity, U, V>::last() const
    {
        ASSERT(!isEmpty());
        return m_tail->m_value;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline void ListHashSet<T, inlineCapacity, U, V>::removeLast()
    {
        ASSERT(!isEmpty());
        m_impl.remove(m_tail);
        unlinkAndDelete(m_tail);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline typename ListHashSet<T, inlineCapacity, U, V>::iterator ListHashSet<T, inlineCapacity, U, V>::find(ValuePeekInType value)
    {
        ImplTypeIterator it = m_impl.template find<BaseTranslator>(value);
        if (it == m_impl.end())
            return end();
        return makeIterator(*it);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline typename ListHashSet<T, inlineCapacity, U, V>::const_iterator ListHashSet<T, inlineCapacity, U, V>::find(ValuePeekInType value) const
    {
        ImplTypeConstIterator it = m_impl.template find<BaseTranslator>(value);
        if (it == m_impl.end())
            return end();
        return makeConstIterator(*it);
    }

    template<typename Translator>
    struct ListHashSetTranslatorAdapter {
        template<typename T> static unsigned hash(const T& key) { return Translator::hash(key); }
        template<typename T, typename U> static bool equal(const T& a, const U& b) { return Translator::equal(a->m_value, b); }
    };

    template<typename ValueType, size_t inlineCapacity, typename U, typename V>
    template<typename HashTranslator, typename T>
    inline typename ListHashSet<ValueType, inlineCapacity, U, V>::iterator ListHashSet<ValueType, inlineCapacity, U, V>::find(const T& value)
    {
        ImplTypeConstIterator it = m_impl.template find<ListHashSetTranslatorAdapter<HashTranslator>>(value);
        if (it == m_impl.end())
            return end();
        return makeIterator(*it);
    }

    template<typename ValueType, size_t inlineCapacity, typename U, typename V>
    template<typename HashTranslator, typename T>
    inline typename ListHashSet<ValueType, inlineCapacity, U, V>::const_iterator ListHashSet<ValueType, inlineCapacity, U, V>::find(const T& value) const
    {
        ImplTypeConstIterator it = m_impl.template find<ListHashSetTranslatorAdapter<HashTranslator>>(value);
        if (it == m_impl.end())
            return end();
        return makeConstIterator(*it);
    }

    template<typename ValueType, size_t inlineCapacity, typename U, typename V>
    template<typename HashTranslator, typename T>
    inline bool ListHashSet<ValueType, inlineCapacity, U, V>::contains(const T& value) const
    {
        return m_impl.template contains<ListHashSetTranslatorAdapter<HashTranslator>>(value);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline bool ListHashSet<T, inlineCapacity, U, V>::contains(ValuePeekInType value) const
    {
        return m_impl.template contains<BaseTranslator>(value);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::AddResult ListHashSet<T, inlineCapacity, U, V>::add(ValuePassInType value)
    {
        createAllocatorIfNeeded();
        // The second argument is a const ref. This is useful for the HashTable
        // because it lets it take lvalues by reference, but for our purposes
        // it's inconvenient, since it constrains us to be const, whereas the
        // allocator actually changes when it does allocations.
        typename ImplType::AddResult result = m_impl.template add<BaseTranslator>(value, *this->allocator());
        if (result.isNewEntry)
            appendNode(*result.storedValue);
        return AddResult(*result.storedValue, result.isNewEntry);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::iterator ListHashSet<T, inlineCapacity, U, V>::addReturnIterator(ValuePassInType value)
    {
        return makeIterator(add(value).storedValue);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::AddResult ListHashSet<T, inlineCapacity, U, V>::appendOrMoveToLast(ValuePassInType value)
    {
        createAllocatorIfNeeded();
        typename ImplType::AddResult result = m_impl.template add<BaseTranslator>(value, *this->allocator());
        Node* node = *result.storedValue;
        if (!result.isNewEntry)
            unlink(node);
        appendNode(node);
        return AddResult(*result.storedValue, result.isNewEntry);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::AddResult ListHashSet<T, inlineCapacity, U, V>::prependOrMoveToFirst(ValuePassInType value)
    {
        createAllocatorIfNeeded();
        typename ImplType::AddResult result = m_impl.template add<BaseTranslator>(value, *this->allocator());
        Node* node = *result.storedValue;
        if (!result.isNewEntry)
            unlink(node);
        prependNode(node);
        return AddResult(*result.storedValue, result.isNewEntry);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::AddResult ListHashSet<T, inlineCapacity, U, V>::insertBefore(iterator it, ValuePassInType newValue)
    {
        createAllocatorIfNeeded();
        typename ImplType::AddResult result = m_impl.template add<BaseTranslator>(newValue, *this->allocator());
        if (result.isNewEntry)
            insertNodeBefore(it.node(), *result.storedValue);
        return AddResult(*result.storedValue, result.isNewEntry);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::AddResult ListHashSet<T, inlineCapacity, U, V>::insertBefore(ValuePeekInType beforeValue, ValuePassInType newValue)
    {
        createAllocatorIfNeeded();
        return insertBefore(find(beforeValue), newValue);
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline void ListHashSet<T, inlineCapacity, U, V>::remove(iterator it)
    {
        if (it == end())
            return;
        m_impl.remove(it.node());
        unlinkAndDelete(it.node());
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    inline void ListHashSet<T, inlineCapacity, U, V>::clear()
    {
        deleteAllNodes();
        m_impl.clear();
        m_head = 0;
        m_tail = 0;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::ValuePassOutType ListHashSet<T, inlineCapacity, U, V>::take(iterator it)
    {
        if (it == end())
            return ValueTraits::emptyValue();

        m_impl.remove(it.node());
        ValuePassOutType result = ValueTraits::passOut(it.node()->m_value);
        unlinkAndDelete(it.node());

        return result;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::ValuePassOutType ListHashSet<T, inlineCapacity, U, V>::take(ValuePeekInType value)
    {
        return take(find(value));
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    typename ListHashSet<T, inlineCapacity, U, V>::ValuePassOutType ListHashSet<T, inlineCapacity, U, V>::takeFirst()
    {
        ASSERT(!isEmpty());
        m_impl.remove(m_head);
        ValuePassOutType result = ValueTraits::passOut(m_head->m_value);
        unlinkAndDelete(m_head);

        return result;
    }

    template<typename T, size_t inlineCapacity, typename U, typename Allocator>
    void ListHashSet<T, inlineCapacity, U, Allocator>::unlink(Node* node)
    {
        if (!node->m_prev) {
            ASSERT(node == m_head);
            m_head = node->next();
        } else {
            ASSERT(node != m_head);
            node->m_prev->m_next = node->m_next;
        }

        if (!node->m_next) {
            ASSERT(node == m_tail);
            m_tail = node->prev();
        } else {
            ASSERT(node != m_tail);
            node->m_next->m_prev = node->m_prev;
        }
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    void ListHashSet<T, inlineCapacity, U, V>::unlinkAndDelete(Node* node)
    {
        unlink(node);
        node->destroy(this->allocator());
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    void ListHashSet<T, inlineCapacity, U, V>::appendNode(Node* node)
    {
        node->m_prev = m_tail;
        node->m_next = 0;

        if (m_tail) {
            ASSERT(m_head);
            m_tail->m_next = node;
        } else {
            ASSERT(!m_head);
            m_head = node;
        }

        m_tail = node;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    void ListHashSet<T, inlineCapacity, U, V>::prependNode(Node* node)
    {
        node->m_prev = 0;
        node->m_next = m_head;

        if (m_head)
            m_head->m_prev = node;
        else
            m_tail = node;

        m_head = node;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    void ListHashSet<T, inlineCapacity, U, V>::insertNodeBefore(Node* beforeNode, Node* newNode)
    {
        if (!beforeNode)
            return appendNode(newNode);

        newNode->m_next = beforeNode;
        newNode->m_prev = beforeNode->m_prev;
        if (beforeNode->m_prev)
            beforeNode->m_prev->m_next = newNode;
        beforeNode->m_prev = newNode;

        if (!newNode->m_prev)
            m_head = newNode;
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    void ListHashSet<T, inlineCapacity, U, V>::deleteAllNodes()
    {
        if (!m_head)
            return;

        for (Node* node = m_head, *next = m_head->next(); node; node = next, next = node ? node->next() : 0)
            node->destroy(this->allocator());
    }

    template<typename T, size_t inlineCapacity, typename U, typename V>
    void ListHashSet<T, inlineCapacity, U, V>::trace(typename Allocator::Visitor* visitor)
    {
        static_assert(HashTraits<T>::weakHandlingFlag == NoWeakHandlingInCollections, "ListHashSet does not support weakness");
        // This marks all the nodes and their contents live that can be
        // accessed through the HashTable. That includes m_head and m_tail
        // so we do not have to explicitly trace them here.
        m_impl.trace(visitor);
    }

#if !ENABLE(OILPAN)
    template<typename T, size_t U, typename V>
    struct NeedsTracing<ListHashSet<T, U, V>> {
        static const bool value = false;
    };
#endif

} // namespace WTF

using WTF::ListHashSet;

#endif /* WTF_ListHashSet_h */