flutter_flutter/sky/engine/wtf/HashTable.h

/*
 * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc.
 * All rights reserved.
 * Copyright (C) 2008 David Levin <levin@chromium.org>
 *
 * 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 SKY_ENGINE_WTF_HASHTABLE_H_
#define SKY_ENGINE_WTF_HASHTABLE_H_

#include "flutter/sky/engine/wtf/Alignment.h"
#include "flutter/sky/engine/wtf/Assertions.h"
#include "flutter/sky/engine/wtf/DefaultAllocator.h"
#include "flutter/sky/engine/wtf/HashTraits.h"
#include "flutter/sky/engine/wtf/WTF.h"

#define DUMP_HASHTABLE_STATS 0
#define DUMP_HASHTABLE_STATS_PER_TABLE 0

#if DUMP_HASHTABLE_STATS_PER_TABLE
#include "flutter/sky/engine/wtf/DataLog.h"
#endif

#if DUMP_HASHTABLE_STATS
#if DUMP_HASHTABLE_STATS_PER_TABLE
#define UPDATE_PROBE_COUNTS()                         \
  ++probeCount;                                       \
  HashTableStats::recordCollisionAtCount(probeCount); \
  ++perTableProbeCount;                               \
  m_stats->recordCollisionAtCount(perTableProbeCount)
#define UPDATE_ACCESS_COUNTS()                   \
  atomicIncrement(&HashTableStats::numAccesses); \
  int probeCount = 0;                            \
  ++m_stats->numAccesses;                        \
  int perTableProbeCount = 0
#else
#define UPDATE_PROBE_COUNTS() \
  ++probeCount;               \
  HashTableStats::recordCollisionAtCount(probeCount)
#define UPDATE_ACCESS_COUNTS()                   \
  atomicIncrement(&HashTableStats::numAccesses); \
  int probeCount = 0
#endif
#else
#if DUMP_HASHTABLE_STATS_PER_TABLE
#define UPDATE_PROBE_COUNTS() \
  ++perTableProbeCount;       \
  m_stats->recordCollisionAtCount(perTableProbeCount)
#define UPDATE_ACCESS_COUNTS() \
  ++m_stats->numAccesses;      \
  int perTableProbeCount = 0
#else
#define UPDATE_PROBE_COUNTS() \
  do {                        \
  } while (0)
#define UPDATE_ACCESS_COUNTS() \
  do {                         \
  } while (0)
#endif
#endif

namespace WTF {

#if DUMP_HASHTABLE_STATS

struct HashTableStats {
  // The following variables are all atomically incremented when modified.
  static int numAccesses;
  static int numRehashes;
  static int numRemoves;
  static int numReinserts;

  // The following variables are only modified in the recordCollisionAtCount
  // method within a mutex.
  static int maxCollisions;
  static int numCollisions;
  static int collisionGraph[4096];

  static void recordCollisionAtCount(int count);
  static void dumpStats();
};

#endif

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
class HashTable;
template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
class HashTableIterator;
template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
class HashTableConstIterator;
template <typename Value,
          typename HashFunctions,
          typename HashTraits,
          typename Allocator>
class LinkedHashSet;

typedef enum { HashItemKnownGood } HashItemKnownGoodTag;

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
class HashTableConstIterator {
 private:
  typedef HashTable<Key,
                    Value,
                    Extractor,
                    HashFunctions,
                    Traits,
                    KeyTraits,
                    Allocator>
      HashTableType;
  typedef HashTableIterator<Key,
                            Value,
                            Extractor,
                            HashFunctions,
                            Traits,
                            KeyTraits,
                            Allocator>
      iterator;
  typedef HashTableConstIterator<Key,
                                 Value,
                                 Extractor,
                                 HashFunctions,
                                 Traits,
                                 KeyTraits,
                                 Allocator>
      const_iterator;
  typedef Value ValueType;
  typedef typename Traits::IteratorConstGetType GetType;
  typedef const ValueType* PointerType;

  friend class HashTable<Key,
                         Value,
                         Extractor,
                         HashFunctions,
                         Traits,
                         KeyTraits,
                         Allocator>;
  friend class HashTableIterator<Key,
                                 Value,
                                 Extractor,
                                 HashFunctions,
                                 Traits,
                                 KeyTraits,
                                 Allocator>;

  void skipEmptyBuckets() {
    while (m_position != m_endPosition &&
           HashTableType::isEmptyOrDeletedBucket(*m_position))
      ++m_position;
  }

  HashTableConstIterator(PointerType position,
                         PointerType endPosition,
                         const HashTableType* container)
      : m_position(position),
        m_endPosition(endPosition)
#if ENABLE(ASSERT)
        ,
        m_container(container),
        m_containerModifications(container->modifications())
#endif
  {
    skipEmptyBuckets();
  }

  HashTableConstIterator(PointerType position,
                         PointerType endPosition,
                         const HashTableType* container,
                         HashItemKnownGoodTag)
      : m_position(position),
        m_endPosition(endPosition)
#if ENABLE(ASSERT)
        ,
        m_container(container),
        m_containerModifications(container->modifications())
#endif
  {
    ASSERT(m_containerModifications == m_container->modifications());
  }

  void checkModifications() const {
    // HashTable and collections that build on it do not support
    // modifications while there is an iterator in use. The exception
    // is ListHashSet, which has its own iterators that tolerate
    // modification of the underlying set.
    ASSERT(m_containerModifications == m_container->modifications());
  }

 public:
  HashTableConstIterator() {}

  GetType get() const {
    checkModifications();
    return m_position;
  }
  typename Traits::IteratorConstReferenceType operator*() const {
    return Traits::getToReferenceConstConversion(get());
  }
  GetType operator->() const { return get(); }

  const_iterator& operator++() {
    ASSERT(m_position != m_endPosition);
    checkModifications();
    ++m_position;
    skipEmptyBuckets();
    return *this;
  }

  // postfix ++ intentionally omitted

  // Comparison.
  bool operator==(const const_iterator& other) const {
    return m_position == other.m_position;
  }
  bool operator!=(const const_iterator& other) const {
    return m_position != other.m_position;
  }
  bool operator==(const iterator& other) const {
    return *this == static_cast<const_iterator>(other);
  }
  bool operator!=(const iterator& other) const {
    return *this != static_cast<const_iterator>(other);
  }

 private:
  PointerType m_position;
  PointerType m_endPosition;
#if ENABLE(ASSERT)
  const HashTableType* m_container;
  int64_t m_containerModifications;
#endif
};

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
class HashTableIterator {
 private:
  typedef HashTable<Key,
                    Value,
                    Extractor,
                    HashFunctions,
                    Traits,
                    KeyTraits,
                    Allocator>
      HashTableType;
  typedef HashTableIterator<Key,
                            Value,
                            Extractor,
                            HashFunctions,
                            Traits,
                            KeyTraits,
                            Allocator>
      iterator;
  typedef HashTableConstIterator<Key,
                                 Value,
                                 Extractor,
                                 HashFunctions,
                                 Traits,
                                 KeyTraits,
                                 Allocator>
      const_iterator;
  typedef Value ValueType;
  typedef typename Traits::IteratorGetType GetType;
  typedef ValueType* PointerType;

  friend class HashTable<Key,
                         Value,
                         Extractor,
                         HashFunctions,
                         Traits,
                         KeyTraits,
                         Allocator>;

  HashTableIterator(PointerType pos,
                    PointerType end,
                    const HashTableType* container)
      : m_iterator(pos, end, container) {}
  HashTableIterator(PointerType pos,
                    PointerType end,
                    const HashTableType* container,
                    HashItemKnownGoodTag tag)
      : m_iterator(pos, end, container, tag) {}

 public:
  HashTableIterator() {}

  // default copy, assignment and destructor are OK

  GetType get() const { return const_cast<GetType>(m_iterator.get()); }
  typename Traits::IteratorReferenceType operator*() const {
    return Traits::getToReferenceConversion(get());
  }
  GetType operator->() const { return get(); }

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

  // postfix ++ intentionally omitted

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

  operator const_iterator() const { return m_iterator; }

 private:
  const_iterator m_iterator;
};

using std::swap;

// Work around MSVC's standard library, whose swap for pairs does not swap by
// component.
template <typename T>
inline void hashTableSwap(T& a, T& b) {
  swap(a, b);
}

template <typename T, typename U>
inline void hashTableSwap(KeyValuePair<T, U>& a, KeyValuePair<T, U>& b) {
  swap(a.key, b.key);
  swap(a.value, b.value);
}

template <typename T, typename Allocator, bool useSwap>
struct Mover;
template <typename T, typename Allocator>
struct Mover<T, Allocator, true> {
  static void move(T& from, T& to) {
    // A swap operation should not normally allocate, but it may do so
    // if it is falling back on some sort of triple assignment in the
    // style of t = a; a = b; b = t because there is no overloaded swap
    // operation. We can't allow allocation both because it is slower
    // than a true swap operation, but also because allocation implies
    // allowing GC: We cannot allow a GC after swapping only the key.
    // The value is only traced if the key is present and therefore the
    // GC will not see the value in the old backing if the key has been
    // moved to the new backing. Therefore, we cannot allow GC until
    // after both key and value have been moved.
    Allocator::enterNoAllocationScope();
    hashTableSwap(from, to);
    Allocator::leaveNoAllocationScope();
  }
};
template <typename T, typename Allocator>
struct Mover<T, Allocator, false> {
  static void move(T& from, T& to) { to = from; }
};

template <typename HashFunctions>
class IdentityHashTranslator {
 public:
  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, b);
  }
  template <typename T, typename U, typename V>
  static void translate(T& location, const U&, const V& value) {
    location = value;
  }
};

template <typename HashTableType, typename ValueType>
struct HashTableAddResult {
  HashTableAddResult(const HashTableType* container,
                     ValueType* storedValue,
                     bool isNewEntry)
      : storedValue(storedValue),
        isNewEntry(isNewEntry)
#if ENABLE(SECURITY_ASSERT)
        ,
        m_container(container),
        m_containerModifications(container->modifications())
#endif
  {
    ASSERT_UNUSED(container, container);
  }

  ~HashTableAddResult() {
    // If rehash happened before accessing storedValue, it's
    // use-after-free. Any modification may cause a rehash, so we check
    // for modifications here.
    // Rehash after accessing storedValue is harmless but will assert if
    // the AddResult destructor takes place after a modification. You
    // may need to limit the scope of the AddResult.
    ASSERT_WITH_SECURITY_IMPLICATION(m_containerModifications ==
                                     m_container->modifications());
  }

  ValueType* storedValue;
  bool isNewEntry;

#if ENABLE(SECURITY_ASSERT)
 private:
  const HashTableType* m_container;
  const int64_t m_containerModifications;
#endif
};

template <typename Value, typename Extractor, typename KeyTraits>
struct HashTableHelper {
  static bool isEmptyBucket(const Value& value) {
    return isHashTraitsEmptyValue<KeyTraits>(Extractor::extract(value));
  }
  static bool isDeletedBucket(const Value& value) {
    return KeyTraits::isDeletedValue(Extractor::extract(value));
  }
  static bool isEmptyOrDeletedBucket(const Value& value) {
    return isEmptyBucket(value) || isDeletedBucket(value);
  }
};

template <typename HashTranslator,
          typename KeyTraits,
          bool safeToCompareToEmptyOrDeleted>
struct HashTableKeyChecker {
  // There's no simple generic way to make this check if
  // safeToCompareToEmptyOrDeleted is false, so the check always passes.
  template <typename T>
  static bool checkKey(const T&) {
    return true;
  }
};

template <typename HashTranslator, typename KeyTraits>
struct HashTableKeyChecker<HashTranslator, KeyTraits, true> {
  template <typename T>
  static bool checkKey(const T& key) {
    // FIXME : Check also equality to the deleted value.
    return !HashTranslator::equal(KeyTraits::emptyValue(), key);
  }
};

// Don't declare a destructor for HeapAllocated hash tables.
template <typename Derived, bool isGarbageCollected>
class HashTableDestructorBase;

template <typename Derived>
class HashTableDestructorBase<Derived, true> {};

template <typename Derived>
class HashTableDestructorBase<Derived, false> {
 public:
  ~HashTableDestructorBase() { static_cast<Derived*>(this)->finalize(); }
};

// Note: empty or deleted key values are not allowed, using them may lead to
// undefined behavior. For pointer keys this means that null pointers are not
// allowed unless you supply custom key traits.
template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
class HashTable
    : public HashTableDestructorBase<HashTable<Key,
                                               Value,
                                               Extractor,
                                               HashFunctions,
                                               Traits,
                                               KeyTraits,
                                               Allocator>,
                                     Allocator::isGarbageCollected> {
 public:
  typedef HashTableIterator<Key,
                            Value,
                            Extractor,
                            HashFunctions,
                            Traits,
                            KeyTraits,
                            Allocator>
      iterator;
  typedef HashTableConstIterator<Key,
                                 Value,
                                 Extractor,
                                 HashFunctions,
                                 Traits,
                                 KeyTraits,
                                 Allocator>
      const_iterator;
  typedef Traits ValueTraits;
  typedef Key KeyType;
  typedef typename KeyTraits::PeekInType KeyPeekInType;
  typedef typename KeyTraits::PassInType KeyPassInType;
  typedef Value ValueType;
  typedef Extractor ExtractorType;
  typedef KeyTraits KeyTraitsType;
  typedef typename Traits::PassInType ValuePassInType;
  typedef IdentityHashTranslator<HashFunctions> IdentityTranslatorType;
  typedef HashTableAddResult<HashTable, ValueType> AddResult;

#if DUMP_HASHTABLE_STATS_PER_TABLE
  struct Stats {
    Stats()
        : numAccesses(0),
          numRehashes(0),
          numRemoves(0),
          numReinserts(0),
          maxCollisions(0),
          numCollisions(0),
          collisionGraph() {}

    int numAccesses;
    int numRehashes;
    int numRemoves;
    int numReinserts;

    int maxCollisions;
    int numCollisions;
    int collisionGraph[4096];

    void recordCollisionAtCount(int count) {
      if (count > maxCollisions)
        maxCollisions = count;
      numCollisions++;
      collisionGraph[count]++;
    }

    void dumpStats() {
      dataLogF("\nWTF::HashTable::Stats dump\n\n");
      dataLogF("%d accesses\n", numAccesses);
      dataLogF("%d total collisions, average %.2f probes per access\n",
               numCollisions,
               1.0 * (numAccesses + numCollisions) / numAccesses);
      dataLogF("longest collision chain: %d\n", maxCollisions);
      for (int i = 1; i <= maxCollisions; i++) {
        dataLogF(
            "  %d lookups with exactly %d collisions (%.2f%% , %.2f%% with "
            "this many or more)\n",
            collisionGraph[i], i,
            100.0 * (collisionGraph[i] - collisionGraph[i + 1]) / numAccesses,
            100.0 * collisionGraph[i] / numAccesses);
      }
      dataLogF("%d rehashes\n", numRehashes);
      dataLogF("%d reinserts\n", numReinserts);
    }
  };
#endif

  HashTable();
  void finalize() {
    ASSERT(!Allocator::isGarbageCollected);
    if (LIKELY(!m_table))
      return;
    deleteAllBucketsAndDeallocate(m_table, m_tableSize);
    m_table = 0;
  }

  HashTable(const HashTable&);
  void swap(HashTable&);
  HashTable& operator=(const HashTable&);

  // When the hash table is empty, just return the same iterator for end as for
  // begin. This is more efficient because we don't have to skip all the empty
  // and deleted buckets, and iterating an empty table is a common case that's
  // worth optimizing.
  iterator begin() { return isEmpty() ? end() : makeIterator(m_table); }
  iterator end() { return makeKnownGoodIterator(m_table + m_tableSize); }
  const_iterator begin() const {
    return isEmpty() ? end() : makeConstIterator(m_table);
  }
  const_iterator end() const {
    return makeKnownGoodConstIterator(m_table + m_tableSize);
  }

  unsigned size() const { return m_keyCount; }
  unsigned capacity() const { return m_tableSize; }
  bool isEmpty() const { return !m_keyCount; }

  AddResult add(ValuePassInType value) {
    return add<IdentityTranslatorType>(Extractor::extract(value), value);
  }

  // A special version of add() that finds the object by hashing and comparing
  // with some other type, to avoid the cost of type conversion if the object is
  // already in the table.
  template <typename HashTranslator, typename T, typename Extra>
  AddResult add(const T& key, const Extra&);
  template <typename HashTranslator, typename T, typename Extra>
  AddResult addPassingHashCode(const T& key, const Extra&);

  iterator find(KeyPeekInType key) { return find<IdentityTranslatorType>(key); }
  const_iterator find(KeyPeekInType key) const {
    return find<IdentityTranslatorType>(key);
  }
  bool contains(KeyPeekInType key) const {
    return contains<IdentityTranslatorType>(key);
  }

  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;

  void remove(KeyPeekInType);
  void remove(iterator);
  void remove(const_iterator);
  void clear();

  static bool isEmptyBucket(const ValueType& value) {
    return isHashTraitsEmptyValue<KeyTraits>(Extractor::extract(value));
  }
  static bool isDeletedBucket(const ValueType& value) {
    return KeyTraits::isDeletedValue(Extractor::extract(value));
  }
  static bool isEmptyOrDeletedBucket(const ValueType& value) {
    return HashTableHelper<ValueType, Extractor,
                           KeyTraits>::isEmptyOrDeletedBucket(value);
  }

  ValueType* lookup(KeyPeekInType key) {
    return lookup<IdentityTranslatorType, KeyPeekInType>(key);
  }
  template <typename HashTranslator, typename T>
  ValueType* lookup(T);
  template <typename HashTranslator, typename T>
  const ValueType* lookup(T) const;

#if ENABLE(ASSERT)
  int64_t modifications() const { return m_modifications; }
  void registerModification() { m_modifications++; }
  // HashTable and collections that build on it do not support
  // modifications while there is an iterator in use. The exception is
  // ListHashSet, which has its own iterators that tolerate modification
  // of the underlying set.
  void checkModifications(int64_t mods) const {
    ASSERT(mods == m_modifications);
  }
#else
  int64_t modifications() const { return 0; }
  void registerModification() {}
  void checkModifications(int64_t mods) const {}
#endif

 private:
  static ValueType* allocateTable(unsigned size);
  static void deleteAllBucketsAndDeallocate(ValueType* table, unsigned size);

  typedef std::pair<ValueType*, bool> LookupType;
  typedef std::pair<LookupType, unsigned> FullLookupType;

  LookupType lookupForWriting(const Key& key) {
    return lookupForWriting<IdentityTranslatorType>(key);
  };
  template <typename HashTranslator, typename T>
  FullLookupType fullLookupForWriting(const T&);
  template <typename HashTranslator, typename T>
  LookupType lookupForWriting(const T&);

  void remove(ValueType*);

  bool shouldExpand() const {
    return (m_keyCount + m_deletedCount) * m_maxLoad >= m_tableSize;
  }
  bool mustRehashInPlace() const {
    return m_keyCount * m_minLoad < m_tableSize * 2;
  }
  bool shouldShrink() const {
    // isAllocationAllowed check should be at the last because it's
    // expensive.
    return m_keyCount * m_minLoad < m_tableSize &&
           m_tableSize > KeyTraits::minimumTableSize &&
           Allocator::isAllocationAllowed();
  }
  ValueType* expand(ValueType* entry = 0);
  void shrink() { rehash(m_tableSize / 2, 0); }

  ValueType* rehash(unsigned newTableSize, ValueType* entry);
  ValueType* reinsert(ValueType&);

  static void initializeBucket(ValueType& bucket);
  static void deleteBucket(ValueType& bucket) {
    bucket.~ValueType();
    Traits::constructDeletedValue(bucket, Allocator::isGarbageCollected);
  }

  FullLookupType makeLookupResult(ValueType* position,
                                  bool found,
                                  unsigned hash) {
    return FullLookupType(LookupType(position, found), hash);
  }

  iterator makeIterator(ValueType* pos) {
    return iterator(pos, m_table + m_tableSize, this);
  }
  const_iterator makeConstIterator(ValueType* pos) const {
    return const_iterator(pos, m_table + m_tableSize, this);
  }
  iterator makeKnownGoodIterator(ValueType* pos) {
    return iterator(pos, m_table + m_tableSize, this, HashItemKnownGood);
  }
  const_iterator makeKnownGoodConstIterator(ValueType* pos) const {
    return const_iterator(pos, m_table + m_tableSize, this, HashItemKnownGood);
  }

  static const unsigned m_maxLoad = 2;
  static const unsigned m_minLoad = 6;

  unsigned tableSizeMask() const {
    size_t mask = m_tableSize - 1;
    ASSERT((mask & m_tableSize) == 0);
    return mask;
  }

  void setEnqueued() { m_queueFlag = true; }
  void clearEnqueued() { m_queueFlag = false; }
  bool enqueued() { return m_queueFlag; }

  ValueType* m_table;
  unsigned m_tableSize;
  unsigned m_keyCount;
  unsigned m_deletedCount : 31;
  bool m_queueFlag : 1;
#if ENABLE(ASSERT)
  unsigned m_modifications;
#endif

#if DUMP_HASHTABLE_STATS_PER_TABLE
 public:
  mutable OwnPtr<Stats> m_stats;
#endif

  template <typename T, typename U, typename V, typename W>
  friend class LinkedHashSet;
};

// Set all the bits to one after the most significant bit: 00110101010 ->
// 00111111111.
template <unsigned size>
struct OneifyLowBits;
template <>
struct OneifyLowBits<0> {
  static const unsigned value = 0;
};
template <unsigned number>
struct OneifyLowBits {
  static const unsigned value = number | OneifyLowBits<(number >> 1)>::value;
};
// Compute the first power of two integer that is an upper bound of the
// parameter 'number'.
template <unsigned number>
struct UpperPowerOfTwoBound {
  static const unsigned value = (OneifyLowBits<number - 1>::value + 1) * 2;
};

// Because power of two numbers are the limit of maxLoad, their capacity is
// twice the UpperPowerOfTwoBound, or 4 times their values.
template <unsigned size, bool isPowerOfTwo>
struct HashTableCapacityForSizeSplitter;
template <unsigned size>
struct HashTableCapacityForSizeSplitter<size, true> {
  static const unsigned value = size * 4;
};
template <unsigned size>
struct HashTableCapacityForSizeSplitter<size, false> {
  static const unsigned value = UpperPowerOfTwoBound<size>::value;
};

// HashTableCapacityForSize computes the upper power of two capacity to hold the
// size parameter. This is done at compile time to initialize the HashTraits.
template <unsigned size>
struct HashTableCapacityForSize {
  static const unsigned value =
      HashTableCapacityForSizeSplitter<size, !(size & (size - 1))>::value;
  COMPILE_ASSERT(size > 0, HashTableNonZeroMinimumCapacity);
  COMPILE_ASSERT(!static_cast<int>(value >> 31), HashTableNoCapacityOverflow);
  COMPILE_ASSERT(value > (2 * size), HashTableCapacityHoldsContentSize);
};

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
inline HashTable<Key,
                 Value,
                 Extractor,
                 HashFunctions,
                 Traits,
                 KeyTraits,
                 Allocator>::HashTable()
    : m_table(0),
      m_tableSize(0),
      m_keyCount(0),
      m_deletedCount(0),
      m_queueFlag(false)
#if ENABLE(ASSERT)
      ,
      m_modifications(0)
#endif
#if DUMP_HASHTABLE_STATS_PER_TABLE
      ,
      m_stats(adoptPtr(new Stats))
#endif
{
}

inline unsigned doubleHash(unsigned key) {
  key = ~key + (key >> 23);
  key ^= (key << 12);
  key ^= (key >> 7);
  key ^= (key << 2);
  key ^= (key >> 20);
  return key;
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T>
inline Value*
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    lookup(T key) {
  return const_cast<Value*>(
      const_cast<const HashTable*>(this)->lookup<HashTranslator, T>(key));
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T>
inline const Value*
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    lookup(T key) const {
  ASSERT((HashTableKeyChecker<
          HashTranslator, KeyTraits,
          HashFunctions::safeToCompareToEmptyOrDeleted>::checkKey(key)));
  const ValueType* table = m_table;
  if (!table)
    return 0;

  size_t k = 0;
  size_t sizeMask = tableSizeMask();
  unsigned h = HashTranslator::hash(key);
  size_t i = h & sizeMask;

  UPDATE_ACCESS_COUNTS();

  while (1) {
    const ValueType* entry = table + i;

    if (HashFunctions::safeToCompareToEmptyOrDeleted) {
      if (HashTranslator::equal(Extractor::extract(*entry), key))
        return entry;

      if (isEmptyBucket(*entry))
        return 0;
    } else {
      if (isEmptyBucket(*entry))
        return 0;

      if (!isDeletedBucket(*entry) &&
          HashTranslator::equal(Extractor::extract(*entry), key))
        return entry;
    }
    UPDATE_PROBE_COUNTS();
    if (!k)
      k = 1 | doubleHash(h);
    i = (i + k) & sizeMask;
  }
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T>
inline typename HashTable<Key,
                          Value,
                          Extractor,
                          HashFunctions,
                          Traits,
                          KeyTraits,
                          Allocator>::LookupType
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    lookupForWriting(const T& key) {
  ASSERT(m_table);
  registerModification();

  ValueType* table = m_table;
  size_t k = 0;
  size_t sizeMask = tableSizeMask();
  unsigned h = HashTranslator::hash(key);
  size_t i = h & sizeMask;

  UPDATE_ACCESS_COUNTS();

  ValueType* deletedEntry = 0;

  while (1) {
    ValueType* entry = table + i;

    if (isEmptyBucket(*entry))
      return LookupType(deletedEntry ? deletedEntry : entry, false);

    if (HashFunctions::safeToCompareToEmptyOrDeleted) {
      if (HashTranslator::equal(Extractor::extract(*entry), key))
        return LookupType(entry, true);

      if (isDeletedBucket(*entry))
        deletedEntry = entry;
    } else {
      if (isDeletedBucket(*entry))
        deletedEntry = entry;
      else if (HashTranslator::equal(Extractor::extract(*entry), key))
        return LookupType(entry, true);
    }
    UPDATE_PROBE_COUNTS();
    if (!k)
      k = 1 | doubleHash(h);
    i = (i + k) & sizeMask;
  }
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T>
inline typename HashTable<Key,
                          Value,
                          Extractor,
                          HashFunctions,
                          Traits,
                          KeyTraits,
                          Allocator>::FullLookupType
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    fullLookupForWriting(const T& key) {
  ASSERT(m_table);
  registerModification();

  ValueType* table = m_table;
  size_t k = 0;
  size_t sizeMask = tableSizeMask();
  unsigned h = HashTranslator::hash(key);
  size_t i = h & sizeMask;

  UPDATE_ACCESS_COUNTS();

  ValueType* deletedEntry = 0;

  while (1) {
    ValueType* entry = table + i;

    if (isEmptyBucket(*entry))
      return makeLookupResult(deletedEntry ? deletedEntry : entry, false, h);

    if (HashFunctions::safeToCompareToEmptyOrDeleted) {
      if (HashTranslator::equal(Extractor::extract(*entry), key))
        return makeLookupResult(entry, true, h);

      if (isDeletedBucket(*entry))
        deletedEntry = entry;
    } else {
      if (isDeletedBucket(*entry))
        deletedEntry = entry;
      else if (HashTranslator::equal(Extractor::extract(*entry), key))
        return makeLookupResult(entry, true, h);
    }
    UPDATE_PROBE_COUNTS();
    if (!k)
      k = 1 | doubleHash(h);
    i = (i + k) & sizeMask;
  }
}

template <bool emptyValueIsZero>
struct HashTableBucketInitializer;

template <>
struct HashTableBucketInitializer<false> {
  template <typename Traits, typename Value>
  static void initialize(Value& bucket) {
    new (NotNull, &bucket) Value(Traits::emptyValue());
  }
};

template <>
struct HashTableBucketInitializer<true> {
  template <typename Traits, typename Value>
  static void initialize(Value& bucket) {
    // This initializes the bucket without copying the empty value.
    // That makes it possible to use this with types that don't support copying.
    // The memset to 0 looks like a slow operation but is optimized by the
    // compilers.
    memset(&bucket, 0, sizeof(bucket));
  }
};

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
inline void
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    initializeBucket(ValueType& bucket) {
  // For hash maps the key and value cannot be initialied simultaneously,
  // and it would be wrong to have a GC when only one was initialized and
  // the other still contained garbage (eg. from a previous use of the
  // same slot). Therefore we forbid allocation (and thus GC) while the
  // slot is initalized to an empty value.
  Allocator::enterNoAllocationScope();
  HashTableBucketInitializer<Traits::emptyValueIsZero>::template initialize<
      Traits>(bucket);
  Allocator::leaveNoAllocationScope();
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T, typename Extra>
typename HashTable<Key,
                   Value,
                   Extractor,
                   HashFunctions,
                   Traits,
                   KeyTraits,
                   Allocator>::AddResult
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    add(const T& key, const Extra& extra) {
  ASSERT(Allocator::isAllocationAllowed());
  if (!m_table)
    expand();

  ASSERT(m_table);

  ValueType* table = m_table;
  size_t k = 0;
  size_t sizeMask = tableSizeMask();
  unsigned h = HashTranslator::hash(key);
  size_t i = h & sizeMask;

  UPDATE_ACCESS_COUNTS();

  ValueType* deletedEntry = 0;
  ValueType* entry;
  while (1) {
    entry = table + i;

    if (isEmptyBucket(*entry))
      break;

    if (HashFunctions::safeToCompareToEmptyOrDeleted) {
      if (HashTranslator::equal(Extractor::extract(*entry), key))
        return AddResult(this, entry, false);

      if (isDeletedBucket(*entry))
        deletedEntry = entry;
    } else {
      if (isDeletedBucket(*entry))
        deletedEntry = entry;
      else if (HashTranslator::equal(Extractor::extract(*entry), key))
        return AddResult(this, entry, false);
    }
    UPDATE_PROBE_COUNTS();
    if (!k)
      k = 1 | doubleHash(h);
    i = (i + k) & sizeMask;
  }

  registerModification();

  if (deletedEntry) {
    // Overwrite any data left over from last use, using placement new
    // or memset.
    initializeBucket(*deletedEntry);
    entry = deletedEntry;
    --m_deletedCount;
  }

  HashTranslator::translate(*entry, key, extra);
  ASSERT(!isEmptyOrDeletedBucket(*entry));

  ++m_keyCount;

  if (shouldExpand())
    entry = expand(entry);

  return AddResult(this, entry, true);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T, typename Extra>
typename HashTable<Key,
                   Value,
                   Extractor,
                   HashFunctions,
                   Traits,
                   KeyTraits,
                   Allocator>::AddResult
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    addPassingHashCode(const T& key, const Extra& extra) {
  ASSERT(Allocator::isAllocationAllowed());
  if (!m_table)
    expand();

  FullLookupType lookupResult = fullLookupForWriting<HashTranslator>(key);

  ValueType* entry = lookupResult.first.first;
  bool found = lookupResult.first.second;
  unsigned h = lookupResult.second;

  if (found)
    return AddResult(this, entry, false);

  registerModification();

  if (isDeletedBucket(*entry)) {
    initializeBucket(*entry);
    --m_deletedCount;
  }

  HashTranslator::translate(*entry, key, extra, h);
  ASSERT(!isEmptyOrDeletedBucket(*entry));

  ++m_keyCount;
  if (shouldExpand())
    entry = expand(entry);

  return AddResult(this, entry, true);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
Value*
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    reinsert(ValueType& entry) {
  ASSERT(m_table);
  registerModification();
  ASSERT(!lookupForWriting(Extractor::extract(entry)).second);
  ASSERT(
      !isDeletedBucket(*(lookupForWriting(Extractor::extract(entry)).first)));
#if DUMP_HASHTABLE_STATS
  atomicIncrement(&HashTableStats::numReinserts);
#endif
#if DUMP_HASHTABLE_STATS_PER_TABLE
  ++m_stats->numReinserts;
#endif
  Value* newEntry = lookupForWriting(Extractor::extract(entry)).first;
  Mover<ValueType, Allocator, Traits::needsDestruction>::move(entry, *newEntry);

  return newEntry;
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T>
inline typename HashTable<Key,
                          Value,
                          Extractor,
                          HashFunctions,
                          Traits,
                          KeyTraits,
                          Allocator>::iterator
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    find(const T& key) {
  ValueType* entry = lookup<HashTranslator>(key);
  if (!entry)
    return end();

  return makeKnownGoodIterator(entry);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T>
inline typename HashTable<Key,
                          Value,
                          Extractor,
                          HashFunctions,
                          Traits,
                          KeyTraits,
                          Allocator>::const_iterator
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    find(const T& key) const {
  ValueType* entry = const_cast<HashTable*>(this)->lookup<HashTranslator>(key);
  if (!entry)
    return end();

  return makeKnownGoodConstIterator(entry);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
template <typename HashTranslator, typename T>
bool HashTable<Key,
               Value,
               Extractor,
               HashFunctions,
               Traits,
               KeyTraits,
               Allocator>::contains(const T& key) const {
  return const_cast<HashTable*>(this)->lookup<HashTranslator>(key);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
void HashTable<Key,
               Value,
               Extractor,
               HashFunctions,
               Traits,
               KeyTraits,
               Allocator>::remove(ValueType* pos) {
  registerModification();
#if DUMP_HASHTABLE_STATS
  atomicIncrement(&HashTableStats::numRemoves);
#endif
#if DUMP_HASHTABLE_STATS_PER_TABLE
  ++m_stats->numRemoves;
#endif

  deleteBucket(*pos);
  ++m_deletedCount;
  --m_keyCount;

  if (shouldShrink())
    shrink();
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
inline void
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    remove(iterator it) {
  if (it == end())
    return;

  remove(const_cast<ValueType*>(it.m_iterator.m_position));
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
inline void
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    remove(const_iterator it) {
  if (it == end())
    return;

  remove(const_cast<ValueType*>(it.m_position));
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
inline void
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    remove(KeyPeekInType key) {
  remove(find(key));
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
Value*
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    allocateTable(unsigned size) {
  typedef typename Allocator::template HashTableBackingHelper<HashTable>::Type
      HashTableBacking;

  size_t allocSize = size * sizeof(ValueType);
  ValueType* result;
  // Assert that we will not use memset on things with a vtable entry.
  // The compiler will also check this on some platforms. We would
  // like to check this on the whole value (key-value pair), but
  // IsPolymorphic will return false for a pair of two types, even if
  // one of the components is polymorphic.
  COMPILE_ASSERT(!Traits::emptyValueIsZero || !IsPolymorphic<KeyType>::value,
                 EmptyValueCannotBeZeroForThingsWithAVtable);
  if (Traits::emptyValueIsZero) {
    result =
        Allocator::template zeroedBackingMalloc<ValueType*, HashTableBacking>(
            allocSize);
  } else {
    result = Allocator::template backingMalloc<ValueType*, HashTableBacking>(
        allocSize);
    for (unsigned i = 0; i < size; i++)
      initializeBucket(result[i]);
  }
  return result;
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
void HashTable<Key,
               Value,
               Extractor,
               HashFunctions,
               Traits,
               KeyTraits,
               Allocator>::deleteAllBucketsAndDeallocate(ValueType* table,
                                                         unsigned size) {
  if (Traits::needsDestruction) {
    for (unsigned i = 0; i < size; ++i) {
      // This code is called when the hash table is cleared or
      // resized. We have allocated a new backing store and we need
      // to run the destructors on the old backing store, as it is
      // being freed. If we are GCing we need to both call the
      // destructor and mark the bucket as deleted, otherwise the
      // destructor gets called again when the GC finds the backing
      // store. With the default allocator it's enough to call the
      // destructor, since we will free the memory explicitly and
      // we won't see the memory with the bucket again.
      if (!isEmptyOrDeletedBucket(table[i])) {
        if (Allocator::isGarbageCollected)
          deleteBucket(table[i]);
        else
          table[i].~ValueType();
      }
    }
  }
  Allocator::backingFree(table);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
Value*
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    expand(Value* entry) {
  unsigned newSize;
  if (!m_tableSize) {
    newSize = KeyTraits::minimumTableSize;
  } else if (mustRehashInPlace()) {
    newSize = m_tableSize;
  } else {
    newSize = m_tableSize * 2;
    RELEASE_ASSERT(newSize > m_tableSize);
  }

  return rehash(newSize, entry);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
Value*
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    rehash(unsigned newTableSize, Value* entry) {
  unsigned oldTableSize = m_tableSize;
  ValueType* oldTable = m_table;

#if DUMP_HASHTABLE_STATS
  if (oldTableSize != 0)
    atomicIncrement(&HashTableStats::numRehashes);
#endif

#if DUMP_HASHTABLE_STATS_PER_TABLE
  if (oldTableSize != 0)
    ++m_stats->numRehashes;
#endif

  m_table = allocateTable(newTableSize);
  m_tableSize = newTableSize;

  Value* newEntry = 0;
  for (unsigned i = 0; i != oldTableSize; ++i) {
    if (isEmptyOrDeletedBucket(oldTable[i])) {
      ASSERT(&oldTable[i] != entry);
      continue;
    }

    Value* reinsertedEntry = reinsert(oldTable[i]);
    if (&oldTable[i] == entry) {
      ASSERT(!newEntry);
      newEntry = reinsertedEntry;
    }
  }

  m_deletedCount = 0;

  deleteAllBucketsAndDeallocate(oldTable, oldTableSize);

  return newEntry;
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
void HashTable<Key,
               Value,
               Extractor,
               HashFunctions,
               Traits,
               KeyTraits,
               Allocator>::clear() {
  registerModification();
  if (!m_table)
    return;

  deleteAllBucketsAndDeallocate(m_table, m_tableSize);
  m_table = 0;
  m_tableSize = 0;
  m_keyCount = 0;
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
    HashTable(const HashTable& other)
    : m_table(0),
      m_tableSize(0),
      m_keyCount(0),
      m_deletedCount(0),
      m_queueFlag(false)
#if ENABLE(ASSERT)
      ,
      m_modifications(0)
#endif
#if DUMP_HASHTABLE_STATS_PER_TABLE
      ,
      m_stats(adoptPtr(new Stats(*other.m_stats)))
#endif
{
  // Copy the hash table the dumb way, by adding each element to the new table.
  // It might be more efficient to copy the table slots, but it's not clear that
  // efficiency is needed.
  const_iterator end = other.end();
  for (const_iterator it = other.begin(); it != end; ++it)
    add(*it);
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
void HashTable<Key,
               Value,
               Extractor,
               HashFunctions,
               Traits,
               KeyTraits,
               Allocator>::swap(HashTable& other) {
  std::swap(m_table, other.m_table);
  std::swap(m_tableSize, other.m_tableSize);
  std::swap(m_keyCount, other.m_keyCount);
  // std::swap does not work for bit fields.
  unsigned deleted = m_deletedCount;
  m_deletedCount = other.m_deletedCount;
  other.m_deletedCount = deleted;
  ASSERT(!m_queueFlag);
  ASSERT(!other.m_queueFlag);

#if ENABLE(ASSERT)
  std::swap(m_modifications, other.m_modifications);
#endif

#if DUMP_HASHTABLE_STATS_PER_TABLE
  m_stats.swap(other.m_stats);
#endif
}

template <typename Key,
          typename Value,
          typename Extractor,
          typename HashFunctions,
          typename Traits,
          typename KeyTraits,
          typename Allocator>
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>&
HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::
operator=(const HashTable& other) {
  HashTable tmp(other);
  swap(tmp);
  return *this;
}

// iterator adapters

template <typename HashTableType, typename Traits>
struct HashTableConstIteratorAdapter {
  HashTableConstIteratorAdapter() {}
  HashTableConstIteratorAdapter(
      const typename HashTableType::const_iterator& impl)
      : m_impl(impl) {}
  typedef typename Traits::IteratorConstGetType GetType;
  typedef
      typename HashTableType::ValueTraits::IteratorConstGetType SourceGetType;

  GetType get() const {
    return const_cast<GetType>(SourceGetType(m_impl.get()));
  }
  typename Traits::IteratorConstReferenceType operator*() const {
    return Traits::getToReferenceConstConversion(get());
  }
  GetType operator->() const { return get(); }

  HashTableConstIteratorAdapter& operator++() {
    ++m_impl;
    return *this;
  }
  // postfix ++ intentionally omitted

  typename HashTableType::const_iterator m_impl;
};

template <typename HashTableType, typename Traits>
struct HashTableIteratorAdapter {
  typedef typename Traits::IteratorGetType GetType;
  typedef typename HashTableType::ValueTraits::IteratorGetType SourceGetType;

  HashTableIteratorAdapter() {}
  HashTableIteratorAdapter(const typename HashTableType::iterator& impl)
      : m_impl(impl) {}

  GetType get() const {
    return const_cast<GetType>(SourceGetType(m_impl.get()));
  }
  typename Traits::IteratorReferenceType operator*() const {
    return Traits::getToReferenceConversion(get());
  }
  GetType operator->() const { return get(); }

  HashTableIteratorAdapter& operator++() {
    ++m_impl;
    return *this;
  }
  // postfix ++ intentionally omitted

  operator HashTableConstIteratorAdapter<HashTableType, Traits>() {
    typename HashTableType::const_iterator i = m_impl;
    return i;
  }

  typename HashTableType::iterator m_impl;
};

template <typename T, typename U>
inline bool operator==(const HashTableConstIteratorAdapter<T, U>& a,
                       const HashTableConstIteratorAdapter<T, U>& b) {
  return a.m_impl == b.m_impl;
}

template <typename T, typename U>
inline bool operator!=(const HashTableConstIteratorAdapter<T, U>& a,
                       const HashTableConstIteratorAdapter<T, U>& b) {
  return a.m_impl != b.m_impl;
}

template <typename T, typename U>
inline bool operator==(const HashTableIteratorAdapter<T, U>& a,
                       const HashTableIteratorAdapter<T, U>& b) {
  return a.m_impl == b.m_impl;
}

template <typename T, typename U>
inline bool operator!=(const HashTableIteratorAdapter<T, U>& a,
                       const HashTableIteratorAdapter<T, U>& b) {
  return a.m_impl != b.m_impl;
}

// All 4 combinations of ==, != and Const,non const.
template <typename T, typename U>
inline bool operator==(const HashTableConstIteratorAdapter<T, U>& a,
                       const HashTableIteratorAdapter<T, U>& b) {
  return a.m_impl == b.m_impl;
}

template <typename T, typename U>
inline bool operator!=(const HashTableConstIteratorAdapter<T, U>& a,
                       const HashTableIteratorAdapter<T, U>& b) {
  return a.m_impl != b.m_impl;
}

template <typename T, typename U>
inline bool operator==(const HashTableIteratorAdapter<T, U>& a,
                       const HashTableConstIteratorAdapter<T, U>& b) {
  return a.m_impl == b.m_impl;
}

template <typename T, typename U>
inline bool operator!=(const HashTableIteratorAdapter<T, U>& a,
                       const HashTableConstIteratorAdapter<T, U>& b) {
  return a.m_impl != b.m_impl;
}

template <typename Collection1, typename Collection2>
inline void removeAll(Collection1& collection, const Collection2& toBeRemoved) {
  if (collection.isEmpty() || toBeRemoved.isEmpty())
    return;
  typedef typename Collection2::const_iterator CollectionIterator;
  CollectionIterator end(toBeRemoved.end());
  for (CollectionIterator it(toBeRemoved.begin()); it != end; ++it)
    collection.remove(*it);
}

}  // namespace WTF

#include "flutter/sky/engine/wtf/HashIterators.h"

#endif  // SKY_ENGINE_WTF_HASHTABLE_H_