third_party/WebKit/Source/wtf/HashMap.h

/*
 * Copyright (C) 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
 *
 * 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_HashMap_h
#define WTF_HashMap_h

#include "wtf/HashTable.h"
#include "wtf/PartitionAllocator.h"

namespace WTF {

template <typename KeyTraits, typename MappedTraits> struct HashMapValueTraits;

template <typename T> struct ReferenceTypeMaker {
    typedef T& ReferenceType;
};
template <typename T> struct ReferenceTypeMaker<T&> {
    typedef T& ReferenceType;
};

struct KeyValuePairKeyExtractor {
    template <typename T>
    static const typename T::KeyType& extract(const T& p) { return p.key; }
};

// 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 KeyArg,
    typename MappedArg,
    typename HashArg = typename DefaultHash<KeyArg>::Hash,
    typename KeyTraitsArg = HashTraits<KeyArg>,
    typename MappedTraitsArg = HashTraits<MappedArg>,
    typename Allocator = PartitionAllocator>
class HashMap {
    WTF_USE_ALLOCATOR(HashMap, Allocator);
private:
    typedef KeyTraitsArg KeyTraits;
    typedef MappedTraitsArg MappedTraits;
    typedef HashMapValueTraits<KeyTraits, MappedTraits> ValueTraits;

public:
    typedef typename KeyTraits::TraitType KeyType;
    typedef const typename KeyTraits::PeekInType& KeyPeekInType;
    typedef typename MappedTraits::TraitType MappedType;
    typedef typename ValueTraits::TraitType ValueType;

private:
    typedef typename MappedTraits::PassInType MappedPassInType;
    typedef typename MappedTraits::PassOutType MappedPassOutType;
    typedef typename MappedTraits::PeekOutType MappedPeekType;

    typedef typename ReferenceTypeMaker<MappedPassInType>::ReferenceType MappedPassInReferenceType;

    typedef HashArg HashFunctions;

    typedef HashTable<KeyType, ValueType, KeyValuePairKeyExtractor,
        HashFunctions, ValueTraits, KeyTraits, Allocator> HashTableType;

    class HashMapKeysProxy;
    class HashMapValuesProxy;

public:
    typedef HashTableIteratorAdapter<HashTableType, ValueType> iterator;
    typedef HashTableConstIteratorAdapter<HashTableType, ValueType> const_iterator;
    typedef typename HashTableType::AddResult AddResult;

public:
    void swap(HashMap& ref)
    {
        m_impl.swap(ref.m_impl);
    }

    void swap(typename Allocator::template OtherType<HashMap>::Type other)
    {
        HashMap& ref = Allocator::getOther(other);
        m_impl.swap(ref.m_impl);
    }

    unsigned size() const;
    unsigned capacity() const;
    void reserveCapacityForSize(unsigned size)
    {
        m_impl.reserveCapacityForSize(size);
    }

    bool isEmpty() const;

    // iterators iterate over pairs of keys and values
    iterator begin();
    iterator end();
    const_iterator begin() const;
    const_iterator end() const;

    HashMapKeysProxy& keys() { return static_cast<HashMapKeysProxy&>(*this); }
    const HashMapKeysProxy& keys() const { return static_cast<const HashMapKeysProxy&>(*this); }

    HashMapValuesProxy& values() { return static_cast<HashMapValuesProxy&>(*this); }
    const HashMapValuesProxy& values() const { return static_cast<const HashMapValuesProxy&>(*this); }

    iterator find(KeyPeekInType);
    const_iterator find(KeyPeekInType) const;
    bool contains(KeyPeekInType) const;
    MappedPeekType get(KeyPeekInType) const;

    // replaces value but not key if key is already present return value is a
    // pair of the iterator to the key location, and a boolean that's true if a
    // new value was actually added
    AddResult set(KeyPeekInType, MappedPassInType);

    // does nothing if key is already present return value is a pair of the
    // iterator to the key location, and a boolean that's true if a new value
    // was actually added
    AddResult add(KeyPeekInType, MappedPassInType);

    void remove(KeyPeekInType);
    void remove(iterator);
    void clear();
    template <typename Collection>
    void removeAll(const Collection& toBeRemoved) { WTF::removeAll(*this, toBeRemoved); }

    MappedPassOutType take(KeyPeekInType); // efficient combination of get with remove

    // An alternate version of find() that finds the object by hashing and
    // comparing with some other type, to avoid the cost of type
    // conversion. HashTranslator must have the following function members:
    //   static unsigned hash(const T&);
    //   static bool equal(const ValueType&, const T&);
    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;

    // An alternate 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. HashTranslator must have the
    // following function members:
    //   static unsigned hash(const T&);
    //   static bool equal(const ValueType&, const T&);
    //   static translate(ValueType&, const T&, unsigned hashCode);
    template <typename HashTranslator, typename T> AddResult add(const T&, MappedPassInType);

    static bool isValidKey(KeyPeekInType);

    template <typename VisitorDispatcher>
    void trace(VisitorDispatcher visitor) { m_impl.trace(visitor); }

private:
    AddResult inlineAdd(KeyPeekInType, MappedPassInReferenceType);

    HashTableType m_impl;
};

template <typename KeyArg, typename MappedArg, typename HashArg, typename KeyTraitsArg, typename MappedTraitsArg, typename Allocator>
class HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg, Allocator>::HashMapKeysProxy :
    private HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg, Allocator> {
public:
    typedef HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg, Allocator> HashMapType;
    typedef typename HashMapType::iterator::Keys iterator;
    typedef typename HashMapType::const_iterator::Keys const_iterator;

    iterator begin()
    {
        return HashMapType::begin().keys();
    }

    iterator end()
    {
        return HashMapType::end().keys();
    }

    const_iterator begin() const
    {
        return HashMapType::begin().keys();
    }

    const_iterator end() const
    {
        return HashMapType::end().keys();
    }

private:
    friend class HashMap;

    // These are intentionally not implemented.
    HashMapKeysProxy();
    HashMapKeysProxy(const HashMapKeysProxy&);
    HashMapKeysProxy& operator=(const HashMapKeysProxy&);
    ~HashMapKeysProxy();
};

template <typename KeyArg, typename MappedArg, typename HashArg,  typename KeyTraitsArg, typename MappedTraitsArg, typename Allocator>
class HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg, Allocator>::HashMapValuesProxy :
    private HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg, Allocator> {
public:
    typedef HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg, Allocator> HashMapType;
    typedef typename HashMapType::iterator::Values iterator;
    typedef typename HashMapType::const_iterator::Values const_iterator;

    iterator begin()
    {
        return HashMapType::begin().values();
    }

    iterator end()
    {
        return HashMapType::end().values();
    }

    const_iterator begin() const
    {
        return HashMapType::begin().values();
    }

    const_iterator end() const
    {
        return HashMapType::end().values();
    }

private:
    friend class HashMap;

    // These are intentionally not implemented.
    HashMapValuesProxy();
    HashMapValuesProxy(const HashMapValuesProxy&);
    HashMapValuesProxy& operator=(const HashMapValuesProxy&);
    ~HashMapValuesProxy();
};

template <typename KeyTraits, typename MappedTraits>
struct HashMapValueTraits : KeyValuePairHashTraits<KeyTraits, MappedTraits> {
    static const bool hasIsEmptyValueFunction = true;
    static bool isEmptyValue(const typename KeyValuePairHashTraits<KeyTraits, MappedTraits>::TraitType& value)
    {
        return isHashTraitsEmptyValue<KeyTraits>(value.key);
    }
};

template <typename ValueTraits, typename HashFunctions>
struct HashMapTranslator {
    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& key, const V& mapped)
    {
        location.key = key;
        ValueTraits::ValueTraits::store(mapped, location.value);
    }
};

template <typename ValueTraits, typename Translator>
struct HashMapTranslatorAdapter {
    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, b); }
    template <typename T, typename U, typename V> static void translate(T& location, const U& key, const V& mapped, unsigned hashCode)
    {
        Translator::translate(location.key, key, hashCode);
        ValueTraits::ValueTraits::store(mapped, location.value);
    }
};

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline unsigned HashMap<T, U, V, W, X, Y>::size() const
{
    return m_impl.size();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline unsigned HashMap<T, U, V, W, X, Y>::capacity() const
{
    return m_impl.capacity();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline bool HashMap<T, U, V, W, X, Y>::isEmpty() const
{
    return m_impl.isEmpty();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline typename HashMap<T, U, V, W, X, Y>::iterator HashMap<T, U, V, W, X, Y>::begin()
{
    return m_impl.begin();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline typename HashMap<T, U, V, W, X, Y>::iterator HashMap<T, U, V, W, X, Y>::end()
{
    return m_impl.end();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline typename HashMap<T, U, V, W, X, Y>::const_iterator HashMap<T, U, V, W, X, Y>::begin() const
{
    return m_impl.begin();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline typename HashMap<T, U, V, W, X, Y>::const_iterator HashMap<T, U, V, W, X, Y>::end() const
{
    return m_impl.end();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline typename HashMap<T, U, V, W, X, Y>::iterator HashMap<T, U, V, W, X, Y>::find(KeyPeekInType key)
{
    return m_impl.find(key);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline typename HashMap<T, U, V, W, X, Y>::const_iterator HashMap<T, U, V, W, X, Y>::find(KeyPeekInType key) const
{
    return m_impl.find(key);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline bool HashMap<T, U, V, W, X, Y>::contains(KeyPeekInType key) const
{
    return m_impl.contains(key);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
template <typename HashTranslator, typename TYPE>
inline typename HashMap<T, U, V, W, X, Y>::iterator
HashMap<T, U, V, W, X, Y>::find(const TYPE& value)
{
    return m_impl.template find<HashMapTranslatorAdapter<ValueTraits, HashTranslator>>(value);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
template <typename HashTranslator, typename TYPE>
inline typename HashMap<T, U, V, W, X, Y>::const_iterator
HashMap<T, U, V, W, X, Y>::find(const TYPE& value) const
{
    return m_impl.template find<HashMapTranslatorAdapter<ValueTraits, HashTranslator>>(value);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
template <typename HashTranslator, typename TYPE>
inline bool
HashMap<T, U, V, W, X, Y>::contains(const TYPE& value) const
{
    return m_impl.template contains<HashMapTranslatorAdapter<ValueTraits, HashTranslator>>(value);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
typename HashMap<T, U, V, W, X, Y>::AddResult
HashMap<T, U, V, W, X, Y>::inlineAdd(KeyPeekInType key, MappedPassInReferenceType mapped)
{
    return m_impl.template add<HashMapTranslator<ValueTraits, HashFunctions>>(key, mapped);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
typename HashMap<T, U, V, W, X, Y>::AddResult
HashMap<T, U, V, W, X, Y>::set(KeyPeekInType key, MappedPassInType mapped)
{
    AddResult result = inlineAdd(key, mapped);
    if (!result.isNewEntry) {
        // The inlineAdd call above found an existing hash table entry; we need
        // to set the mapped value.
        MappedTraits::store(mapped, result.storedValue->value);
    }
    return result;
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
template <typename HashTranslator, typename TYPE>
typename HashMap<T, U, V, W, X, Y>::AddResult
HashMap<T, U, V, W, X, Y>::add(const TYPE& key, MappedPassInType value)
{
    return m_impl.template addPassingHashCode<HashMapTranslatorAdapter<ValueTraits, HashTranslator>>(key, value);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
typename HashMap<T, U, V, W, X, Y>::AddResult
HashMap<T, U, V, W, X, Y>::add(KeyPeekInType key, MappedPassInType mapped)
{
    return inlineAdd(key, mapped);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
typename HashMap<T, U, V, W, X, Y>::MappedPeekType
HashMap<T, U, V, W, X, Y>::get(KeyPeekInType key) const
{
    ValueType* entry = const_cast<HashTableType&>(m_impl).lookup(key);
    if (!entry)
        return MappedTraits::peek(MappedTraits::emptyValue());
    return MappedTraits::peek(entry->value);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline void HashMap<T, U, V, W, X, Y>::remove(iterator it)
{
    m_impl.remove(it.m_impl);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline void HashMap<T, U, V, W, X, Y>::remove(KeyPeekInType key)
{
    remove(find(key));
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline void HashMap<T, U, V, W, X, Y>::clear()
{
    m_impl.clear();
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
typename HashMap<T, U, V, W, X, Y>::MappedPassOutType
HashMap<T, U, V, W, X, Y>::take(KeyPeekInType key)
{
    iterator it = find(key);
    if (it == end())
        return MappedTraits::passOut(MappedTraits::emptyValue());
    MappedPassOutType result = MappedTraits::passOut(it->value);
    remove(it);
    return result;
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline bool HashMap<T, U, V, W, X, Y>::isValidKey(KeyPeekInType key)
{
    if (KeyTraits::isDeletedValue(key))
        return false;

    if (HashFunctions::safeToCompareToEmptyOrDeleted) {
        if (key == KeyTraits::emptyValue())
            return false;
    } else {
        if (isHashTraitsEmptyValue<KeyTraits>(key))
            return false;
    }

    return true;
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
bool operator==(const HashMap<T, U, V, W, X, Y>& a, const HashMap<T, U, V, W, X, Y>& b)
{
    if (a.size() != b.size())
        return false;

    typedef typename HashMap<T, U, V, W, X, Y>::const_iterator const_iterator;

    const_iterator aEnd = a.end();
    const_iterator bEnd = b.end();
    for (const_iterator it = a.begin(); it != aEnd; ++it) {
        const_iterator bPos = b.find(it->key);
        if (bPos == bEnd || it->value != bPos->value)
            return false;
    }

    return true;
}

template <typename T, typename U, typename V, typename W, typename X, typename Y>
inline bool operator!=(const HashMap<T, U, V, W, X, Y>& a, const HashMap<T, U, V, W, X, Y>& b)
{
    return !(a == b);
}

template <typename T, typename U, typename V, typename W, typename X, typename Y, typename Z>
inline void copyKeysToVector(const HashMap<T, U, V, W, X, Y>& collection, Z& vector)
{
    typedef typename HashMap<T, U, V, W, X, Y>::const_iterator::Keys iterator;

    vector.resize(collection.size());

    iterator it = collection.begin().keys();
    iterator end = collection.end().keys();
    for (unsigned i = 0; it != end; ++it, ++i)
        vector[i] = *it;
}

template <typename T, typename U, typename V, typename W, typename X, typename Y, typename Z>
inline void copyValuesToVector(const HashMap<T, U, V, W, X, Y>& collection, Z& vector)
{
    typedef typename HashMap<T, U, V, W, X, Y>::const_iterator::Values iterator;

    vector.resize(collection.size());

    iterator it = collection.begin().values();
    iterator end = collection.end().values();
    for (unsigned i = 0; it != end; ++it, ++i)
        vector[i] = *it;
}

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

} // namespace WTF

using WTF::HashMap;

#endif // WTF_HashMap_h