Source/WTF/wtf/HashIterators.h

/*
 * Copyright (C) 2007 Apple Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#pragma once

#include <iterator>

namespace WTF {

    template<typename KeyTypeArg, typename ValueTypeArg>
    struct KeyValuePair;

    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableConstKeysIterator;
    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableConstValuesIterator;
    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableKeysIterator;
    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableValuesIterator;

    template<typename HashTableType, typename ValueType> struct HashTableConstIteratorAdapter;
    template<typename HashTableType, typename ValueType> struct HashTableIteratorAdapter;

    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableConstIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> {
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = KeyValuePair<KeyType, MappedType>;
        using difference_type = ptrdiff_t;
        using pointer = const value_type*;
        using reference = const value_type&;

    private:
        typedef KeyValuePair<KeyType, MappedType> ValueType;
    public:
        typedef HashTableConstKeysIterator<HashTableType, KeyType, MappedType> Keys;
        typedef HashTableConstValuesIterator<HashTableType, KeyType, MappedType> Values;

        HashTableConstIteratorAdapter() {}
        HashTableConstIteratorAdapter(const typename HashTableType::const_iterator& impl) : m_impl(impl) {}

        const ValueType* get() const { return (const ValueType*)m_impl.get(); }
        const ValueType& operator*() const { return *get(); }
        const ValueType* operator->() const { return get(); }

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

        Keys keys() { return Keys(*this); }
        Values values() { return Values(*this); }

        typename HashTableType::const_iterator m_impl;
    };

    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> {
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = KeyValuePair<KeyType, MappedType>;
        using difference_type = ptrdiff_t;
        using pointer = value_type*;
        using reference = value_type&;

    private:
        typedef KeyValuePair<KeyType, MappedType> ValueType;
    public:
        typedef HashTableKeysIterator<HashTableType, KeyType, MappedType> Keys;
        typedef HashTableValuesIterator<HashTableType, KeyType, MappedType> Values;

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

        ValueType* get() const { return (ValueType*)m_impl.get(); }
        ValueType& operator*() const { return *get(); }
        ValueType* operator->() const { return get(); }

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

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

        Keys keys() { return Keys(*this); }
        Values values() { return Values(*this); }

        typename HashTableType::iterator m_impl;
    };

    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableConstKeysIterator {
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = KeyType;
        using difference_type = ptrdiff_t;
        using pointer = const value_type*;
        using reference = const value_type&;

    private:
        typedef HashTableConstIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> ConstIterator;

    public:
        HashTableConstKeysIterator(const ConstIterator& impl) : m_impl(impl) {}
        
        const KeyType* get() const { return &(m_impl.get()->key); }
        const KeyType& operator*() const { return *get(); }
        const KeyType* operator->() const { return get(); }

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

        ConstIterator m_impl;
    };

    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableConstValuesIterator {
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = MappedType;
        using difference_type = ptrdiff_t;
        using pointer = const value_type*;
        using reference = const value_type&;

    private:
        typedef HashTableConstIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> ConstIterator;

    public:
        HashTableConstValuesIterator(const ConstIterator& impl) : m_impl(impl) {}
        
        const MappedType* get() const { return std::addressof(m_impl.get()->value); }
        const MappedType& operator*() const { return *get(); }
        const MappedType* operator->() const { return get(); }

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

        ConstIterator m_impl;
    };

    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableKeysIterator {
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = KeyType;
        using difference_type = ptrdiff_t;
        using pointer = value_type*;
        using reference = value_type&;

    private:
        typedef HashTableIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> Iterator;
        typedef HashTableConstIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> ConstIterator;

    public:
        HashTableKeysIterator(const Iterator& impl) : m_impl(impl) {}
        
        KeyType* get() const { return &(m_impl.get()->key); }
        KeyType& operator*() const { return *get(); }
        KeyType* operator->() const { return get(); }

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

        operator HashTableConstKeysIterator<HashTableType, KeyType, MappedType>() {
            ConstIterator i = m_impl;
            return i;
        }

        Iterator m_impl;
    };

    template<typename HashTableType, typename KeyType, typename MappedType> struct HashTableValuesIterator {
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = MappedType;
        using difference_type = ptrdiff_t;
        using pointer = value_type*;
        using reference = value_type&;

    private:
        typedef HashTableIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> Iterator;
        typedef HashTableConstIteratorAdapter<HashTableType, KeyValuePair<KeyType, MappedType>> ConstIterator;

    public:
        HashTableValuesIterator(const Iterator& impl) : m_impl(impl) {}
        
        MappedType* get() const { return std::addressof(m_impl.get()->value); }
        MappedType& operator*() const { return *get(); }
        MappedType* operator->() const { return get(); }

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

        operator HashTableConstValuesIterator<HashTableType, KeyType, MappedType>() {
            ConstIterator i = m_impl;
            return i;
        }

        Iterator m_impl;
    };

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

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

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

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

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

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

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

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

} // namespace WTF