o3de/Code/Legacy/CryCommon/VectorMap.h

/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */


// Description : std::map replacement implemented using sorted vector.


#ifndef CRYINCLUDE_CRYCOMMON_VECTORMAP_H
#define CRYINCLUDE_CRYCOMMON_VECTORMAP_H
#pragma once

#include <CryCommon/StlUtils.h>

//--------------------------------------------------------------------------
// VectorMap
//
// Usage Notes:
// This class is designed to be an (almost, see below) drop-in replacement
// for std::map. It features an almost identical interface, but it is
// implemented using a sorted vector rather than a tree. This is in most
// cases more efficient, as there is less dynamic memory allocation and
// pointer dereferencing.
//
// *************************************************************************
// PLEASE NOTE: There is one vital difference between std::map and VectorMap
// that you will need to note before trying to replace std::map. Since
// VectorMap is implemented using a vector, iterators can and will be
// invalidated by many operations, such as insertions and deletions, and
// due to sorting potentially even normal lookups. Please Please PLEASE make
// sure that you are not storing any iterators to this class.
// *************************************************************************
//
// The class varies from the std::set API in that two of the erase methods
// methods are not of void return type but return an iterator - this is
// required in practice because they invalidate iterators, as noted above.
//
// * iterator erase(iterator where);
// * iterator erase(iterator first, iterator last);
//
//
// Performance Notes:
//
// This class uses the empty base optimization hack to allow comparison
// predicate objects that have no state to take up no space in the object.
// As a result the size of the overall VectorMap instance is the same as
// that of the std::vector it uses to store the elements.
//
// In addition to the normal map interface, this class provides the
// following members that can be used to manage memory requirements:
//
// * void reserve(size_type count);
//   Allocate enough space for count elements (see vector::reserve()).
//
// * size_type capacity() const;
//   Report how many elements can be stored without reallocating (see
//   vector::capacity()).
//
//--------------------------------------------------------------------------

template <typename K, typename V, typename T = std::less<K>, typename A = std::allocator<std::pair <K, V> > >
class VectorMap
    : private T             // Empty base optimization
{
public:
    typedef K key_type;
    typedef V mapped_type;
    typedef A allocator_type;

    typedef std::pair</*const */ key_type, mapped_type> value_type;

    typedef T key_compare;

    class FirstLess
    {
    public:
        FirstLess(const key_compare& comp)
            : m_comp(comp) {}

        bool operator()(const value_type& left, const value_type& right) const
        {
            return m_comp(left.first, right.first);
        }

    private:
        const key_compare& m_comp;
    };

    typedef std::vector<value_type, allocator_type> container_type;
    typedef typename container_type::iterator iterator;
    typedef typename container_type::const_iterator const_iterator;
    typedef typename container_type::reverse_iterator reverse_iterator;
    typedef typename container_type::const_reverse_iterator const_reverse_iterator;
    typedef value_type& reference;
    typedef const value_type& const_reference;
    typedef value_type* pointer;
    typedef const value_type* const_pointer;
    typedef typename std::allocator_traits<allocator_type>::size_type size_type;

    VectorMap();
    explicit VectorMap(const key_compare& comp);
    explicit VectorMap(const key_compare& comp, const allocator_type& alloc);
    VectorMap(const VectorMap& right);
    template <class InputIterator>
    VectorMap(InputIterator first, InputIterator last);
    template <class InputIterator>
    VectorMap(InputIterator first, InputIterator last, const key_compare& comp);
    template <class InputIterator>
    VectorMap(InputIterator first, InputIterator last, const key_compare& comp, const allocator_type& alloc);
    void SwapElementsWithVector(container_type& elementVector);
    iterator begin();
    const_iterator begin() const;
    size_type capacity() const;
    void clear();
    void clearAndFreeMemory();
    size_type count(const key_type& key) const;
    bool empty() const;
    iterator end();
    const_iterator end() const;
    std::pair<iterator, iterator> equal_range(const key_type& key);
    std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const;
    iterator erase(iterator where);                 // See documentation above
    iterator erase(iterator first, iterator last);  // See documentation above
    void erase(const key_type& key);
    template <typename Predicate>
    void erase_if(const Predicate& predicate);
    iterator find(const key_type& key);
    const_iterator find(const key_type& key) const;
    allocator_type get_allocator() const;
    std::pair<iterator, bool> insert(const value_type& val);
    iterator insert(iterator where, const value_type& val);
    template <class InputIterator>
    void insert(InputIterator first, InputIterator last);
    key_compare key_comp() const;
    iterator lower_bound(const key_type& key);
    const_iterator lower_bound(const key_type& key) const;
    size_type max_size() const;
    reverse_iterator rbegin();
    const_reverse_iterator rbegin() const;
    reverse_iterator rend();
    const_reverse_iterator rend() const;
    void reserve(size_type count);
    size_type size() const;
    void swap(VectorMap& other);
    iterator upper_bound(const key_type& key);
    const_iterator upper_bound(const key_type& key) const;
    mapped_type& operator[](const key_type& key);

    template<typename Sizer>
    void GetMemoryUsage(Sizer* pSizer) const
    {
        pSizer->AddObject(m_entries);
    }
private:
    container_type m_entries;
};

template <typename K, typename V, typename T, typename A>
VectorMap<K, V, T, A>::VectorMap()
{
}

template <typename K, typename V, typename T, typename A>
VectorMap<K, V, T, A>::VectorMap(const key_compare& comp)
    :   key_compare(comp)
{
}

template <typename K, typename V, typename T, typename A>
VectorMap<K, V, T, A>::VectorMap(const key_compare& comp, const allocator_type& alloc)
    :   key_compare(comp)
    , m_entries(alloc)
{
}

template <typename K, typename V, typename T, typename A>
VectorMap<K, V, T, A>::VectorMap(const VectorMap& right)
    :   key_compare(right)
    , m_entries(right.m_entries)
{
}

template <typename K, typename V, typename T, typename A>
template <class InputIterator>
VectorMap<K, V, T, A>::VectorMap(InputIterator first, InputIterator last)
{
    for (; first != last; ++first)
    {
        m_entries.push_back(*first);
    }
    std::sort(m_entries.begin(), m_entries.end(), FirstLess(static_cast<key_compare>(*this)));
}

template <typename K, typename V, typename T, typename A>
template <class InputIterator>
VectorMap<K, V, T, A>::VectorMap(InputIterator first, InputIterator last, const key_compare& comp)
    :   key_compare(comp)
{
    for (; first != last; ++first)
    {
        m_entries.push_back(*first);
    }
    std::sort(m_entries.begin(), m_entries.end(), FirstLess(static_cast<key_compare>(*this)));
}

template <typename K, typename V, typename T, typename A>
template <class InputIterator>
VectorMap<K, V, T, A>::VectorMap(InputIterator first, InputIterator last, const key_compare& comp, const allocator_type& alloc)
    :   key_compare(comp)
    , m_entries(alloc)
{
    for (; first != last; ++first)
    {
        m_entries.push_back(*first);
    }
    std::sort(m_entries.begin(), m_entries.end(), FirstLess(static_cast<key_compare>(*this)));
}

template <typename K, typename V, typename T, typename A>
void VectorMap<K, V, T, A>::SwapElementsWithVector(typename VectorMap<K, V, T, A>::container_type& elementVector)
{
    m_entries.swap(elementVector);
    std::sort(m_entries.begin(), m_entries.end(), FirstLess(static_cast<key_compare>(*this)));
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::begin()
{
    return m_entries.begin();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::const_iterator VectorMap<K, V, T, A>::begin() const
{
    return m_entries.begin();
}

template <typename K, typename V, typename T, typename A>
void VectorMap<K, V, T, A>::clear()
{
    m_entries.resize(0);
}

template <typename K, typename V, typename T, typename A>
void VectorMap<K, V, T, A>::clearAndFreeMemory()
{
    stl::free_container(m_entries);
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::size_type VectorMap<K, V, T, A>::capacity() const
{
    return m_entries.capacity();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::size_type VectorMap<K, V, T, A>::count(const key_type& key) const
{
    return size_type(std::binary_search(m_entries.begin(), m_entries.end(), value_type(key, mapped_type()), static_cast<key_compare>(*this)));
}

template <typename K, typename V, typename T, typename A>
bool VectorMap<K, V, T, A>::empty() const
{
    return m_entries.empty();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::end()
{
    return m_entries.end();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::const_iterator VectorMap<K, V, T, A>::end() const
{
    return m_entries.end();
}

template <typename K, typename V, typename T, typename A>
std::pair<typename VectorMap<K, V, T, A>::iterator, typename VectorMap<K, V, T, A>::iterator> VectorMap<K, V, T, A>::equal_range(const key_type& key)
{
    iterator lower = lower_bound(key);
    if (lower != m_entries.end() && key_compare::operator()(key, (*lower).first))
    {
        lower = m_entries.end();
    }
    iterator upper = lower;
    if (upper != m_entries.end())
    {
        ++upper;
    }
    return std::make_pair(lower, upper);
}

template <typename K, typename V, typename T, typename A>
std::pair<typename VectorMap<K, V, T, A>::const_iterator, typename VectorMap<K, V, T, A>::const_iterator> VectorMap<K, V, T, A>::equal_range(const key_type& key) const
{
    const_iterator lower = lower_bound(key);
    if (lower != m_entries.end() && key_compare::operator()(key, (*lower).first))
    {
        lower = m_entries.end();
    }
    const_iterator upper = lower;
    if (upper != m_entries.end())
    {
        ++upper;
    }
    return std::make_pair(lower, upper);
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::erase(iterator where)
{
    return m_entries.erase(where);
}

template <typename K, typename V, typename T, typename A>
template <typename Predicate>
void VectorMap<K, V, T, A>::erase_if(const Predicate& predicate)
{
    m_entries.erase(std::remove_if(m_entries.begin(), m_entries.end(), predicate), m_entries.end());
    std::sort(m_entries.begin(), m_entries.end(), FirstLess(static_cast<key_compare>(*this)));
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::erase(iterator first, iterator last)
{
    return m_entries.erase(first, last);
}

template <typename K, typename V, typename T, typename A>
void VectorMap<K, V, T, A>::erase(const key_type& key)
{
    iterator where = find(key);

    if (where != m_entries.end())
    {
        m_entries.erase(where);
    }
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::find(const key_type& key)
{
    iterator it = lower_bound(key);
    if (it != m_entries.end() && key_compare::operator()(key, (*it).first))
    {
        it = m_entries.end();
    }
    return it;
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::const_iterator VectorMap<K, V, T, A>::find(const key_type& key) const
{
    const_iterator it = lower_bound(key);
    if (it != m_entries.end() && key_compare::operator()(key, (*it).first))
    {
        it = m_entries.end();
    }
    return it;
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::allocator_type VectorMap<K, V, T, A>::get_allocator() const
{
    return m_entries.get_allocator();
}

template <typename K, typename V, typename T, typename A>
std::pair<typename VectorMap<K, V, T, A>::iterator, bool> VectorMap<K, V, T, A>::insert(const value_type& val)
{
    iterator it = lower_bound(val.first);
    bool insertionMade = false;
    if (it == m_entries.end() || key_compare::operator()(val.first, (*it).first))
    {
        it = m_entries.insert(it, val), insertionMade = true;
    }
    return std::make_pair(it, insertionMade);
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::insert(iterator where, const value_type& val)
{
    return insert(val);
}

template <typename K, typename V, typename T, typename A>
template <class InputIterator>
void VectorMap<K, V, T, A>::insert(InputIterator first, InputIterator last)
{
    for (; first != last; ++first)
    {
        insert(*first);
    }
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::key_compare VectorMap<K, V, T, A>::key_comp() const
{
    return static_cast<key_compare>(*this);
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::lower_bound(const key_type& key)
{
    int count = static_cast<int>(m_entries.size());
    iterator first = m_entries.begin();
    for (; 0 < count; )
    {   // divide and conquer, find half that contains answer
        int count2 = count / 2;
        iterator mid = first + count2;

        if (key_compare::operator()(mid->first, key))
        {
            first = ++mid, count -= count2 + 1;
        }
        else
        {
            count = count2;
        }
    }
    return first;
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::const_iterator VectorMap<K, V, T, A>::lower_bound(const key_type& key) const
{
    int count = static_cast<int>(m_entries.size());
    const_iterator first = m_entries.begin();
    for (; 0 < count; )
    {   // divide and conquer, find half that contains answer
        int count2 = count / 2;
        const_iterator mid = first + count2;

        if (key_compare::operator()(mid->first, key))
        {
            first = ++mid, count -= count2 + 1;
        }
        else
        {
            count = count2;
        }
    }
    return first;
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::size_type VectorMap<K, V, T, A>::max_size() const
{
    return m_entries.max_size();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::reverse_iterator VectorMap<K, V, T, A>::rbegin()
{
    return m_entries.rbegin();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::const_reverse_iterator VectorMap<K, V, T, A>::rbegin() const
{
    return m_entries.rbegin();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::reverse_iterator VectorMap<K, V, T, A>::rend()
{
    return m_entries.rend();
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::const_reverse_iterator VectorMap<K, V, T, A>::rend() const
{
    return m_entries.rend();
}

template <typename K, typename V, typename T, typename A>
void VectorMap<K, V, T, A>::reserve(size_type count)
{
    m_entries.reserve(count);
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::size_type VectorMap<K, V, T, A>::size() const
{
    return m_entries.size();
}

template <typename K, typename V, typename T, typename A>
void VectorMap<K, V, T, A>::swap(VectorMap& other)
{
    m_entries.swap(other.m_entries);
    std::swap(static_cast<key_compare&>(*this), static_cast<key_compare&>(other));
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::iterator VectorMap<K, V, T, A>::upper_bound(const key_type& key)
{
    iterator upper = lower_bound(key);
    if (upper != m_entries.end() && !key_compare::operator()(key, (*upper).first))
    {
        ++upper;
    }
    return upper;
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::const_iterator VectorMap<K, V, T, A>::upper_bound(const key_type& key) const
{
    iterator upper = lower_bound(key);
    if (upper != m_entries.end() && !key_compare::operator()(key, (*upper).first))
    {
        ++upper;
    }
    return upper;
}

template <typename K, typename V, typename T, typename A>
typename VectorMap<K, V, T, A>::mapped_type& VectorMap<K, V, T, A>::operator[](const key_type& key)
{
    iterator it = find(key);
    if (it == m_entries.end())
    {
        it = insert(value_type(key, mapped_type())).first;
    }
    return (*it).second;
}

#endif // CRYINCLUDE_CRYCOMMON_VECTORMAP_H