NoShrinkVector.h

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#ifndef MiscLib__NOSHRINKVECTOR_HEADER__
#define MiscLib__NOSHRINKVECTOR_HEADER__
#include <MiscLib/AlignedAllocator.h>
 
namespace MiscLib
{
    // This is a special implementation of std::vector. You should be able to use it whereever you could you use std::vector.
    // For some reason it is faster than the actual std::vector (at least under windows and with the Intel Compiler)
    // It also has the special property that it never (!!!) frees memory automatically, even if you call clear()
    // The only way to get rid of the allocated mem is to call ClearTotal() (or during destruction of course)
    // Note that element constructors and destructors are invoked correctly though, e.g. when calling clear
    // all elements are destructed.
    // The advantage is however that no copying takes place for resize operations (unless new memory must be allocated)
    // So if you have an array whose size constantly varies between 0 and a max size this class is a good choice
    // SO BE CAREFUL WHEN USING THIS CLASS, IT MAY WASTE A LOT OF MEMORY!
    template <class T, class AllocatorT = MiscLib::AlignedAllocator<T>>
    class NoShrinkVector : protected AllocatorT
    {
    public:
        typedef size_t size_type;
        typedef T value_type;
        typedef T* iterator;
        typedef const T* const_iterator;
        typedef T& reference;
        typedef const T& const_reference;
        typedef T* pointer;
        typedef const T* const_pointer;
        typedef size_t ptrdiff_t;
        typedef std::reverse_iterator<T*> reverse_iterator;
        typedef std::reverse_iterator<const T*> const_reverse_iterator;
 
        NoShrinkVector()
        {
            m_begin = NULL;
            m_end = NULL;
            m_capacity = NULL;
        }
 
        NoShrinkVector(size_type s)
        {
            m_begin = AllocatorT::allocate(s);
            m_end = m_begin + s;
            m_capacity = m_end;
            value_type v;
            for (size_type i = 0; i < s; ++i)
            {
                AllocatorT::construct(m_begin + i, v);
            }
        }
 
        NoShrinkVector(size_type s, const T& v)
        {
            m_begin = AllocatorT::allocate(s);
            m_end = m_begin + s;
            m_capacity = m_end;
            for (size_type i = 0; i < s; ++i)
            {
                AllocatorT::construct(m_begin + i, v);
            }
        }
 
        NoShrinkVector(const NoShrinkVector<T, AllocatorT>& v)
        {
            size_type s = v.size();
            if (!s)
            {
                m_begin = NULL;
                m_end = NULL;
                m_capacity = NULL;
                return;
            }
            m_begin = AllocatorT::allocate(s);
            m_end = m_begin + s;
            m_capacity = m_end;
            for (size_type i = 0; i < s; ++i)
            {
                AllocatorT::construct(m_begin + i, v.m_begin[i]);
            }
        }
 
        template <class OtherAllocatorT>
        NoShrinkVector(const NoShrinkVector<T, OtherAllocatorT>& v)
        {
            size_type s = v.size();
            if (!s)
            {
                m_begin = NULL;
                m_end = NULL;
                m_capacity = NULL;
                return;
            }
            m_begin = AllocatorT::allocate(s);
            m_end = m_begin + s;
            m_capacity = m_end;
            for (size_type i = 0; i < s; ++i)
            {
                AllocatorT::construct(m_begin + i, v.m_begin[i]);
            }
        }
 
        ~NoShrinkVector()
        {
            if (m_begin)
            {
                for (size_type i = 0; i < size(); ++i)
                {
                    AllocatorT::destroy(m_begin + i);
                }
                AllocatorT::deallocate(m_begin, capacity());
            }
        }
 
        NoShrinkVector<T>&
        operator=(const NoShrinkVector<T, AllocatorT>& v)
        {
            if (&v == this)
            {
                return *this;
            }
            size_type s = v.size();
            if (!s)
            {
                clear();
                return *this;
            }
            if (m_begin)
            {
                for (size_type i = 0; i < size(); ++i)
                {
                    AllocatorT::destroy(m_begin + i);
                }
                AllocatorT::deallocate(m_begin, capacity());
            }
            m_begin = AllocatorT::allocate(s);
            m_end = m_begin + s;
            m_capacity = m_end;
            for (size_type i = 0; i < s; ++i)
            {
                AllocatorT::construct(m_begin + i, v.m_begin[i]);
            }
            return *this;
        }
 
        template <class OtherAllocatorT>
        NoShrinkVector<T>&
        operator=(const NoShrinkVector<T, OtherAllocatorT>& v)
        {
            size_type s = v.size();
            if (!s)
            {
                clear();
                return *this;
            }
            if (m_begin)
            {
                for (size_type i = 0; i < size(); ++i)
                {
                    AllocatorT::destroy(m_begin + i);
                }
                AllocatorT::deallocate(m_begin, capacity());
            }
            m_begin = AllocatorT::allocate(s);
            m_end = m_begin + s;
            m_capacity = m_end;
            for (size_type i = 0; i < s; ++i)
            {
                AllocatorT::construct(m_begin + i, v.m_begin[i]);
            }
            return *this;
        }
 
        void
        clear()
        {
            for (size_type i = 0; i < size(); ++i)
            {
                AllocatorT::destroy(m_begin + i);
            }
            m_end = m_begin;
        }
 
        void
        ClearTotal()
        {
            if (m_begin)
            {
                for (size_type i = 0; i < size(); ++i)
                {
                    AllocatorT::destroy(m_begin + i);
                }
                AllocatorT::deallocate(m_begin, capacity());
            }
            m_end = m_begin = m_capacity = NULL;
        }
 
        void
        reserve(size_type s)
        {
            if (!s)
            {
                return;
            }
            if (capacity() < s)
            {
                size_type olds = size();
                T* newBegin = AllocatorT::allocate(s);
                if (m_begin)
                {
                    for (size_type i = 0; i < olds; ++i)
                    {
                        AllocatorT::construct(newBegin + i, m_begin[i]);
                        AllocatorT::destroy(m_begin + i);
                    }
                    AllocatorT::deallocate(m_begin, capacity());
                }
                m_end = newBegin + olds;
                m_begin = newBegin;
                m_capacity = m_begin + s;
            }
        }
 
        size_type
        size() const
        {
            return m_end - m_begin;
        }
 
        size_type
        capacity() const
        {
            return m_capacity - m_begin;
        }
 
        void
        resize(size_type s, const value_type& v)
        {
            if (!s)
            {
                clear();
                return;
            }
            if (capacity() >= s)
            {
                for (size_type i = s; i < size(); ++i)
                {
                    AllocatorT::destroy(m_begin + i);
                }
                for (size_type i = size(); i < s; ++i)
                {
                    AllocatorT::construct(m_begin + i, v);
                }
                m_end = m_begin + s;
                return;
            }
            T* newBegin = AllocatorT::allocate(2 * s);
            if (m_begin)
            {
                for (size_type i = 0; i < size(); ++i)
                {
                    AllocatorT::construct(newBegin + i, m_begin[i]);
                    AllocatorT::destroy(m_begin + i);
                }
                AllocatorT::deallocate(m_begin, capacity());
                for (size_type i = size(); i < s; ++i)
                {
                    AllocatorT::construct(newBegin + i, v);
                }
            }
            else
            {
                for (size_type i = 0; i < s; ++i)
                {
                    AllocatorT::construct(newBegin + i, v);
                }
            }
            m_end = newBegin + s;
            m_begin = newBegin;
            m_capacity = m_begin + 2 * s;
        }
 
        void
        resize(size_type s)
        {
            resize(s, value_type());
        }
 
        operator T*()
        {
            return m_begin;
        }
 
        operator const T*() const
        {
            return m_begin;
        }
 
        T&
        at(size_type i)
        {
            return m_begin[i];
        }
 
        const T&
        at(size_type i) const
        {
            return m_begin[i];
        }
 
        void
        push_back(const T& v)
        {
            if (m_end >= m_capacity)
            {
                size_type olds = size();
                size_type s = olds * 2;
                if (!s)
                {
                    s = 1;
                }
                T* newBegin = AllocatorT::allocate(s);
                if (m_begin)
                {
                    for (size_type i = 0; i < olds; ++i)
                    {
                        AllocatorT::construct(newBegin + i, m_begin[i]);
                        AllocatorT::destroy(m_begin + i);
                    }
                    AllocatorT::deallocate(m_begin, capacity());
                }
                m_end = newBegin + olds;
                m_begin = newBegin;
                m_capacity = m_begin + s;
            }
            AllocatorT::construct(m_end, v);
            ++m_end;
        }
 
        void
        insert(T* where, const T& v)
        {
            size_type whereIdx = where - m_begin;
            if (m_end >= m_capacity)
            {
                size_type olds = size();
                size_type s = olds * 2;
                if (!s)
                {
                    s = 1;
                }
                T* newBegin = AllocatorT::allocate(s);
                if (m_begin)
                {
                    for (size_type i = 0; i < olds; ++i)
                    {
                        AllocatorT::construct(newBegin + i, m_begin[i]);
                        AllocatorT::destroy(m_begin + i);
                    }
                    AllocatorT::deallocate(m_begin, capacity());
                }
                m_end = newBegin + olds;
                m_begin = newBegin;
                m_capacity = m_begin + s;
                where = m_begin + whereIdx;
            }
            if (size() > whereIdx)
            {
                AllocatorT::construct(m_end, m_begin[size() - 1]);
                for (size_type i = size() - 1; i > whereIdx; --i)
                {
                    m_begin[i] = m_begin[i - 1];
                }
                *where = v;
            }
            else
            {
                AllocatorT::construct(where, v);
            }
            ++m_end;
        }
 
        void
        erase(T* where)
        {
            for (size_type i = where - m_begin; i < size() - 1; ++i)
            {
                m_begin[i] = m_begin[i + 1];
            }
            --m_end;
            AllocatorT::destroy(m_end);
        }
 
        void
        pop_back()
        {
            --m_end;
            AllocatorT::destroy(m_end);
        }
 
        T*
        begin()
        {
            return m_begin;
        }
 
        const T*
        begin() const
        {
            return m_begin;
        }
 
        T*
        end()
        {
            return m_end;
        }
 
        const T*
        end() const
        {
            return m_end;
        }
 
        reverse_iterator
        rbegin()
        {
            return std::reverse_iterator<T*>(m_end);
        }
 
        const_reverse_iterator
        rbegin() const
        {
            return std::reverse_iterator<const T*>(m_end);
        }
 
        reverse_iterator
        rend()
        {
            return std::reverse_iterator<T*>(m_begin);
        }
 
        const_reverse_iterator
        rend() const
        {
            return std::reverse_iterator<const T*>(m_begin);
        }
 
        T&
        back()
        {
            return *(m_end - 1);
        }
 
        const T&
        back() const
        {
            return *(m_end - 1);
        }
 
        T&
        front()
        {
            return *m_begin;
        }
 
        const T&
        front() const
        {
            return *m_begin;
        }
 
    private:
        T* m_begin;
        T* m_end;
        T* m_capacity;
    };
}; // namespace MiscLib
 
#endif