template<typename Type>
class Grid
{
public:
    Grid() : memory(nullptr)
    {   }
    
    //Construct and call Resize().
    Grid(const cRect &newBounds, const Type &value = Type()) : memory(nullptr)
    {
        this->Resize(newBounds, value);
    }
    
    ~Grid()
    {
        //Clear the grid, calling the destructors on any constructed elements.
        this->Clear();
        
        //Deallocate any reserved memory.
        this->deallocate(this->memory);
    }
    
    //Erases the grid, resetting the bounds to (0,0,0,0).
    //Does not free the reserved capacity. Call Conserve() afterward to do that.
    void Clear()
    {
        this->Resize(cRect(0,0,0,0));
    }
    
    //================================================================
    
    //Resizes the grid to 'newBounds', constructing the new elements with 'value' (or the default constructor if 'value' is not set).
    //If Grid doesn't have enough capacity, it'll reallocate storage and move the elements to new memory addresses.
    //Throws std::bad_alloc if the allocation failed, and rethrows any exceptions thrown by element constructors or destructors.
    void Resize(const cRect &newBounds, const Type &value = Type())
    {
        try
        {
            //[CAN THROW - Make sure no member variables are changed before these function calls]
            cRect newCapacity = this->ensureCapacity(newBounds, true);
            
            //[CAN THROW - Make sure no member variables are changed before these function calls]
            this->constructAdditions(this->bounds, newBounds, value);
            
            //Record the new capacity, after we are sure no exceptions were thrown and everything succeeded.
            this->capacity = newCapacity;
        }
        catch(std::exception &exception)
        {
            Log::Message("...blah..."); //exception.what()
            throw;
        }
        catch(...)
        {
            Log::Message("...blah..."); //Unknown exception
            throw;
        }

        this->bounds = newBounds;
    }

    //================================================================
    
private:
    //Constructs all the new elements between oldBounds and newBounds setting them to 'value'.
    //If 'newBounds' is smaller than 'oldBounds', deconstructs the old elements.
    void constructAdditions(const cRect &oldBounds, const cRect &newBounds, const Type &value = Type())
    {
        //The largest extent of both rects.
        cRect totalArea = cRect::Encompassing(oldBounds, newBounds);
        //The overlapping portion of both rects (if any).
        cRect reducedArea = cRect::Intersection(oldBounds, newBounds);
        
        //-------------------------------------------
        
        //If a constructor throws an exception, we want to know which element it was,
        //so we keep track of what the last point was before the exception was thrown.
        cPoint lastPoint;
        
        try
        {
            for(cPoint point : newBounds)
            {
                if(reducedArea.Contains(point))
                {
                    //Do nothing - this area is already constructed.
                }
                else
                {
                    lastPoint = point;
                    
                    //Needs to be constructed.
                    this->construct((*this)[point], value);
                }
            }
        }
        catch(...)
        {
            //Since we caught an exception, destruct every element we had previously constructed.
            for(cPoint point : newBounds)
            {
                if(reducedArea.Contains(point))
                {
                    //Do nothing - this area is already constructed.
                }
                else if(point == lastPoint)
                {
                    //Stop here - we didn't construct anything beyond this element.
                    break;
                }
                else
                {
                    //Destruct the element we previously constructed.
                    this->destruct((*this)[point]);
                }
            }
            
            throw;
        }
        
        //-------------------------------------------
        
        //Destruct any elements that we no longer want (if we're resizing smaller than our previous size).
        for(cPoint point : oldBounds)
        {
            if(reducedArea.Contains(point))
            {
                //Do nothing - we're preserving these elements.
            }
            else
            {
                //Needs to be destructed.
                this->destruct((*this)[point]);
            }
        }
    }
    
    //================================================================
    
    //Construct a single element.
    void construct(Type &element, const Type &value = Type())
    {
        new (&element) Type(value); //Call constructor.
    } 
    
    //Constructs an element with move semantics.
    void moveConstruct(Type &element, Type &&value)
    {
        new (&element) Type(value); //Call move constructor.
    }

    //Destruct a single element.
    void destruct(Type &element)
    {
        element.~Type(); //Call destructor.
    }
    
    //================================================================
    
    //Ensures *at least* enough room for 'bounds'. Returns the resulting capacity.
    //If 'addExtra' is true, includes even more capacity for future growth.
    cRect ensureCapacity(const cRect &bounds, bool addExtra)
    {
        //Check whether we have enough capacity to resize.
        if(!this->capacity.Contains(bounds))
        {
            cRect desiredCapacity = bounds;
            
            if(addExtra)
            {
                //If we're bothering to grow in size, we might as well reserve a little extra for future growth.
                int quarterWidth = (bounds.size.width / 4) + 1;
                int quarterHeight = (bounds.size.height / 4) + 1;
                
                desiredCapacity.Pad(quarterWidth, quarterWidth, quarterHeight, quarterHeight);
            }
            
            //Allocate and move the elements.
            //[CAN THROW - Make sure no member variables are changed before this function call]
            this->reallocateMemory(desiredCapacity);
            
            //Return the new capacity.
            return desiredCapacity;
        }
        
        //Return the current capacity.
        return this->capacity;
    }    
    
    //================================================================
    
    //This allocates enough memory for 'capacity', without constructing any elements.
    Type *allocate(const cRect &capacity)
    {
        //Allocate the new memory.
        size_t numElements = capacity.size.Area();
        size_t numBytes = (sizeof(Type) * numElements);
        void *data = ::operator new(numBytes);
        
        return static_cast<Type*>(data);
    }
    
    //This deallocates 'memory', without calling any destructors.
    void deallocate(Type *data)
    {
        ::operator delete(data);
    }
    
    //================================================================
    
    //Reallocates the memory and migrates the elements over using moveElements().
    //Throws std::bad_alloc if the allocation failed, and throws any exceptions thrown by element constructors.
    void reallocateMemory(const cRect &newCapacity)
    {
        if(!this->memory)
        {
            //If we don't have any memory, just allocate some and don't worry about moving any elements.
            //[CAN THROW - Make sure no member variables are changed before this function call]
            this->memory = this->allocate(newCapacity);
        }
        else if(newCapacity.IsEmpty())
        {
            //Free all the memory.
            this->deallocate(this->memory);
            this->memory = nullptr;
        }
        else
        {
            //Allocate the new memory.
            //Note: I put the allocated memory into a unique_ptr here, incase moveElements() throws.
            //This way, the new memory is properly released.
            //[CAN THROW - Make sure no member variables are changed before this function call]
            std::unique_ptr<Type, use_operator_delete> newMemory = this->allocate(newCapacity);

            //A few extra variables for readability.
            Type *oldMemory = this->memory;
            const cRect &oldCapacity = this->capacity;
            
            //Move the elements.
            //[CAN THROW - Make sure no member variables are changed before this function call]
            this->moveElements(oldMemory, oldCapacity, newMemory.get(), newCapacity, this->bounds);

            //Delete the old memory.
            this->deallocate(oldMemory);
            
            //And store the new pointer. Have the unique_ptr release ownership of the memory as well.
            this->memory = newMemory.release();
        }
        
        //Record the new capacity.
        this->capacity = newCapacity;
    }
    
    //Called by 'reallocateMemory' only.
    void moveElements(Type *oldMemory, const cRect &oldCapacity, Type *newMemory,
                      const cRect &newCapacity, const cRect &bounds)
    {
        //Insanity preservation.
        //Assert that our elements are actually within the capacity of both the new and old blocks of memory.
        BOOST_ASSERT(oldCapacity.Contains(bounds));
        BOOST_ASSERT(newCapacity.Contains(bounds));
        
        //Assert that neither block of memory's size is empty (they have to have a positive non-zero width and height).
        BOOST_ASSERT(!oldCapacity.IsEmpty());
        BOOST_ASSERT(!newCapacity.IsEmpty());
        
        //Assert that neither pointer to the allocated memory is empty.
        BOOST_ASSERT(oldMemory != nullptr);
        BOOST_ASSERT(newMemory != nullptr);
        
        //The length of each 'row' of the grid's capacity in memory.
        size_t oldStride = oldCapacity.size.width;
        size_t newStride = newCapacity.size.width;
        
        //The initial offset of the actual bounds from the memory capacity.
        size_t oldOffset = oldCapacity.Index(bounds.position);
        size_t newOffset = newCapacity.Index(bounds.position);
        
        //The number of rows and columns of actual elements we need to move.
        size_t rows = bounds.size.height;
        size_t columns = bounds.size.width;
        
        //=================================================================
        
        //Incase a constructor throws an exception, keep track of the last row and column.
        size_t lastRow = 0;
        size_t lastColumn = 0;
        
        try
        {
            //Move-construct all the new elements.
            for(size_t row = 0; row < rows; lastRow = row++)
            {
                for(size_t column = 0; column < columns; lastColumn = column++)
                {
                    size_t oldIndex = (row * oldStride) + column;
                    oldIndex += oldOffset;
                    
                    size_t newIndex = (row * newStride) + column;
                    newIndex += newOffset;
                    
                    //Construct the new location, and move the element.
                    this->moveConstruct(newMemory[newIndex], std::move(oldMemory[oldIndex]));
                }
            }
        }
        catch(...)
        {
            //Since we just caught an exception thrown from one of the element move-constructors,
            //destruct all the new elements we just constructed, up until the failed constructor.
            for(size_t row = 0; row < lastRow; row++)
            {
		//Go to the end of every row, but on the last row, just go to the last element we encountered.
                int &endOfColumn = (row == lastRow? lastColumn : columns);
		
                for(size_t column = 0; column < endOfColumn; column++)
                {
                    size_t newIndex = (row * newStride) + column;
                    newIndex += newOffset;
                    
                    //Destruct the element we constructed in the previous for() loops.
                    this->destruct(newMemory[newIndex]);
                }
            }
            
            throw;
        }
        
        //=================================================================
        
        //Destruct all the old elements.
        for(size_t row = 0; row < rows; row++)
        {
            for(size_t column = 0; column < columns; column++)
            {
                size_t oldIndex = (row * oldStride) + column;
                oldIndex += oldOffset;
                
                //Destruct old location.
                this->destruct(oldMemory[oldIndex]);
            }
        }
    }

    //================================================================
    
private:
    Type *memory;
    
    cRect bounds; //Current grid boundaries.
    cRect capacity; //Currently allocated memory capacity, guaranteed to be at least 'bounds' and maybe larger.
};