xnabox2demo/Box2D.XNA/Common/GrowableStack.cs

/*
* Box2D.XNA port of Box2D:
* Copyright (c) 2009 Brandon Furtwangler, Nathan Furtwangler
*
* Original source Box2D:
* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com 
* 
* This software is provided 'as-is', without any express or implied 
* warranty.  In no event will the authors be held liable for any damages 
* arising from the use of this software. 
* Permission is granted to anyone to use this software for any purpose, 
* including commercial applications, and to alter it and redistribute it 
* freely, subject to the following restrictions: 
* 1. The origin of this software must not be misrepresented; you must not 
* claim that you wrote the original software. If you use this software 
* in a product, an acknowledgment in the product documentation would be 
* appreciated but is not required. 
* 2. Altered source versions must be plainly marked as such, and must not be 
* misrepresented as being the original software. 
* 3. This notice may not be removed or altered from any source distribution. 
*/

#ifndef B2_GROWABLE_STACK_H
#define B2_GROWABLE_STACK_H
#include <Box2D/Common/b2Settings.h>

/// This is a growable LIFO stack with an initial capacity of N.
/// If the stack size exceeds the initial capacity, the heap is used
/// to increase the size of the stack.
template <typename T, int32 N>
class b2GrowableStack
{
public:
	b2GrowableStack()
	{
		m_stack = m_array;
		m_count = 0;
		m_capacity = N;
	}

	~b2GrowableStack()
	{
		if (m_stack != m_array)
		{
			b2Free(m_stack);
			m_stack = NULL;
		}
	}

	void Push(const T& element)
	{
		if (m_count == m_capacity)
		{
			T* old = m_stack;
			m_capacity *= 2;
			m_stack = (T*)b2Alloc(m_capacity * sizeof(T));
			memcpy(m_stack, old, m_count * sizeof(T));
			if (old != m_array)
			{
				b2Free(old);
			}
		}

		m_stack[m_count] = element;
		++m_count;
	}

	T Pop()
	{
		b2Assert(m_count > 0);
		--m_count;
		return m_stack[m_count];
	}

	int32 GetCount()
	{
		return m_count;
	}

private:
	T* m_stack;
	T m_array[N];
	int32 m_count;
	int32 m_capacity;
};


#endif