axmol/Box2D/Common/b2GrowableStack.h

/*
* Copyright (c) 2010 Erin Catto http://www.box2d.org
*
* 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>
#include <cstring>

/// 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));
            std::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