// Unity C# reference source

// Copyright (c) Unity Technologies. For terms of use, see

// https://unity3d.com/legal/licenses/Unity_Reference_Only_License

using System;

using System.Collections.Generic;

namespace UnityEngine.UIElements

{

class ObjectPool<T> where T : new()

{

private readonly Stack<T> m_Stack = new Stack<T>();

private int m_MaxSize;

internal Func<T> CreateFunc;

public int maxSize

{

get { return m_MaxSize; }

set

{

m_MaxSize = Math.Max(0, value);

while (Size() > m_MaxSize)

{

Get();

}

}

}

public ObjectPool(Func<T> CreateFunc, int maxSize = 100)

{

this.maxSize = maxSize;

if (CreateFunc == null)

{

this.CreateFunc = () => new T();

}

else

{

this.CreateFunc = CreateFunc;

}

}

public int Size()

{

return m_Stack.Count;

}

public void Clear()

{

m_Stack.Clear();

}

public T Get()

{

T evt = m_Stack.Count == 0 ? CreateFunc() : m_Stack.Pop();

return evt;

}

public void Release(T element)

{

if (m_Stack.Count > 0 && ReferenceEquals(m_Stack.Peek(), element))

Debug.LogError("Internal error. Trying to destroy object that is already released to pool.");

if (m_Stack.Count < maxSize)

{

m_Stack.Push(element);

}

}

}

}