C# 方法扩展

using System.Collections.Generic;

namespace Extra_Function
{
    public static class Function
    {
        public static T Pop<T>(this List<T> list)
        {
            if (list != null && list.Count > )
            {
                T value = list[list.Count - ];
                list.RemoveAt(list.Count - );
                return value;
            }
            else
            {
                return default(T);
            }
        }

        public static T Peek<T>(this List<T> list)
        {
            if (list != null && list.Count > )
            {
                return list[list.Count - ];
            }
            else
            {
                return default(T);
            }
        }

        public static void Push<T>(this List<T> list, T value)
        {
            list.Add(value);
        }
    }
}