Intlist class

Intlist.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;

namespace Matlib
{
    public class Intlist
    {
        readonly static int NIL = -1;
        readonly static int EMPTY = -2;

        int[] data;
        int ip;
        int count;
        int size;

        public Intlist(int size)
        {

            this.size = size;
            this.ip = NIL;
            this.data = new int[size];
            for (int i = 0; i < size; i++)
                data[i] = EMPTY;

            Reset();
        }

        public void Reset()
        {
            int i = ip;
            int p = ip;
            while (NIL != i)
            {
                p = i;
                i = data[i];
                data[p] = EMPTY;
            }
            if (NIL != p)
            {
                data[p] = EMPTY;
            }
            ip = NIL;
            count = 0;
        }

        public void Clear()
        {
            while (count > 0)
            {
                Pop();
            }
        }

        public int Count { get { return count; } }
        public int Size { get { return size; } }
        public bool Empty { get { return 0 == count; } }

        public bool Contains(int value)
        {
            Debug.Assert(value >= 0);
            Debug.Assert(value < size);

            return EMPTY != data[value];
        }

        public void Push(int value)
        {
            if (Contains(value))
            {
                return;
            }

            data[value] = ip;
            ip = value;
            count += 1;
        }

        public int Pop()
        {
            Debug.Assert(ip >= 0);

            int value = ip;
            ip = data[ip];
            data[value] = EMPTY;
            count -= 1;

            return value;
        }

        public List<int> Move()
        {
            List<int> list = new List<int>(count);

            Move(ref list);

            return list;
        }

        public void Move(ref List<int> list)
        {
            list.Clear();
            list.Capacity = count;

            while (count > 0)
            {
                list.Add(Pop());
            }
        }
    }
}

IntlistTests.cs

using System;
using Matlib;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace Matlib.Tests
{
    [TestClass]
    public class IntlistTests
    {
        [TestMethod]
        public void IntlistPush()
        {
            var il = new Intlist(10);
            il.Push(1);
            il.Push(7);
            il.Push(3);
            il.Push(2);

            Assert.AreEqual(4, il.Count);
        }

        [TestMethod]
        public void IntlistContains()
        {
            var il = new Intlist(10);
            il.Push(1);
            il.Push(7);
            il.Push(3);
            il.Push(2);

            Assert.IsTrue(il.Contains(1));
            Assert.IsTrue(il.Contains(2));
            Assert.IsTrue(il.Contains(3));
            Assert.IsTrue(il.Contains(7));

            Assert.IsTrue(!il.Contains(0));
            Assert.IsTrue(!il.Contains(4));
        }

        [TestMethod]
        public void IntlistPop()
        {
            var il = new Intlist(10);
            il.Push(1);
            il.Push(7);
            il.Push(3);
            il.Push(2);

            Assert.AreEqual(2, il.Pop());
            Assert.AreEqual(3, il.Pop());
            Assert.AreEqual(7, il.Pop());
            Assert.AreEqual(1, il.Pop());
        }

        [TestMethod]
        public void IntlistMove()
        {
            var il = new Intlist(10);
            il.Push(1);
            il.Push(7);
            il.Push(3);
            il.Push(2);

            Assert.AreEqual(4, il.Count);

            var list = il.Move();

            Assert.AreEqual(0, il.Count);

            Assert.AreEqual(2, list[0]);
            Assert.AreEqual(3, list[1]);
            Assert.AreEqual(7, list[2]);
            Assert.AreEqual(1, list[3]);
        }
    }
}