Cyclic Queue : Queue « Collections Data Structure « C# / C Sharp

1. C# / C Sharp
2. Collections Data Structure
3. Queue

Cyclic Queue

        

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace Lilium.Collections
{
  public class CyclicQueue<T>: IEnumerable<T>
  {
    public CyclicQueue(int length)
    {
      if (length < 0)
        throw new InvalidOperationException("Queue length can't be less then zero");

      m_Queue = new T[length];
    }

    public void Enqueue(T item)
    {   
      var length = Queue.Length ;
      if (length == 0)
        return;
      
      Queue[Tail] = item;
      Tail = (Tail + 1) % length;
      if (Count == length)
        Head = (Head + 1) % length;
      else
        Count++;
    }

    public T Dequeue()
    {
      if (Count == 0)
        throw new InvalidOperationException("Queue is empty");

      T local = Queue[Head];
      Queue[Head] = default(T);
      Head = (Head + 1) % Queue.Length;
      return local;
    }


    /// <summary>
    /// Returns enumerator which enumerates from queue tail to the head.
    /// </summary>
    /// <returns></returns>
    public IEnumerator<T> GetReversedEnumerator()
    {
      var length = Count;
      if (length == 0)
        yield break;

      if (Tail > Head)
        for (int i = Tail - 1; i >= Head; i--)
          yield return Queue[i];
      else
      {
        for (int i = Tail - 1; i >= 0; i--)
          yield return Queue[i];
        for (int i = length - 1; i >= Head; i--)
          yield return Queue[i];
      }
    }

    public bool TryPeekLast(out T item)
    {
      if (Count != 0)
      {
        item = Queue[Tail != 0 ? Tail - 1 : Queue.Length - 1];
        return true;
      }
      else
      {
        item = default(T);
        return false;
      }
    }

    #region public int Count

    private int m_Count;

    public int Count
    {
      get
      {
        return m_Count;
      }
      private set
      {
        m_Count = value;
      }
    }

    #endregion

    #region IEnumerable<T> Members

    public IEnumerator<T> GetEnumerator()
    {
      var length = Queue.Length;
      if (length == 0)
        yield break;

      if (Tail > Head)
        for (int i = Head; i < Tail; i++)
          yield return Queue[i];
      else
      {
        for (int i = Head; i < length; i++)
          yield return Queue[i];
        for (int i = 0; i < Tail - 1; i++)
          yield return Queue[i];
      }
    }

    #endregion

    #region IEnumerable Members

    IEnumerator IEnumerable.GetEnumerator()
    {
      return GetEnumerator();
    }

    #endregion

    #region private T[] Queue

    private readonly T[] m_Queue;

    private T[] Queue
    {
      get
      {
        return m_Queue;
      }
    }

    #endregion

    #region private int Head

    private int m_Head;

    private int Head
    {
      get
      {
        return m_Head;
      }
      set
      {
        m_Head = value;
      }
    }

    #endregion

    #region private int Tail

    private int m_Tail;

    private int Tail
    {
      get
      {
        return m_Tail;
      }
      set
      {
        m_Tail = value;
      }
    }

    #endregion
  }
}

   
    
    
    
    
    
    
    
  

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