source: trunk/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Util/CloneableStack.cs

//
// CloneableStack.cs
//
// Author:
//       Mike Krüger <mkrueger@xamarin.com>
//
// Copyright (c) 2014 Xamarin Inc. (http://xamarin.com)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;
using System.Collections.Generic;
using System.Collections;

namespace ICSharpCode.NRefactory.CSharp
{
  class CloneableStack<T> : IEnumerable<T>, ICollection<T>, ICloneable, IEquatable<CloneableStack<T>>
  {
    int count;
    StackItem top;

    #region IEnumerable[T] implementation
    public IEnumerator<T> GetEnumerator ()
    {
      return new StackItemEnumerator (top);
    }

    IEnumerator IEnumerable.GetEnumerator ()
    {
      return new StackItemEnumerator (top);
    }
    #endregion

    #region ICloneable implementation
    public CloneableStack<T> Clone ()
    {
      CloneableStack<T> result = new CloneableStack<T> ();
      result.count = count;
      result.top   = top;
      return result;
    }

    object ICloneable.Clone ()
    {
      return Clone();
    }
    #endregion

    public void Clear ()
    {
      top = null;
      count = 0;
    }

    public void Push (T item)
    {
      top = new StackItem (top, item);
      count++;
    }

    public T Peek ()
    {
      return top.Item;
    }

    public T Pop ()
    {
      T result = top.Item;
      top = top.Parent;
      count--;
      return result;
    }

    #region IEquatable[T] implementation
    public bool Equals (CloneableStack<T> other)
    {
      return ReferenceEquals (top, other.top);
    }
    #endregion

    #region ICollection[T] implementation
    void ICollection<T>.Add (T item)
    {
      Push (item);
    }

    void ICollection<T>.Clear ()
    {
      top = null;
      count = 0;
    }

    bool ICollection<T>.Contains (T item)
    {
      foreach (T t in this) {
        if (t.Equals (item))
          return true;
      }
      return false;
    }

    void ICollection<T>.CopyTo (T[] array, int arrayIndex)
    {
      int idx = arrayIndex;
      foreach (T t in this) {
        array[idx++] = t;
      }
    }

    bool ICollection<T>.Remove (T item)
    {
      throw new NotImplementedException ();
    }

    public int Count {
      get {
        return count;
      }
    }

    bool ICollection<T>.IsReadOnly {
      get {
        return false;
      }
    }
    #endregion

    class StackItem
    {
      public readonly StackItem Parent;
      public readonly T Item;

      public StackItem (StackItem parent, T item)
      {
        Parent = parent;
        Item = item;
      }
    }

    class StackItemEnumerator : IEnumerator<T>
    {
      StackItem cur, first;

      public StackItemEnumerator (StackItem cur)
      {
        this.cur = first = new StackItem (cur, default(T));
      }

      #region IDisposable implementation
      void IDisposable.Dispose ()
      {
        cur = first = null;
      }
      #endregion

      #region IEnumerator implementation
      bool IEnumerator.MoveNext ()
      {
        if (cur == null)
          return false;
        cur = cur.Parent;
        return cur != null;
      }

      void IEnumerator.Reset ()
      {
        cur = first;
      }

      object IEnumerator.Current {
        get {
          return cur.Item;
        }
      }
      #endregion

      #region IEnumerator[T] implementation
      T IEnumerator<T>.Current {
        get {
          return cur.Item;
        }
      }
      #endregion
    }
  }
}