OoasTools

/*

 Copyright (c) 2003-2006 Niels Kokholm and Peter Sestoft

 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.Diagnostics;

using SCG = System.Collections.Generic;

namespace C5

{

  /// <summary>

  /// Characterize the mutual position of some view B (other) relative to view A (this)

  /// </summary>

  enum MutualViewPosition

  {

    /// <summary>

    /// B contains A(this)

    /// </summary>

    Contains,

    /// <summary>

    /// B is containd in A(this), but not vice versa

    /// </summary>

    ContainedIn,

    /// <summary>

    /// A and B does not overlap

    /// </summary>

    NonOverlapping,

    /// <summary>

    /// A and B overlap, but neither is contained in the other

    /// </summary>

    Overlapping

  }

  #region View List Nested class

  /// <summary>

  /// This class is shared between the linked list and array list implementations.

  /// </summary>

  /// <typeparam name="V"></typeparam>

  [Serializable]

  class WeakViewList<V> where V : class

  {

    Node start;

    [Serializable]

    internal class Node

    {

      internal WeakReference weakview; internal Node prev, next;

      internal Node(V view) { weakview = new WeakReference(view); }

    }

    internal Node Add(V view)

    {

      Node newNode = new Node(view);

      if (start != null) { start.prev = newNode; newNode.next = start; }

      start = newNode;

      return newNode;

    }

    internal void Remove(Node n)

    {

      if (n == start) { start = start.next; if (start != null) start.prev = null; }

      else { n.prev.next = n.next; if (n.next != null) n.next.prev = n.prev; }

    }

    /// <summary>

    /// Note that it is safe to call views.Remove(view.myWeakReference) if view

    /// is the currently yielded object

    /// </summary>

    /// <returns></returns>

    public SCG.IEnumerator<V> GetEnumerator()

    {

      Node n = start;

      while (n != null)

      {

        //V view = n.weakview.Target as V; //This provokes a bug in the beta1 verifyer

        object o = n.weakview.Target;

        V view = o is V ? (V)o : null;

        if (view == null)

          Remove(n);

        else

          yield return view;

        n = n.next;

      }

    }

  }

  #endregion

}