Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / Controls / ModelTreeEnumerator.cs / 1305600 / ModelTreeEnumerator.cs
//---------------------------------------------------------------------------- // //// Copyright (C) Microsoft Corporation. All rights reserved. // // //--------------------------------------------------------------------------- using System; using System.Collections; using System.ComponentModel; using System.Diagnostics; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using MS.Internal.Controls; using MS.Internal.Data; using MS.Utility; namespace MS.Internal.Controls { internal abstract class ModelTreeEnumerator : IEnumerator { internal ModelTreeEnumerator(object content) { _content = content; } #region IEnumerator object IEnumerator.Current { get { return this.Current; } } bool IEnumerator.MoveNext() { return this.MoveNext(); } void IEnumerator.Reset() { this.Reset(); } #endregion #region Protected protected object Content { get { return _content; } } protected int Index { get { return _index; } set { _index = value; } } protected virtual object Current { get { // Don't VerifyUnchanged(); According to MSDN: // If the collection is modified between MoveNext and Current, // Current will return the element that it is set to, even if // the enumerator is already invalidated. if (_index == 0) { return _content; } #pragma warning disable 1634 // about to use PreSharp message numbers - unknown to C# // Fall through -- can't enumerate (before beginning or after end) #pragma warning suppress 6503 throw new InvalidOperationException(SR.Get(SRID.EnumeratorInvalidOperation)); // above exception is part of the IEnumerator.Current contract when moving beyond begin/end #pragma warning restore 1634 } } protected virtual bool MoveNext() { if (_index < 1) { // Singular content, can move next to 0 and that's it. _index++; if (_index == 0) { // don't call VerifyUnchanged if we're returning false anyway. // This permits users to change the Content after enumerating // the content (e.g. in the invalidation callback of an inherited // property). See bug 955389. VerifyUnchanged(); return true; } } return false; } protected virtual void Reset() { VerifyUnchanged(); _index = -1; } protected abstract bool IsUnchanged { get; } protected void VerifyUnchanged() { // If the content has changed, then throw an exception if (!IsUnchanged) { throw new InvalidOperationException(SR.Get(SRID.EnumeratorVersionChanged)); } } #endregion #region Data private int _index = -1; private object _content; #endregion } internal class ContentModelTreeEnumerator : ModelTreeEnumerator { internal ContentModelTreeEnumerator(ContentControl contentControl, object content) : base(content) { Debug.Assert(contentControl != null, "contentControl should be non-null."); _owner = contentControl; } protected override bool IsUnchanged { get { return Object.ReferenceEquals(Content, _owner.Content); } } private ContentControl _owner; } internal class HeaderedContentModelTreeEnumerator : ModelTreeEnumerator { internal HeaderedContentModelTreeEnumerator(HeaderedContentControl headeredContentControl, object content, object header) : base(header) { Debug.Assert(headeredContentControl != null, "headeredContentControl should be non-null."); Debug.Assert(header != null, "Header should be non-null. If Header was null, the base ContentControl enumerator should have been used."); _owner = headeredContentControl; _content = content; } protected override object Current { get { if ((Index == 1) && (_content != null)) { return _content; } return base.Current; } } protected override bool MoveNext() { if (_content != null) { if (Index == 0) { // Moving from the header to content Index++; VerifyUnchanged(); return true; } else if (Index == 1) { // Going from content to the end Index++; return false; } } return base.MoveNext(); } protected override bool IsUnchanged { get { object header = Content; // Header was passed to the base so that it would appear in index 0 return Object.ReferenceEquals(header, _owner.Header) && Object.ReferenceEquals(_content, _owner.Content); } } private HeaderedContentControl _owner; private object _content; } internal class HeaderedItemsModelTreeEnumerator : ModelTreeEnumerator { internal HeaderedItemsModelTreeEnumerator(HeaderedItemsControl headeredItemsControl, IEnumerator items, object header) : base(header) { Debug.Assert(headeredItemsControl != null, "headeredItemsControl should be non-null."); Debug.Assert(items != null, "items should be non-null."); Debug.Assert(header != null, "header should be non-null. If Header was null, the base ItemsControl enumerator should have been used."); _owner = headeredItemsControl; _items = items; } protected override object Current { get { if (Index > 0) { return _items.Current; } return base.Current; } } protected override bool MoveNext() { if (Index >= 0) { Index++; return _items.MoveNext(); } return base.MoveNext(); } protected override void Reset() { base.Reset(); _items.Reset(); } protected override bool IsUnchanged { get { object header = Content; // Header was passed to the base so that it would appear in index 0 return Object.ReferenceEquals(header, _owner.Header); } } private HeaderedItemsControl _owner; private IEnumerator _items; } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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