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/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / Documents / TextElementEnumerator.cs / 1 / TextElementEnumerator.cs
//---------------------------------------------------------------------------- // //// Copyright (C) Microsoft Corporation. All rights reserved. // // // // Description: IEnumerator for TextRange and TextElement content. // // // History: // 05/27/2003 : [....] - Created // //--------------------------------------------------------------------------- using System; using System.Collections; using System.Collections.Generic; using MS.Internal; using System.Text; using MS.Utility; using System.Windows.Controls; #pragma warning disable 1634, 1691 // suppressing PreSharp warnings namespace System.Windows.Documents { internal class TextElementEnumerator: IEnumerator where TextElementType : TextElement { //----------------------------------------------------- // // Constructors // //----------------------------------------------------- #region Constructors // Creates an enumerator instance. // Null start/end creates an empty enumerator. internal TextElementEnumerator(TextPointer start, TextPointer end) { Invariant.Assert(start != null && end != null || start == null && end == null, "If start is null end should be null!"); _start = start; _end = end; // Remember what generation the backing store was in when we started, // so we can throw if this enumerator is accessed after content has // changed. if (_start != null) { _generation = _start.TextContainer.Generation; } } #endregion Constructors //------------------------------------------------------ // // Public Methods // //----------------------------------------------------- #region Public Methods public void Dispose() { // Empty the enumerator _current = null; _navigator = null; } object System.Collections.IEnumerator.Current { get { return this.Current; } } /// /// Return the current object this enumerator is pointing to. This is /// generally a FrameworkElement, TextElement, an embedded /// object, or Text content. /// ////// According to the IEnumerator spec, the Current property keeps /// the element even after the content has been modified /// (even if the current element has been deleted from the collection). /// This is unlike to Reset or MoveNext which throw after any content change. /// public TextElementType Current { get { if (_navigator == null) { #pragma warning suppress 6503 // IEnumerator.Current is documented to throw this exception throw new InvalidOperationException(SR.Get(SRID.EnumeratorNotStarted)); } if (_current == null) { #pragma warning suppress 6503 // IEnumerator.Current is documented to throw this exception throw new InvalidOperationException(SR.Get(SRID.EnumeratorReachedEnd)); } return _current; } } ////// Advance the enumerator to the next object in the range. Return true if content /// was found. /// public bool MoveNext() { // Throw if the tree has been modified since this enumerator was created. if (_start != null && _generation != _start.TextContainer.Generation) { throw new InvalidOperationException(SR.Get(SRID.EnumeratorVersionChanged)); } // Return false if the collection is empty if (_start == null || _start.CompareTo(_end) == 0) { return false; } // Return false if the navigator reached the end of the collection if (_navigator != null && _navigator.CompareTo(_end) >= 0) { return false; } // Advance the navigator if (_navigator == null) { // Set it to the first element for the very first move _navigator = new TextPointer(_start); _navigator.MoveToNextContextPosition(LogicalDirection.Forward); } else { // Move to the next element in the collection Invariant.Assert(_navigator.GetPointerContext(LogicalDirection.Backward) == TextPointerContext.ElementStart, "Unexpected run type in TextElementEnumerator"); _navigator.MoveToElementEdge(ElementEdge.AfterEnd); _navigator.MoveToNextContextPosition(LogicalDirection.Forward); } // Update current cache if (_navigator.CompareTo(_end) < 0) { _current = (TextElementType)_navigator.Parent; } else { _current = null; } // Return true if the content was found return (_current != null); } ////// Reset the enumerator to the start of the range. /// public void Reset() { // Throw if the tree has been modified since this enumerator was created. if (_start != null && _generation != _start.TextContainer.Generation) { throw new InvalidOperationException(SR.Get(SRID.EnumeratorVersionChanged)); } _navigator = null; _current = null; } #endregion Public Methods //------------------------------------------------------ // // Public Properties // //------------------------------------------------------ #region Public Properties #endregion Public Properties //----------------------------------------------------- // // Public Events // //------------------------------------------------------ #region Public Events #endregion Public Events //----------------------------------------------------- // // Protected Methods // //----------------------------------------------------- #region Protected Methods #endregion Protected Events //----------------------------------------------------- // // Internal Methods // //------------------------------------------------------ #region Internal Methods #endregion Internal methods //----------------------------------------------------- // // Internal Properties // //------------------------------------------------------ #region Internal Properties #endregion Internal Properties //------------------------------------------------------ // // Internal Events // //----------------------------------------------------- #region Internal Events #endregion Internal Events //------------------------------------------------------ // // Private Properties // //----------------------------------------------------- #region Private Properties #endregion Private Properties //----------------------------------------------------- // // Private Fields // //----------------------------------------------------- #region Private Fields // Edges of the span to enumerator over. private readonly TextPointer _start; private readonly TextPointer _end; // Backing store generation when this enumerator was created. private readonly uint _generation; // Current position in the enumeration. private TextPointer _navigator; // Calculated content at the current position. private TextElementType _current; #endregion Private Fields } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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