Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / documents / HostedElements.cs / 1305600 / HostedElements.cs
//---------------------------------------------------------------------------- // // Copyright (C) Microsoft Corporation. All rights reserved. // // File: HostedElements.cs // // Enumerator class for returning descendants of TextBlock and FlowDocumentPage // // History: // 01/17/2005 : [....] - created. // //--------------------------------------------------------------------------- using System.Collections; using MS.Internal.Documents; using System.Collections.Generic; using System.Collections.ObjectModel; using System; using System.Diagnostics; #pragma warning disable 1634, 1691 // suppressing PreSharp warnings namespace System.Windows.Documents { ////// Enumerator class for implementation of IContentHost on TextBlock and FlowDocumentPage. /// Used to iterate through descendants of the content host /// internal class HostedElements : IEnumerator{ //------------------------------------------------------------------- // // Constructors // //------------------------------------------------------------------- #region Constructors internal HostedElements(ReadOnlyCollection textSegments) { _textSegments = textSegments; _currentPosition = null; _currentTextSegment = 0; } #endregion Constructors //-------------------------------------------------------------------- // // IDisposable Methods // //------------------------------------------------------------------- #region IDisposable Methods void IDisposable.Dispose() { _textSegments = null; GC.SuppressFinalize(this); } #endregion IDisposable Methods //-------------------------------------------------------------------- // // Private Methods // //-------------------------------------------------------------------- #region Private Methods public bool MoveNext() { // If _textSegments has been disposed, throw exception if (_textSegments == null) { throw new ObjectDisposedException("HostedElements"); } if (_textSegments.Count == 0) return false; // Verify that current position matches with current text segment, and set it if it's null. if (_currentPosition == null) { // We should be at the start Debug.Assert(_currentTextSegment == 0); // Type check that we can create _currentPosition here if (_textSegments[0].Start is TextPointer) { _currentPosition = new TextPointer(_textSegments[0].Start as TextPointer); } else { // We cannot search, return false _currentPosition = null; return false; } } else if (_currentTextSegment < _textSegments.Count) { // We have not yet reached the end of the container. Assert that our position matches with // our current text segment Debug.Assert(((ITextPointer)_currentPosition).CompareTo(_textSegments[_currentTextSegment].Start) >= 0 && ((ITextPointer)_currentPosition).CompareTo(_textSegments[_currentTextSegment].End) < 0); // This means that we are in the middle of content, so the previous search would have returned // something. We want to now move beyond that position _currentPosition.MoveToNextContextPosition(LogicalDirection.Forward); } // Search strarting from the position in the current segment while (_currentTextSegment < _textSegments.Count) { Debug.Assert(((ITextPointer)_currentPosition).CompareTo(_textSegments[_currentTextSegment].Start) >= 0); while (((ITextPointer)_currentPosition).CompareTo(_textSegments[_currentTextSegment].End) < 0) { if (_currentPosition.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.ElementStart || _currentPosition.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.EmbeddedElement) { return true; } else { _currentPosition.MoveToNextContextPosition(LogicalDirection.Forward); } } // We have reached the end of a segement. Update counters _currentTextSegment++; if (_currentTextSegment < _textSegments.Count) { // Move to the next segment if (_textSegments[_currentTextSegment].Start is TextPointer) { _currentPosition = new TextPointer(_textSegments[_currentTextSegment].Start as TextPointer); } else { // This state is invalid, set to null and return false _currentPosition = null; return false; } } } // We have reached the end without finding an element. Return false. return false; } #endregion Private Methods //------------------------------------------------------------------- // // Private Properties // //-------------------------------------------------------------------- #region Private Properties object IEnumerator.Current { get { return this.Current; } } void IEnumerator.Reset() { throw new NotImplementedException(); } public IInputElement Current { get { // Disable PRESharp warning 6503: "Property get methods should not throw exceptions". // HostedElements must throw exception if Current property is incorrectly accessed if (_textSegments == null) { // Collection was modified #pragma warning suppress 6503 // IEnumerator.Current is documented to throw this exception throw new InvalidOperationException(SR.Get(SRID.EnumeratorCollectionDisposed)); } if (_currentPosition == null) { // Enumerator not started. Call MoveNext to see if we can move ahead #pragma warning suppress 6503 // IEnumerator.Current is documented to throw this exception throw new InvalidOperationException(SR.Get(SRID.EnumeratorNotStarted)); } IInputElement currentElement = null; switch (_currentPosition.GetPointerContext(LogicalDirection.Forward)) { case TextPointerContext.ElementStart: Debug.Assert(_currentPosition.GetAdjacentElementFromOuterPosition(LogicalDirection.Forward) is IInputElement); currentElement = _currentPosition.GetAdjacentElementFromOuterPosition(LogicalDirection.Forward); break; case TextPointerContext.EmbeddedElement: Debug.Assert(_currentPosition.GetAdjacentElement(LogicalDirection.Forward) is IInputElement); currentElement = (IInputElement)_currentPosition.GetAdjacentElement(LogicalDirection.Forward); break; default: // Throw exception because this function should only be called after MoveNext, and not // if MoveNext returns false Debug.Assert(false, "Invalid state in HostedElements.cs"); break; } return currentElement; } } #endregion Private Properties //------------------------------------------------------------------- // // Private Fields // //------------------------------------------------------------------- #region Private Fields ReadOnlyCollection _textSegments; TextPointer _currentPosition; int _currentTextSegment; #endregion Private Fields } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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