DocumentChangeOperation.cs

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
//
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// to whom the Software is furnished to do so, subject to the following conditions:
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// substantial portions of the Software.
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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using System.Diagnostics;

namespace Unity.CodeEditor.Document
{
	/// <summary>
	/// Describes a change to a TextDocument.
	/// </summary>
	internal sealed class DocumentChangeOperation : IUndoableOperationWithContext
	{
	    private readonly TextDocument _document;
	    private readonly DocumentChangeEventArgs _change;

		internal DocumentChangeOperation(TextDocument document, DocumentChangeEventArgs change)
		{
			_document = document;
			_change = change;
		}

		public void Undo(UndoStack stack)
		{
			Debug.Assert(stack.State == UndoStack.StatePlayback);
			stack.RegisterAffectedDocument(_document);
			stack.State = UndoStack.StatePlaybackModifyDocument;
			Undo();
			stack.State = UndoStack.StatePlayback;
		}

		public void Redo(UndoStack stack)
		{
			Debug.Assert(stack.State == UndoStack.StatePlayback);
			stack.RegisterAffectedDocument(_document);
			stack.State = UndoStack.StatePlaybackModifyDocument;
			Redo();
			stack.State = UndoStack.StatePlayback;
		}

		public void Undo()
		{
			var map = _change.OffsetChangeMapOrNull;
			_document.Replace(_change.Offset, _change.InsertionLength, _change.RemovedText, map?.Invert());
		}

		public void Redo()
		{
			_document.Replace(_change.Offset, _change.RemovalLength, _change.InsertedText, _change.OffsetChangeMapOrNull);
		}
	}
}