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Creating a simplest refactoring using the RefactoringProvider control

September 30th, 2011

In this article we will create the simplest refactoring which will remove the active comment. Sometimes, there are comments left that are not utilized any longer, such as implemented TO-DO comments, UNDONE comment that is now complete, etc. We will use the RefactoringProvider control shipped in DevExpress Refactor! Pro for this purpose.

Here are the steps we need to perform:

1. Create a new DXCore plug-in
2. Drop the RefactoringProvider component from the Toolbox:

DXCore Refactoring Provider on the toolbox

3. Fill its properties:

  • ProviderName (e.g. “Remove Comment”)
  • Description (e.g. “Completely removes this comment and its neighboring comments”)
  • AutoUndo (true)

DXCore Refactoring Provider sample properties

4. Subscribe to the CheckAvailability, Apply and PreparePreview events:

DXCore Refactoring Provider sample subscribed events

5. Add the following code into event handlers:

CheckAvailability event handler

To indicate that the refactoring provider is available in the current context, we need to set the corresponding Available property. This refactoring should be available when the active code element is a comment, so we simply check if the element is of the Comment type:

private void refactoringProvider1_CheckAvailability(object sender, CheckContentAvailabilityEventArgs ea)
ea.Available = ea.Element is Comment;

Apply event handler

In the Apply event handler we are going to remove the comment with its neighboring comments and surrounding white space characters including empty lines. To do this, we get the active comment, then calculate its cut range for removal using the special SourceRange methods, and, finally, deleting the calculated range:

private void refactoringProvider1_Apply(object sender, ApplyContentEventArgs ea)
SourceRange cutRange = GetCutRange(ea.Element as Comment);

GetCutRange method:

private SourceRange GetCutRange(Comment comment)
Comment startComment;
Comment endComment;
comment.GetFirstAndLastConnectedComments(out startComment, out endComment);

BlockElements blockElements = BlockElements.AllWhiteSpaces | BlockElements.SupportComments;
return new SourceRange(startComment.GetFullBlockCutRange(blockElements).Start,

PreparePreview event handler

This event handler is required if you would like to show a preview hint for the refactoring. We will strike-through the cut range of a comment:

private void refactoringProvider1_PreparePreview(object sender, PrepareContentPreviewEventArgs ea)
SourceRange cutRange = GetCutRange(ea.Element as Comment);

Now, compile the plug-in and see it in action:

Refactor! Pro Remove Comment preview

The sample code is attached (14,098 bytes, Visual Studio 2010, C#).

Products: DXCore, Refactor! Pro
Versions: 11.1 and up
VS IDEs: any
Updated: Sep/30/2011
ID: D118

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