Conditionally insert parenthesis for completion provider on functions

The following code is getting me closer.  However, I need to know which key was pressed to commit the completion provider, as if the user did use the open parenthesis, then I dont want this code to run.

private void Session_Committed(object sender, EventArgs e)
{
	if (sender is CompletionSession completionSession)
	{
		var options = new TextChangeOptions
		{
			CanMergeIntoPreviousChange = true,
			OffsetDelta = TextChangeOffsetDelta.SequentialOnly
		};
		var changes = CompletionSession.View.SyntaxEditor.Document.CreateTextChange(TextChangeTypes.Typing, options);
		changes.InsertText(completionSession.View.Selection.EndOffset, "(");
		changes.Apply();
	}
}

Is there a better way to do this?

Hi Josh,

That sounds like expected behavior right now.  If the '(' is typed in and the DelimiterAutoCompleter is actively tracking it to insert the corresponding ')', then the caret should skip over the ')' if the caret is right before it, and ')' is typed.  However if you insert "()" as part of the completion item, then the DelimiterAutoCompleter isn't doing any tracking and therefore typing ')' won't skip over an existing ')'.

Typically you do not want to include parentheses in the text that completion items are inserting.  This is so that you can select a function and type '(' and it will then have DelimiterAutoCompleter tracking enabled.

There isn't anything at the moment that tracks what kind of event triggered the completion session commit.

If you do want to dynamically alter what the completion session inserts, a better way might be to make a class that inherits CompletionSession.  You could default the items to including the parens in their auto-complete text.  Then override the session's OnViewTextInput method and see if the e.Text is a '('.  If it is, then you'd want to change the selected completion item's text to not include the parens prior to calling the base method, where the Commit can occur.  You'd have to update your completion provider language service to create an instance of this custom CompletionSession class instead of the base CompletionSession class.