public void FormatSpan(SnapshotSpan span)
{
// At this point, the $selection$ token has been replaced with the selected text and
// declarations have been replaced with their default text. We need to format the
// inserted snippet text while carefully handling $end$ position (where the caret goes
// after Return is pressed). The IExpansionSession keeps a tracking point for this
// position but we do the tracking ourselves to properly deal with virtual space. To
// ensure the end location is correct, we take three extra steps:
// 1. Insert an empty comment ("/**/" or "'") at the current $end$ position (prior
// to formatting), and keep a tracking span for the comment.
// 2. After formatting the new snippet text, find and delete the empty multiline
// comment (via the tracking span) and notify the IExpansionSession of the new
// $end$ location. If the line then contains only whitespace (due to the formatter
// putting the empty comment on its own line), then delete the white space and
// remember the indentation depth for that line.
// 3. When the snippet is finally completed (via Return), and PositionCaretForEditing()
// is called, check to see if the end location was on a line containing only white
// space in the previous step. If so, and if that line is still empty, then position
// the caret in virtual space.
// This technique ensures that a snippet like "if($condition$) { $end$ }" will end up
// as:
// if ($condition$)
// {
// $end$
// }
if (!TryGetSubjectBufferSpan(span, out var snippetSpan))
{
return;
}
Contract.ThrowIfNull(ExpansionSession);
// Insert empty comment and track end position
var snippetTrackingSpan = snippetSpan.CreateTrackingSpan(SpanTrackingMode.EdgeInclusive);
var fullSnippetSpan = ExpansionSession.GetSnippetSpan();
var isFullSnippetFormat = fullSnippetSpan == span;
var endPositionTrackingSpan = isFullSnippetFormat ? InsertEmptyCommentAndGetEndPositionTrackingSpan() : null;
var formattingSpan = CommonFormattingHelpers.GetFormattingSpan(SubjectBuffer.CurrentSnapshot, snippetTrackingSpan.GetSpan(SubjectBuffer.CurrentSnapshot));
SubjectBuffer.FormatAndApplyToBuffer(formattingSpan, EditorOptionsService, CancellationToken.None);
if (isFullSnippetFormat)
{
CleanUpEndLocation(endPositionTrackingSpan);
SetNewEndPosition(endPositionTrackingSpan);
}
}