protected TextLine?GetPreviousNonBlankOrPreprocessorLine()
{
if (Tree == null)
{
throw new ArgumentNullException(nameof(Tree));
}
if (LineToBeIndented.LineNumber <= 0)
{
return(null);
}
var sourceText = this.LineToBeIndented.Text;
var lineNumber = this.LineToBeIndented.LineNumber - 1;
while (lineNumber >= 0)
{
var actualLine = sourceText.Lines[lineNumber];
// Empty line, no indentation to match.
if (string.IsNullOrWhiteSpace(actualLine.ToString()))
{
lineNumber--;
continue;
}
// No preprocessors in the entire tree, so this
// line definitely doesn't have one
var root = Tree.GetRoot(CancellationToken);
if (!root.ContainsDirectives)
{
return(sourceText.Lines[lineNumber]);
}
// This line is inside an inactive region. Examine the
// first preceding line not in an inactive region.
var disabledSpan = _syntaxFacts.GetInactiveRegionSpanAroundPosition(this.Tree, actualLine.Span.Start, CancellationToken);
if (disabledSpan != default(TextSpan))
{
var targetLine = sourceText.Lines.GetLineFromPosition(disabledSpan.Start).LineNumber;
lineNumber = targetLine - 1;
continue;
}
// A preprocessor directive starts on this line.
if (HasPreprocessorCharacter(actualLine) &&
root.DescendantTokens(actualLine.Span, tk => tk.FullWidth() > 0).Any(s_tokenHasDirective))
{
lineNumber--;
continue;
}
return(sourceText.Lines[lineNumber]);
}
return(null);
}