/// <summary>
/// Checks if a given <see cref="SyntaxTree"/> only contains whitespace. We don't want to analyze empty files.
/// </summary>
/// <param name="tree">The syntax tree to examine.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> that the task will observe.</param>
/// <returns>
/// <see langword="true"/> if <paramref name="tree"/> only contains whitespace; otherwise,
/// <see langword="false"/>.
/// </returns>
public static bool IsWhitespaceOnly(this SyntaxTree tree, CancellationToken cancellationToken)
{
var root = tree.GetRoot(cancellationToken);
var firstToken = root.GetFirstToken(includeZeroWidth: true);
return(firstToken.IsKind(SyntaxKind.EndOfFileToken) &&
TriviaHelper.IndexOfFirstNonWhitespaceTrivia(firstToken.LeadingTrivia) == -1);
}
internal static XmlFileHeader ParseXmlFileHeader(SyntaxNode root)
{
var firstToken = root.GetFirstToken(includeZeroWidth: true);
string xmlString;
int fileHeaderStart;
int fileHeaderEnd;
var firstNonWhitespaceTrivia = TriviaHelper.IndexOfFirstNonWhitespaceTrivia(firstToken.LeadingTrivia, true);
if (firstNonWhitespaceTrivia == -1)
{
return(XmlFileHeader.MissingFileHeader);
}
switch (firstToken.LeadingTrivia[firstNonWhitespaceTrivia].Kind())
{
case SyntaxKind.SingleLineCommentTrivia:
xmlString = ProcessSingleLineCommentsHeader(firstToken.LeadingTrivia, firstNonWhitespaceTrivia, out fileHeaderStart, out fileHeaderEnd);
break;
case SyntaxKind.MultiLineCommentTrivia:
xmlString = ProcessMultiLineCommentsHeader(firstToken.LeadingTrivia[firstNonWhitespaceTrivia], out fileHeaderStart, out fileHeaderEnd);
break;
default:
return(XmlFileHeader.MissingFileHeader);
}
if (fileHeaderStart > fileHeaderEnd)
{
return(XmlFileHeader.MissingFileHeader);
}
try
{
var parsedFileHeaderXml = XElement.Parse(xmlString);
// a header without any XML tags is malformed.
if (!parsedFileHeaderXml.Descendants().Any())
{
return(XmlFileHeader.MalformedFileHeader);
}
return(new XmlFileHeader(parsedFileHeaderXml, fileHeaderStart, fileHeaderEnd));
}
catch (XmlException)
{
return(XmlFileHeader.MalformedFileHeader);
}
}
internal static FileHeader ParseFileHeader(SyntaxNode root)
{
var firstToken = root.GetFirstToken(includeZeroWidth: true);
var firstNonWhitespaceTrivia = TriviaHelper.IndexOfFirstNonWhitespaceTrivia(firstToken.LeadingTrivia, true);
if (firstNonWhitespaceTrivia == -1)
{
return(FileHeader.MissingFileHeader);
}
var sb = StringBuilderPool.Allocate();
var endOfLineCount = 0;
var done = false;
var fileHeaderStart = int.MaxValue;
var fileHeaderEnd = int.MinValue;
for (var i = firstNonWhitespaceTrivia; !done && (i < firstToken.LeadingTrivia.Count); i++)
{
var trivia = firstToken.LeadingTrivia[i];
switch (trivia.Kind())
{
case SyntaxKind.WhitespaceTrivia:
endOfLineCount = 0;
break;
case SyntaxKind.SingleLineCommentTrivia:
endOfLineCount = 0;
var commentString = trivia.ToFullString();
fileHeaderStart = Math.Min(trivia.FullSpan.Start, fileHeaderStart);
fileHeaderEnd = trivia.FullSpan.End;
sb.AppendLine(commentString.Substring(2).Trim());
break;
case SyntaxKind.MultiLineCommentTrivia:
// only process a MultiLineCommentTrivia if no SingleLineCommentTrivia have been processed
if (sb.Length == 0)
{
var triviaString = trivia.ToFullString();
var startIndex = triviaString.IndexOf("/*", StringComparison.Ordinal) + 2;
var endIndex = triviaString.LastIndexOf("*/", StringComparison.Ordinal);
if (endIndex == -1)
{
// While editing, it is possible to have a multiline comment trivia that does not contain the closing '*/' yet.
return(FileHeader.MissingFileHeader);
}
var commentContext = triviaString.Substring(startIndex, endIndex - startIndex).Trim();
var triviaStringParts = commentContext.Replace("\r\n", "\n").Split('\n');
foreach (var part in triviaStringParts)
{
var trimmedPart = part.TrimStart(' ', '*');
sb.AppendLine(trimmedPart);
}
fileHeaderStart = trivia.FullSpan.Start;
fileHeaderEnd = trivia.FullSpan.End;
}
done = true;
break;
case SyntaxKind.EndOfLineTrivia:
endOfLineCount++;
done = endOfLineCount > 1;
break;
default:
done = (fileHeaderStart < fileHeaderEnd) || !trivia.IsDirective;
break;
}
}
if (fileHeaderStart > fileHeaderEnd)
{
StringBuilderPool.Free(sb);
return(FileHeader.MissingFileHeader);
}
if (sb.Length > 0)
{
// remove the final newline
var eolLength = Environment.NewLine.Length;
sb.Remove(sb.Length - eolLength, eolLength);
}
return(new FileHeader(StringBuilderPool.ReturnAndFree(sb), fileHeaderStart, fileHeaderEnd));
}