protected void GetDiagnosticSpanForMissingToken(out int offset, out int width)
{
// If the previous token has a trailing EndOfLineTrivia,
// the missing token diagnostic position is moved to the
// end of line containing the previous token and
// its width is set to zero.
// Otherwise the diagnostic offset and width is set
// to the corresponding values of the current token
var trivia = this.prevTokenTrailingTrivia;
if (trivia != null)
{
SyntaxList <CSharpSyntaxNode> triviaList = new SyntaxList <CSharpSyntaxNode>(trivia);
bool prevTokenHasEndOfLineTrivia = triviaList.Any(SyntaxKind.EndOfLineTrivia);
if (prevTokenHasEndOfLineTrivia)
{
offset = -trivia.FullWidth;
width = 0;
return;
}
}
SyntaxToken ct = this.CurrentToken;
offset = ct.GetLeadingTriviaWidth();
width = ct.Width;
}
protected TNode AddError <TNode>(TNode node, ErrorCode code, params object[] args) where TNode : CSharpSyntaxNode
{
if (!node.IsMissing)
{
return(WithAdditionalDiagnostics(node, MakeError(node, code, args)));
}
int offset, width;
SyntaxToken token = node as SyntaxToken;
if (token != null && token.ContainsSkippedText)
{
// This code exists to clean up an anti-pattern:
// 1) an undesirable token is parsed,
// 2) a desirable missing token is created and the parsed token is appended as skipped text,
// 3) an error is attached to the missing token describing the problem.
// If this occurs, then this.previousTokenTrailingTrivia is still populated with the trivia
// of the undesirable token (now skipped text). Since the trivia no longer precedes the
// node to which the error is to be attached, the computed offset will be incorrect.
offset = token.GetLeadingTriviaWidth(); // Should always be zero, but at least we'll do something sensible if it's not.
Debug.Assert(offset == 0, "Why are we producing a missing token that has both skipped text and leading trivia?");
width = 0;
bool seenSkipped = false;
foreach (var trivia in token.TrailingTrivia)
{
if (trivia.Kind == SyntaxKind.SkippedTokensTrivia)
{
seenSkipped = true;
width += trivia.Width;
}
else if (seenSkipped)
{
break;
}
else
{
offset += trivia.Width;
}
}
}
else
{
this.GetDiagnosticSpanForMissingToken(out offset, out width);
}
return(WithAdditionalDiagnostics(node, MakeError(offset, width, code, args)));
}
/// <summary>
/// Converts skippedSyntax node into tokens and adds these as trivia on the target token.
/// Also adds the first error (in depth-first preorder) found in the skipped syntax tree to the target token.
/// </summary>
internal SyntaxToken AddSkippedSyntax(SyntaxToken target, CSharpSyntaxNode skippedSyntax, bool trailing)
{
var builder = new SyntaxListBuilder(4);
// the error in we'll attach to the node
SyntaxDiagnosticInfo diagnostic = null;
// the position of the error within the skipedSyntax node full tree
int diagnosticOffset = 0;
int currentOffset = 0;
foreach (var node in skippedSyntax.EnumerateNodes())
{
SyntaxToken token = node as SyntaxToken;
if (token != null)
{
builder.Add(token.GetLeadingTrivia());
if (token.Width > 0)
{
// separate trivia from the tokens
SyntaxToken tk = token.WithLeadingTrivia(null).WithTrailingTrivia(null);
// adjust relative offsets of diagnostics attached to the token:
int leadingWidth = token.GetLeadingTriviaWidth();
if (leadingWidth > 0)
{
var tokenDiagnostics = tk.GetDiagnostics();
for (int i = 0; i < tokenDiagnostics.Length; i++)
{
var d = (SyntaxDiagnosticInfo)tokenDiagnostics[i];
tokenDiagnostics[i] = new SyntaxDiagnosticInfo(d.Offset - leadingWidth, d.Width, (ErrorCode)d.Code, d.Arguments);
}
}
builder.Add(SyntaxFactory.SkippedTokensTrivia(tk));
}
else
{
// do not create zero-width structured trivia, GetStructure doesn't work well for them
var existing = (SyntaxDiagnosticInfo)token.GetDiagnostics().FirstOrDefault();
if (existing != null)
{
diagnostic = existing;
diagnosticOffset = currentOffset;
}
}
builder.Add(token.GetTrailingTrivia());
currentOffset += token.FullWidth;
}
else if (node.ContainsDiagnostics && diagnostic == null)
{
// only propagate the first error to reduce noise:
var existing = (SyntaxDiagnosticInfo)node.GetDiagnostics().FirstOrDefault();
if (existing != null)
{
diagnostic = existing;
diagnosticOffset = currentOffset;
}
}
}
int triviaWidth = currentOffset;
var trivia = builder.ToListNode();
// total width of everything preceding the added trivia
int triviaOffset;
if (trailing)
{
var trailingTrivia = target.GetTrailingTrivia();
triviaOffset = target.FullWidth; //added trivia is full width (before addition)
target = target.WithTrailingTrivia(SyntaxList.Concat(trailingTrivia, trivia));
}
else
{
// Since we're adding triviaWidth before the token, we have to add that much to
// the offset of each of its diagnostics.
if (triviaWidth > 0)
{
var targetDiagnostics = target.GetDiagnostics();
for (int i = 0; i < targetDiagnostics.Length; i++)
{
var d = (SyntaxDiagnosticInfo)targetDiagnostics[i];
targetDiagnostics[i] = new SyntaxDiagnosticInfo(d.Offset + triviaWidth, d.Width, (ErrorCode)d.Code, d.Arguments);
}
}
var leadingTrivia = target.GetLeadingTrivia();
target = target.WithLeadingTrivia(SyntaxList.Concat(trivia, leadingTrivia));
triviaOffset = 0; //added trivia is first, so offset is zero
}
if (diagnostic != null)
{
int newOffset = triviaOffset + diagnosticOffset + diagnostic.Offset;
target = WithAdditionalDiagnostics(target,
new SyntaxDiagnosticInfo(newOffset, diagnostic.Width, (ErrorCode)diagnostic.Code, diagnostic.Arguments)
);
}
return(target);
}