/// <summary>
/// Scan past the hole inside an interpolated string literal, leaving the current character on the '}' (if any)
/// </summary>
private void ScanInterpolatedStringLiteralHoleBalancedText(char endingChar, bool isHole, ref int colonPosition)
{
while (true)
{
char ch = _lexer.TextWindow.PeekChar();
// Note: within a hole newlines are always allowed. The restriction on if newlines are allowed or not
// is only within a text-portion of the interpolated string.
if (IsAtEnd(allowNewline: true))
{
// the caller will complain
return;
}
switch (ch)
{
case '#':
// preprocessor directives not allowed.
TrySetUnrecoverableError(_lexer.MakeError(_lexer.TextWindow.Position, 1, ErrorCode.ERR_SyntaxError, endingChar.ToString()));
_lexer.TextWindow.AdvanceChar();
continue;
case '$':
if (_lexer.TextWindow.PeekChar(1) == '"' || _lexer.TextWindow.PeekChar(1) == '@' && _lexer.TextWindow.PeekChar(2) == '"')
{
var discarded = default(TokenInfo);
_lexer.ScanInterpolatedStringLiteral(
isVerbatim: _lexer.TextWindow.PeekChar(1) == '@',
ref discarded);
continue;
}
goto default;
case ':':
// the first colon not nested within matching delimiters is the start of the format string
if (isHole)
{
Debug.Assert(colonPosition == 0);
colonPosition = _lexer.TextWindow.Position;
ScanFormatSpecifier();
return;
}
goto default;
case '}':
case ')':
case ']':
if (ch == endingChar)
{
return;
}
TrySetUnrecoverableError(_lexer.MakeError(_lexer.TextWindow.Position, 1, ErrorCode.ERR_SyntaxError, endingChar.ToString()));
goto default;
case '"' when RecoveringFromRunawayLexing():
// When recovering from mismatched delimiters, we consume the next
// quote character as the close quote for the interpolated string. In
// practice this gets us out of trouble in scenarios we've encountered.
// See, for example, https://github.com/dotnet/roslyn/issues/44789
return;
case '"':
case '\'':
// handle string or character literal inside an expression hole.
ScanInterpolatedStringLiteralNestedString();
continue;
case '@':
if (_lexer.TextWindow.PeekChar(1) == '"' && !RecoveringFromRunawayLexing())
{
// check for verbatim string inside an expression hole.
var nestedStringPosition = _lexer.TextWindow.Position;
// Note that this verbatim string may encounter an error (for example if it contains a
// new line and we don't allow that). This should be reported to the user, but should
// not put us into an unrecoverable position. We can clearly see that this was intended
// to be a normal verbatim string, so we can continue on an attempt to understand the
// outer interpolated string properly.
var discarded = default(TokenInfo);
var errorCode = _lexer.ScanVerbatimStringLiteral(ref discarded);
if (errorCode is ErrorCode code)
{
TrySetRecoverableError(_lexer.MakeError(nestedStringPosition, width: 2, code));
}
continue;
}
else if (_lexer.TextWindow.PeekChar(1) == '$' && _lexer.TextWindow.PeekChar(2) == '"')
{
var discarded = default(TokenInfo);
_lexer.ScanInterpolatedStringLiteral(isVerbatim: true, ref discarded);
continue;
}
goto default;
case '/':
switch (_lexer.TextWindow.PeekChar(1))
{
case '/':
_lexer.ScanToEndOfLine();
continue;
case '*':
_lexer.ScanMultiLineComment(out _);
continue;
default:
_lexer.TextWindow.AdvanceChar();
continue;
}
case '{':
// TODO: after the colon this has no special meaning.
ScanInterpolatedStringLiteralHoleBracketed('{', '}');
continue;
case '(':
// TODO: after the colon this has no special meaning.
ScanInterpolatedStringLiteralHoleBracketed('(', ')');
continue;
case '[':
// TODO: after the colon this has no special meaning.
ScanInterpolatedStringLiteralHoleBracketed('[', ']');
continue;
default:
// part of code in the expression hole
_lexer.TextWindow.AdvanceChar();
continue;
}
}
}
private void ScanInterpolatedStringLiteralNestedVerbatimString()
{
var discarded = default(TokenInfo);
lexer.ScanVerbatimStringLiteral(ref discarded, allowNewlines: allowNewlines);
}
/// <summary>
/// Scan past the hole inside an interpolated string literal, leaving the current character on the '}' (if any)
/// </summary>
private void ScanInterpolatedStringLiteralHoleBalancedText(char endingChar, bool isHole, ref int colonPosition)
{
while (true)
{
char ch = _lexer.TextWindow.PeekChar();
// See if we ran into a disallowed new line. If so, this is recoverable, so just skip past it but
// give a good message about the issue. This will prevent a lot of cascading issues with the
// remainder of the interpolated string that comes on the following lines.
var allowNewLines = _isVerbatim && _allowNewlines;
if (!allowNewLines && SyntaxFacts.IsNewLine(ch))
{
TrySetRecoverableError(_lexer.MakeError(_lexer.TextWindow.Position, width: 0, ErrorCode.ERR_NewlinesAreNotAllowedInsideANonVerbatimInterpolatedString));
}
if (IsAtEnd(allowNewline: true))
{
// the caller will complain
return;
}
switch (ch)
{
case '#':
// preprocessor directives not allowed.
TrySetUnrecoverableError(_lexer.MakeError(_lexer.TextWindow.Position, 1, ErrorCode.ERR_SyntaxError, endingChar.ToString()));
_lexer.TextWindow.AdvanceChar();
continue;
case '$':
if (_lexer.TextWindow.PeekChar(1) == '"' || _lexer.TextWindow.PeekChar(1) == '@' && _lexer.TextWindow.PeekChar(2) == '"')
{
bool isVerbatimSubstring = _lexer.TextWindow.PeekChar(1) == '@';
var interpolations = (ArrayBuilder <Interpolation>?)null;
var info = default(TokenInfo);
bool wasVerbatim = _isVerbatim;
bool wasAllowNewlines = _allowNewlines;
try
{
_isVerbatim = isVerbatimSubstring;
_allowNewlines &= _isVerbatim;
ScanInterpolatedStringLiteralTop(interpolations, ref info, closeQuoteMissing: out _);
}
finally
{
_isVerbatim = wasVerbatim;
_allowNewlines = wasAllowNewlines;
}
continue;
}
goto default;
case ':':
// the first colon not nested within matching delimiters is the start of the format string
if (isHole)
{
Debug.Assert(colonPosition == 0);
colonPosition = _lexer.TextWindow.Position;
ScanFormatSpecifier();
return;
}
goto default;
case '}':
case ')':
case ']':
if (ch == endingChar)
{
return;
}
TrySetUnrecoverableError(_lexer.MakeError(_lexer.TextWindow.Position, 1, ErrorCode.ERR_SyntaxError, endingChar.ToString()));
goto default;
case '"' when RecoveringFromRunawayLexing():
// When recovering from mismatched delimiters, we consume the next
// quote character as the close quote for the interpolated string. In
// practice this gets us out of trouble in scenarios we've encountered.
// See, for example, https://github.com/dotnet/roslyn/issues/44789
return;
case '"':
case '\'':
// handle string or character literal inside an expression hole.
ScanInterpolatedStringLiteralNestedString();
continue;
case '@':
if (_lexer.TextWindow.PeekChar(1) == '"' && !RecoveringFromRunawayLexing())
{
// check for verbatim string inside an expression hole.
var nestedStringPosition = _lexer.TextWindow.Position;
// Note that this verbatim string may encounter an error (for example if it contains a
// new line and we don't allow that). This should be reported to the user, but should
// not put us into an unrecoverable position. We can clearly see that this was intended
// to be a normal verbatim string, so we can continue on an attempt to understand the
// outer interpolated string properly.
var discarded = default(TokenInfo);
var errorCode = _lexer.ScanVerbatimStringLiteral(ref discarded, _allowNewlines);
if (errorCode is ErrorCode code)
{
TrySetRecoverableError(_lexer.MakeError(nestedStringPosition, width: 2, code));
}
continue;
}
else if (_lexer.TextWindow.PeekChar(1) == '$' && _lexer.TextWindow.PeekChar(2) == '"')
{
_lexer.CheckFeatureAvailability(MessageID.IDS_FeatureAltInterpolatedVerbatimStrings);
var interpolations = (ArrayBuilder <Interpolation>?)null;
var info = default(TokenInfo);
bool wasVerbatim = _isVerbatim;
bool wasAllowNewlines = _allowNewlines;
try
{
_isVerbatim = true;
_allowNewlines = true;
ScanInterpolatedStringLiteralTop(interpolations, ref info, closeQuoteMissing: out _);
}
finally
{
_isVerbatim = wasVerbatim;
_allowNewlines = wasAllowNewlines;
}
continue;
}
goto default;
case '/':
switch (_lexer.TextWindow.PeekChar(1))
{
case '/':
if (!_isVerbatim || !_allowNewlines)
{
// error: single-line comment not allowed in an interpolated string.
// report the error but keep going for good error recovery.
TrySetRecoverableError(_lexer.MakeError(_lexer.TextWindow.Position, 2, ErrorCode.ERR_SingleLineCommentInExpressionHole));
}
_lexer.TextWindow.AdvanceChar(); // skip /
_lexer.TextWindow.AdvanceChar(); // skip /
while (!IsAtEnd(allowNewline: false))
{
_lexer.TextWindow.AdvanceChar(); // skip // comment character
}
continue;
case '*':
// check for and scan /* comment */
ScanInterpolatedStringLiteralNestedComment();
continue;
default:
_lexer.TextWindow.AdvanceChar();
continue;
}
case '{':
// TODO: after the colon this has no special meaning.
ScanInterpolatedStringLiteralHoleBracketed('{', '}');
continue;
case '(':
// TODO: after the colon this has no special meaning.
ScanInterpolatedStringLiteralHoleBracketed('(', ')');
continue;
case '[':
// TODO: after the colon this has no special meaning.
ScanInterpolatedStringLiteralHoleBracketed('[', ']');
continue;
default:
// part of code in the expression hole
_lexer.TextWindow.AdvanceChar();
continue;
}
}
}
