/// <summary>
/// When the parser encounters an invalid token before the end of the rule :
/// consume all tokens until a PeriodSeparator, the end of the line, or the next compiler directive / statement starting keyword.
/// </summary>
public override void Recover(Antlr4.Runtime.Parser recognizer, RecognitionException e)
{
if (lastErrorIndex == ((ITokenStream)recognizer.InputStream).Index && lastErrorStates != null && lastErrorStates.Contains(recognizer.State))
{
// uh oh, another error at same token index and previously-visited
// state in ATN; must be a case where LT(1) is in the recovery
// token set so nothing got consumed. Consume a single token
// at least to prevent an infinite loop; this is a failsafe.
recognizer.Consume();
}
lastErrorIndex = ((ITokenStream)recognizer.InputStream).Index;
if (lastErrorStates == null)
{
lastErrorStates = new IntervalSet();
}
lastErrorStates.Add(recognizer.State);
// Consume until next compiler directive / statement starting keyword (excluded), PeriodSeparator (included), or the end of line
Token lastConsumedToken = (Token)((ITokenStream)recognizer.InputStream).Lt(-1);
Token currentInvalidToken = (Token)((ITokenStream)recognizer.InputStream).Lt(1);
while ((lastConsumedToken == null || currentInvalidToken.TokensLine == lastConsumedToken.TokensLine) && currentInvalidToken.Type != TokenConstants.Eof)
{
if (((Token)currentInvalidToken).TokenFamily == TokenFamily.CompilerDirectiveStartingKeyword || ((Token)currentInvalidToken).TokenFamily == TokenFamily.StatementStartingKeyword ||
((Token)currentInvalidToken).TokenFamily == TokenFamily.StatementEndingKeyword || ((Token)currentInvalidToken).TokenFamily == TokenFamily.CodeElementStartingKeyword)
{
break;
}
recognizer.Consume();
if (currentInvalidToken.Type == (int)TokenType.PeriodSeparator)
{
break;
}
currentInvalidToken = (Token)((ITokenStream)recognizer.InputStream).Lt(1);
}
}
/// <summary>
/// When parsing a compiler directive, single token deletion should never
/// eat the statement starting keyword
/// </summary>
public override IToken RecoverInline(Antlr4.Runtime.Parser recognizer)
{
// SINGLE TOKEN DELETION
Token nextToken = (Token)((ITokenStream)recognizer.InputStream).Lt(1);
if (nextToken.TokenFamily != TokenFamily.StatementStartingKeyword &&
nextToken.TokenFamily != TokenFamily.StatementEndingKeyword &&
nextToken.TokenFamily != TokenFamily.CodeElementStartingKeyword)
{
IToken matchedSymbol = SingleTokenDeletion(recognizer);
if (matchedSymbol != null)
{
// we have deleted the extra token.
// now, move past ttype token as if all were ok
recognizer.Consume();
return matchedSymbol;
}
}
// SINGLE TOKEN INSERTION
if (SingleTokenInsertion(recognizer))
{
return GetMissingSymbol(recognizer);
}
// even that didn't work; must throw the exception
throw new InputMismatchException(recognizer);
}
