void ProduceStringLiteral()
{
while (Peek() != '"' && !IsAtEnd())
{
if (Peek() == '\n')
{
_line++;
}
Consume();
}
if (IsAtEnd())
{
Lox.StaticError(_line, "Unterminated string.");
return;
}
Consume();
var length = _currentCharacter - _startOfNextLexeme;
var literal = Source.Substring(_startOfNextLexeme + 1, length - 2);
ProduceToken(TokenType.String, literal);
}
void ScanToken()
{
var character = Consume();
switch (character)
{
case '(':
ProduceToken(TokenType.LeftParen);
break;
case ')':
ProduceToken(TokenType.RightParen);
break;
case '{':
ProduceToken(TokenType.LeftBrace);
break;
case '}':
ProduceToken(TokenType.RightBrace);
break;
case ',':
ProduceToken(TokenType.Comma);
break;
case '.':
ProduceToken(TokenType.Dot);
break;
case '-':
ProduceToken(TokenType.Minus);
break;
case '+':
ProduceToken(TokenType.Plus);
break;
case ';':
ProduceToken(TokenType.SemiColon);
break;
case '*':
ProduceToken(TokenType.Star);
break;
case '!':
ProduceToken(MaybeConsume('=') ? TokenType.BangEqual : TokenType.Bang);
break;
case '=':
ProduceToken(MaybeConsume('=') ? TokenType.EqualEqual : TokenType.Equal);
break;
case '<':
ProduceToken(MaybeConsume('=') ? TokenType.LessEqual : TokenType.Less);
break;
case '>':
ProduceToken(MaybeConsume('=') ? TokenType.GreaterEqual : TokenType.Greater);
break;
case '/':
if (MaybeConsume('/'))
{
while (Peek() != '\n' && !IsAtEnd())
{
Consume();
}
}
else
{
ProduceToken(TokenType.Slash);
}
break;
case '"':
ProduceStringLiteral();
break;
case char digit when char.IsDigit(digit):
ProduceNumericLiteral();
break;
case char alpha when char.IsLetter(alpha):
ProduceIdentifier();
break;
case ' ':
case '\t':
case '\r':
break;
case '\n':
_line++;
break;
default:
Lox.StaticError(_line, $"Unexpected character '{character}'.");
break;
}
}
Exception CreateStaticError(Token badToken, string message)
{
Lox.StaticError(badToken.Line, $"At '{badToken.Lexeme}'. {message}");
return(new LoxStaticErrorException(badToken, message));
}