private void ScanToken()
{
char c = Advance();
switch (c)
{
case '(': AddToken(TokenType.LeftParen); break;
case ')': AddToken(TokenType.RightParen); break;
case '{': AddToken(TokenType.LeftBrace); break;
case '}': AddToken(TokenType.RightBrace); break;
case ',': AddToken(TokenType.Comma); break;
case '.': AddToken(TokenType.Dot); break;
case '-': AddToken(TokenType.Minus); break;
case '+': AddToken(TokenType.Plus); break;
case ';': AddToken(TokenType.Semicolon); break;
case '*': AddToken(TokenType.Star); break;
case '!': AddToken(Match('=') ? TokenType.BangEqual : TokenType.Bang); break;
case '=': AddToken(Match('=') ? TokenType.EqualEqual : TokenType.Equal); break;
case '<': AddToken(Match('=') ? TokenType.LessEqual : TokenType.Less); break;
case '>': AddToken(Match('=') ? TokenType.GreaterEqual : TokenType.Greater); break;
case '/':
if (Match('/'))
{
// a comment goes until the end of the line
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
}
else
{
AddToken(TokenType.Slash);
}
break;
case ' ':
case '\r':
case '\t':
break;
case '\n':
line++;
break;
case '"': ParseString(); break;
default:
if (IsDigit(c))
{
ParseNumber();
}
else if (IsAlpha(c))
{
ParseIdentifier();
}
else
{
Lox.Error(line, string.Format("Unexpected character '{0}'.", c));
}
break;
}
}
private void ScanToken()
{
char c = Advance();
switch (c)
{
// Single char tokens.
case '(': AddToken(TokenType.LEFT_PAREN); break;
case ')': AddToken(TokenType.RIGHT_PAREN); break;
case '{': AddToken(TokenType.LEFT_BRACE); break;
case '}': AddToken(TokenType.RIGHT_BRACE); break;
case ',': AddToken(TokenType.COMMA); break;
case '.': AddToken(TokenType.DOT); break;
case '-': AddToken(TokenType.MINUS); break;
case '+': AddToken(TokenType.PLUS); break;
case ';': AddToken(TokenType.SEMICOLON); break;
case '*': AddToken(TokenType.STAR); break;
case '!': AddToken(Match('=') ? TokenType.BANG_EQUAL : TokenType.BANG); break;
case '=': AddToken(Match('=') ? TokenType.EQUAL_EQUAL : TokenType.EQUAL); break;
case '<': AddToken(Match('=') ? TokenType.LESS_EQUAL : TokenType.LESS); break;
case '>': AddToken(Match('=') ? TokenType.GREATER_EQUAL : TokenType.GREATER); break;
case '/':
if (Match('/'))
{
// A comment goes until the end of the line.
// Use peek so we dont consume the newline token since we want it to go to its switch-case below
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
// Dont add the comment as token.
}
else
{
AddToken(TokenType.SLASH);
}
break;
case ' ':
case '\r':
case '\t':
// Ignore whitespace.
break;
case '\n':
line++;
break;
case '"': String(); break;
default:
if (IsDigit(c))
{
Number();
}
else if (IsAlphabetical(c))
{
Identifier();
}
Lox.Error(line, "Unexpected character.");
break;
}
}
private ParseError Error(Token token, string message)
{
Lox.Error(token, message);
return(new ParseError());
}
