private void ScanToken()
{
var c = Advance();
switch (c)
{
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.
while (Peek() != '\n' && !AtEnd())
{
Advance();
}
}
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 (IsAlpha(c))
{
Identifier();
}
else
{
_lox.Error(_line, "Unexpected character.");
}
break;
}
}
private Option <Token> ScanToken()
{
char c = Advance();
switch (c)
{
case '(': return(GenerateToken(TokenType.LeftParen).Some());
case ')': return(GenerateToken(TokenType.RightParen).Some());
case '{': return(GenerateToken(TokenType.LeftBrace).Some());
case '}': return(GenerateToken(TokenType.RightBrace).Some());
case ',': return(GenerateToken(TokenType.Comma).Some());
case '.': return(GenerateToken(TokenType.Dot).Some());
case '-': return(GenerateToken(TokenType.Minus).Some());
case '+': return(GenerateToken(TokenType.Plus).Some());
case ';': return(GenerateToken(TokenType.SemiColon).Some());
case '*': return(GenerateToken(TokenType.Star).Some());
case '?': return(GenerateToken(TokenType.Question).Some());
case ':': return(GenerateToken(TokenType.Colon).Some());
// operators
case '!': return(GenerateToken(Match('=') ? TokenType.BangEqual : TokenType.Bang).Some());
case '=': return(GenerateToken(Match('=') ? TokenType.EqualEqual : TokenType.Equal).Some());
case '<': return(GenerateToken(Match('=') ? TokenType.LessEqual : TokenType.Less).Some());
case '>': return(GenerateToken(Match('=') ? TokenType.GreaterEqual : TokenType.Greater).Some());
case '/':
if (Match('/'))
{
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
}
else if (Match('*'))
{
MultiLine();
}
else
{
return(GenerateToken(TokenType.Slash).Some());
}
break;
// whitespace
case ' ':
case '\r':
case '\t':
break;
case '\n':
_line++;
break;
case '"': return(String().Some());
// unrecognized character
default:
if (IsDigit(c))
{
return(Number().Some());
}
else if (IsAlpha(c))
{
return(Identifier().Some());
}
else
{
Lox.Error(_line, "Unexpected character.");
break;
}
}
return(Option.None <Token>());
}
private void ScanToken()
{
char c = Advance();
switch (c)
{
case '(':
AddToken(LeftParen);
break;
case ')':
AddToken(RightParen);
break;
case '{':
AddToken(LeftBrace);
break;
case '}':
AddToken(RightBrace);
break;
case ',':
AddToken(Comma);
break;
case '.':
AddToken(Dot);
break;
case '-':
AddToken(Minus);
break;
case '+':
AddToken(Plus);
break;
case ';':
AddToken(Semicolon);
break;
case '*':
AddToken(Star);
break;
case '!':
AddToken(Match('=') ? BangEqual : Bang);
break;
case '=':
AddToken(Match('=') ? EqualEqual : Equal);
break;
case '<':
AddToken(Match('=') ? LessEqual : Less);
break;
case '>':
AddToken(Match('=') ? GreaterEqual : Greater);
break;
case '/':
if (Match('/'))
{
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
}
else
{
AddToken(Slash);
}
break;
case ' ':
case '\r':
case '\t':
break;
case '\n':
Line++;
break;
case '"':
String();
break;
default:
if (IsDigit(c))
{
Number();
}
else if (IsAlpha(c))
{
Identifier();
}
else
{
Lox.Error(Line, "Unexpected character.");
}
break;
}
}
private static ParseException Error(Token token, string message)
{
Lox.Error(token, message);
return(new ParseException());
}