private ParseError error(Token token, String message)
{
Lox.error(token, message);
return(new ParseError());
}
private void ScanToken()
{
var c = Advance();
switch (c)
{
case '(': AddToken(LEFT_PAREN); break;
case ')': AddToken(RIGHT_PAREN); break;
case '{': AddToken(LEFT_BRACE); break;
case '}': AddToken(RIGHT_BRACE); 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('=') ? BANG_EQUAL : BANG);
break;
case '=':
AddToken(Match('=') ? EQUAL_EQUAL : EQUAL);
break;
case '<':
AddToken(Match('=') ? LESS_EQUAL : LESS);
break;
case '>':
AddToken(Match('=') ? GREATER_EQUAL : GREATER);
break;
case '/':
if (Match('/'))
{
// A comment goes until the end of the line.
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
}
else
{
AddToken(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 void scanToken()
{
char 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.LESS_EQUAL : TokenType.LESS); break;
case '>': addToken(match('=') ? TokenType.GREATER_EQUAL : TokenType.GREATER); break;
case '=': addToken(match('=') ? TokenType.EQUAL_EQUAL : TokenType.EQUAL); break;
case '/':
if (match('/'))
{
while (peek() != '\n' && !isAtEnd())
{
advance();
}
}
else
{
addToken(TokenType.SLASH);
}
break; // todo
case '"':
int closingPos = closingMatchPos('"');
if (closingPos > 0)
{
string literal = source.Substring(current, closingPos - 1);
addToken(TokenType.STRING, literal);
current += closingPos;
}
else
{
Lox.Error(line, $"Missing closing \"");
}
break;
case 'f':
// If we get an f, check if we get a n followed by a space
if (match('n'))
{
if (match(' '))
{
addToken(TokenType.FUN);
}
}
break;
case '\t': break;
case '\r': break;
case '\n': line++; break;
case ' ': break;
default: Lox.Error(line, $"Unexpected character {c}:{(byte)c}"); break;
}
}
private void ScanToken()
{
char c = Advance();
switch (c)
{
case '(': AddToken(LEFT_PAREN); break;
case ')': AddToken(RIGHT_PAREN); break;
case '{': AddToken(LEFT_BRACE); break;
case '}': AddToken(RIGHT_BRACE); 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(COLON); break;
case '?': AddToken(QUESTION_MARK); break;
case '!': AddToken(Match('=') ? BANG_EQUAL : BANG); break;
case '=': AddToken(Match('=') ? EQUAL_EQUAL : EQUAL); break;
case '<': AddToken(Match('=') ? LESS_EQUAL : LESS); break;
case '>': AddToken(Match('=') ? GREATER_EQUAL : GREATER); break;
case '/':
if (Match('/'))
{
// eat the whole line
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
}
else if (Match('*'))
{
ParseBlockComment();
}
else
{
AddToken(SLASH);
}
break;
case ' ':
case '\r':
case '\t':
// ignore whitespace
break;
case '\n':
line++;
break;
case '"': ParseString(); break;
default:
if (IsDigit(c))
{
ParseNumber();
}
else if (IsAlpha(c))
{
ParseIdentifier();
}
else
{
Lox.Error(line, "Unexpected character.");
}
break;
}
}
private ParseError Error(Token token, string msg)
{
Lox.Error(token, msg);
return(new ParseError(token, msg));
}
private static ParseError Error(Token token, string message)
{
Lox.Error(token, message);
return(new ParseError());
}