static void Main(string[] args)
{
if (args.Length > 1)
{
Console.WriteLine("Usage: loxsharp [script]");
}
else if (args.Length == 1)
{
if (File.Exists(args[0]))
{
RunFile(args[0]);
}
else
{
LoxError.ThrowError("[ERROR] The specified script could not be found.");
_exitCode = 1;
}
}
else
{
RunPrompt();
}
Environment.Exit(_exitCode);
}
private void ParseString()
{
while (Peek() != '"' && !IsAtEnd())
{
if (Peek() == '\n')
{
_line++;
}
Advance();
}
// Unterminated string
if (IsAtEnd())
{
LoxError.ThrowError(_line, "Unterminated string.");
return;
}
// Closed string
Advance();
// Trim the surrounding quotes
int length = _current - _start;
string value = _source.Substring(_start + 1, length - 2);
// Implementation specific: unescape string, so '\n' etc are supported
value = Regex.Unescape(value);
AddToken(TokenType.STRING, value);
}
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.ASTERISK); 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_THAN); break;
case '>': AddToken(Match('=') ? TokenType.GREATER_EQUAL : TokenType.GREATER_THAN); break;
case '/':
if (Match('/'))
{
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
}
else if (Match('*'))
{
int commentDepth = 0;
while ((!(Peek() == '*' && PeekNext() == '/') && !IsAtEnd()) || commentDepth > 0)
{
if (Peek() == '\n')
{
_line++;
}
if (Peek() == '/' && PeekNext() == '*')
{
commentDepth++;
}
if (commentDepth > 0 && Peek() == '*' && PeekNext() == '/')
{
commentDepth--;
}
Advance();
}
// Eat the closing comment tokens
Advance();
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
{
LoxError.ThrowError(_line, "Unexpected character.");
}
break;
}
}