Esempio n. 1
0
        private void HandleString()
        {
            while (Peek() != '"' && !IsAtEnd())
            {
                if (Peek() == '\n')
                {
                    line++;
                }
                Advance();
            }

            if (IsAtEnd())
            {
                // we've hit the end before we found the closing quotes
                CsLox.Error(line, "Unterminated string");
                return;
            }

            // consume the closing quotes
            Advance();

            // trim the surrounding quotes away
            string value = source.Substring(start + 1, current - 1);

            AddToken(TokenType.String, value);
        }
Esempio n. 2
0
        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(FollowedBy('=') ? TokenType.BangEqual : TokenType.Bang); break;

            case '=': AddToken(FollowedBy('=') ? TokenType.EqualEqual : TokenType.Equal); break;

            case '<': AddToken(FollowedBy('=') ? TokenType.LessEqual : TokenType.Less); break;

            case '>': AddToken(FollowedBy('=') ? TokenType.GreaterEqual : TokenType.Greater); break;

            case '/':
                if (FollowedBy('/'))
                {
                    // a comment goes until the end of the line
                    while (Peek() != '\n' && !IsAtEnd())
                    {
                        Advance();
                    }
                }
                else
                {
                    AddToken(TokenType.Slash);
                }
                break;

            case ' ':
            case '\r':
            case '\t':
                // ignore whitespaces
                break;

            case '\n':
                line++;
                break;

            case '"': HandleString(); break;

            default:
                if (IsDigit(c))
                {
                    HandleNumber();
                }
                else if (IsAlpha(c))
                {
                    HandleIdentifier();
                }
                else
                {
                    CsLox.Error(line, $"Unexpected character '{c}'.");
                }
                break;
            }
        }