Original Scanning Case Statement

Scanner.java

...

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; // [slash]
//> two-char-tokens
      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;
//< two-char-tokens
//> slash
      case '/':
        if (match('/')) {
          // A comment goes until the end of the line.
          while (peek() != '\n' && !isAtEnd()) advance();
        } else {
          addToken(SLASH);
        }
        break;
//< slash
//> whitespace

      case ' ':
      case '\r':
      case '\t':
        // Ignore whitespace.
        break;

      case '\n':
        line++;
        break;
//< whitespace
//> string-start

      case '"': string(); break;
//< string-start
//> char-error

      default:
/* Scanning char-error < Scanning digit-start
          Lox.error(line, "Unexpected character.");
*/
//> digit-start
        if (isDigit(c)) {
          number();
//> identifier-start
        } else if (isAlpha(c)) {
          identifier();
//< identifier-start
        } else {
          Lox.error(line, "Unexpected character.");
        }
//< digit-start
        break;
//< char-error
    }
  }

...