Method parseClass

java/com/google/re2j/Parser.java:1615–1697

(StringIterator t)

  // Pre: at '['; Post: after ']'.
  // Mutates stack.  Advances iterator.  May throw.
  private void parseClass(StringIterator t) throws PatternSyntaxException {
    int startPos = t.pos();
    t.skip(1); // '['
    Regexp re = newRegexp(Regexp.Op.CHAR_CLASS);
    re.flags = flags;
    CharClass cc = new CharClass();

    int sign = +1;
    if (t.more() && t.lookingAt('^')) {
      sign = -1;
      t.skip(1); // '^'

      // If character class does not match \n, add it here,
      // so that negation later will do the right thing.
      if ((flags & RE2.CLASS_NL) == 0) {
        cc.appendRange('\n', '\n');
      }
    }

    boolean first = true; // ']' and '-' are okay as first char in class
    while (!t.more() || t.peek() != ']' || first) {
      // POSIX: - is only okay unescaped as first or last in class.
      // Perl: - is okay anywhere.
      if (t.more() && t.lookingAt('-') && (flags & RE2.PERL_X) == 0 && !first) {
        String s = t.rest();
        if (s.equals("-") || !s.startsWith("-]")) {
          t.rewindTo(startPos);
          throw new PatternSyntaxException(ERR_INVALID_CHAR_RANGE, t.rest());
        }
      }
      first = false;

      int beforePos = t.pos();

      // Look for POSIX [:alnum:] etc.
      if (t.lookingAt("[:")) {
        if (parseNamedClass(t, cc)) {
          continue;
        }
        t.rewindTo(beforePos);
      }

      // Look for Unicode character group like \p{Han}.
      if (parseUnicodeClass(t, cc)) {
        continue;
      }

      // Look for Perl character class symbols (extension).
      if (parsePerlClassEscape(t, cc)) {
        continue;
      }
      t.rewindTo(beforePos);

      // Single character or simple range.
      int lo = parseClassChar(t, startPos);
      int hi = lo;
      if (t.more() && t.lookingAt('-')) {
        t.skip(1); // '-'