Method parseUnicodeClass

java/com/google/re2j/Parser.java:1547–1608

(StringIterator t, CharClass cc)

  // flag is not enabled; |t.pos()| is not advanced in this case.
  // Indicates error by throwing PatternSyntaxException.
  private boolean parseUnicodeClass(StringIterator t, CharClass cc) throws PatternSyntaxException {
    int startPos = t.pos();
    if ((flags & RE2.UNICODE_GROUPS) == 0 || (!t.lookingAt("\\p") && !t.lookingAt("\\P"))) {
      return false;
    }
    t.skip(1); // '\\'
    // Committed to parse or throw exception.
    int sign = +1;
    int c = t.pop(); // 'p' or 'P'
    if (c == 'P') {
      sign = -1;
    }
    if (!t.more()) {
      t.rewindTo(startPos);
      throw new PatternSyntaxException(ERR_INVALID_CHAR_RANGE, t.rest());
    }
    c = t.pop();
    String name;
    if (c != '{') {
      // Single-letter name.
      name = Utils.runeToString(c);
    } else {
      // Name is in braces.
      String rest = t.rest();
      int end = rest.indexOf('}');
      if (end < 0) {
        t.rewindTo(startPos);
        throw new PatternSyntaxException(ERR_INVALID_CHAR_RANGE, t.rest());
      }
      name = rest.substring(0, end); // e.g. "Han"
      t.skipString(name);
      t.skip(1); // '}'
      // Don't use skip(end) because it assumes UTF-16 coding, and
      // StringIterator doesn't guarantee that.
    }

    // Group can have leading negation too.
    //  \p{^Han} == \P{Han}, \P{^Han} == \p{Han}.
    if (!name.isEmpty() && name.charAt(0) == '^') {
      sign = -sign;
      name = name.substring(1);
    }

    Pair<int[][], int[][]> pair = unicodeTable(name);
    if (pair == null) {
      throw new PatternSyntaxException(ERR_INVALID_CHAR_RANGE, t.from(startPos));
    }
    int[][] tab = pair.first;
    int[][] fold = pair.second; // fold-equivalent table

    // Variation of CharClass.appendGroup() for tables.
    if ((flags & RE2.FOLD_CASE) == 0 || fold == null) {
      cc.appendTableWithSign(tab, sign);
    } else {
      // Merge and clean tab and fold in a temporary buffer.
      // This is necessary for the negative case and just tidy
      // for the positive case.
      int[] tmp = new CharClass().appendTable(tab).appendTable(fold).cleanClass().toArray();