Method match

java/com/google/re2j/Machine.java:215–301

(MachineInput in, int pos, int anchor)

  // It reports whether a match was found.
  // If so, matchcap holds the submatch information.
  boolean match(MachineInput in, int pos, int anchor) {
    int startCond = re2.cond;
    if (startCond == Utils.EMPTY_ALL) { // impossible
      return false;
    }
    if ((anchor == RE2.ANCHOR_START || anchor == RE2.ANCHOR_BOTH) && pos != 0) {
      return false;
    }
    matched = false;
    Arrays.fill(matchcap, 0, prog.numCap, -1);
    Queue runq = q0, nextq = q1;
    int r = in.step(pos);
    int rune = r >> 3;
    int width = r & 7;
    int rune1 = -1;
    int width1 = 0;
    if (r != MachineInput.EOF) {
      r = in.step(pos + width);
      rune1 = r >> 3;
      width1 = r & 7;
    }
    int flag; // bitmask of EMPTY_* flags
    if (pos == 0) {
      flag = Utils.emptyOpContext(-1, rune);
    } else {
      flag = in.context(pos);
    }
    for (; ; ) {

      if (runq.isEmpty()) {
        if ((startCond & Utils.EMPTY_BEGIN_TEXT) != 0 && pos != 0) {
          // Anchored match, past beginning of text.
          break;
        }
        if (matched) {
          // Have match; finished exploring alternatives.
          break;
        }
        if (!re2.prefix.isEmpty() && rune1 != re2.prefixRune && in.canCheckPrefix()) {
          // Match requires literal prefix; fast search for it.
          int advance = in.index(re2, pos);
          if (advance < 0) {
            break;
          }
          pos += advance;
          r = in.step(pos);
          rune = r >> 3;
          width = r & 7;
          r = in.step(pos + width);
          rune1 = r >> 3;
          width1 = r & 7;
        }
      }
      if (!matched && (pos == 0 || anchor == RE2.UNANCHORED)) {
        // If we are anchoring at begin then only add threads that begin
        // at |pos| = 0.
        if (ncap > 0) {
          matchcap[0] = pos;