Method pad

java/com/google/re2j/RE2.java:514–526

(int[] a)

  // an expression for \1.  Pad returns a with -1s appended as needed;
  // the result may alias a.
  private int[] pad(int[] a) {
    if (a == null) {
      return null; // No match.
    }
    int n = (1 + numSubexp) * 2;
    if (a.length < n) {
      int[] a2 = new int[n];
      System.arraycopy(a, 0, a2, 0, a.length);
      Arrays.fill(a2, a.length, n, -1);
      a = a2;
    }
    return a;
  }

  private interface DeliverFunc {
    // Called iteratively with a list of submatch indices in the same