Direction directionForNeighbor()

in h3_algos.c [509:525]

• 14 lines of code
• 5 McCabe index (conditional complexity)

Direction directionForNeighbor(H3Index origin, H3Index destination) {
    bool isPent = H3_EXPORT(isPentagon)(origin);
    // Checks each neighbor, in order, to determine which direction the
    // destination neighbor is located. Skips CENTER_DIGIT since that
    // would be the origin; skips deleted K direction for pentagons.
    for (Direction direction = isPent ? J_AXES_DIGIT : K_AXES_DIGIT;
         direction < NUM_DIGITS; direction++) {
        H3Index neighbor;
        int rotations = 0;
        H3Error neighborError =
            h3NeighborRotations(origin, direction, &rotations, &neighbor);
        if (!neighborError && neighbor == destination) {
            return direction;
        }
    }
    return INVALID_DIGIT;
}