priorities

enum testcases = [
    "a1bc3d4" : [0, 1, 0, 3, 4],
    "to2gr" : [0, 0, 2],
    "1to" : [1],
    "x3c2" : [0, 3, 2],
    "1a2b3c4" : [1, 2, 3, 4],
];
foreach (pat, prios; testcases)
    assert(equal(priorities(pat), prios));