DouKaku?

Iterator::with_peek: method fiber {
    prev, curr: null, null;
    noloop: true;
    this {|next|
        if (curr) {
            yield prev, curr, next;
        }
        prev, curr = curr, next;
        noloop = false;
    }
    if (!noloop) {
        yield prev, curr, null;
    }
}

remover: fun(str) fiber {
    in_comment: false;
    str.split("").each.with_peek {|prev,it,next|
        if (in_comment) {
            if (prev == "*" && it == "/") {
                in_comment = false;
            }
        } else {
            if (it == "/" && next == "*") {
                in_comment = true;
            } else {
                yield it;
            }
        }
    }
}

remove_comment: fun(str) {
    return remover(str).to_a.join("");
}

assert remove_comment("AAA") == "AAA";
assert remove_comment("AAA/*BBB*/") == "AAA";
assert remove_comment("AAA/*BBB") == "AAA";
assert remove_comment("AAA/*BBB*/CCC") == "AAACCC";
assert remove_comment("AAA/*BBB/*CCC*/DDD*/EEE") == "AAADDD*/EEE";
assert remove_comment("AAA/a//*BB*B**/CCC") == "AAA/a/CCC";