Function intersect

src/Kit.ts:556–569

(a: CharRangeRepr, b: CharRangeRepr)

  }

  export function intersect(a: CharRangeRepr, b: CharRangeRepr): Maybe<CharRangeRepr> {
    let a1 = begin(a);
    let a2 = end(a);
    let b1 = begin(b);
    let b2 = end(b);
    if (b2 < a1 || a2 < b1) return;
    if (a1 <= b1) {
      if (b2 <= a2) return b;
      else return pack(b1, a2);
    } else {
      if (a2 <= b2) return a;
      else return pack(a1, b2);
    }
  }

  export function join(a: CharRangeRepr, b: CharRangeRepr): Maybe<CharRangeRepr> {
    let a1 = begin(a);