mutating func _swapNonemptySubrangePrefixes()

in Sources/SE0270_RangeSet/Partition.swift [99:114]

• 15 lines of code
• 3 McCabe index (conditional complexity)

  mutating func _swapNonemptySubrangePrefixes(
    _ lhs: Range<Index>, _ rhs: Range<Index>
  ) -> (Index, Index) {
    assert(!lhs.isEmpty)
    assert(!rhs.isEmpty)
    
    var p = lhs.lowerBound
    var q = rhs.lowerBound
    repeat {
      swapAt(p, q)
      formIndex(after: &p)
      formIndex(after: &q)
    }
      while p != lhs.upperBound && q != rhs.upperBound
    return (p, q)
  }