Segment

segment.swift

extension Array {
    func segment(atJunction shouldSegment: (Element, Element) throws -> Bool) rethrows -> [ArraySlice<Element>] {
        var result: [ArraySlice<Element>] = []
        var previousValue: Element?
        for (index, value) in enumerated() {
            defer { previousValue = value }
            if let previousValue = previousValue, try shouldSegment(previousValue, value) {
                result.append(self[(result.last?.endIndex ?? startIndex)..<index])
            }
        }
        return result
    }
}