range_contains_hang.swift

public extension ClosedRange<Int> {
    func crop(by other: ClosedRange<Int>) -> [ClosedRange<Int>] {
        //print("cropping...")
        guard self.overlaps(other) else {
            //return [self]
            fatalError("No overlap")
        }
        
        print("they overlap")
        
        guard self != other else {
            //return []
            fatalError("these arrays are the same.")
        }
        
        print("they are not the same")
        
         //HANGS!!! Why???
         guard !other.contains(self) else {
             print("other contains source entirely. Nothing left over.")
             return []
         }
        
        print("Does it hand in the playground?")
        
        guard !other.fullyContains(self) else {
            print("other contains source entirely. Nothing left over.")
            return []
        }
        
        //print("Other does not fully contain self")
        
        guard self.upperBound != other.lowerBound else {
            return [self.lowerBound...self.upperBound-1]
        }
        
        //print("self.upperBound != other.lowerBound")
        
        guard other.upperBound != self.lowerBound else {
            return [self.lowerBound+1...self.upperBound]
        }
        
        //print("other.upperBound != self.lowerBound")
        
        guard self.lowerBound != other.lowerBound else {
            return [(other.upperBound + 1)...self.upperBound]
        }
        
        //print("self.lowerBound != other.lowerBound")
        
        guard self.upperBound != other.upperBound else {
            return [self.lowerBound...(other.upperBound-1)]
        }
        
        //print("self.upperBound != other.upperBound")
        
        guard !self.fullyContains(other) else {
            return [(self.lowerBound...other.lowerBound-1), (other.upperBound+1...self.upperBound)]
        }
        
        //print("!self.fullyContains(other)")
        
        if self.contains(other.lowerBound) {
            //print("found lower")
            return [self.lowerBound...other.lowerBound-1]
        } else if self.contains(other.upperBound) {
            //print("found upper")
            return [other.upperBound+1...self.upperBound]
        } else {
            fatalError("Range divide:Forgot something...")
        }
        
    }
    func fullyContains(_ other: ClosedRange<Int>) -> Bool {
        self.lowerBound < other.lowerBound && self.upperBound > other.upperBound
    }
}

let resultC = (2442...2679).crop(by:2321...2446)
print(resultC)

print(Int.max)

//This one Hangs.
let resultD = (2442763622...2679835230).crop(by:2321931404...2446354471)
//let result = (0...9).crop(by:3...8)
print(resultD)