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extension MKCoordinateRegion {
    static func region(forLocations waypoints: [CLLocation], zoomPercent: Double = 0.2) -> MKCoordinateRegion {
        var r = MKMapRectNull
        
        for wp in waypoints {
            var point = MKMapPointForCoordinate(wp.coordinate)
            r = MKMapRectUnion(r, MKMapRectMake(point.x, point.y, 0, 0))
        }
        
        let zoomed = MKMapRectMake(r.origin.x-r.size.width*zoomPercent, r.origin.y-r.size.height*zoomPercent, r.size.width*(1+zoomPercent*2), r.size.height*(1+zoomPercent*2))

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func pairwise<T>(d: [T]) -> [(T,T)] {
    switch d.count {
    case 0: return []
    case 1: return []
    case let n:
        let r = [(d[0],d[1])]
        return r + pairwise(Array(d[1..<n]))
    }
}

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extension String {
    func size(withAttributes attrs: [String:AnyObject], constrainedTo box: NSSize) -> NSRect {
        let storage = NSTextStorage(string: self)
        let container = NSTextContainer(containerSize: NSSize(width: box.width, height: box.height))
        let layout = NSLayoutManager()
        layout.addTextContainer(container)
        storage.addLayoutManager(layout)
        storage.addAttributes(attrs, range: NSMakeRange(0, storage.length))
        container.lineFragmentPadding = 0.0
        let _ = layout.glyphRangeForTextContainer(container)

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import Cocoa

//: # An exercise in specifying and simplifying Maths functions using Swift
/*: This is cut-down version of some code I've been working on to parse, simplify and display mathematical expressions. The source below shows some of the power of pattern matching and (recursive) enumerated types within Swift in defining and evaluating the expression domain. Note, it doesn't cover all cases but is intended to give a flavour of what can be achieved.

    No optimisations applied
*/

//: # Supporting functions
//: ### Function Pipeline

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extension NSTextView {
    func rectForRange(range: NSRange) -> NSRect? {
        guard let layout = self.layoutManager, container = self.textContainer else {return nil}
        let rng = layout.glyphRangeForCharacterRange(range, actualCharacterRange: nil)
        let rct = layout.boundingRectForGlyphRange(rng, inTextContainer: container)
        return NSOffsetRect(rct, self.textContainerOrigin.x, self.textContainerOrigin.y)
    }
    
    func rectForSelectedRange() -> NSRect? {
        return rectForRange(self.selectedRange())