map.swift

import Foundation
extension Array {
    func map7<U>(@noescape transform: Element ->U) -> [U] {

        var result = UnsafeMutablePointer<U>.alloc(1000)
        let resultBuffer = UnsafeMutableBufferPointer(start: result, count: 1000)

        self.withUnsafeBufferPointer { (buffer:UnsafeBufferPointer<Element>) in

            for element in buffer {

                result.memory = transform(element)
                result = result.successor()
            }
        }

        return [U](resultBuffer)
    }
}

var time = NSDate().timeIntervalSince1970
func measure(message: String? = nil) -> Double {
    let now = NSDate().timeIntervalSince1970
    let diff = now - time
    if let message = message {
      print("\(message): \(diff)")
    }
    time = now
    return diff
}

let a:[Int] = (1...1000).map{$0}
measure("=== ")
let b = a.map{$0 + 1}
measure("map ")
let b1 = a.map{$0 + 1}
measure("map ")
let h1 = a.map7{$0 + 1}
measure("map7")
let b2 = a.map{$0 + 1}
measure("map ")
let h2 = a.map7{$0 + 1}
measure("map7")
let b3 = a.map{$0 + 1}
measure("map ")
let h3 = a.map7{$0 + 1}
measure("map7")
let b4 = a.map{$0 + 1}
measure("map ")
let h4 = a.map7{$0 + 1}
measure("map7")

// $ xcrun -sdk macosx swiftc map.swift  # CoreGraphicsがimportできないからこうしろとおこられた
// $ ./map
// === : 0.000325918197631836
// map : 0.000761985778808594
// map : 0.000236988067626953
// map7: 0.000210046768188477
// map : 0.000227928161621094
// map7: 0.00017094612121582
// map : 0.000341176986694336
// map7: 0.000142812728881836
// map : 0.000211954116821289
// map7: 0.000133037567138672

// $ xcrun -sdk macosx swiftc -O map.swift
// $ ./map 
// === : 0.000318050384521484
// map : 0.000821113586425781
// map : 5.79357147216797e-05
// map7: 3.00407409667969e-05
// map : 5.10215759277344e-05
// map7: 2.88486480712891e-05
// map : 5.10215759277344e-05
// map7: 2.62260437011719e-05
// map : 4.98294830322266e-05
// map7: 2.59876251220703e-05
// 0255a1c9c760eb7da52a $ 
//