Swift - Repeating Code Using Loops(Array, for loop(for/in), map method, forEach method(Array extension))

The Swift Programming Language
Apple Inc.

開発環境

• OS X Mavericks - Apple(OS)
• Xcode 6.0 Beta 6
• Swift (プログラミング言語)

Practical Programming: An Introduction to Computer Science Using Python 3 (Pragmatic Programmers) (Paul Gries (著)、Jennifer Campbell (著)、Jason Montojo (著)、Lynn Beighley (編集)、Pragmatic Bookshelf)のChapter 9(Repeating Code Using Loops)、9.10(Exercises) 3.をSwiftで考えてみる。

9.10(Exercises) 3.

コード(Xcode)

main.swift

//
//  main.swift
//  sample3
//
//  Created by kamimura on 9/4/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

let whales:[Int] = [5,4,7,3,2,3,2,6,4,2,1,7,1,3]

var more_whales:[Int] = []

for whale in whales {
    more_whales.append(whale + 1)
}

let more_whales1:[Int] = whales.map({(x) in x + 1})

let a:[[Int]] = [whales, more_whales, more_whales1]

println("for loop")
for x in a {
    println(x)
}

println("forEach method(Array extension)")
a.forEach(println)

array.swift

//
//  array.swift
//  array
//
//  Created by kamimura on 8/21/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

extension Array {
    func indexAt(i:Int) -> T {
        if i >= 0 {
            return self[i]
        }
        let new_index:Int = self.count + i
        return self[new_index]
    }
    func slice(start:Int = 0, end:Int? = nil) -> Array {
        var new_start = start >= 0 ? start : self.count + start
        var new_end:Int
        if end == nil {
            new_end = self.count
        } else if end! >= 0 {
            new_end = end!
        } else {
            new_end = self.count + end!
        }
        var result:Array = []
        if new_start >= new_end {
            return []
        }
        for i in new_start..<new_end {
            result.append(self[i])
        }
        return result
    }
    func forEach(f:(T) -> ()) {
        for e in self {
            f(e)
        }
    }
}

入出力結果(Console Output)

for loop
[5, 4, 7, 3, 2, 3, 2, 6, 4, 2, 1, 7, 1, 3]
[6, 5, 8, 4, 3, 4, 3, 7, 5, 3, 2, 8, 2, 4]
[6, 5, 8, 4, 3, 4, 3, 7, 5, 3, 2, 8, 2, 4]
forEach method(Array extension)
[5, 4, 7, 3, 2, 3, 2, 6, 4, 2, 1, 7, 1, 3]
[6, 5, 8, 4, 3, 4, 3, 7, 5, 3, 2, 8, 2, 4]
[6, 5, 8, 4, 3, 4, 3, 7, 5, 3, 2, 8, 2, 4]
Program ended with exit code: 0