golangどう書く

hoge.go

// rubyで言う
// (0..42).select(&:even?).each_slice(3).to_a
// # => [[0, 2, 4], [6, 8, 10], [12, 14, 16], [18, 20, 22], [24, 26, 28], [30, 32, 34], [36, 38, 40], [42]]
// がしたい!!

package main

import "fmt"

func main() {
  fmt.Println(
    createArrays(42, 3, func(i int) bool {
      return i%2 == 0
    }),
  )
  // => [[0 2 4] [6 8 10] [12 14 16] [18 20 22] [24 26 28] [30 32 34] [36 38 40] [42]]
}

func createArrays(max, each_arr_size int, selector func(i int) bool) [][]int {
  result := make([][]int, 0, max/each_arr_size)

  index := -1
  current_arr_size := 0

  for i := 0; i <= max; i++ {
    if !selector(i) {
      continue
    }

    if current_arr_size == 0 {
      index++
      result = append(result, make([]int, 0, each_arr_size))
      current_arr_size = each_arr_size
    }
    result[index] = append(result[index], i)
    current_arr_size--
  }

  return result
}