public/go/tests/slice/main.go

package main

import (
	student "student"

	"lib"
)

func ifNegative(a []string, n int) int {
	if n < 0 {
		n = len(a) + n
	}

	if n < 0 {
		n = 0
	} else if n > len(a) {
		n = len(a)
	}

	return n
}

func slice(a []string, nbr ...int) []string {
	if len(nbr) == 0 {
		return a
	}

	first := nbr[0]
	if len(nbr) == 1 {
		if first < 0 {
			first = len(a) + first
			if first < 0 {
				return a
			}
		}
		return a[first:]
	}
	second := nbr[1]

	first = ifNegative(a, first)
	second = ifNegative(a, second)

	if first > second {
		return nil
	}

	return a[first:second]
}

func main() {
	elems := [][]interface{}{
		{
			[]string{"coding", "algorithm", "ascii", "package", "golang"},
			1,
		},
		{
			[]string{"coding", "algorithm", "ascii", "package", "golang"},
			-3,
		},
		{
			[]string{"coding", "algorithm", "ascii", "package", "golang"},
			2, 4,
		},
		{
			[]string{"coding", "algorithm", "ascii", "package", "golang"},
			-2, -1,
		},
		{
			[]string{"coding", "algorithm", "ascii", "package", "golang"},
			2, 0,
		},
	}

	s := lib.MultRandWords()

	elems = append(elems, []interface{}{s, -len(s) - 10, -len(s) - 5})

	for i := 0; i < 3; i++ {
		s = lib.MultRandWords()
		elems = append(elems, []interface{}{s, lib.RandIntBetween(-len(s)-10, len(s)+10), lib.RandIntBetween(-len(s)-8, len(s)+10)})
	}

	for _, a := range elems {
		lib.Challenge("Slice", student.Slice, slice, a...)
	}
}