codewars/go/kyu7/square_strings_1/k.go

package kata

import "strings"

func Reverse(s string) string {
	rs := []rune(s)
	for i, j := 0, len(rs)-1; i < j; i, j = i+1, j-1 {
		rs[i], rs[j] = rs[j], rs[i]
	}
	return string(rs)
}

const NL = "\n"

// VertMirror reverses each line in the multiline string.
func VertMirror(s string) string {
	ss := strings.Split(s, NL)
	rs := make([]string, len(ss))
	for i, row := range ss {
		rs[i] = Reverse(row)
	}
	rev := strings.Join(rs, NL)
	return rev
}

// HorMirror reverses the line order in the multiline strings.
func HorMirror(s string) string {
	ss := strings.Split(s, NL)
	for i, j := 0, len(ss)-1; i < j; i, j = i+1, j-1 {
		ss[i], ss[j] = ss[j], ss[i]
	}
	return strings.Join(ss, NL)
}

type FParam func(string) string

func Oper(f FParam, x string) string {
	return f(x)
}