How to reverse a string in Go?

Question

How can we reverse a simple string in Go?

Answer 1

This code preserves sequences of combining characters intact, and should work with invalid UTF-8 input too.

package stringutil
import "code.google.com/p/go.text/unicode/norm"

func Reverse(s string) string {
    bound := make([]int, 0, len(s) + 1)

    var iter norm.Iter
    iter.InitString(norm.NFD, s)
    bound = append(bound, 0)
    for !iter.Done() {
        iter.Next()
        bound = append(bound, iter.Pos())
    }
    bound = append(bound, len(s))
    out := make([]byte, 0, len(s))
    for i := len(bound) - 2; i >= 0; i-- {
        out = append(out, s[bound[i]:bound[i+1]]...)
    }
    return string(out)
}

It could be a little more efficient if the unicode/norm primitives allowed iterating through the boundaries of a string without allocating. See also https://code.google.com/p/go/issues/detail?id=9055 .