strings_join_nonempty.go

// JoinNonEmpty concatenates the elements of a to create a single string. The separator string
// sep is placed between elements in the resulting string, and ignores empty strings.
func JoinNonEmpty(a []string, sep string) string {
	switch len(a) {
	case 0:
		return ""
	case 1:
		return a[0]
	}
	n := 0
	for i := 0; i < len(a); i++ {
		length := len(a[i])
		if length == 0 {
			continue
		}
		n += length + len(sep)
	}
	if n > len(sep) {
		n -= len(sep)
	}

	var b strings.Builder
	b.Grow(n)
	b.WriteString(a[0])
	for _, s := range a[1:] {
		if s == "" {
			continue
		}
		b.WriteString(sep)
		b.WriteString(s)
	}
	return b.String()
}