Function normalizeExtensions

dialog.go:282–305

normalizeExtensions trims and lowercases each extension and ensures it starts with a dot.

(in []string)

// normalizeExtensions trims and lowercases each extension and ensures it
// starts with a dot.
func normalizeExtensions(in []string) []string {
	if len(in) == 0 {
		return nil
	}
	out := make([]string, 0, len(in))
	for _, s := range in {
		if s == "" {
			continue
		}
		// strings.ToLower without importing strings: manual cast.
		b := []byte(s)
		for i, c := range b {
			if c >= 'A' && c <= 'Z' {
				b[i] = c + 32
			}
		}
		s = string(b)
		if s[0] != '.' {
			s = "." + s
		}
		out = append(out, s)
	}
	return out
}