1// Copyright 2015 The Go Authors. All rights reserved.
 2// Use of this source code is governed by a BSD-style
 3// license that can be found in the LICENSE file.
 4
 5// Package internal contains non-exported functionality that are used by
 6// packages in the text repository.
 7package internal // import "golang.org/x/text/internal"
 8
 9import (
10	"sort"
11
12	"golang.org/x/text/language"
13)
14
15// SortTags sorts tags in place.
16func SortTags(tags []language.Tag) {
17	sort.Sort(sorter(tags))
18}
19
20type sorter []language.Tag
21
22func (s sorter) Len() int {
23	return len(s)
24}
25
26func (s sorter) Swap(i, j int) {
27	s[i], s[j] = s[j], s[i]
28}
29
30func (s sorter) Less(i, j int) bool {
31	return s[i].String() < s[j].String()
32}
33
34// UniqueTags sorts and filters duplicate tags in place and returns a slice with
35// only unique tags.
36func UniqueTags(tags []language.Tag) []language.Tag {
37	if len(tags) <= 1 {
38		return tags
39	}
40	SortTags(tags)
41	k := 0
42	for i := 1; i < len(tags); i++ {
43		if tags[k].String() < tags[i].String() {
44			k++
45			tags[k] = tags[i]
46		}
47	}
48	return tags[:k+1]
49}