blob: 380f4c09f7f235ca8ecdc1f05ef2863120995940 [file] [log] [blame]
Don Newton98fd8812019-09-23 15:15:02 -04001// Copyright 2013 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// +build !go1.2
6
7package language
8
9import "sort"
10
11func sortStable(s sort.Interface) {
12 ss := stableSort{
13 s: s,
14 pos: make([]int, s.Len()),
15 }
16 for i := range ss.pos {
17 ss.pos[i] = i
18 }
19 sort.Sort(&ss)
20}
21
22type stableSort struct {
23 s sort.Interface
24 pos []int
25}
26
27func (s *stableSort) Len() int {
28 return len(s.pos)
29}
30
31func (s *stableSort) Less(i, j int) bool {
32 return s.s.Less(i, j) || !s.s.Less(j, i) && s.pos[i] < s.pos[j]
33}
34
35func (s *stableSort) Swap(i, j int) {
36 s.s.Swap(i, j)
37 s.pos[i], s.pos[j] = s.pos[j], s.pos[i]
38}