diff --git a/vendor/golang.org/x/text/collate/sort.go b/vendor/golang.org/x/text/collate/sort.go
new file mode 100644
index 0000000..62f1e75
--- /dev/null
+++ b/vendor/golang.org/x/text/collate/sort.go
@@ -0,0 +1,81 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package collate
+
+import (
+	"bytes"
+	"sort"
+)
+
+const (
+	maxSortBuffer  = 40960
+	maxSortEntries = 4096
+)
+
+type swapper interface {
+	Swap(i, j int)
+}
+
+type sorter struct {
+	buf  *Buffer
+	keys [][]byte
+	src  swapper
+}
+
+func (s *sorter) init(n int) {
+	if s.buf == nil {
+		s.buf = &Buffer{}
+		s.buf.init()
+	}
+	if cap(s.keys) < n {
+		s.keys = make([][]byte, n)
+	}
+	s.keys = s.keys[0:n]
+}
+
+func (s *sorter) sort(src swapper) {
+	s.src = src
+	sort.Sort(s)
+}
+
+func (s sorter) Len() int {
+	return len(s.keys)
+}
+
+func (s sorter) Less(i, j int) bool {
+	return bytes.Compare(s.keys[i], s.keys[j]) == -1
+}
+
+func (s sorter) Swap(i, j int) {
+	s.keys[i], s.keys[j] = s.keys[j], s.keys[i]
+	s.src.Swap(i, j)
+}
+
+// A Lister can be sorted by Collator's Sort method.
+type Lister interface {
+	Len() int
+	Swap(i, j int)
+	// Bytes returns the bytes of the text at index i.
+	Bytes(i int) []byte
+}
+
+// Sort uses sort.Sort to sort the strings represented by x using the rules of c.
+func (c *Collator) Sort(x Lister) {
+	n := x.Len()
+	c.sorter.init(n)
+	for i := 0; i < n; i++ {
+		c.sorter.keys[i] = c.Key(c.sorter.buf, x.Bytes(i))
+	}
+	c.sorter.sort(x)
+}
+
+// SortStrings uses sort.Sort to sort the strings in x using the rules of c.
+func (c *Collator) SortStrings(x []string) {
+	c.sorter.init(len(x))
+	for i, s := range x {
+		c.sorter.keys[i] = c.KeyFromString(c.sorter.buf, s)
+	}
+	c.sorter.sort(sort.StringSlice(x))
+}