1 files changed, 15 insertions, 0 deletions
diff --git a/plumbing/hash.go b/plumbing/hash.go
index 7fa953d..8e60877 100644
--- a/plumbing/hash.go
+++ b/plumbing/hash.go
@@ -1,9 +1,11 @@
 package plumbing
 
 import (
+	"bytes"
 	"crypto/sha1"
 	"encoding/hex"
 	"hash"
+	"sort"
 	"strconv"
 )
 
@@ -56,3 +58,16 @@ func (h Hasher) Sum() (hash Hash) {
 	copy(hash[:], h.Hash.Sum(nil))
 	return
 }
+
+// HashesSort sorts a slice of Hashes in increasing order.
+func HashesSort(a []Hash) {
+	sort.Sort(HashSlice(a))
+}
+
+// HashSlice attaches the methods of sort.Interface to []Hash, sorting in
+// increasing order.
+type HashSlice []Hash
+
+func (p HashSlice) Len() int           { return len(p) }
+func (p HashSlice) Less(i, j int) bool { return bytes.Compare(p[i][:], p[j][:]) < 0 }
+func (p HashSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }