1 files changed, 87 insertions, 0 deletions
diff --git a/modules/git/sha1.go b/modules/git/sha1.go
new file mode 100644
index 0000000000..5c57e89b6a
--- /dev/null
+++ b/modules/git/sha1.go
@@ -0,0 +1,87 @@
+// Copyright 2014 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import (
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+var (
+	IdNotExist = errors.New("sha1 id not exist")
+)
+
+type sha1 [20]byte
+
+// Return true if s has the same sha1 as caller.
+// Support 40-length-string, []byte, sha1
+func (id sha1) Equal(s2 interface{}) bool {
+	switch v := s2.(type) {
+	case string:
+		if len(v) != 40 {
+			return false
+		}
+		return v == id.String()
+	case []byte:
+		if len(v) != 20 {
+			return false
+		}
+		for i, v := range v {
+			if id[i] != v {
+				return false
+			}
+		}
+	case sha1:
+		for i, v := range v {
+			if id[i] != v {
+				return false
+			}
+		}
+	default:
+		return false
+	}
+	return true
+}
+
+// Return string (hex) representation of the Oid
+func (s sha1) String() string {
+	result := make([]byte, 0, 40)
+	hexvalues := []byte("0123456789abcdef")
+	for i := 0; i < 20; i++ {
+		result = append(result, hexvalues[s[i]>>4])
+		result = append(result, hexvalues[s[i]&0xf])
+	}
+	return string(result)
+}
+
+// Create a new sha1 from a 20 byte slice.
+func NewId(b []byte) (sha1, error) {
+	var id sha1
+	if len(b) != 20 {
+		return id, errors.New("Length must be 20")
+	}
+
+	for i := 0; i < 20; i++ {
+		id[i] = b[i]
+	}
+	return id, nil
+}
+
+// Create a new sha1 from a Sha1 string of length 40.
+func NewIdFromString(s string) (sha1, error) {
+	s = strings.TrimSpace(s)
+	var id sha1
+	if len(s) != 40 {
+		return id, fmt.Errorf("Length must be 40")
+	}
+	b, err := hex.DecodeString(s)
+	if err != nil {
+		return id, err
+	}
+
+	return NewId(b)
+}