object: Add Encode method to all objects. (#70)

Encode method encodes a typed object (commit, tree,
tag, blob) into raw core.Object representation.

Additionally, Decode does not trim commit message
lines. This is needed for Decode/Encode to be
idempotent.

1 files changed, 23 insertions, 0 deletions

diff --git a/tree.go b/tree.go
index cfe457e..86f1aaa 100644
--- a/tree.go
+++ b/tree.go
@@ -3,6 +3,7 @@ package git
 import (
 	"bufio"
 	"errors"
+	"fmt"
 	"io"
 	"os"
 	"strconv"
@@ -210,6 +211,28 @@ func (t *Tree) decodeFileMode(mode string) (os.FileMode, error) {
 	return m, nil
 }
 
+// Encode transforms a Tree into a core.Object.
+func (t *Tree) Encode(o core.Object) error {
+	o.SetType(core.TreeObject)
+	w, err := o.Writer()
+	if err != nil {
+		return err
+	}
+	defer checkClose(w, &err)
+	for _, entry := range t.Entries {
+		if _, err = fmt.Fprintf(w, "%o %s", entry.Mode, entry.Name); err != nil {
+			return err
+		}
+		if _, err = w.Write([]byte{0x00}); err != nil {
+			return err
+		}
+		if _, err = w.Write([]byte(entry.Hash[:])); err != nil {
+			return err
+		}
+	}
+	return err
+}
+
 func (t *Tree) buildMap() {
 	t.m = make(map[string]*TreeEntry)
 	for i := 0; i < len(t.Entries); i++ {