1 files changed, 23 insertions, 0 deletions
diff --git a/object/tree/insert.go b/object/tree/insert.go
new file mode 100644
index 00000000..bca4aa49
--- /dev/null
+++ b/object/tree/insert.go
@@ -0,0 +1,23 @@
+package tree
+
+import (
+	"fmt"
+	"sort"
+)
+
+// InsertEntry inserts a tree entry while preserving Git ordering.
+func (tree *Tree) InsertEntry(newEntry TreeEntry) error {
+	if tree.entry(newEntry.Name, true) != nil || tree.entry(newEntry.Name, false) != nil {
+		return fmt.Errorf("object: tree: entry %q already exists", newEntry.Name)
+	}
+
+	newIsTree := newEntry.Mode == FileModeDir
+	insertAt := sort.Search(len(tree.Entries), func(i int) bool {
+		return TreeEntryNameCompare(tree.Entries[i].Name, tree.Entries[i].Mode, newEntry.Name, newIsTree) >= 0
+	})
+	tree.Entries = append(tree.Entries, TreeEntry{})
+	copy(tree.Entries[insertAt+1:], tree.Entries[insertAt:])
+	tree.Entries[insertAt] = newEntry
+
+	return nil
+}