1 files changed, 32 insertions, 0 deletions
diff --git a/object/id/objectid_parse.go b/object/id/objectid_parse.go
new file mode 100644
index 00000000..e6cbb641
--- /dev/null
+++ b/object/id/objectid_parse.go
@@ -0,0 +1,32 @@
+package objectid
+
+import (
+	"encoding/hex"
+	"fmt"
+)
+
+// ParseHex parses an object ID from hex for the specified algorithm.
+func ParseHex(algo Algorithm, s string) (ObjectID, error) {
+	var id ObjectID
+	if algo.Size() == 0 {
+		return id, ErrInvalidAlgorithm
+	}
+
+	if len(s)%2 != 0 {
+		return id, fmt.Errorf("%w: odd hex length %d", ErrInvalidObjectID, len(s))
+	}
+
+	if len(s) != algo.HexLen() {
+		return id, fmt.Errorf("%w: got %d chars, expected %d", ErrInvalidObjectID, len(s), algo.HexLen())
+	}
+
+	decoded, err := hex.DecodeString(s)
+	if err != nil {
+		return id, fmt.Errorf("%w: decode: %w", ErrInvalidObjectID, err)
+	}
+
+	copy(id.data[:], decoded)
+	id.algo = algo
+
+	return id, nil
+}