add rudimentary packed-refs parsing

refs.lisp

@@ -0,0 +1,34 @@
+(in-package :glitter)
+
+(defclass packed-ref ()
+  ((hash :initarg :hash :reader ref-hash)
+   (name :initarg :name :reader ref-name)))
+
+(defparameter *print-packed-refs-sha-length* 6)
+
+(defmethod print-object ((object packed-ref) stream)
+  (print-unreadable-object (object stream)
+    (format stream "Packed-Ref ~A ~A" (ref-name object)
+            (binascii:encode (ref-hash object) :hex
+                             :end *print-packed-refs-sha-length*))))
+
+(defun read-packed-refs-file (filename)
+  (with-open-file (stream filename :direction :input
+                          :element-type 'character)
+    (do ((line (read-line stream nil stream)
+           (read-line stream nil stream))
+         (refs nil))
+        ((eq line stream) (nreverse refs))
+      (cond
+        ((char= (aref line 0) #\#)
+         ;; FIXME: parse '# pack-refs with:' lines
+         )
+        ((char= (aref line 0) #\^)
+         ;; FIXME: parse these
+         )
+        (t
+         (let* ((hash-end (position #\Space line))
+                (hash (binascii:decode line :hex :end hash-end))
+                (name (subseq line (1+ hash-end))))
+           (push (make-instance 'packed-ref :hash hash :name name)
+                 refs)))))))