sparse.scm

diff --git a/ext/sparse/sparse.scm b/ext/sparse/sparse.scm
index 76199b8..ed869cc 100644
--- a/ext/sparse/sparse.scm
+++ b/ext/sparse/sparse.scm
@@ -33,6 +33,7 @@
 
 
 (define-module util.sparse
+  (use gauche.collection)
   (use gauche.dictionary)
   (export <sparse-table> make-sparse-table sparse-table-num-entries
           sparse-table-ref sparse-table-set! sparse-table-exists?
@@ -302,3 +303,23 @@
   :pop!      sparse-vector-pop!
   :push!     sparse-vector-push!
   :update!   sparse-vector-update!)
+
+;;===================================================================
+;; collection protocol
+
+; collection.scmのhash-tableのものを流用した
+(define-method call-with-iterator ((coll <sparse-table>) proc :allow-other-keys)
+  (let ([eof-marker (cons #f #f)]
+        [iter (%sparse-table-iter coll)])
+    (receive (k v) (iter eof-marker)
+      (proc (cut eq? k eof-marker)
+            (^[] (begin0 (cons k v)
+                   (set!-values (k v) (iter eof-marker))))))))
+
+(define-method call-with-iterator ((coll <sparse-vector-base>) proc :allow-other-keys)
+  (let ([eof-marker (cons #f #f)]
+        [iter (%sparse-vector-iter coll)])
+    (receive (k v) (iter eof-marker)
+      (proc (cut eq? k eof-marker)
+            (^[] (begin0 (cons k v)
+                   (set!-values (k v) (iter eof-marker))))))))