(COS_Object_release_function_table): Add `cos_release_cons'.

(cos_retain_object): Use `COS_OBJECT_P' to check `obj' is a fat
object.
(cos_release_object): Likewise.
(cos_cons): New function.
(cos_release_cons): New function.
(cos_car): New function.
(cos_cdr): New function.

diff --git a/cos.c b/cos.c
index 303b2dd..299852b 100644 (file)
--- a/cos.c
+++ b/cos.c
@@ -33,6 +33,7 @@ int (*COS_Object_release_function_table
   (COS_Object)
   = { cos_release_string,
       cos_release_symbol,
+      cos_release_cons,
       cos_release_container,
       cos_release_sexp,
       cos_release_binary,
@@ -104,22 +105,24 @@ cos_allocate_object_0 (enum COS_Object_Type type, size_t size)
 COS_Object
 cos_retain_object (COS_Object obj)
 {
-  obj->header.reference_count++;
-
+  if (COS_OBJECT_P (obj))
+    obj->header.reference_count++;
   return obj;
 }
 
 int
 cos_release_object (COS_object obj)
 {
-  ((COS_Object)obj)->header.reference_count--;
+  if (COS_OBJECT_P (obj))
+    {
+      ((COS_Object)obj)->header.reference_count--;
 
-  if ( ((COS_Object)obj)->header.reference_count <= 0 )
-    return (*COS_Object_release_function_table
-           [((COS_Object)obj)->header.type
-            - COS_FAT_OBJECT_TYPE_MIN])(obj);
-  else
-    return 0;
+      if ( ((COS_Object)obj)->header.reference_count <= 0 )
+       return (*COS_Object_release_function_table
+               [((COS_Object)obj)->header.type
+                - COS_FAT_OBJECT_TYPE_MIN])(obj);
+    }
+  return 0;
 }
 
 
@@ -199,6 +202,53 @@ cos_string_data (COS_String string)
 }
 
 
+COS_Cons
+cos_cons (COS_object car, COS_object cdr)
+{
+  COS_Cons obj = COS_ALLOCATE_OBJECT (Cons);
+
+  if (obj == NULL)
+    return NULL;
+
+  obj->car = car;
+  obj->cdr = cdr;
+  cos_retain_object (car);
+  cos_retain_object (cdr);
+
+  return obj;
+}
+
+int
+cos_release_cons (COS_Object obj)
+{
+  if (obj == NULL)
+    return 0;
+
+  cos_release_object (COS_CAR (obj));
+  cos_release_object (COS_CDR (obj));
+  free (obj);
+  return 0;
+}
+
+COS_object
+cos_car (COS_Cons pair)
+{
+  if (COS_OBJECT_CONS_P (pair))
+    return COS_CAR (pair);
+  else
+    return NULL;
+}
+
+COS_object
+cos_cdr (COS_Cons pair)
+{
+  if (COS_OBJECT_CONS_P (pair))
+    return COS_CDR (pair);
+  else
+    return NULL;
+}
+
+
 int
 cos_release_container (COS_Object obj)
 {