1 files changed, 64 insertions, 0 deletions
diff --git a/modules/opaque/opaque.c b/modules/opaque/opaque.c
new file mode 100644
index 00000000000..2366b2ed2e9
--- /dev/null
+++ b/modules/opaque/opaque.c
@@ -0,0 +1,64 @@
+#include <config.h>
+#include <lisp.h>
+
+int plugin_is_GPL_compatible;
+static Lisp_Object Qopaque;
+
+struct opaque
+{
+  int a, b, c;
+};
+
+static Lisp_Object Qa, Qb, Qc;
+
+EXFUN (Fopaque_make, 3);
+DEFUN ("opaque-make", Fopaque_make, Sopaque_make, 3, 3, 0,
+       doc: "Make opaque type.")
+  (Lisp_Object a, Lisp_Object b, Lisp_Object c)
+{
+  struct opaque *p = malloc (sizeof (*p));
+  p->a = XINT (a);
+  p->b = XINT (b);
+  p->c = XINT (c);
+
+  /*
+    store p as a the first slot (index 0) of a Lisp_Save_Value (which
+    is a Lisp_Misc)
+  */
+  return make_save_ptr ((void*)p);
+}
+
+EXFUN (Fopaque_free, 1);
+DEFUN ("opaque-free", Fopaque_free, Sopaque_free, 1, 1, 0,
+       doc: "Free opaque object OBJ.")
+  (Lisp_Object obj)
+{
+  /* the pointer is in the first slot (index 0) */
+  free (XSAVE_POINTER (obj, 0));
+  return Qnil;
+}
+
+EXFUN (Fopaque_get, 2);
+DEFUN ("opaque-get", Fopaque_get, Sopaque_get, 2, 2, 0,
+       doc: "Return the field F (`a', `b', `c') of the opaque object OBJ.")
+  (Lisp_Object obj, Lisp_Object f)
+{
+  struct opaque *p = XSAVE_POINTER (obj, 0);
+  int val = EQ (f, Qa) ? p->a : EQ (f, Qb) ? p->b : EQ (f, Qc) ? p->c : -1;
+  return make_number (val);
+}
+
+void init ()
+{
+  DEFSYM (Qopaque, "opaque");
+
+  DEFSYM (Qa, "a");
+  DEFSYM (Qb, "b");
+  DEFSYM (Qc, "c");
+
+  defsubr (&Sopaque_make);
+  defsubr (&Sopaque_free);
+  defsubr (&Sopaque_get);
+
+  Fprovide (Qopaque, Qnil);
+}