From baa2be0bcf86c435c999bbdcff2a6aa40d5ed12c Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Mon, 18 Apr 2016 22:07:57 -0400
Subject: [PATCH] Added opaque types

---
 include/cyclone/types.h | 10 ++++++++++
 runtime.c               |  6 +++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index 70c2461b..808c45b5 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -197,6 +197,7 @@ typedef long tag_type;
 #define mutex_tag 19
 #define cond_var_tag 20
 #define bytevector_tag 21
+#define c_opaque_tag 22
 
 #define nil NULL
 #define eq(x,y) (x == y)
@@ -239,6 +240,15 @@ typedef struct {gc_header_type hdr; tag_type tag; object *pvar;} cvar_type;
 typedef cvar_type *cvar;
 #define make_cvar(n,v) cvar_type n; n.hdr.mark = gc_color_red; n.hdr.grayed = 0; n.tag = cvar_tag; n.pvar = v;
 
+/* C Opaque type - a wrapper around a pointer of any type.
+   Note this requires application code to free any memory
+   before an object is collected by GC.  */
+typedef struct {gc_header_type hdr; tag_type tag; void *ptr;} c_opaque_type;
+typedef c_opaque_type *c_opaque;
+#define make_c_opaque(var, ptr) c_opaque_type var; var.hdr.mark = gc_color_red; n.ndr.grayed = 0; n.tag = c_opaque_type; n.ptr = ptr;
+
+#define opaque_ptr(x) (((c_opaque)x)->ptr)
+
 /* Define mutex type */
 typedef struct {gc_header_type hdr; tag_type tag; pthread_mutex_t lock;} mutex_type;
 typedef mutex_type *mutex;
diff --git a/runtime.c b/runtime.c
index 80da55d5..9bbfe4b8 100644
--- a/runtime.c
+++ b/runtime.c
@@ -27,7 +27,7 @@ object Cyc_global_set(void *thd, object *glo, object value)
 
 /* Error checking section - type mismatch, num args, etc */
 /* Type names to use for error messages */
-const char *tag_names[23] = { \
+const char *tag_names[24] = { \
    "pair" \
  , "symbol" \
  , "" \
@@ -50,6 +50,7 @@ const char *tag_names[23] = { \
  , "mutex" \
  , "condition variable" \
  , "bytevector" \
+ , "opaque" \
  , "Reserved for future use" };
 
 void Cyc_invalid_type_error(void *data, int tag, object found) {
@@ -565,6 +566,9 @@ object Cyc_display(object x, FILE *port)
     case cvar_tag:
       Cyc_display(Cyc_get_cvar(x), port);
       break;
+    case c_opaque_tag:
+      fprintf(port, "<C opaque %p>", opaque_ptr(x));
+      break;
     case mutex_tag:
       fprintf(port, "<mutex %p>", x);
       break;