From 87f48ec68183df56bcfcf5296cfa8963cec1a262 Mon Sep 17 00:00:00 2001
From: Joshua Suskalo <joshua@iris.tv>
Date: Mon, 20 Sep 2021 14:17:43 -0500
Subject: [PATCH] Add support for union types

---
 src/coffi/ffi.clj | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/coffi/ffi.clj b/src/coffi/ffi.clj
index 5e7eab0..36d1eb1 100644
--- a/src/coffi/ffi.clj
+++ b/src/coffi/ffi.clj
@@ -440,7 +440,7 @@
        deserialize-from)
      obj type)))
 
-;; C String type
+;;; C String type
 
 (defmethod primitive-type ::c-string
   [_type]
@@ -468,6 +468,27 @@
                          (rec (slice segment size))))))]
         (rec segment))))
 
+;;; Union types
+
+(defmethod c-layout ::union
+  [[_union _dispatch types & {:as _opts} :as _type]]
+  (let [items (map c-layout types)]
+    (MemoryLayout/unionLayout
+     (into-array MemoryLayout items))))
+
+(defmethod serialize-into ::union
+  [obj [_union dispatch _types & {:keys [extract]}] segment scope]
+  (let [type (dispatch obj)]
+    (serialize-into
+     (if extract
+       (extract type obj)
+       obj)
+     type
+     segment
+     scope)))
+
+;;; FFI Code loading and function access
+
 (defn load-system-library
   "Loads the library named `libname` from the system's load path."
   [libname]