1 files changed, 68 insertions, 0 deletions
diff --git a/source/core/slang-com-object.h b/source/core/slang-com-object.h
index 50dac5ba2..617b7ccca 100644
--- a/source/core/slang-com-object.h
+++ b/source/core/slang-com-object.h
@@ -6,6 +6,74 @@
 
 namespace Slang
 {
+
+/// A base class for COM interfaces that require atomic ref counting 
+/// and are *NOT* derived from RefObject
+class ComBaseObject
+{
+public:
+    
+        /// If assigned the the ref count is *NOT* copied
+    ComBaseObject& operator=(const ComBaseObject&) { return *this; }
+
+        /// Copy Ctor, does not copy ref count
+    ComBaseObject(const ComBaseObject&) :
+        m_refCount(0)
+    {}
+
+        /// Default Ctor sets with no refs
+    ComBaseObject()
+        : m_refCount(0)
+    {}
+
+        /// Dtor needs to be virtual to avoid needing to 
+        /// Implement release for all derived types.
+    virtual ~ComBaseObject()
+    {}
+
+protected:
+    inline uint32_t _releaseImpl();
+
+    std::atomic<uint32_t> m_refCount;
+};
+
+// ------------------------------------------------------------------
+inline uint32_t ComBaseObject::_releaseImpl()
+{
+    // Check there is a ref count to avoid underflow
+    SLANG_ASSERT(m_refCount != 0);
+    const uint32_t count = --m_refCount;
+    if (count == 0)
+    {
+        delete this;
+    }
+    return count;
+}
+
+#define SLANG_COM_BASE_IUNKNOWN_QUERY_INTERFACE                                                  \
+    SLANG_NO_THROW SlangResult SLANG_MCALL queryInterface(SlangUUID const& uuid, void** outObject) \
+        SLANG_OVERRIDE                                                                             \
+    {                                                                                              \
+        void* intf = getInterface(uuid);                                                           \
+        if (intf)                                                                                  \
+        {                                                                                          \
+            ++m_refCount;                                                                          \
+            *outObject = intf;                                                                     \
+            return SLANG_OK;                                                                       \
+        }                                                                                          \
+        return SLANG_E_NO_INTERFACE;                                                               \
+    }
+#define SLANG_COM_BASE_IUNKNOWN_ADD_REF \
+    SLANG_NO_THROW uint32_t SLANG_MCALL addRef() SLANG_OVERRIDE { return ++m_refCount; }
+#define SLANG_COM_BASE_IUNKNOWN_RELEASE \
+    SLANG_NO_THROW uint32_t SLANG_MCALL release() SLANG_OVERRIDE { return _releaseImpl(); }
+#define SLANG_COM_BASE_IUNKNOWN_ALL         \
+    SLANG_COM_BASE_IUNKNOWN_QUERY_INTERFACE \
+    SLANG_COM_BASE_IUNKNOWN_ADD_REF         \
+    SLANG_COM_BASE_IUNKNOWN_RELEASE
+
+
+/// COM object that derives from RefObject
 class ComObject : public RefObject
 {
 protected: