2 files changed, 69 insertions, 59 deletions
diff --git a/src/libutil/ref.hh b/src/libutil/ref.hh
new file mode 100644
index 000000000000..a6d338d79622
--- /dev/null
+++ b/src/libutil/ref.hh
@@ -0,0 +1,67 @@
+#pragma once
+
+#include <memory>
+#include <exception>
+
+namespace nix {
+
+/* A simple non-nullable reference-counted pointer. Actually a wrapper
+   around std::shared_ptr that prevents non-null constructions. */
+template<typename T>
+class ref
+{
+private:
+
+    std::shared_ptr<T> p;
+
+public:
+
+    ref<T>(const ref<T> & r)
+        : p(r.p)
+    { }
+
+    explicit ref<T>(const std::shared_ptr<T> & p)
+        : p(p)
+    {
+        if (!p)
+            throw std::invalid_argument("null pointer cast to ref");
+    }
+
+    T* operator ->() const
+    {
+        return &*p;
+    }
+
+    T& operator *() const
+    {
+        return *p;
+    }
+
+    operator std::shared_ptr<T> ()
+    {
+        return p;
+    }
+
+    template<typename T2>
+    operator ref<T2> ()
+    {
+        return ref<T2>((std::shared_ptr<T2>) p);
+    }
+
+private:
+
+    template<typename T2, typename... Args>
+    friend ref<T2>
+    make_ref(Args&&... args);
+
+};
+
+template<typename T, typename... Args>
+inline ref<T>
+make_ref(Args&&... args)
+{
+    auto p = std::make_shared<T>(std::forward<Args>(args)...);
+    return ref<T>(p);
+}
+
+}
diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index 0eae46c5fe93..33aaf5fc9c4d 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -2,6 +2,8 @@
 
 #include "config.h"
 
+#include "ref.hh"
+
 #include <string>
 #include <list>
 #include <set>
@@ -97,63 +99,4 @@ typedef enum {
 } Verbosity;
 
 
-/* A simple non-nullable reference-counted pointer. Actually a wrapper
-   around std::shared_ptr that prevents non-null constructions. */
-template<typename T>
-class ref
-{
-private:
-
-    std::shared_ptr<T> p;
-
-public:
-
-    ref<T>(const ref<T> & r)
-        : p(r.p)
-    { }
-
-    explicit ref<T>(const std::shared_ptr<T> & p)
-        : p(p)
-    {
-        if (!p)
-            throw std::invalid_argument("null pointer cast to ref");
-    }
-
-    T* operator ->() const
-    {
-        return &*p;
-    }
-
-    T& operator *() const
-    {
-        return *p;
-    }
-
-    operator std::shared_ptr<T> ()
-    {
-        return p;
-    }
-
-    template<typename T2>
-    operator ref<T2> ()
-    {
-        return ref<T2>((std::shared_ptr<T2>) p);
-    }
-
-private:
-
-    template<typename T2, typename... Args>
-    friend ref<T2>
-    make_ref(Args&&... args);
-
-};
-
-template<typename T, typename... Args>
-inline ref<T>
-make_ref(Args&&... args)
-{
-    auto p = std::make_shared<T>(std::forward<Args>(args)...);
-    return ref<T>(p);
-}
-
 }