From 7d33cf62a5d5108425c1bfd1f4ca45bdbaf55f7b Mon Sep 17 00:00:00 2001
From: Gleb Natapov <gleb@cloudius-systems.com>
Date: Thu, 2 Jul 2015 16:43:37 +0300
Subject: [PATCH] Add is_smart_ptr metafunction to detect know smart pointers
 objects

---
 core/sharded.hh      |  4 ++++
 core/shared_ptr.hh   |  7 +++++++
 util/is_smart_ptr.hh | 30 ++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+)
 create mode 100644 util/is_smart_ptr.hh

diff --git a/core/sharded.hh b/core/sharded.hh
index 89f85e7b4..d30bea043 100644
--- a/core/sharded.hh
+++ b/core/sharded.hh
@@ -23,6 +23,7 @@
 
 #include "reactor.hh"
 #include "future-util.hh"
+#include "util/is_smart_ptr.hh"
 
 namespace seastar {
 
@@ -415,5 +416,8 @@ foreign_ptr<T> make_foreign(T ptr) {
     return foreign_ptr<T>(std::move(ptr));
 }
 
+template<typename T>
+struct is_smart_ptr<::foreign_ptr<T>> : std::true_type {};
+
 /// @}
 
diff --git a/core/shared_ptr.hh b/core/shared_ptr.hh
index 56219a07e..49c5e0901 100644
--- a/core/shared_ptr.hh
+++ b/core/shared_ptr.hh
@@ -27,6 +27,7 @@
 #include <type_traits>
 #include <functional>
 #include <iostream>
+#include "util/is_smart_ptr.hh"
 
 // This header defines two shared pointer facilities, lw_shared_ptr<> and
 // shared_ptr<>, both modeled after std::shared_ptr<>.
@@ -719,4 +720,10 @@ struct hash<::shared_ptr<T>> : private hash<T*> {
 
 }
 
+template<typename T>
+struct is_smart_ptr<::shared_ptr<T>> : std::true_type {};
+
+template<typename T>
+struct is_smart_ptr<::lw_shared_ptr<T>> : std::true_type {};
+
 #endif /* SHARED_PTR_HH_ */
diff --git a/util/is_smart_ptr.hh b/util/is_smart_ptr.hh
new file mode 100644
index 000000000..9a45bc157
--- /dev/null
+++ b/util/is_smart_ptr.hh
@@ -0,0 +1,30 @@
+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  You may not use this file except in compliance with the License.
+ *
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*
+ * Copyright (C) 2015 Cloudius Systems, Ltd.
+ */
+
+#pragma once
+
+#include <memory> // for std::unique_ptr
+
+template<typename T>
+struct is_smart_ptr : std::false_type {};
+
+template<typename T>
+struct is_smart_ptr<std::unique_ptr<T>> : std::true_type {};