Implementation of swap() added. As the specification of the

noexcept-value is missing in the document it is implemented as for
std::swap(). Fixes #73.

include/unique_resource.h

@@ -37,6 +37,12 @@ namespace sr
     constexpr auto is_nothrow_move_or_copy_constructible_from_v = is_ntmocp_constructible<T, TT>::value;
 
 
+    template<class T>
+    constexpr auto is_nothrow_swappable_v = std::is_nothrow_move_constructible<T>::value
+                                            && std::is_nothrow_move_assignable<T>::value;
+
+
+
     template<class T, class U = std::conditional_t<std::is_nothrow_move_constructible<T>::value, T&&, const T&>>
     constexpr U forward_if_nothrow_move_constructible(T&& value) noexcept
     {
@@ -162,6 +168,16 @@ namespace sr
         }
 
 
+        void swap(unique_resource& other) noexcept(is_nothrow_swappable_v<R>
+                                                    && is_nothrow_swappable_v<D>
+                                                    && is_nothrow_swappable_v<bool>)
+        {
+            using std::swap;
+            swap(m_resource.get(), other.m_resource.get());
+            swap(m_deleter.get(), other.m_deleter.get());
+            swap(m_execute_on_destruction, other.m_execute_on_destruction);
+        }
+
         void reset()
         {
             if( m_execute_on_destruction == true )

test/UniqueResourceTest.cpp

@@ -283,6 +283,20 @@ TEST_CASE("deleter access", "[UniqueResource]")
     }
 }
 
+TEST_CASE("swap", "[UniqueResource]")
+{
+    REQUIRE_CALL(m, deleter(7));
+    auto guard1 = sr::make_unique_resource(Handle{3}, deleter);
+
+    {
+        REQUIRE_CALL(m, deleter(3));
+        auto guard2 = sr::make_unique_resource(Handle{7}, deleter);
+        guard2.swap(guard1);
+        REQUIRE(guard1.get() == 7);
+        REQUIRE(guard2.get() == 3);
+    }
+}
+
 TEST_CASE("make unique resource", "[UniqueResource]")
 {
     REQUIRE_CALL(m, deleter(7));