From e9367246b57652c3a879822b9917873dde46b26c Mon Sep 17 00:00:00 2001
From: q66 <daniel@octaforge.org>
Date: Tue, 26 May 2015 21:28:12 +0100
Subject: [PATCH] completely genericized octa::swap (no need for global
 overloads ever)

---
 octa/array.h      |  5 -----
 octa/functional.h |  5 -----
 octa/utility.h    | 27 +++++++++++++++++++++------
 octa/vector.h     |  5 -----
 4 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/octa/array.h b/octa/array.h
index 7931b3f..1620f5f 100644
--- a/octa/array.h
+++ b/octa/array.h
@@ -62,11 +62,6 @@ namespace octa {
 
         T p_buf[(N > 0) ? N : 1];
     };
-
-    template<typename T, size_t N>
-    void swap(Array<T, N> &a, Array<T, N> &b) {
-        a.swap(b);
-    }
 }
 
 #endif
\ No newline at end of file
diff --git a/octa/functional.h b/octa/functional.h
index d0dd6ef..67ae35d 100644
--- a/octa/functional.h
+++ b/octa/functional.h
@@ -617,11 +617,6 @@ namespace octa {
         }
     };
 
-    template<typename T>
-    void swap(Function<T> &a, Function<T> &b) {
-        a.swap(b);
-    }
-
     template<typename T>
     bool operator==(nullptr_t, const Function<T> &rhs) { return !rhs; }
 
diff --git a/octa/utility.h b/octa/utility.h
index de78ecb..dfcaaaa 100644
--- a/octa/utility.h
+++ b/octa/utility.h
@@ -36,12 +36,32 @@ namespace octa {
 
     /* swap */
 
-    template<typename T> void swap(T &a, T &b) {
+    template<typename T>
+    struct __OctaSwapTest {
+        template<typename U, void (U::*)(U &)> struct __OctaTest {};
+        template<typename U> static char __octa_test(__OctaTest<U, &U::swap> *);
+        template<typename U> static  int __octa_test(...);
+        static constexpr bool value = (sizeof(__octa_test<T>(0)) == sizeof(char));
+    };
+
+    template<typename T> inline void __octa_swap(T &a, T &b, EnableIf<
+        __OctaSwapTest<T>::value, bool
+    > = true) {
+        a.swap(b);
+    }
+
+    template<typename T> inline void __octa_swap(T &a, T &b, EnableIf<
+        !__OctaSwapTest<T>::value, bool
+    > = true) {
         T c(move(a));
         a = move(b);
         b = move(c);
     }
 
+    template<typename T> void swap(T &a, T &b) {
+        __octa_swap(a, b);
+    }
+
     template<typename T, size_t N> void swap(T (&a)[N], T (&b)[N]) {
         for (size_t i = 0; i < N; ++i) {
             swap(a[i], b[i]);
@@ -103,11 +123,6 @@ namespace octa {
             octa::swap(second, v.second);
         }
     };
-
-    template<typename T, typename U>
-    void swap(Pair<T, U> &a, Pair<T, U> &b) {
-        a.swap(b);
-    }
 }
 
 #endif
\ No newline at end of file
diff --git a/octa/vector.h b/octa/vector.h
index 300e468..aa62aac 100644
--- a/octa/vector.h
+++ b/octa/vector.h
@@ -311,11 +311,6 @@ namespace octa {
             octa::swap(p_buf, v.p_buf);
         }
     };
-
-    template<typename T>
-    void swap(Vector<T> &a, Vector<T> &b) {
-        a.swap(b);
-    }
 }
 
 #endif
\ No newline at end of file