From 0e1493ec5e125adfb7531b2a05c26bff26325cb2 Mon Sep 17 00:00:00 2001
From: Howard Hinnant <hhinnant@apple.com>
Date: Sat, 11 Dec 2010 20:47:50 +0000
Subject: [PATCH] LWG 1385 [FCD] tuple_cat should be a single variadic
 signature (http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#1385).
  This issue is only in Ready status, meaning it is not official, but probably
 will be this March in Madrid.  It was tentatively accepted in Batavia with
 the previso that Bill and I didn't have any problems implementing it.  This
 is my part of that agreement.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@121619 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/__tuple                               |   7 +-
 include/tuple                                 | 136 +++++++++++-------
 .../tuple.creation/tuple_cat.pass.cpp         | 105 ++++++++++++--
 3 files changed, 176 insertions(+), 72 deletions(-)

diff --git a/include/__tuple b/include/__tuple
index 72e36fbb..9fc54d47 100644
--- a/include/__tuple
+++ b/include/__tuple
@@ -68,12 +68,13 @@ template <class _Tp, size_t _Size> struct _LIBCPP_VISIBLE array;
 
 template <class _Tp> struct __tuple_like : false_type {};
 
+template <class _Tp> struct __tuple_like<const _Tp> : public __tuple_like<_Tp> {};
+template <class _Tp> struct __tuple_like<volatile _Tp> : public __tuple_like<_Tp> {};
+template <class _Tp> struct __tuple_like<const volatile _Tp> : public __tuple_like<_Tp> {};
+
 template <class... _Tp> struct __tuple_like<tuple<_Tp...>> : true_type {};
-template <class... _Tp> struct __tuple_like<const tuple<_Tp...>> : true_type {};
 template <class _T1, class _T2> struct __tuple_like<pair<_T1, _T2> > : true_type {};
-template <class _T1, class _T2> struct __tuple_like<const pair<_T1, _T2> > : true_type {};
 template <class _Tp, size_t _Size> struct __tuple_like<array<_Tp, _Size> > : true_type {};
-template <class _Tp, size_t _Size> struct __tuple_like<const array<_Tp, _Size> > : true_type {};
 
 template <size_t _Ip, class ..._Tp>
 typename tuple_element<_Ip, tuple<_Tp...>>::type&
diff --git a/include/tuple b/include/tuple
index 27c16ed5..97d21139 100644
--- a/include/tuple
+++ b/include/tuple
@@ -74,11 +74,8 @@ const unspecified ignore;
 template <class... T> tuple<V...>  make_tuple(T&&...);
 template <class... T> tuple<ATypes...> forward_as_tuple(T&&...);
 template <class... T> tuple<T&...> tie(T&...);
-template <class... T, class... U> tuple<T..., U...> tuple_cat(const tuple<T...>&, const tuple<U...>&);
-template <class... T, class... U> tuple<T..., U...> tuple_cat(tuple<T...>&&, const tuple<U...>&);
-template <class... T, class... U> tuple<T..., U...> tuple_cat(const tuple<T...>&, tuple<U...>&&);
-template <class... T, class... U> tuple<T..., U...> tuple_cat(tuple<T...>&&, tuple<U...>&&);
-
+template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls);
+  
 // 20.4.1.4, tuple helper classes:
 template <class T> class tuple_size; // undefined
 template <class... T> class tuple_size<tuple<T...>>;
@@ -751,72 +748,103 @@ operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 
 // tuple_cat
 
-template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
-inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-__tuple_cat(const tuple<_Tp...>& __x, __tuple_indices<_I1...>, const tuple<_Up...>& __y, __tuple_indices<_I2...>)
+template <class _Tp, class _Up> struct __tuple_cat_type;
+
+template <class ..._Ttypes, class ..._Utypes>
+struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...>>
 {
-    return tuple<_Tp..., _Up...>(get<_I1>(__x)..., get<_I2>(__y)...);
+    typedef tuple<_Ttypes..., _Utypes...> type;
+};
+
+template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
+struct __tuple_cat_return_1
+{
+};
+
+template <class ..._Types, class _Tuple0>
+struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
+{
+    typedef typename __tuple_cat_type<tuple<_Types...>,
+            typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type>::type
+                                                                           type;
+};
+
+template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
+struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
+    : public __tuple_cat_return_1<
+                 typename __tuple_cat_type<
+                     tuple<_Types...>,
+                     typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type
+                 >::type,
+                 __tuple_like<typename remove_reference<_Tuple1>::type>::value,
+                 _Tuple1, _Tuples...>
+{
+};
+
+template <class ..._Tuples> struct __tuple_cat_return;
+
+template <class _Tuple0, class ..._Tuples>
+struct __tuple_cat_return<_Tuple0, _Tuples...>
+    : public __tuple_cat_return_1<tuple<>,
+         __tuple_like<typename remove_reference<_Tuple0>::type>::value, _Tuple0,
+                                                                     _Tuples...>
+{
+};
+
+template <>
+struct __tuple_cat_return<>
+{
+    typedef tuple<> type;
+};
+
+inline _LIBCPP_INLINE_VISIBILITY
+tuple<>
+tuple_cat()
+{
+    return tuple<>();
 }
 
-template <class... _Tp, class... _Up>
+template <class _Tuple>
 inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-tuple_cat(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+typename __tuple_cat_return<_Tuple>::type
+tuple_cat(_Tuple&& __tpl)
 {
-    return __tuple_cat(__x, typename __make_tuple_indices<sizeof...(_Tp)>::type(),
-                       __y, typename __make_tuple_indices<sizeof...(_Up)>::type());
+    typedef typename __tuple_cat_return<_Tuple>::type _R;
+    return _R(_STD::forward<_Tuple>(__tpl));
 }
 
-template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
+template <class _Tuple0, size_t ..._I0, class _Tuple1, size_t ..._I1>
 inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-__tuple_cat(tuple<_Tp...>&& __x, __tuple_indices<_I1...>, const tuple<_Up...>& __y, __tuple_indices<_I2...>)
+typename __tuple_cat_return<_Tuple0, _Tuple1>::type
+__tuple_cat(_Tuple0&& __t0, __tuple_indices<_I0...>,
+            _Tuple1&& __t1, __tuple_indices<_I1...>)
 {
-    return tuple<_Tp..., _Up...>(_STD::forward<_Tp>(get<_I1>(__x))..., get<_I2>(__y)...);
+    typedef typename __tuple_cat_return<_Tuple0, _Tuple1>::type _R;
+    return _R(get<_I0>(_STD::forward<_Tuple0>(__t0))...,
+              get<_I1>(_STD::forward<_Tuple1>(__t1))...);
 }
 
-template <class... _Tp, class... _Up>
+template <class _Tuple0, class _Tuple1>
 inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-tuple_cat(tuple<_Tp...>&& __x, const tuple<_Up...>& __y)
+typename __tuple_cat_return<_Tuple0, _Tuple1>::type
+tuple_cat(_Tuple0&& __t0, _Tuple1&& __t1)
 {
-    return __tuple_cat(_STD::move(__x), typename __make_tuple_indices<sizeof...(_Tp)>::type(),
-                       __y, typename __make_tuple_indices<sizeof...(_Up)>::type());
+    typedef typename remove_reference<_Tuple0>::type _T0;
+    typedef typename remove_reference<_Tuple1>::type _T1;
+    return __tuple_cat(_STD::forward<_Tuple0>(__t0),
+                       typename __make_tuple_indices<tuple_size<_T0>::value>::type(),
+                       _STD::forward<_Tuple1>(__t1),
+                       typename __make_tuple_indices<tuple_size<_T1>::value>::type());
 }
 
-template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
+template <class _Tuple0, class _Tuple1, class... _Tuples>
 inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-__tuple_cat(const tuple<_Tp...>& __x, __tuple_indices<_I1...>, tuple<_Up...>&& __y, __tuple_indices<_I2...>)
+typename __tuple_cat_return<_Tuple0, _Tuple1, _Tuples...>::type
+tuple_cat(_Tuple0&& __t0, _Tuple1&& __t1, _Tuples&&... __tpls)
 {
-    return tuple<_Tp..., _Up...>(get<_I1>(__x)..., _STD::forward<_Up>(get<_I2>(__y))...);
-}
-
-template <class... _Tp, class... _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-tuple_cat(const tuple<_Tp...>& __x, tuple<_Up...>&& __y)
-{
-    return __tuple_cat(__x, typename __make_tuple_indices<sizeof...(_Tp)>::type(),
-                       _STD::move(__y), typename __make_tuple_indices<sizeof...(_Up)>::type());
-}
-
-template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
-inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-__tuple_cat(tuple<_Tp...>&& __x, __tuple_indices<_I1...>, tuple<_Up...>&& __y, __tuple_indices<_I2...>)
-{
-    return tuple<_Tp..., _Up...>(_STD::forward<_Tp>(get<_I1>(__x))..., _STD::forward<_Up>(get<_I2>(__y))...);
-}
-
-template <class... _Tp, class... _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp..., _Up...>
-tuple_cat(tuple<_Tp...>&& __x, tuple<_Up...>&& __y)
-{
-    return __tuple_cat(_STD::move(__x), typename __make_tuple_indices<sizeof...(_Tp)>::type(),
-                       _STD::move(__y), typename __make_tuple_indices<sizeof...(_Up)>::type());
+    return tuple_cat(tuple_cat(_STD::forward<_Tuple0>(__t0),
+                               _STD::forward<_Tuple1>(__t1)),
+                               _STD::forward<_Tuples>(__tpls)...);
 }
 
 template <class ..._Tp, class _Alloc>
diff --git a/test/utilities/tuple/tuple.tuple/tuple.creation/tuple_cat.pass.cpp b/test/utilities/tuple/tuple.tuple/tuple.creation/tuple_cat.pass.cpp
index 7a84c78a..7cfc736f 100644
--- a/test/utilities/tuple/tuple.tuple/tuple.creation/tuple_cat.pass.cpp
+++ b/test/utilities/tuple/tuple.tuple/tuple.creation/tuple_cat.pass.cpp
@@ -11,23 +11,11 @@
 
 // template <class... Types> class tuple;
 
-// template <class... TTypes, class... UTypes>
-//   tuple<TTypes..., UTypes...>
-//   tuple_cat(const tuple<TTypes...>& t, const tuple<UTypes...>& u);
-//
-// template <class... TTypes, class... UTypes>
-//   tuple<TTypes..., UTypes...>
-//   tuple_cat(const tuple<TTypes...>&& t, const tuple<UTypes...>& u);
-//
-// template <class... TTypes, class... UTypes>
-//   tuple<TTypes..., UTypes...>
-//   tuple_cat(const tuple<TTypes...>& t, const tuple<UTypes...>&& u);
-//
-// template <class... TTypes, class... UTypes>
-//   tuple<TTypes..., UTypes...>
-//   tuple_cat(const tuple<TTypes...>&& t, const tuple<UTypes...>&& u);
+// template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls);
 
 #include <tuple>
+#include <utility>
+#include <array>
 #include <string>
 #include <cassert>
 
@@ -35,6 +23,43 @@
 
 int main()
 {
+    {
+        std::tuple<> t = std::tuple_cat();
+    }
+    {
+        std::tuple<> t1;
+        std::tuple<> t2 = std::tuple_cat(t1);
+    }
+    {
+        std::tuple<> t = std::tuple_cat(std::tuple<>());
+    }
+    {
+        std::tuple<> t = std::tuple_cat(std::array<int, 0>());
+    }
+
+    {
+        std::tuple<int> t1(1);
+        std::tuple<int> t = std::tuple_cat(t1);
+        assert(std::get<0>(t) == 1);
+    }
+    {
+        std::tuple<int, MoveOnly> t =
+                                std::tuple_cat(std::tuple<int, MoveOnly>(1, 2));
+        assert(std::get<0>(t) == 1);
+        assert(std::get<1>(t) == 2);
+    }
+    {
+        std::tuple<int, int, int> t = std::tuple_cat(std::array<int, 3>());
+        assert(std::get<0>(t) == 0);
+        assert(std::get<1>(t) == 0);
+        assert(std::get<2>(t) == 0);
+    }
+    {
+        std::tuple<int, MoveOnly> t = std::tuple_cat(std::pair<int, MoveOnly>(2, 1));
+        assert(std::get<0>(t) == 2);
+        assert(std::get<1>(t) == 1);
+    }
+
     {
         std::tuple<> t1;
         std::tuple<> t2;
@@ -112,4 +137,54 @@ int main()
         assert(std::get<2>(t3) == nullptr);
         assert(std::get<3>(t3) == 4);
     }
+
+    {
+        std::tuple<MoveOnly, MoveOnly> t1(1, 2);
+        std::tuple<int*, MoveOnly> t2(nullptr, 4);
+        std::tuple<MoveOnly, MoveOnly, int*, MoveOnly> t3 =
+                                   std::tuple_cat(std::tuple<>(),
+                                                  std::move(t1),
+                                                  std::move(t2));
+        assert(std::get<0>(t3) == 1);
+        assert(std::get<1>(t3) == 2);
+        assert(std::get<2>(t3) == nullptr);
+        assert(std::get<3>(t3) == 4);
+    }
+    {
+        std::tuple<MoveOnly, MoveOnly> t1(1, 2);
+        std::tuple<int*, MoveOnly> t2(nullptr, 4);
+        std::tuple<MoveOnly, MoveOnly, int*, MoveOnly> t3 =
+                                   std::tuple_cat(std::move(t1),
+                                                  std::tuple<>(),
+                                                  std::move(t2));
+        assert(std::get<0>(t3) == 1);
+        assert(std::get<1>(t3) == 2);
+        assert(std::get<2>(t3) == nullptr);
+        assert(std::get<3>(t3) == 4);
+    }
+    {
+        std::tuple<MoveOnly, MoveOnly> t1(1, 2);
+        std::tuple<int*, MoveOnly> t2(nullptr, 4);
+        std::tuple<MoveOnly, MoveOnly, int*, MoveOnly> t3 =
+                                   std::tuple_cat(std::move(t1),
+                                                  std::move(t2),
+                                                  std::tuple<>());
+        assert(std::get<0>(t3) == 1);
+        assert(std::get<1>(t3) == 2);
+        assert(std::get<2>(t3) == nullptr);
+        assert(std::get<3>(t3) == 4);
+    }
+    {
+        std::tuple<MoveOnly, MoveOnly> t1(1, 2);
+        std::tuple<int*, MoveOnly> t2(nullptr, 4);
+        std::tuple<MoveOnly, MoveOnly, int*, MoveOnly, int> t3 =
+                                   std::tuple_cat(std::move(t1),
+                                                  std::move(t2),
+                                                  std::tuple<int>(5));
+        assert(std::get<0>(t3) == 1);
+        assert(std::get<1>(t3) == 2);
+        assert(std::get<2>(t3) == nullptr);
+        assert(std::get<3>(t3) == 4);
+        assert(std::get<4>(t3) == 5);
+    }
 }