From 30ad985b6b427da2459e7231190774fffbb81f3c Mon Sep 17 00:00:00 2001
From: Howard Hinnant <hhinnant@apple.com>
Date: Mon, 27 Sep 2010 17:54:17 +0000
Subject: Cleaning up some tuple code.

llvm-svn: 114848
---
 libcxx/include/__tuple | 52 +++++++++++++++++++++-----------------------------
 1 file changed, 22 insertions(+), 30 deletions(-)

(limited to 'libcxx/include/__tuple')

diff --git a/libcxx/include/__tuple b/libcxx/include/__tuple
index 7fa74148fd3..e10f8d78b57 100644
--- a/libcxx/include/__tuple
+++ b/libcxx/include/__tuple
@@ -127,6 +127,11 @@ template <class... _Tp> struct __tuple_like<__tuple_types<_Tp...>> : true_type {
 
 // __make_tuple_types
 
+// __make_tuple_types<_Tuple<_Types...>, _Ep, _Sp>::type is a
+// __tuple_types<_Types...> using only those _Types in the range [_Sp, _Ep).
+// _Sp defaults to 0 and _Ep defaults to tuple_size<_Tuple>.  If _Tuple is a
+// lvalue_reference type, then __tuple_types<_Types&...> is the result.
+
 template <class _TupleTypes, class _Tp, size_t _Sp, size_t _Ep>
 struct __make_tuple_types_imp;
 
@@ -135,7 +140,7 @@ struct __make_tuple_types_imp<__tuple_types<_Types...>, _Tp, _Sp, _Ep>
 {
     typedef typename remove_reference<_Tp>::type _Tpr;
     typedef typename __make_tuple_types_imp<__tuple_types<_Types...,
-                                            typename conditional<is_reference<_Tp>::value,
+                                            typename conditional<is_lvalue_reference<_Tp>::value,
                                                 typename tuple_element<_Sp, _Tpr>::type&,
                                                 typename tuple_element<_Sp, _Tpr>::type>::type>,
                                             _Tp, _Sp+1, _Ep>::type type;
@@ -154,32 +159,6 @@ struct __make_tuple_types
     typedef typename __make_tuple_types_imp<__tuple_types<>, _Tp, _Sp, _Ep>::type type;
 };
 
-// __make_assignable_types
-
-template <class _Tuple, class _Tp, size_t _Sp, size_t _Ep>
-struct __make_assignable_types_imp;
-
-template <class ..._Types, class _Tp, size_t _Sp, size_t _Ep>
-struct __make_assignable_types_imp<__tuple_types<_Types...>, _Tp, _Sp, _Ep>
-{
-    typedef typename __make_assignable_types_imp<__tuple_types<_Types...,
-                                      typename remove_reference<typename tuple_element<_Sp, _Tp>::type>::type>,
-                                      _Tp, _Sp+1, _Ep>::type type;
-};
-
-template <class ..._Types, class _Tp, size_t _Ep>
-struct __make_assignable_types_imp<__tuple_types<_Types...>, _Tp, _Ep, _Ep>
-{
-    typedef __tuple_types<_Types...> type;
-};
-
-template <class _Tp, size_t _Ep = tuple_size<typename remove_reference<_Tp>::type>::value, size_t _Sp = 0>
-struct __make_assignable_types
-{
-    static_assert(_Sp <= _Ep, "__make_assignable_types input error");
-    typedef typename __make_assignable_types_imp<__tuple_types<>, typename remove_reference<_Tp>::type, _Sp, _Ep>::type type;
-};
-
 // __tuple_convertible
 
 template <bool, class _Tp, class _Up>
@@ -209,6 +188,19 @@ struct __tuple_convertible<_Tp, _Up, true, true>
 
 // __tuple_assignable
 
+template <bool, class _Tp, class _Up>
+struct __tuple_assignable_imp : public false_type {};
+
+template <class _Tp0, class ..._Tp, class _Up0, class ..._Up>
+struct __tuple_assignable_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...>>
+    : public integral_constant<bool,
+                               __is_assignable<_Up0&, _Tp0>::value &&
+                               __tuple_assignable_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...>>::value> {};
+
+template <>
+struct __tuple_assignable_imp<true, __tuple_types<>, __tuple_types<>>
+    : public true_type {};
+
 template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
                                 bool = __tuple_like<_Up>::value>
 struct __tuple_assignable
@@ -216,9 +208,9 @@ struct __tuple_assignable
 
 template <class _Tp, class _Up>
 struct __tuple_assignable<_Tp, _Up, true, true>
-    : public __tuple_convertible_imp<tuple_size<typename remove_reference<_Tp>::type>::value ==
-                                     tuple_size<_Up>::value,
-             typename __make_tuple_types<_Tp>::type, typename __make_assignable_types<_Up>::type>
+    : public __tuple_assignable_imp<tuple_size<typename remove_reference<_Tp>::type>::value ==
+                                    tuple_size<_Up>::value,
+             typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type>
 {};
 
 _LIBCPP_END_NAMESPACE_STD
-- 
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