From 75e27a14b017c3778a423bd26f2f876f5cca2a78 Mon Sep 17 00:00:00 2001
From: q66 <daniel@octaforge.org>
Date: Mon, 2 May 2016 18:21:54 +0100
Subject: [PATCH] overload rvalue refs to const for tuple

---
 ostd/array.hh          |  7 ++++++-
 ostd/internal/tuple.hh |  9 +++++++++
 ostd/range.hh          |  4 ++--
 ostd/tuple.hh          | 11 ++++++++++-
 ostd/utility.hh        | 13 +++++++++++++
 5 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/ostd/array.hh b/ostd/array.hh
index 87da0e6..74eb61a 100644
--- a/ostd/array.hh
+++ b/ostd/array.hh
@@ -96,7 +96,12 @@ const TupleElement<I, Array<T, N>> &get(const Array<T, N> &a) {
 
 template<Size I, typename T, Size N>
 TupleElement<I, Array<T, N>> &&get(Array<T, N> &&a) {
-    return a[I];
+    return move(a.p_buf[I]);
+}
+
+template<Size I, typename T, Size N>
+const TupleElement<I, Array<T, N>> &&get(const Array<T, N> &&a) {
+    return move(a.p_buf[I]);
 }
 
 template<typename T, Size N>
diff --git a/ostd/internal/tuple.hh b/ostd/internal/tuple.hh
index eafe244..4e8143b 100644
--- a/ostd/internal/tuple.hh
+++ b/ostd/internal/tuple.hh
@@ -64,6 +64,9 @@ const TupleElement<I, Tuple<A...>> &get(const Tuple<A...> &);
 template<Size I, typename ...A>
 TupleElement<I, Tuple<A...>> &&get(Tuple<A...> &&);
 
+template<Size I, typename ...A>
+const TupleElement<I, Tuple<A...>> &&get(const Tuple<A...> &&);
+
 /* pair specializations */
 
 template<typename T, typename U> constexpr bool IsTupleLike<Pair<T, U>> = true;
@@ -77,6 +80,9 @@ const TupleElement<I, Pair<T, U>> &get(const Pair<T, U> &);
 template<Size I, typename T, typename U>
 TupleElement<I, Pair<T, U>> &&get(Pair<T, U> &&);
 
+template<Size I, typename T, typename U>
+const TupleElement<I, Pair<T, U>> &&get(const Pair<T, U> &&);
+
 /* array specializations */
 
 template<typename T, Size I> constexpr bool IsTupleLike<Array<T, I>> = true;
@@ -90,6 +96,9 @@ const T &get(const Array<T, S> &);
 template<Size I, typename T, Size S>
 T &&get(Array<T, S> &&);
 
+template<Size I, typename T, Size S>
+const T &&get(const Array<T, S> &&);
+
 /* make tuple indices */
 
 namespace detail {
diff --git a/ostd/range.hh b/ostd/range.hh
index 7351b32..09a3af6 100644
--- a/ostd/range.hh
+++ b/ostd/range.hh
@@ -609,12 +609,12 @@ inline auto chunks(T n) {
 namespace detail {
     template<typename T, typename ...R, Size ...I>
     inline auto join_proxy(T &&obj, Tuple<R &&...> &&tup, TupleIndices<I...>) {
-        return obj.join(forward<R>(get<I>(tup))...);
+        return obj.join(forward<R>(get<I>(forward<Tuple<R &&...>>(tup)))...);
     }
 
     template<typename T, typename ...R, Size ...I>
     inline auto zip_proxy(T &&obj, Tuple<R &&...> &&tup, TupleIndices<I...>) {
-        return obj.zip(forward<R>(get<I>(tup))...);
+        return obj.zip(forward<R>(get<I>(forward<Tuple<R &&...>>(tup)))...);
     }
 }
 
diff --git a/ostd/tuple.hh b/ostd/tuple.hh
index 25d32fa..1146946 100644
--- a/ostd/tuple.hh
+++ b/ostd/tuple.hh
@@ -277,6 +277,9 @@ class Tuple {
     template<Size I, typename ...T>
     friend TupleElement<I, Tuple<T...>> &&get(Tuple<T...> &&);
 
+    template<Size I, typename ...T>
+    friend const TupleElement<I, Tuple<T...>> &&get(const Tuple<T...> &&);
+
 public:
     template<bool D = true, typename = EnableIf<
         detail::TupleAll<(D && IsDefaultConstructible<A>)...>
@@ -421,7 +424,13 @@ inline const TupleElement<I, Tuple<A...>> &get(const Tuple<A...> &t) {
 template<Size I, typename ...A>
 inline TupleElement<I, Tuple<A...>> &&get(Tuple<A...> &&t) {
     using Type = TupleElement<I, Tuple<A...>>;
-    return ((detail::TupleLeaf<I, Type> &&)t.p_base).get();
+    return (Type &&)(((detail::TupleLeaf<I, Type> &&)t.p_base).get());
+}
+
+template<Size I, typename ...A>
+inline const TupleElement<I, Tuple<A...>> &&get(const Tuple<A...> &&t) {
+    using Type = TupleElement<I, Tuple<A...>>;
+    return (const Type &&)(((const detail::TupleLeaf<I, Type> &&)t.p_base).get());
 }
 
 /* tie */
diff --git a/ostd/utility.hh b/ostd/utility.hh
index b44b37b..65481d6 100644
--- a/ostd/utility.hh
+++ b/ostd/utility.hh
@@ -231,6 +231,10 @@ namespace detail {
         static const T &get(const Pair<T, U> &p) { return p.first; }
         template<typename T, typename U>
         static T &&get(Pair<T, U> &&p) { return forward<T>(p.first); }
+        template<typename T, typename U>
+        static const T &&get(const Pair<T, U> &&p) {
+            return forward<const T>(p.first);
+        }
     };
 
     template<> struct GetPair<1> {
@@ -240,6 +244,10 @@ namespace detail {
         static const U &get(const Pair<T, U> &p) { return p.second; }
         template<typename T, typename U>
         static U &&get(Pair<T, U> &&p) { return forward<U>(p.second); }
+        template<typename T, typename U>
+        static const T &&get(const Pair<T, U> &&p) {
+            return forward<const T>(p.second);
+        }
     };
 }
 
@@ -258,6 +266,11 @@ TupleElement<I, Pair<T, U>> &&get(Pair<T, U> &&p) {
     return detail::GetPair<I>::get(move(p));
 }
 
+template<Size I, typename T, typename U>
+const TupleElement<I, Pair<T, U>> &&get(const Pair<T, U> &&p) {
+    return detail::GetPair<I>::get(move(p));
+}
+
 namespace detail {
     template<typename T, typename U,
         bool = IsSame<RemoveCv<T>, RemoveCv<U>>,