From 1047f2f245e5afd4dcecd0b09b26168401331a45 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Thu, 30 Nov 2017 23:19:31 +0100
Subject: [PATCH] Library: decide on the overall shape of the type rebinding
 helper

- we do strip references
- we delegate to nested typedefs

Hoever, we do *not* treat const or pointers in any way special --
if the user want to strip or level these, he has to do so explicitly.
Initially it seemed like a good idea to do something clever here, but
on the long run, such "special treatment" is just good for surprises
---
 src/lib/meta/value-type-binding.hpp           | 76 +++++++------------
 .../library/meta/value-type-binding-test.cpp  | 43 +++++++++--
 2 files changed, 63 insertions(+), 56 deletions(-)

diff --git a/src/lib/meta/value-type-binding.hpp b/src/lib/meta/value-type-binding.hpp
index 4e274cd23..353108502 100644
--- a/src/lib/meta/value-type-binding.hpp
+++ b/src/lib/meta/value-type-binding.hpp
@@ -45,10 +45,6 @@
 
 
 
-namespace std {
-  template<typename _Tp>
-  class shared_ptr;
-}
 
 namespace lib {
 namespace meta {
@@ -75,67 +71,51 @@ namespace meta {
       };
   }
   
-  /** 
-   * Type re-binding helper template for creating nested typedefs
-   * for use by IterAdapter or similar "Lumiera Forward Iterators".
-   * This trait provides a value-, reference- and pointer type,
-   * similar to what the STL does.
-   * @note client code might define specialisations
-   *       to handle tricky situations (like const_reverse_iter)
-   */
   template<typename TY, typename SEL =void>
-  struct TypeBinding
+  struct ValueTypeBinding
     {
       typedef TY value_type;
       typedef TY& reference;
       typedef TY* pointer;
     };
   
-  template<typename TY>
-  struct TypeBinding<TY *>
-    {
-      typedef TY value_type;
-      typedef TY& reference;
-      typedef TY* pointer;
-    };
-  
-  template<typename TY>
-  struct TypeBinding<const TY *>
-    {
-      typedef TY value_type;
-      typedef const TY& reference;
-      typedef const TY* pointer;
-    };
-  
-  template<typename TY>
-  struct TypeBinding<TY &>
-    {
-      typedef TY value_type;
-      typedef TY& reference;
-      typedef TY* pointer;
-    };
-  
-  template<typename TY>
-  struct TypeBinding<TY const&>
-    {
-      typedef TY value_type;
-      typedef const TY& reference;
-      typedef const TY* pointer;
-    };
-  
   /**
    * specialisation for classes providing
    * STL style type binding definitions themselves
    */
   template<typename TY>
-  struct TypeBinding<TY,           enable_if<has_nested_ValueTypeBindings<TY>> >
+  struct ValueTypeBinding<TY,      enable_if<has_nested_ValueTypeBindings<TY>> >
     {
-      typedef typename TY::pointer pointer;
-      typedef typename TY::reference reference;
       typedef typename TY::value_type value_type;
+      typedef typename TY::reference reference;
+      typedef typename TY::pointer pointer;
     };
   
   
+  /**
+   * Type re-binding helper template for creating nested typedefs
+   * for use by IterAdapter or similar "Lumiera Forward Iterators".
+   * This trait provides a value-, reference- and pointer type,
+   * similar to what the STL does.
+   * @note client code might define specialisations
+   *       to handle tricky situations (like const_reverse_iter)
+   */
+  template<typename TY>
+  struct TypeBinding
+    : ValueTypeBinding<TY>
+    { };
+  
+  template<typename TY>
+  struct TypeBinding<TY &>
+    : TypeBinding<TY>
+    { };
+  
+  template<typename TY>
+  struct TypeBinding<TY &&>
+    : TypeBinding<TY>
+    { };
+  
+  
   
 }} // namespace lib::meta
 #endif /*LIB_META_VALUE_TYPE_BINDING_H*/
diff --git a/tests/library/meta/value-type-binding-test.cpp b/tests/library/meta/value-type-binding-test.cpp
index 782918354..49285af96 100644
--- a/tests/library/meta/value-type-binding-test.cpp
+++ b/tests/library/meta/value-type-binding-test.cpp
@@ -52,8 +52,8 @@ namespace test{
           };
         
         typedef T value_type;
-        typedef Inner const& reference;
-        typedef std::shared_ptr<Inner> pointer;
+        typedef Inner & reference;
+        typedef std::shared_ptr<T> pointer;
       };
     
     struct Space { };
@@ -69,44 +69,72 @@ namespace test{
     struct TypeDiagnostics
       {
         using Type = X;
+        static constexpr auto prefix  = "";
         static constexpr auto postfix = "";
       };
     template<typename X>
     struct TypeDiagnostics<X&>
       {
         using Type = X;
+        static constexpr auto prefix  = "";
         static constexpr auto postfix = "&";
       };
     template<typename X>
     struct TypeDiagnostics<X&&>
       {
         using Type = X;
+        static constexpr auto prefix  = "";
         static constexpr auto postfix = " &&";
       };
     template<typename X>
     struct TypeDiagnostics<X const&>
       {
         using Type = X;
+        static constexpr auto prefix  = "";
         static constexpr auto postfix = " const&";
       };
     template<typename X>
     struct TypeDiagnostics<X const&&>
       {
         using Type = X;
-        static constexpr auto postfix = " const &&";
+        static constexpr auto prefix  = "const ";
+        static constexpr auto postfix = " &&";
       };
     template<typename X>
     struct TypeDiagnostics<X *>
       {
         using Type = X;
+        static constexpr auto prefix  = "";
         static constexpr auto postfix = " *";
       };
     template<typename X>
+    struct TypeDiagnostics<const X *>
+      {
+        using Type = X;
+        static constexpr auto prefix  = "const ";
+        static constexpr auto postfix = " *";
+      };
+    template<typename X>
+    struct TypeDiagnostics<const X * const>
+      {
+        using Type = X;
+        static constexpr auto prefix  = "const ";
+        static constexpr auto postfix = " * const";
+      };
+    template<typename X>
     struct TypeDiagnostics<X * const>
       {
         using Type = X;
+        static constexpr auto prefix  = "";
         static constexpr auto postfix = " * const";
       };
+    template<typename X>
+    struct TypeDiagnostics<X * const *>
+      {
+        using Type = X;
+        static constexpr auto prefix  = "";
+        static constexpr auto postfix = " * const *";
+      };
     
     template<typename X>
     inline string
@@ -115,7 +143,8 @@ namespace test{
       using Case = TypeDiagnostics<X>;
       using Type = typename Case::Type;
       
-      return humanReadableTypeID (typeid(Type).name())
+      return Case::prefix
+           + humanReadableTypeID (typeid(Type).name())
            + Case::postfix;
     }
     
@@ -166,11 +195,9 @@ namespace test{
           cout << showType<TypeBinding<OuterSpace&>::reference>() <<endl;
           cout << showType<TypeBinding<OuterSpace&>::pointer>() <<endl;
           
-#if false /////////////////////////////////////////////////////////////////////////////////////////////////////////////UNIMPLEMENTED :: TICKET #888
           cout << showType<TypeBinding<OuterSpace&&>::value_type>() <<endl;
           cout << showType<TypeBinding<OuterSpace&&>::reference>() <<endl;
           cout << showType<TypeBinding<OuterSpace&&>::pointer>() <<endl;
-#endif    /////////////////////////////////////////////////////////////////////////////////////////////////////////////UNIMPLEMENTED :: TICKET #888
           
           cout << showType<TypeBinding<OuterSpace const&>::value_type>() <<endl;
           cout << showType<TypeBinding<OuterSpace const&>::reference>() <<endl;
@@ -200,11 +227,9 @@ namespace test{
           cout << showType<TypeBinding<Join&>::reference>() <<endl;
           cout << showType<TypeBinding<Join&>::pointer>() <<endl;
           
-#if false /////////////////////////////////////////////////////////////////////////////////////////////////////////////UNIMPLEMENTED :: TICKET #888
           cout << showType<TypeBinding<Join&&>::value_type>() <<endl;
           cout << showType<TypeBinding<Join&&>::reference>() <<endl;
           cout << showType<TypeBinding<Join&&>::pointer>() <<endl;
-#endif    /////////////////////////////////////////////////////////////////////////////////////////////////////////////UNIMPLEMENTED :: TICKET #888
           
           cout << showType<TypeBinding<Join const&>::value_type>() <<endl;
           cout << showType<TypeBinding<Join const&>::reference>() <<endl;
@@ -231,8 +256,10 @@ namespace test{
           cout << showType<int&&>() <<endl;
           cout << showType<int const&>() <<endl;
           cout << showType<int const&&>() <<endl;
+          cout << showType<int       *>() <<endl;
           cout << showType<int const *>() <<endl;
           cout << showType<int const * const>() <<endl;
+          cout << showType<int const *      &>() <<endl;
           cout << showType<int const * const&>() <<endl;
         }
     };