base: eliminate TupleTraits and TupleTypes

base/tuple.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A Tuple is a generic templatized container, similar in concept to std::pair
 // and std::tuple.  The convenient MakeTuple() function takes any number of
 // arguments and will construct and return the appropriate Tuple object.  The
 // functions DispatchToMethod and DispatchToFunction take a function pointer or
 // instance and method pointer, and unpack a tuple into arguments to the call.
 //
@@ skipping 92 matching lines @@
 
 template <size_t N, size_t... Ns>
 struct MakeIndexSequenceImpl<N, Ns...>
     : MakeIndexSequenceImpl<N - 1, N - 1, Ns...> {};
 
 #endif  // defined(WIN) && defined(_PREFAST_)
 
 template <size_t N>
 using MakeIndexSequence = typename MakeIndexSequenceImpl<N>::Type;
 
-// Traits ----------------------------------------------------------------------
-//
-// A simple traits class for tuple arguments.
-//
-// ValueType: the bare, nonref version of a type (same as the type for nonrefs).
-// RefType: the ref version of a type (same as the type for refs).
-// ParamType: what type to pass to functions (refs should not be constified).
-
-template <class P>
-struct TupleTraits {
-  typedef P ValueType;
-  typedef P& RefType;
-  typedef const P& ParamType;
-};
-
-template <class P>
-struct TupleTraits<P&> {
-  typedef P ValueType;
-  typedef P& RefType;
-  typedef P& ParamType;
-};
-
 // Tuple -----------------------------------------------------------------------
 //
 // This set of classes is useful for bundling 0 or more heterogeneous data types
 // into a single variable.  The advantage of this is that it greatly simplifies
 // function objects that need to take an arbitrary number of parameters; see
 // RunnableMethod and IPC::MessageWithTuple.
 //
 // Tuple<> is supplied to act as a 'void' type.  It can be used, for example,
 // when dispatching to a function that accepts no arguments (see the
 // Dispatchers below).
 // Tuple<A> is rarely useful.  One such use is when A is non-const ref that you
 // want filled by the dispatchee, and the tuple is merely a container for that
 // output (a "tier").  See MakeRefTuple and its usages.
 
 template <typename... Ts>
 using Tuple = std::tuple<Ts...>;
 
 using std::get;
 
-// Tuple types ----------------------------------------------------------------
-//
-// Allows for selection of ValueTuple/RefTuple/ParamTuple without needing the
-// definitions of class types the tuple takes as parameters.
-
-template <typename T>
-struct TupleTypes;
-
-template <typename... Ts>
-struct TupleTypes<Tuple<Ts...>> {
-  using ValueTuple = Tuple<typename TupleTraits<Ts>::ValueType...>;
-  using RefTuple = Tuple<typename TupleTraits<Ts>::RefType...>;
-  using ParamTuple = Tuple<typename TupleTraits<Ts>::ParamType...>;
-};
-
 // Tuple creators -------------------------------------------------------------
 //
 // Helper functions for constructing tuples while inferring the template
 // argument types.
 
 template <typename... Ts>
 inline Tuple<Ts...> MakeTuple(const Ts&... arg) {
   return Tuple<Ts...>(arg...);
 }
 
@@ skipping 68 matching lines @@
                              const Tuple<InTs...>& in,
                              Tuple<OutTs...>* out) {
   DispatchToMethodImpl(obj, method, in, out,
                        MakeIndexSequence<sizeof...(InTs)>(),
                        MakeIndexSequence<sizeof...(OutTs)>());
 }
 
 }  // namespace base
 
 #endif  // BASE_TUPLE_H_