Enable using result_of with Boost.Lambda. Fixes #426. Fixes #864

[SVN r62627]

include/boost/lambda/detail/function_adaptors.hpp

@@ -12,25 +12,167 @@
 #ifndef BOOST_LAMBDA_FUNCTION_ADAPTORS_HPP
 #define BOOST_LAMBDA_FUNCTION_ADAPTORS_HPP
 
+#include "boost/mpl/has_xxx.hpp"
+#include "boost/tuple/tuple.hpp"
 #include "boost/type_traits/same_traits.hpp"
+#include "boost/type_traits/remove_reference.hpp"
+#include "boost/utility/result_of.hpp"
 
 namespace boost { 
 namespace lambda {
 
+namespace detail {
+
+BOOST_MPL_HAS_XXX_TEMPLATE_NAMED_DEF(has_template_sig, sig, 1, true)
+
+template<class Tuple>
+struct remove_references_from_elements {
+  typedef typename boost::tuples::cons<
+    typename boost::remove_reference<typename Tuple::head_type>::type,
+    typename remove_references_from_elements<typename Tuple::tail_type>::type
+  > type;
+};
+
+template<>
+struct remove_references_from_elements<boost::tuples::null_type> {
+  typedef boost::tuples::null_type type;
+};
+
+}
+
 template <class Func> struct function_adaptor {
 
+  typedef typename detail::remove_reference_and_cv<Func>::type plainF;
+
+#if !defined(BOOST_NO_RESULT_OF)
+  // Support functors that use the boost::result_of return type convention.
+  template<class Tuple, int Length, bool HasSig>
+  struct result_converter;
+  template<class Tuple, int Length>
+  struct result_converter<Tuple, Length, true>
+    : plainF::template sig<
+        typename detail::remove_references_from_elements<Tuple>::type
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 0, false>
+    : result_of<plainF()>
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 1, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 2, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 3, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type,
+        typename tuples::element<3, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 4, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type,
+        typename tuples::element<3, Tuple>::type,
+        typename tuples::element<4, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 5, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type,
+        typename tuples::element<3, Tuple>::type,
+        typename tuples::element<4, Tuple>::type,
+        typename tuples::element<5, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 6, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type,
+        typename tuples::element<3, Tuple>::type,
+        typename tuples::element<4, Tuple>::type,
+        typename tuples::element<5, Tuple>::type,
+        typename tuples::element<6, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 7, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type,
+        typename tuples::element<3, Tuple>::type,
+        typename tuples::element<4, Tuple>::type,
+        typename tuples::element<5, Tuple>::type,
+        typename tuples::element<6, Tuple>::type,
+        typename tuples::element<7, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 8, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type,
+        typename tuples::element<3, Tuple>::type,
+        typename tuples::element<4, Tuple>::type,
+        typename tuples::element<5, Tuple>::type,
+        typename tuples::element<6, Tuple>::type,
+        typename tuples::element<7, Tuple>::type,
+        typename tuples::element<8, Tuple>::type)
+      >
+  {};
+  template<class Tuple>
+  struct result_converter<Tuple, 9, false>
+    : result_of<plainF(
+        typename tuples::element<1, Tuple>::type,
+        typename tuples::element<2, Tuple>::type,
+        typename tuples::element<3, Tuple>::type,
+        typename tuples::element<4, Tuple>::type,
+        typename tuples::element<5, Tuple>::type,
+        typename tuples::element<6, Tuple>::type,
+        typename tuples::element<7, Tuple>::type,
+        typename tuples::element<8, Tuple>::type,
+        typename tuples::element<9, Tuple>::type)
+      >
+  {};
+
   // we do not know the return type off-hand, we must ask it from Func
-  template <class Args> class sig { 
-    typedef typename Args::head_type F; 
+  // To sig we pass a cons list, where the head is the function object type
+  // itself (potentially cv-qualified)
+  // and the tail contains the types of the actual arguments to be passed
+  // to the function object. The arguments can be cv qualified
+  // as well.
+  template <class Args>
+  struct sig
+    : result_converter<
+        Args
+      , tuples::length<typename Args::tail_type>::value
+      , detail::has_template_sig<plainF, Args>::value
+      >
+  {};
+#else // BOOST_NO_RESULT_OF
+
+  template <class Args> class sig {
     typedef typename detail::remove_reference_and_cv<Func>::type plainF;
   public:
-    // To sig we pass a cons list, where the head is the function object type
-    // itself (potentially cv-qualified)
-    // and the tail contains the types of the actual arguments to be passed
-    // to the function object. The arguments can be cv qualified
-    // as well.
-    typedef typename plainF::template sig<Args>::type type;
+    typedef typename plainF::template sig<
+      typename detail::remove_references_from_elements<Args>::type
+    >::type type;
   };
+#endif
 
   template<class RET, class A1>
   static RET apply(A1& a1) {

include/boost/lambda/detail/lambda_functor_base.hpp

@@ -383,7 +383,7 @@ public:                                                                \
                                                                        \
   template<class SigArgs> struct sig {                                 \
     typedef typename                                                   \
-    detail::deduce_non_ref_argument_types<Args, SigArgs>::type rets_t; \
+    detail::deduce_argument_types<Args, SigArgs>::type rets_t;         \
   public:                                                              \
     typedef typename                                                   \
       return_type_N_prot<Act, rets_t>::type type;                      \

include/boost/lambda/detail/lambda_functors.hpp

@@ -161,6 +161,25 @@ public:
     inherited::template sig<null_type>::type
       nullary_return_type;
 
+  // Support for boost::result_of.
+  template <class Sig> struct result;
+  template <class F>
+  struct result<F()> {
+    typedef nullary_return_type type;
+  };
+  template <class F, class A>
+  struct result<F(A)> {
+    typedef typename sig<tuple<F, A> >::type type;
+  };
+  template <class F, class A, class B>
+  struct result<F(A, B)> {
+    typedef typename sig<tuple<F, A, B> >::type type;
+  };
+  template <class F, class A, class B, class C>
+  struct result<F(A, B, C)> {
+    typedef typename sig<tuple<F, A, B, C> >::type type;
+  };
+
   nullary_return_type operator()() const { 
     return inherited::template 
       call<nullary_return_type>

include/boost/lambda/detail/return_type_traits.hpp

@@ -216,8 +216,6 @@ typedef typename
 
 
   // currently there are no protectable actions with > 2 args
-  // Note, that if there will be, lambda_functor_base will have to be 
-  // changed to not get rid of references in Args elements
 
 template<class Act, class Args> struct return_type_N_prot {
   typedef typename return_type_N<Act, Args>::type type;