Ticket #4910: display_expr-66440.2.patch

./boost/proto/debug.hpp

@@ -83 +83 @@
 
     namespace hidden_detail_
     {
-        struct ostream_wrapper
-        {
-            ostream_wrapper(std::ostream &sout)
-              : sout_(sout)
-            {}
-
-            std::ostream &sout_;
-        };
-
-        template<typename Tag>
-        std::ostream &operator <<(ostream_wrapper sout_wrap, Tag const &)
-        {
-            return sout_wrap.sout_ << BOOST_SP_TYPEID(Tag).name();
-        }
+        // has_ostream_shift trait
+        struct yes_type { char x; };
+        struct no_type  { yes_type x[2]; };
+
+        template<typename T> T fake();
+
+        no_type has_ostream_shift_test(...);
+
+        template<typename T>
+        typename boost::enable_if_c< sizeof( fake<std::ostream&>() << fake<const T&>() )
+                                   , yes_type >::type
+        has_ostream_shift_test(const T&);
+
+        template<typename T>
+        struct has_ostream_shift
+          : boost::mpl::bool_<
+                sizeof( has_ostream_shift_test(fake<const T&>()) ) == sizeof( yes_type )
+            >
+        {};
+        
+        // output
+        template<typename T> inline
+        void output_impl( std::ostream& os, const T& x, boost::mpl::true_ )
+        {
+            os << x;
+        }
+
+        template<typename T> inline
+        void output_impl( std::ostream& os, const T& x, boost::mpl::false_ )
+        {
+            os << typeid(T).name();
+        }
+
+        template<typename T> inline
+        void output( std::ostream& os, const T& x )
+        {
+          output_impl( os, x, has_ostream_shift<T>() );
+        }
     }
 
     namespace functional
@@ -138 +162 @@
             template<typename Expr>
             void impl(Expr const &expr, mpl::long_<0>) const
             {
-                using namespace hidden_detail_;
                 typedef typename tag_of<Expr>::type tag;
                 this->sout_.width(this->depth_);
                 this->sout_ << (this->first_? "" : ", ");
-                this->sout_ << tag() << "(" << proto::value(expr) << ")\n";
+                hidden_detail_::out( this->sout_, tag() );
+                this->sout_ << "(";
+                hidden_detail_::out( this->sout_, proto::value(expr) );
+                this->sout_ << ")\n";
                 this->first_ = false;
             }
 
             template<typename Expr, typename Arity>
             void impl(Expr const &expr, Arity) const
             {
-                using namespace hidden_detail_;
                 typedef typename tag_of<Expr>::type tag;
                 this->sout_.width(this->depth_);
                 this->sout_ << (this->first_? "" : ", ");
-                this->sout_ << tag() << "(\n";
+                hidden_detail_::out( this->sout_, tag() );
+                this->sout_ << "(\n";
                 display_expr display(this->sout_, this->depth_ + 4);
                 fusion::for_each(expr, display);
                 this->sout_.width(this->depth_);