[Boost-commit] svn:boost r65551 - sandbox/variadic_templates/libs/composite_storage/sandbox/pack

Subject: [Boost-commit] svn:boost r65551 - sandbox/variadic_templates/libs/composite_storage/sandbox/pack
From: cppljevans_at_[hidden]
Date: 2010-09-23 11:46:59

Author: cppljevans
Date: 2010-09-23 11:46:58 EDT (Thu, 23 Sep 2010)
New Revision: 65551
URL: http://svn.boost.org/trac/boost/changeset/65551

Log:
demo same size as ebo for inherited components
Added:
   sandbox/variadic_templates/libs/composite_storage/sandbox/pack/empty_base.cpp   (contents, props changed)

Added: sandbox/variadic_templates/libs/composite_storage/sandbox/pack/empty_base.cpp
==============================================================================
--- (empty file)
+++ sandbox/variadic_templates/libs/composite_storage/sandbox/pack/empty_base.cpp	2010-09-23 11:46:58 EDT (Thu, 23 Sep 2010)
@@ -0,0 +1,87 @@
+//Purpose:
+//  See if more than 1 empty base types contribute 
+//  more to size of derived type than just 1
+//  empty_base type.
+//Result:
+//  No. Output is:
+//    sizeof(empty_class<0>)=1
+//    sizeof(empties_inherits)=1
+//    sizeof(empties_member)=2
+//    sizeof(empties_all_of)=1
+//
+#include <boost/composite_storage/pack/container_all_of_aligned.hpp>
+#include <iostream>
+
+  template
+  < unsigned I
+  >
+struct empty_class
+{
+        friend
+      std::ostream&
+    operator<<
+      ( std::ostream& sout
+      , empty_class<I>const&
+      )
+    {
+        sout<<"empty_class<"<<I<<">const&";
+        return sout;
+    }
+      unsigned
+    get(void)const
+    {
+        return I;
+    }
+  #if 0
+    unsigned my_i;
+    empty_class(void):my_i(I){}
+  #endif
+};
+
+struct empties_inherit
+: empty_class<0>
+, empty_class<1>
+{};
+
+struct empties_member
+{
+  empty_class<0> m0;
+  empty_class<1> m1;
+};
+    typedef
+  boost::composite_storage::pack::container
+  < boost::composite_storage::tags::all_of_aligned
+  , boost::mpl::integral_c<unsigned,0>
+  , empty_class<0>
+  , empty_class<1>
+  >
+empties_all_of
+;
+int main(void)
+{
+    std::cout<<"sizeof(empty_class<0>)="<<sizeof(empty_class<0>)<<"\n";
+    std::cout<<"sizeof(empties_inherit)="<<sizeof(empties_inherit)<<"\n";
+    std::cout<<"sizeof(empties_member)="<<sizeof(empties_member)<<"\n";
+    std::cout<<"sizeof(empties_all_of)="<<sizeof(empties_all_of)<<"\n";
+    {
+        empties_inherit ei_v;
+        empty_class<0>*p0=&ei_v;
+        empty_class<1>*p1=&ei_v;
+        std::cout<<"p0="<<p0<<"\n";
+        std::cout<<"p1="<<p1<<"\n";
+        std::cout<<"*p0="<<*p0<<"\n";
+        std::cout<<"*p1="<<*p1<<"\n";
+    }
+    {
+        empties_all_of ea_v;
+        empty_class<0>&r0=ea_v.project<0>();
+        empty_class<1>&r1=ea_v.project<1>();
+        std::cout<<"r0="<<r0<<"\n";
+        std::cout<<"r1="<<r1<<"\n";
+        std::cout<<"&ea_v="<<&ea_v<<"\n";
+        std::cout<<"&r0="<<&r0<<"\n";
+        std::cout<<"&r1="<<&r1<<"\n";
+        std::cout<<"r1.get()="<<r1.get()<<"\n";
+    }
+    return 0;
+}