[FOLD]

Author: vinniefalco

src_zlib/service/deflate_service.cpp

@@ -11,10 +11,15 @@
 #include <zlib.h>
 #include "src_zlib/service/stream_cast.hpp"
 
+#include <boost/static_assert.hpp>
+
 namespace boost {
 namespace http_proto {
 namespace zlib {
 
+BOOST_STATIC_ASSERT(sizeof(stream_t) == sizeof(z_stream_s));
+BOOST_STATIC_ASSERT(is_layout_identical<stream_t, z_stream_s>());
+
 //------------------------------------------------
 
 class deflate_service_impl

src_zlib/service/stream_cast.hpp

@@ -19,7 +19,40 @@ namespace boost {
 namespace http_proto {
 namespace zlib {
 
-template<bool isStrict>
+//------------------------------------------------
+
+#define SAME_FIELD(T1,T2,M) \
+    offsetof(T1,M)==offsetof(T2,M) && \
+    sizeof(decltype(T1::M)) == sizeof(decltype(T2::M))
+
+template<class T1, class T2>
+constexpr
+bool
+is_layout_identical()
+{
+    return
+        sizeof(T1) == sizeof(T2) &&
+        SAME_FIELD(T1, T2, next_in) &&
+        SAME_FIELD(T1, T2, avail_in) &&
+        SAME_FIELD(T1, T2, total_in) &&
+        SAME_FIELD(T1, T2, next_out) &&
+        SAME_FIELD(T1, T2, avail_out) &&
+        SAME_FIELD(T1, T2, total_out) &&
+        SAME_FIELD(T1, T2, msg) &&
+        SAME_FIELD(T1, T2, state) &&
+        SAME_FIELD(T1, T2, zalloc) &&
+        SAME_FIELD(T1, T2, zfree) &&
+        SAME_FIELD(T1, T2, opaque) &&
+        SAME_FIELD(T1, T2, data_type) &&
+        SAME_FIELD(T1, T2, adler) &&
+        SAME_FIELD(T1, T2, reserved)
+        ;
+}
+
+//------------------------------------------------
+
+template<bool isLayoutIdentical =
+    is_layout_identical<stream_t, z_stream_s>()>
 struct stream_cast_impl
 {
     explicit
@@ -82,6 +115,7 @@ struct stream_cast_impl<false>
     explicit
     stream_cast_impl(
         stream_t& st)
+        // VFALCO A pinch of undefined behavior here
         : pzs_(reinterpret_cast<z_stream_s*>(&st))
     {
 
@@ -99,42 +133,7 @@ struct stream_cast_impl<false>
 
 //------------------------------------------------
 
-template<class T1, class T2>
-constexpr
-bool
-is_layout_identical()
-{
-#define SAME_FIELD(T1, T2, M)( \
-    (offsetof(T1,M)==offsetof(T2,M)) && \
-    (std::is_same<T1::M,T2::M>::value) && \
-    (sizeof(T1::M)==sizeof(T2::M)) )
-    return
-        sizeof(T1) == sizeof(T2)
-#if 0
-        SAME_FIELD(T1, T2, next_in)
-        &&
-        SAME_FIELD(T1, T2, avail_in) &&
-        SAME_FIELD(T1, T2, total_in) &&
-        SAME_FIELD(T1, T2, next_out) &&
-        SAME_FIELD(T1, T2, avail_out) &&
-        SAME_FIELD(T1, T2, total_out) &&
-        SAME_FIELD(T1, T2, msg) &&
-        SAME_FIELD(T1, T2, state) &&
-        SAME_FIELD(T1, T2, zalloc) &&
-        SAME_FIELD(T1, T2, zfree) &&
-        SAME_FIELD(T1, T2, opaque) &&
-        SAME_FIELD(T1, T2, data_type) &&
-        SAME_FIELD(T1, T2, adler) &&
-        SAME_FIELD(T1, T2, reserved)
-#endif
-        ;
-}
-
-//------------------------------------------------
-
-// VFALCO A pinch of undefined behavior here
-using stream_cast = stream_cast_impl<
-    is_layout_identical<stream_t, z_stream_s>()>;
+using stream_cast = stream_cast_impl<>;
 
 } // zlib
 } // http_proto