message::body is a member function (API Change):

fix #778

* The body data member is replaced with accessor
  member functions.

Actions Required:

* Call member function message::body instead of accessing
  the data member at call sites.

include/boost/beast/core/detail/empty_base_optimization.hpp

@@ -19,31 +19,32 @@ namespace beast {
 namespace detail {
 
 template<class T>
-struct empty_base_optimization_decide
+struct is_empty_base_optimization_derived
     : std::integral_constant<bool,
         std::is_empty<T>::value &&
         ! boost::is_final<T>::value>
 {
 };
 
-template<
-    class T,
-    int UniqueID = 0,
-    bool ShouldDeriveFrom =
-        empty_base_optimization_decide<T>::value
->
+template<class T, int UniqueID = 0,
+    bool isDerived =
+        is_empty_base_optimization_derived<T>::value>
 class empty_base_optimization : private T
 {
 public:
     empty_base_optimization() = default;
+    empty_base_optimization(empty_base_optimization&&) = default;
+    empty_base_optimization(empty_base_optimization const&) = default;
+    empty_base_optimization& operator=(empty_base_optimization&&) = default;
+    empty_base_optimization& operator=(empty_base_optimization const&) = default;
 
-    empty_base_optimization(T const& t)
-        : T (t)
-    {}
-
-    empty_base_optimization(T&& t)
-        : T (std::move (t))
-    {}
+    template<class Arg1, class... ArgN>
+    explicit
+    empty_base_optimization(Arg1&& arg1, ArgN&&... argn)
+        : T(std::forward<Arg1>(arg1),
+            std::forward<ArgN>(argn)...)
+    {
+    }
 
     T& member() noexcept
     {
@@ -64,29 +65,32 @@ template<
 >
 class empty_base_optimization <T, UniqueID, false>
 {
+    T t_;
+
 public:
     empty_base_optimization() = default;
+    empty_base_optimization(empty_base_optimization&&) = default;
+    empty_base_optimization(empty_base_optimization const&) = default;
+    empty_base_optimization& operator=(empty_base_optimization&&) = default;
+    empty_base_optimization& operator=(empty_base_optimization const&) = default;
 
-    empty_base_optimization(T const& t)
-        : m_t (t)
-    {}
-
-    empty_base_optimization(T&& t)
-        : m_t (std::move (t))
-    {}
+    template<class Arg1, class... ArgN>
+    explicit
+    empty_base_optimization(Arg1&& arg1, ArgN&&... argn)
+        : t_(std::forward<Arg1>(arg1),
+            std::forward<ArgN>(argn)...)
+    {
+    }
 
     T& member() noexcept
     {
-        return m_t;
+        return t_;
     }
 
     T const& member() const noexcept
     {
-        return m_t;
+        return t_;
     }
-
-private:
-    T m_t;
 };
 
 } // detail

include/boost/beast/http/basic_dynamic_body.hpp

@@ -74,7 +74,7 @@ struct basic_dynamic_body
         explicit
         reader(message<isRequest,
                 basic_dynamic_body, Fields> const& m)
-            : body_(m.body)
+            : body_(m.body())
         {
         }
 
@@ -109,7 +109,7 @@ struct basic_dynamic_body
         explicit
         writer(message<isRequest,
                 basic_dynamic_body, Fields>& msg)
-            : body_(msg.body)
+            : body_(msg.body())
         {
         }
 

include/boost/beast/http/basic_file_body.hpp

@@ -291,7 +291,7 @@ template<bool isRequest, class Fields>
 basic_file_body<File>::
 reader::
 reader(message<isRequest, basic_file_body, Fields>& m)
-    : body_(m.body)
+    : body_(m.body())
 {
     // The file must already be open
     BOOST_ASSERT(body_.file_.is_open());
@@ -442,7 +442,7 @@ template<bool isRequest, class Fields>
 basic_file_body<File>::
 writer::
 writer(message<isRequest, basic_file_body, Fields>& m)
-    : body_(m.body)
+    : body_(m.body())
 {
 }
 

include/boost/beast/http/buffer_body.hpp

@@ -111,7 +111,7 @@ struct buffer_body
         explicit
         reader(message<isRequest,
                 buffer_body, Fields> const& msg)
-            : body_(msg.body)
+            : body_(msg.body())
         {
         }
 
@@ -169,7 +169,7 @@ struct buffer_body
         template<bool isRequest, class Fields>
         explicit
         writer(message<isRequest, buffer_body, Fields>& m)
-            : body_(m.body)
+            : body_(m.body())
         {
         }
 

include/boost/beast/http/impl/file_body_win32.ipp

@@ -125,7 +125,7 @@ struct basic_file_body<file_win32>
         template<bool isRequest, class Fields>
         reader(message<isRequest,
                 basic_file_body<file_win32>, Fields>& m)
-            : body_(m.body)
+            : body_(m.body())
         {
         }
 
@@ -168,7 +168,7 @@ struct basic_file_body<file_win32>
         template<bool isRequest, class Fields>
         explicit
         writer(message<isRequest, basic_file_body, Fields>& m)
-            : body_(m.body)
+            : body_(m.body())
         {
         }
 
@@ -437,7 +437,7 @@ operator()()
     ov.OffsetHigh = highPart(r.pos_);
     auto const bSuccess = ::TransmitFile(
         sock_.native_handle(),
-        sr_.get().body.file_.native_handle(),
+        sr_.get().body().file_.native_handle(),
         nNumberOfBytesToWrite,
         0,
         overlapped.get(),

include/boost/beast/http/impl/message.ipp

@@ -209,7 +209,9 @@ template<class... BodyArgs>
 message<isRequest, Body, Fields>::
 message(header_type&& h, BodyArgs&&... body_args)
     : header_type(std::move(h))
-    , body(std::forward<BodyArgs>(body_args)...)
+    , beast::detail::empty_base_optimization<
+        typename Body::value_type>(
+            std::forward<BodyArgs>(body_args)...)
 {
 }
 
@@ -218,7 +220,9 @@ template<class... BodyArgs>
 message<isRequest, Body, Fields>::
 message(header_type const& h, BodyArgs&&... body_args)
     : header_type(h)
-    , body(std::forward<BodyArgs>(body_args)...)
+    , beast::detail::empty_base_optimization<
+        typename Body::value_type>(
+            std::forward<BodyArgs>(body_args)...)
 {
 }
 
@@ -236,7 +240,9 @@ message<isRequest, Body, Fields>::
 message(verb method, string_view target,
         Version version, BodyArg&& body_arg)
     : header_type(method, target, version)
-    , body(std::forward<BodyArg>(body_arg))
+    , beast::detail::empty_base_optimization<
+        typename Body::value_type>(
+            std::forward<BodyArg>(body_arg))
 {
 }
 
@@ -249,7 +255,9 @@ message(
     FieldsArg&& fields_arg)
     : header_type(method, target, version,
         std::forward<FieldsArg>(fields_arg))
-    , body(std::forward<BodyArg>(body_arg))
+    , beast::detail::empty_base_optimization<
+        typename Body::value_type>(
+            std::forward<BodyArg>(body_arg))
 {
 }
 
@@ -267,7 +275,9 @@ message<isRequest, Body, Fields>::
 message(status result, Version version,
     BodyArg&& body_arg)
     : header_type(result, version)
-    , body(std::forward<BodyArg>(body_arg))
+    , beast::detail::empty_base_optimization<
+        typename Body::value_type>(
+            std::forward<BodyArg>(body_arg))
 {
 }
 
@@ -278,7 +288,9 @@ message(status result, Version version,
     BodyArg&& body_arg, FieldsArg&& fields_arg)
     : header_type(result, version,
         std::forward<FieldsArg>(fields_arg))
-    , body(std::forward<BodyArg>(body_arg))
+    , beast::detail::empty_base_optimization<
+        typename Body::value_type>(
+            std::forward<BodyArg>(body_arg))
 {
 }
 
@@ -409,7 +421,7 @@ swap(
     swap(
         static_cast<header<isRequest, Fields>&>(m1),
         static_cast<header<isRequest, Fields>&>(m2));
-    swap(m1.body, m2.body);
+    swap(m1.body(), m2.body());
 }
 
 } // http

include/boost/beast/http/message.hpp

@@ -16,6 +16,7 @@
 #include <boost/beast/http/status.hpp>
 #include <boost/beast/http/type_traits.hpp>
 #include <boost/beast/core/string.hpp>
+#include <boost/beast/core/detail/empty_base_optimization.hpp>
 #include <boost/beast/core/detail/integer_sequence.hpp>
 #include <boost/optional.hpp>
 #include <boost/throw_exception.hpp>
@@ -391,6 +392,14 @@ using request_header = header<true, Fields>;
 template<class Fields = fields>
 using response_header = header<false, Fields>;
 
+#if defined(BOOST_MSVC)
+// Workaround for MSVC bug with private base classes
+namespace detail {
+template<class T>
+using value_type_t = typename T::value_type;
+} // detail
+#endif
+
 /** A container for a complete HTTP message.
 
     This container is derived from the `Fields` template type.
@@ -421,7 +430,12 @@ using response_header = header<false, Fields>;
     field value pairs.
 */
 template<bool isRequest, class Body, class Fields = fields>
-struct message : header<isRequest, Fields>
+struct message
+    : header<isRequest, Fields>
+#if ! BOOST_BEAST_DOXYGEN
+    , beast::detail::empty_base_optimization<
+        typename Body::value_type>
+#endif
 {
     /// The base class used to hold the header portion of the message.
     using header_type = header<isRequest, Fields>;
@@ -432,9 +446,6 @@ struct message : header<isRequest, Fields>
     */
     using body_type = Body;
 
-    /// A value representing the body.
-    typename Body::value_type body;
-
     /// Constructor
     message() = default;
 
@@ -736,7 +747,7 @@ struct message : header<isRequest, Fields>
         @code
         request<string_body> req{verb::post, "/"};
         req.set(field::user_agent, "Beast");
-        req.body = "Hello, world!";
+        req.body() = "Hello, world!";
         req.prepare_payload();
         @endcode
     */
@@ -746,6 +757,28 @@ struct message : header<isRequest, Fields>
         prepare_payload(typename header_type::is_request{});
     }
 
+    /// Returns the body
+#if BOOST_BEAST_DOXYGEN || ! defined(BOOST_MSVC)
+    typename body_type::value_type&
+#else
+    detail::value_type_t<Body>&
+#endif
+    body() noexcept
+    {
+        return this->member();
+    }
+
+    /// Returns the body
+#if BOOST_BEAST_DOXYGEN || ! defined(BOOST_MSVC)
+    typename body_type::value_type const&
+#else
+    detail::value_type_t<Body> const&
+#endif
+    body() const noexcept
+    {
+        return this->member();
+    }
+
 private:
     static_assert(is_body<Body>::value,
         "Body requirements not met");
@@ -757,8 +790,10 @@ private:
         std::piecewise_construct_t,
         std::tuple<BodyArgs...>& body_args,
         beast::detail::index_sequence<IBodyArgs...>)
-        : body(std::forward<BodyArgs>(
-            std::get<IBodyArgs>(body_args))...)
+        : beast::detail::empty_base_optimization<
+            typename Body::value_type>(
+                std::forward<BodyArgs>(
+                std::get<IBodyArgs>(body_args))...)
     {
         boost::ignore_unused(body_args);
     }
@@ -776,8 +811,10 @@ private:
         beast::detail::index_sequence<IFieldsArgs...>)
         : header_type(std::forward<FieldsArgs>(
             std::get<IFieldsArgs>(fields_args))...)
-        , body(std::forward<BodyArgs>(
-            std::get<IBodyArgs>(body_args))...)
+        , beast::detail::empty_base_optimization<
+            typename Body::value_type>(
+                std::forward<BodyArgs>(
+                std::get<IBodyArgs>(body_args))...)
     {
         boost::ignore_unused(body_args);
         boost::ignore_unused(fields_args);
@@ -786,7 +823,7 @@ private:
     boost::optional<std::uint64_t>
     payload_size(std::true_type) const
     {
-        return Body::size(body);
+        return Body::size(this->body());
     }
 
     boost::optional<std::uint64_t>

include/boost/beast/http/span_body.hpp

@@ -78,7 +78,7 @@ public:
         explicit
         reader(message<isRequest,
                 span_body, Fields> const& msg)
-            : body_(msg.body)
+            : body_(msg.body())
         {
         }
 
@@ -117,7 +117,7 @@ public:
         explicit
         writer(message<isRequest,
                 span_body, Fields>& m)
-            : body_(m.body)
+            : body_(m.body())
         {
         }
 

include/boost/beast/http/string_body.hpp

@@ -86,7 +86,7 @@ public:
         explicit
         reader(message<isRequest,
                 basic_string_body, Fields> const& msg)
-            : body_(msg.body)
+            : body_(msg.body())
         {
         }
 
@@ -122,7 +122,7 @@ public:
         explicit
         writer(message<isRequest,
                 basic_string_body, Fields>& m)
-            : body_(m.body)
+            : body_(m.body())
         {
         }
 

include/boost/beast/http/vector_body.hpp

@@ -81,7 +81,7 @@ public:
         explicit
         reader(message<isRequest,
                 vector_body, Fields> const& msg)
-            : body_(msg.body)
+            : body_(msg.body())
         {
         }
 
@@ -117,7 +117,7 @@ public:
         explicit
         writer(message<isRequest,
                 vector_body, Fields>& m)
-            : body_(m.body)
+            : body_(m.body())
         {
         }
 

include/boost/beast/websocket/impl/stream.ipp

@@ -577,7 +577,7 @@ build_response(http::request<Body,
             response_type res;
             res.version = req.version;
             res.result(http::status::bad_request);
-            res.body = text;
+            res.body() = text;
             res.prepare_payload();
             decorate(res);
             return res;