New ostream() returns dynamic buffer output stream (API Change):

This eliminates beast::write output for dynamic buffers and replaces
it with the function ostream() that wraps a caller provided dynamic
buffer and returns the result as a std::ostream derived object.
Callers may now produce formatted output into any object meeting the
requirements of DynamicBuffer using operator<< and the standard stream
modifiers such as std::endl.

This new technique is more efficient, as implementations of operator<<
can now write directly into the output using std::ostream::write and
std::ostream::put.

Example of use:

  beast::streambuf sb;
  beast::ostream(sb) << "Hello, world!" << std::endl;

test/core/CMakeLists.txt

@@ -22,6 +22,7 @@ add_executable (core-tests
     handler_alloc.cpp
     handler_concepts.cpp
     handler_ptr.cpp
+    ostream.cpp
     placeholders.cpp
     prepare_buffer.cpp
     prepare_buffers.cpp
@@ -30,7 +31,6 @@ add_executable (core-tests
     stream_concepts.cpp
     streambuf.cpp
     to_string.cpp
-    write_dynabuf.cpp
     base64.cpp
     empty_base_optimization.cpp
     get_lowest_layer.cpp

test/core/ostream.cpp

@@ -0,0 +1,32 @@
+//
+// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Test that header file is self-contained.
+#include <beast/core/ostream.hpp>
+
+#include <beast/core/streambuf.hpp>
+#include <beast/unit_test/suite.hpp>
+#include <ostream>
+
+#include <beast/core/to_string.hpp>
+
+namespace beast {
+
+class ostream_test : public beast::unit_test::suite
+{
+public:
+    void run() override
+    {
+        streambuf sb;
+        ostream(sb) << "Hello, world!\n";
+        BEAST_EXPECT(to_string(sb.data()) == "Hello, world!\n");
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(ostream,core,beast);
+
+} // beast

test/core/streambuf.cpp

@@ -273,13 +273,6 @@ public:
         BEAST_EXPECT(test::buffer_count(sb.data()) == 4);
     }
 
-    void testOutputStream()
-    {
-        streambuf sb;
-        sb << "x";
-        BEAST_EXPECT(to_string(sb.data()) == "x");
-    }
-
     void testCapacity()
     {
         using boost::asio::buffer_size;
@@ -353,7 +346,6 @@ public:
         testConsume();
         testMatrix();
         testIterators();
-        testOutputStream();
         testCapacity();
     }
 };

test/core/write_dynabuf.cpp

@@ -1,36 +0,0 @@
-//
-// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-// Test that header file is self-contained.
-#include <beast/core/write_dynabuf.hpp>
-
-#include <beast/core/streambuf.hpp>
-#include <beast/unit_test/suite.hpp>
-
-namespace beast {
-
-class write_dynabuf_test : public beast::unit_test::suite
-{
-public:
-    void run() override
-    {
-        streambuf sb;
-        std::string s;
-        write(sb, boost::asio::const_buffer{"", 0});
-        write(sb, boost::asio::mutable_buffer{nullptr, 0});
-        write(sb, boost::asio::null_buffers{});
-        write(sb, boost::asio::const_buffers_1{"", 0});
-        write(sb, boost::asio::mutable_buffers_1{nullptr, 0});
-        write(sb, s);
-        write(sb, 23);
-        pass();
-    }
-};
-
-BEAST_DEFINE_TESTSUITE(write_dynabuf,core,beast);
-
-} // beast