New buffers() replaces to_string() (API Change):

A new function, buffers(), returns an implementation defined object
which wraps a ConstBufferSequence and supports formatting to a
std::ostream.

The function to_string is removed, as the new implementation allows
conversion to string using boost::lexical_cast on the return value
of the call to buffers(). Streaming to an output stream is more
efficient: no dynamic allocations are performed.

Example:

    streambuf sb;
    std::cout << buffers(sb.data()) << std::endl;

test/core/CMakeLists.txt

@@ -30,7 +30,6 @@ add_executable (core-tests
     static_string.cpp
     stream_concepts.cpp
     streambuf.cpp
-    to_string.cpp
     base64.cpp
     empty_base_optimization.cpp
     get_lowest_layer.cpp

test/core/buffers_adapter.cpp

@@ -8,10 +8,12 @@
 // Test that header file is self-contained.
 #include <beast/core/buffers_adapter.hpp>
 
+#include <beast/core/ostream.hpp>
 #include <beast/core/streambuf.hpp>
 #include <beast/unit_test/suite.hpp>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/streambuf.hpp>
+#include <boost/lexical_cast.hpp>
 #include <iterator>
 
 namespace beast {
@@ -24,14 +26,8 @@ public:
     std::string
     to_string(ConstBufferSequence const& bs)
     {
-        using boost::asio::buffer_cast;
-        using boost::asio::buffer_size;
-        std::string s;
-        s.reserve(buffer_size(bs));
-        for(auto const& b : bs)
-            s.append(buffer_cast<char const*>(b),
-                buffer_size(b));
-        return s;
+        return boost::lexical_cast<
+            std::string>(buffers(bs));
     }
 
     void testBuffersAdapter()

test/core/consuming_buffers.cpp

@@ -9,7 +9,7 @@
 #include <beast/core/consuming_buffers.hpp>
 
 #include "buffer_test.hpp"
-#include <beast/core/to_string.hpp>
+#include <beast/core/ostream.hpp>
 #include <beast/unit_test/suite.hpp>
 #include <boost/asio/buffer.hpp>
 #include <string>
@@ -19,6 +19,15 @@ namespace beast {
 class consuming_buffers_test : public beast::unit_test::suite
 {
 public:
+    template<class ConstBufferSequence>
+    static
+    std::string
+    to_string(ConstBufferSequence const& bs)
+    {
+        return boost::lexical_cast<
+            std::string>(buffers(bs));
+    }
+
     template<class BufferSequence>
     static
     consuming_buffers<BufferSequence>

test/core/flat_streambuf.cpp

@@ -9,9 +9,10 @@
 #include <beast/core/flat_streambuf.hpp>
 
 #include "buffer_test.hpp"
-#include <beast/core/to_string.hpp>
+#include <beast/core/ostream.hpp>
 #include <beast/test/test_allocator.hpp>
 #include <beast/unit_test/suite.hpp>
+#include <boost/lexical_cast.hpp>
 #include <algorithm>
 
 namespace beast {
@@ -22,6 +23,15 @@ static_assert(is_DynamicBuffer<flat_streambuf>::value,
 class flat_streambuf_test : public beast::unit_test::suite
 {
 public:
+    template<class ConstBufferSequence>
+    static
+    std::string
+    to_string(ConstBufferSequence const& bs)
+    {
+        return boost::lexical_cast<
+            std::string>(buffers(bs));
+    }
+
     template<class Alloc1, class Alloc2>
     static
     bool

test/core/ostream.cpp

@@ -10,10 +10,9 @@
 
 #include <beast/core/streambuf.hpp>
 #include <beast/unit_test/suite.hpp>
+#include <boost/lexical_cast.hpp>
 #include <ostream>
 
-#include <beast/core/to_string.hpp>
-
 namespace beast {
 
 class ostream_test : public beast::unit_test::suite
@@ -23,7 +22,8 @@ public:
     {
         streambuf sb;
         ostream(sb) << "Hello, world!\n";
-        BEAST_EXPECT(to_string(sb.data()) == "Hello, world!\n");
+        BEAST_EXPECT(boost::lexical_cast<std::string>(
+            buffers(sb.data())) == "Hello, world!\n");
     }
 };
 

test/core/streambuf.cpp

@@ -10,7 +10,7 @@
 
 #include "buffer_test.hpp"
 #include <beast/core/buffer_concepts.hpp>
-#include <beast/core/to_string.hpp>
+#include <beast/core/ostream.hpp>
 #include <beast/test/test_allocator.hpp>
 #include <beast/unit_test/suite.hpp>
 #include <boost/asio/buffer.hpp>
@@ -26,6 +26,15 @@ static_assert(is_DynamicBuffer<streambuf>::value, "");
 class basic_streambuf_test : public beast::unit_test::suite
 {
 public:
+    template<class ConstBufferSequence>
+    static
+    std::string
+    to_string(ConstBufferSequence const& bs)
+    {
+        return boost::lexical_cast<
+            std::string>(buffers(bs));
+    }
+
     template<class Alloc1, class Alloc2>
     static
     bool

test/core/to_string.cpp

@@ -1,28 +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/to_string.hpp>
-
-#include <beast/unit_test/suite.hpp>
-#include <boost/asio/buffer.hpp>
-
-namespace beast {
-
-class to_string_test : public beast::unit_test::suite
-{
-public:
-    void run()
-    {
-        BEAST_EXPECT(to_string(boost::asio::const_buffers_1("x", 1)) == "x");
-    }
-};
-
-BEAST_DEFINE_TESTSUITE(to_string,core,beast);
-
-} // beast
-