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/http/chunk_encode.cpp

@@ -8,8 +8,9 @@
 // Test that header file is self-contained.
 #include <beast/http/chunk_encode.hpp>
 
-#include <beast/core/to_string.hpp>
+#include <beast/core/ostream.hpp>
 #include <beast/unit_test/suite.hpp>
+#include <boost/lexical_cast.hpp>
 
 namespace beast {
 namespace http {
@@ -30,6 +31,15 @@ public:
         }
     };
 
+    template<class ConstBufferSequence>
+    static
+    std::string
+    to_string(ConstBufferSequence const& bs)
+    {
+        return boost::lexical_cast<
+            std::string>(buffers(bs));
+    }
+
     static
     void
     encode1(std::string& s, final_chunk const& fc)

test/http/dynamic_body.cpp

@@ -8,7 +8,7 @@
 // Test that header file is self-contained.
 #include <beast/http/dynamic_body.hpp>
 
-#include <beast/core/to_string.hpp>
+#include <beast/core/ostream.hpp>
 #include <beast/http/fields.hpp>
 #include <beast/http/message_parser.hpp>
 #include <beast/http/read.hpp>
@@ -25,7 +25,8 @@ class dynamic_body_test : public beast::unit_test::suite
     boost::asio::io_service ios_;
 
 public:
-    void run() override
+    void
+    run() override
     {
         std::string const s =
             "HTTP/1.1 200 OK\r\n"
@@ -38,7 +39,8 @@ public:
         streambuf sb;
         read(ss, sb, p);
         auto const& m = p.get();
-        BEAST_EXPECT(to_string(m.body.data()) == "xyz");
+        BEAST_EXPECT(boost::lexical_cast<std::string>(
+            buffers(m.body.data())) == "xyz");
         BEAST_EXPECT(boost::lexical_cast<std::string>(m) == s);
     }
 };

test/http/parser_bench.cpp

@@ -10,9 +10,10 @@
 
 #include <beast/http.hpp>
 #include <beast/core/consuming_buffers.hpp>
+#include <beast/core/ostream.hpp>
 #include <beast/core/streambuf.hpp>
-#include <beast/core/to_string.hpp>
 #include <beast/unit_test/suite.hpp>
+#include <boost/lexical_cast.hpp>
 #include <chrono>
 #include <iostream>
 #include <vector>
@@ -31,6 +32,15 @@ public:
     corpus cres_;
     std::size_t size_ = 0;
 
+    template<class ConstBufferSequence>
+    static
+    std::string
+    to_string(ConstBufferSequence const& bs)
+    {
+        return boost::lexical_cast<
+            std::string>(buffers(bs));
+    }
+
     parser_bench_test()
     {
         creq_ = build_corpus(N/2, std::true_type{});

test/http/write.cpp

@@ -14,7 +14,6 @@
 #include <beast/http/write.hpp>
 #include <beast/core/error.hpp>
 #include <beast/core/streambuf.hpp>
-#include <beast/core/to_string.hpp>
 #include <beast/test/fail_stream.hpp>
 #include <beast/test/string_ostream.hpp>
 #include <beast/test/yield_to.hpp>