Add abstract streams module:

* New basic_abstract_ostream template for generic output
* New abstract_ostream, common type alias
* basic_scoped_ostream, RAII output to abstract streams

beast/streams/basic_scoped_ostream.h

@@ -0,0 +1,149 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of Beast: https://github.com/vinniefalco/Beast
+    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef BEAST_STREAMS_BASIC_SCOPED_OSTREAM_H_INCLUDED
+#define BEAST_STREAMS_BASIC_SCOPED_OSTREAM_H_INCLUDED
+
+#include "../cxx14/memory.h" // <memory>
+#include <functional>
+#include <memory>
+#include <sstream>
+
+// gcc libstd++ doesn't have move constructors for basic_ostringstream
+// http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54316
+//
+#ifndef BEAST_NO_STDLIB_STREAM_MOVE
+# ifdef __GLIBCXX__
+#  define BEAST_NO_STDLIB_STREAM_MOVE 1
+# else
+#  define BEAST_NO_STDLIB_STREAM_MOVE 0
+# endif
+#endif
+
+namespace beast {
+
+template <
+    class CharT,
+    class Traits
+>
+class basic_abstract_ostream;
+
+/** Scoped output stream that forwards to a functor upon destruction. */
+template <
+    class CharT,
+    class Traits = std::char_traits <CharT>,
+    class Allocator = std::allocator <CharT>
+>
+class basic_scoped_ostream
+{
+private:
+    typedef std::function <void (
+        std::basic_string <CharT, Traits, Allocator> const&)> handler_t;
+
+    typedef std::basic_ostringstream <
+        CharT, Traits, Allocator> stream_type;
+
+    handler_t m_handler;
+
+#if BEAST_NO_STDLIB_STREAM_MOVE
+    std::unique_ptr <stream_type> m_ss;
+
+    stream_type& stream()
+    {
+        return *m_ss;
+    }
+
+#else
+    stream_type m_ss;
+
+    stream_type& stream()
+    {
+        return m_ss;
+    }
+
+#endif
+
+public:
+    typedef std::basic_string <CharT, Traits> string_type;
+
+    // Disallow copy since that would duplicate the output
+    basic_scoped_ostream (basic_scoped_ostream const&) = delete;
+    basic_scoped_ostream& operator= (basic_scoped_ostream const) = delete;
+
+    template <class Handler>
+    explicit basic_scoped_ostream (Handler&& handler)
+        : m_handler (std::forward <Handler> (handler))
+    #if BEAST_NO_STDLIB_STREAM_MOVE
+        , m_ss (std::make_unique <stream_type>())
+    #endif
+    {
+    }
+
+    template <class T, class Handler>
+    basic_scoped_ostream (T const& t, Handler&& handler)
+        : m_handler (std::forward <Handler> (handler))
+    #if BEAST_NO_STDLIB_STREAM_MOVE
+        , m_ss (std::make_unique <stream_type>())
+    #endif
+    {
+        stream() << t;
+    }
+
+    basic_scoped_ostream (basic_abstract_ostream <
+        CharT, Traits>& ostream)
+        : m_handler (
+            [&](string_type const& s)
+            {
+                ostream.write (s);
+            })
+    {
+    }
+
+    basic_scoped_ostream (basic_scoped_ostream&& other)
+        : m_handler (std::move (other.m_handler))
+        , m_ss (std::move (other.m_ss))
+    {
+    }
+
+    ~basic_scoped_ostream()
+    {
+        auto const& s (stream().str());
+        if (! s.empty())
+            m_handler (s);
+    }
+
+    basic_scoped_ostream&
+    operator<< (std::ostream& manip (std::ostream&))
+    {
+        stream() << manip;
+        return *this;
+    }
+
+    template <class T>
+    basic_scoped_ostream&
+    operator<< (T const& t)
+    {
+        stream() << t;
+        return *this;
+    }
+};
+
+}
+
+#endif