Optimization - Get rid of the vector that held the unique_ptr.

Use the replies list directly. I can't see any significant
performance improvement yet, but there is something else I want to
try starting from this point.

include/incredis/batch.hpp

@@ -20,8 +20,9 @@
 
 #include "reply.hpp"
 #include "arg_to_bin_safe.hpp"
-#include <vector>
+#include "sized_range.hpp"
 #include <memory>
+#include <forward_list>
 
 namespace redis {
 	class Command;
@@ -31,12 +32,15 @@ namespace redis {
 	class Batch {
 		friend class Command;
 	public:
+		using ConstReplies = SizedRange<std::forward_list<Reply>::const_iterator>;
+		using Replies = SizedRange<std::forward_list<Reply>::iterator>;
+
 		Batch ( Batch&& parOther );
 		Batch ( const Batch& ) = delete;
 		~Batch ( void ) noexcept;
 
-		const std::vector<Reply>& replies ( void );
-		std::vector<Reply>& replies_nonconst ( void );
+		ConstReplies replies ( void ) const;
+		Replies replies_nonconst ( void );
 		bool replies_requested ( void ) const;
 		void throw_if_failed ( void );
 
@@ -54,8 +58,6 @@ namespace redis {
 		explicit Batch ( AsyncConnection* parConn, ThreadContext& parThreadContext );
 		void run_pvt ( int parArgc, const char** parArgv, std::size_t* parLengths );
 
-		std::vector<std::unique_ptr<Reply>> m_futures;
-		std::vector<Reply> m_replies;
 		std::unique_ptr<LocalData> m_local_data;
 		AsyncConnection* m_async_conn;
 	};

include/incredis/incredis_batch.hpp

@@ -27,6 +27,8 @@
 namespace redis {
 	class IncRedisBatch {
 	public:
+		using ConstReplies = Batch::ConstReplies;
+
 		enum ZADD_Mode {
 			ZADD_XX_UpdateOnly,
 			ZADD_NX_AlwaysAdd,
@@ -46,7 +48,7 @@ namespace redis {
 
 		void reset ( void );
 		void throw_if_failed ( void );
-		const std::vector<Reply>& replies ( void ) { return m_batch.replies(); }
+		ConstReplies replies ( void ) { return m_batch.replies(); }
 		Batch& batch ( void ) { return m_batch; }
 		const Batch& batch ( void ) const { return m_batch; }
 

include/incredis/sized_range.hpp

@@ -0,0 +1,56 @@
+/* Copyright 2016, Michele Santullo
+ * This file is part of "incredis".
+ *
+ * "incredis" is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * "incredis" is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with "incredis".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef idC3909E193A3C4DBEB9B646A4F5ED3518
+#define idC3909E193A3C4DBEB9B646A4F5ED3518
+
+#include <boost/range/iterator_range_core.hpp>
+#include <cstddef>
+#include <cassert>
+#include <ciso646>
+
+namespace redis {
+	template <typename I>
+	class SizedRange : public boost::iterator_range<I> {
+	public:
+		SizedRange ( I parBegin, I parEnd, std::size_t parSize ) :
+			boost::iterator_range<I>(parBegin, parEnd),
+			m_size(parSize)
+		{
+		}
+
+		template <typename R>
+		SizedRange ( R& parRange, std::size_t parSize ) :
+			boost::iterator_range<I>(parRange),
+			m_size(parSize)
+		{
+		}
+
+		~SizedRange ( void ) noexcept = default;
+
+		std::size_t size ( void ) const { return m_size; }
+		bool empty ( void ) const { return static_cast<bool>(0 == m_size); }
+
+		typename I::reference front ( void ) { assert(not empty()); return *this->begin(); }
+		const typename I::reference front ( void ) const { assert(not empty()); return *this->begin(); }
+
+	private:
+		std::size_t m_size;
+	};
+} //namespace redis
+
+#endif