replace constexpr with const becasuse vs2013 lack of support

include/c11log/details/fast_oss.h

@@ -4,6 +4,7 @@
 // uses stack_buf as the underlying buffer (upto 192 bytes before using the heap)
 
 #include <ostream>
+#include <iomanip>
 #include "stack_buf.h"
 
 namespace c11log
@@ -13,8 +14,8 @@ namespace details
 
 class stack_devicebuf :public std::streambuf
 {
-public:    
-	static constexpr unsigned short stack_size = 192;
+public:
+    static const unsigned short stack_size = 192;
     using stackbuf_t = stack_buf<stack_size>;
 
     stack_devicebuf() = default;

include/c11log/details/line_logger.h

@@ -6,7 +6,6 @@
 #include "fast_oss.h"
 
 
-
 // line_logger class.
 // aggregates single log line (on the stack if possibe) and calls the logger upon destruction
 

include/c11log/details/stack_buf.h

@@ -17,7 +17,7 @@ class stack_buf
 public:
     using bufpair_t = std::pair<const char*, std::size_t>;
     using iterator = char const*;
-    static constexpr unsigned short stack_size = STACK_SIZE;
+    static const unsigned short stack_size = STACK_SIZE;
     stack_buf() :_v(), _stack_size(0) {}
     ~stack_buf() = default;
 

include/c11log/formatter.h

@@ -34,10 +34,12 @@ public:
     {
         details::fast_oss oss;
         _format_time(msg.time, oss);
+
         if(!msg.logger_name.empty())
             oss << " [" <<  msg.logger_name << ':' << c11log::level::to_str(msg.level) << "] ";
         else
             oss << " [" << c11log::level::to_str(msg.level) << "] ";
+
         oss << msg.raw << details::os::eol();
         msg.formatted = oss.str();
     }

include/c11log/logger.h

@@ -31,7 +31,7 @@ public:
     using sinks_vector_t = std::vector<sink_ptr>;
     using sinks_init_list = std::initializer_list<sink_ptr>;
 
-    using formatter_ptr = std::shared_ptr<c11log::formatters::formatter>;
+    using formatter_ptr = std::unique_ptr<c11log::formatters::formatter>;
 
     logger(const std::string& name, sinks_init_list, formatter_ptr = nullptr);
     logger(const std::string& name, sink_ptr, formatter_ptr = nullptr);
@@ -92,18 +92,19 @@ logger& get_logger(const std::string& name);
 
 inline c11log::logger::logger(const std::string& name, sinks_init_list sinks_list, formatter_ptr f) :
     _logger_name(name),
-    _formatter(f),
+    _formatter(std::move(f)),
     _sinks(sinks_list)
 {
     //Seems that vs2013 doesnt support std::atomic member initialization, so its done here
     _min_level = level::INFO;
     if(!_formatter)
-        _formatter = std::make_shared<formatters::default_formatter>();
+        _formatter = std::make_unique<formatters::default_formatter>();
+
 }
 
 
 inline c11log::logger::logger(const std::string& name, sink_ptr sink, formatter_ptr f) :
-    logger(name, {sink}, f) {}
+    logger(name, {sink}, std::move(f)) {}