Add LoggingOstream to make a std::ostream that prints to logging

fpsdk_common/include/fpsdk_common/logging.hpp

@@ -359,6 +359,50 @@ void LoggingPrint(const LoggingLevel level, const std::size_t repeat, const char
 void LoggingHexdump(const LoggingLevel level, const uint8_t* data, const std::size_t size, const char* prefix,
     const char* fmt, ...) PRINTF_ATTR(5);
 
+/**
+ * @brief Utility to create a std::ostream that prints through the logging system
+ *
+ * For example:
+ *
+ * @code{cpp}
+ * auto w = LoggingOstream(LoggingLevel::WARNING);
+ * *w << "Hello world!" << std::endl;  // This should print: Warning: Hello world!
+ * @endcode
+ *
+ * @note Flushing the stream is required for the log message to be printed. Typically, std::endl flushes. Otherwise
+ *       explicitly flush using std::flush when appropriate.
+ */
+class LoggingOstream
+{
+   public:
+    /**
+     * @brief Constructor
+     *
+     * @param[in]  level  The logging level to use
+     */
+    LoggingOstream(const LoggingLevel level);
+
+    /**
+     * @brief Get stream handle
+     *
+     * @returns the stream handle
+     */
+    std::ostream& operator*()
+    {
+        return str_;
+    }
+
+   private:
+    //! Helper buffer that prints through logging
+    struct StrBuf : public std::stringbuf
+    {
+        virtual int sync();   //!< Print function implementation
+        LoggingLevel level_;  //!< Logging level
+    };
+    StrBuf buf_;        //!< Helper buffer
+    std::ostream str_;  //!< Stream handle
+};
+
 // Helper macros
 #ifndef _DOXYGEN_
 #  define _FPSDK_LOGGING_LOG(_level_, ...) \

fpsdk_common/src/logging.cpp

@@ -360,6 +360,34 @@ void LoggingHexdump(
     }
 }
 
+// ---------------------------------------------------------------------------------------------------------------------
+
+LoggingOstream::LoggingOstream(const LoggingLevel level) : str_{ &buf_ }
+{
+    buf_.level_ = level;
+}
+
+int LoggingOstream::StrBuf::sync()
+{
+    // Print each line
+    const auto s = this->str();
+    std::size_t offs = 0;
+    std::size_t pos = 0;
+    while ((pos = s.find("\n", offs)) != std::string::npos) {
+        switch (level_) {  // clang-format off
+            case LoggingLevel::FATAL:   FATAL(  "%s", s.substr(offs, pos).c_str()); break;
+            case LoggingLevel::ERROR:   ERROR(  "%s", s.substr(offs, pos).c_str()); break;
+            case LoggingLevel::WARNING: WARNING("%s", s.substr(offs, pos).c_str()); break;
+            case LoggingLevel::NOTICE:  NOTICE( "%s", s.substr(offs, pos).c_str()); break;
+            case LoggingLevel::INFO:    INFO(   "%s", s.substr(offs, pos).c_str()); break;
+            case LoggingLevel::DEBUG:   DEBUG(  "%s", s.substr(offs, pos).c_str()); break;
+            case LoggingLevel::TRACE:   TRACE(  "%s", s.substr(offs, pos).c_str()); break;
+            }  // clang-format on
+        offs = pos + 1;
+    }
+    return 0;
+}
+
 /* ****************************************************************************************************************** */
 }  // namespace logging
 }  // namespace common