Optionally use std::format in LOG4CXX_XXXXX_FMT macros instead of fmt…

…::format

src/examples/cpp/format-string.cpp

@@ -18,9 +18,13 @@
 #include <stdlib.h>
 #include <log4cxx/basicconfigurator.h>
 #include <locale.h>
+#if LOG4CXX_USING_STD_FORMAT
+#include <format>
+#else
 #include <fmt/core.h>
 #include <fmt/color.h>
 #include <fmt/ostream.h>
+#endif
 #include <iomanip>
 
 using namespace log4cxx;
@@ -34,7 +38,22 @@ std::ostream& operator<<( std::ostream& stream, const MyStruct& mystruct ){
 		stream << "[MyStruct x:" << mystruct.x << "]";
 		return stream;
 }
-#if FMT_VERSION >= (9 * 10000)
+
+#if LOG4CXX_USING_STD_FORMAT
+template <typename Char>
+struct basic_ostream_formatter
+	: std::formatter<std::basic_string_view<Char>, Char>
+{
+	template <typename T, typename OutputIt>
+	auto format(const T& value, std::basic_format_context<OutputIt, Char>& ctx) const -> OutputIt
+	{
+		std::basic_stringstream<Char> ss;
+		ss << value;
+		return std::formatter<std::basic_string_view<Char>, Char>::format(ss.view(), ctx);
+	}
+};
+template <> struct std::formatter<MyStruct> : basic_ostream_formatter<char> {};
+#elif FMT_VERSION >= (9 * 10000)
 template <> struct fmt::formatter<MyStruct> : ostream_formatter {};
 #endif
 
@@ -46,10 +65,12 @@ int main()
 	LoggerPtr rootLogger = Logger::getRootLogger();
 
 	LOG4CXX_INFO_FMT( rootLogger, "This is a {} mesage", "test" );
+#if !LOG4CXX_USING_STD_FORMAT
 	LOG4CXX_INFO_FMT( rootLogger, fmt::fg(fmt::color::red), "Messages can be colored" );
+#endif
 	LOG4CXX_INFO_FMT( rootLogger, "We can also align text to the {:<10} or {:>10}", "left", "right" );
 
-	MyStruct mine;
+	MyStruct mine{ 42 };
 	LOG4CXX_INFO_FMT( rootLogger, "This custom type {} can also be logged, since it implements operator<<", mine );
 
 	LOG4CXX_INFO( rootLogger, "Numbers can be formatted with excessive operator<<: "

src/main/include/CMakeLists.txt

@@ -96,6 +96,13 @@ if(NOT "log4cxx" STREQUAL "${LOG4CXX_NS}")
     set(LOG4CXX_DECLARE_DEFAULT_NS_ALIAS 1)
 endif()
 
+set(LOG4CXX_FORMAT_NAMESPACE "fmt" CACHE STRING "format() function namespace, choice of fmt (default), std")
+set_property(CACHE LOG4CXX_FORMAT_NAMESPACE PROPERTY STRINGS "fmt" "std")
+set(LOG4CXX_USE_STANDARD_FORMAT 0)
+if("std" STREQUAL "${LOG4CXX_FORMAT_NAMESPACE}")
+    set(LOG4CXX_USE_STANDARD_FORMAT 1)
+endif()
+
 # Configure log4cxx_private.h
 set(LOG4CXX_CHARSET "utf-8" CACHE STRING "LogString characters, choice of utf-8 (default), ISO-8859-1, US-ASCII, EBCDIC, locale")
 set_property(CACHE LOG4CXX_CHARSET PROPERTY STRINGS "utf-8" "ISO-8859-1" "US-ASCII" "EBCDIC" "locale")

src/main/include/log4cxx/log4cxx.h.in

@@ -123,4 +123,11 @@ LOG4CXX_EXPORT uint32_t libraryVersion();
 namespace log4cxx = LOG4CXX_NS;
 #endif
 
+#define LOG4CXX_USING_STD_FORMAT @LOG4CXX_USE_STANDARD_FORMAT@
+#if LOG4CXX_USING_STD_FORMAT
+#define LOG4CXX_FORMAT_NS std
+#elif !defined(LOG4CXX_FORMAT_NS)
+#define LOG4CXX_FORMAT_NS fmt
+#endif
+
 #endif

src/main/include/log4cxx/logger.h

@@ -2037,7 +2037,7 @@ Add a new logging event containing libfmt formatted <code>...</code> to attached
 */
 #define LOG4CXX_LOG_FMT(logger, level, ...) do { \
 		if (logger->isEnabledFor(level)) {\
-			logger->addEvent(level, fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(level, ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 
 /**
 Add a new logging event containing \c message to attached appender(s) if this logger is enabled for \c events.
@@ -2083,7 +2083,7 @@ Add a new logging event containing libfmt formatted <code>...</code> to attached
 */
 #define LOG4CXX_DEBUG_FMT(logger, ...) do { \
 		if (LOG4CXX_UNLIKELY(::LOG4CXX_NS::Logger::isDebugEnabledFor(logger))) {\
-			logger->addEvent(::LOG4CXX_NS::Level::getDebug(), fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(::LOG4CXX_NS::Level::getDebug(), ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 #else
 #define LOG4CXX_DEBUG(logger, message)
 #define LOG4CXX_DEBUG_FMT(logger, ...)
@@ -2115,7 +2115,7 @@ Add a new logging event containing libfmt formatted <code>...</code> to attached
 */
 #define LOG4CXX_TRACE_FMT(logger, ...) do { \
 		if (LOG4CXX_UNLIKELY(::LOG4CXX_NS::Logger::isTraceEnabledFor(logger))) {\
-			logger->addEvent(::LOG4CXX_NS::Level::getTrace(), fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(::LOG4CXX_NS::Level::getTrace(), ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 #else
 #define LOG4CXX_TRACE(logger, message)
 #define LOG4CXX_TRACE_FMT(logger, ...)
@@ -2151,7 +2151,7 @@ Add a new logging event containing libfmt formatted <code>...</code> to attached
 */
 #define LOG4CXX_INFO_FMT(logger, ...) do { \
 		if (::LOG4CXX_NS::Logger::isInfoEnabledFor(logger)) {\
-			logger->addEvent(::LOG4CXX_NS::Level::getInfo(), fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(::LOG4CXX_NS::Level::getInfo(), ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 #else
 #define LOG4CXX_INFO(logger, message)
 #define LOG4CXX_INFO_FMT(logger, ...)
@@ -2185,7 +2185,7 @@ Add a new logging event containing libfmt formatted <code>...</code> to attached
 */
 #define LOG4CXX_WARN_FMT(logger, ...) do { \
 		if (::LOG4CXX_NS::Logger::isWarnEnabledFor(logger)) {\
-			logger->addEvent(::LOG4CXX_NS::Level::getWarn(), fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(::LOG4CXX_NS::Level::getWarn(), ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 #else
 #define LOG4CXX_WARN(logger, message)
 #define LOG4CXX_WARN_FMT(logger, ...)
@@ -2219,7 +2219,7 @@ Add a new logging event containing libfmt formatted <code>...</code> to attached
 */
 #define LOG4CXX_ERROR_FMT(logger, ...) do { \
 		if (::LOG4CXX_NS::Logger::isErrorEnabledFor(logger)) {\
-			logger->addEvent(::LOG4CXX_NS::Level::getError(), fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(::LOG4CXX_NS::Level::getError(), ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 
 /**
 If \c condition is not true, add a new logging event containing \c message to attached appender(s) if \c logger is enabled for <code>ERROR</code> events.
@@ -2244,7 +2244,7 @@ If \c condition is not true, add a new logging event containing libfmt formatted
 #define LOG4CXX_ASSERT_FMT(logger, condition, ...) do { \
 		if (!(condition) && ::LOG4CXX_NS::Logger::isErrorEnabledFor(logger)) {\
 			LOG4CXX_STACKTRACE \
-			logger->addEvent(::LOG4CXX_NS::Level::getError(), fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(::LOG4CXX_NS::Level::getError(), ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 
 #else
 #define LOG4CXX_ERROR(logger, message)
@@ -2278,7 +2278,7 @@ Add a new logging event containing libfmt formatted <code>...</code> to attached
 */
 #define LOG4CXX_FATAL_FMT(logger, ...) do { \
 		if (::LOG4CXX_NS::Logger::isFatalEnabledFor(logger)) {\
-			logger->addEvent(::LOG4CXX_NS::Level::getFatal(), fmt::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
+			logger->addEvent(::LOG4CXX_NS::Level::getFatal(), ::LOG4CXX_FORMAT_NS::format( __VA_ARGS__ ), LOG4CXX_LOCATION); }} while (0)
 #else
 #define LOG4CXX_FATAL(logger, message)
 #define LOG4CXX_FATAL_FMT(logger, ...)

src/test/cpp/benchmark/benchmark.cpp

@@ -4,7 +4,11 @@
 #include <log4cxx/helpers/optionconverter.h>
 #include <log4cxx/helpers/stringhelper.h>
 #include <log4cxx/asyncappender.h>
+#if LOG4CXX_USING_STD_FORMAT
+#include <format>
+#else
 #include <fmt/format.h>
+#endif
 #include <benchmark/benchmark.h>
 #include <thread>
 

src/test/cpp/throughput/log4cxxbenchmarker.cpp

@@ -20,8 +20,11 @@
 #include <log4cxx/patternlayout.h>
 #include <log4cxx/appenderskeleton.h>
 
+#if LOG4CXX_USING_STD_FORMAT
+#include <format>
+#else
 #include <fmt/format.h>
-
+#endif
 namespace LOG4CXX_NS
 {
 

src/test/cpp/throughput/throughput-main.cpp

@@ -24,9 +24,13 @@
 #include <string>
 #include <thread>
 
+#if LOG4CXX_USING_STD_FORMAT
+#include <format>
+#else
 #include <fmt/core.h>
 #include <fmt/chrono.h>
 #include <fmt/ostream.h>
+#endif
 
 #include "log4cxxbenchmarker.h"
 using log4cxx::LogString;