Added experimental C++ feature define `_TRACE_USE_FMT`

Fortune for tracemac's current commit: Future blessing − 末吉

Makefile

@@ -158,6 +158,6 @@ uninstall:
 	cd $(INCLUDE) && find . -type f | xargs -I {} rm "$(DESTDIR)$(PREFIX)/include/{}"
 	-rmdir $(DESTDIR)$(PREFIX)/include/$(PROJECT)
 
-$(PROJECT)-test: lib$(PROJECT).so
+$(PROJECT)-test: lib$(PROJECT).a
-	$(CC) $(CFLAGS) src/test/*.c -o $@ -l:$< -Wl,-flto -Wl,-O3 $(LDFLAGS)
+	$(CXX) $(CXXFLAGS) src/test/*.cpp -o $@ -l:$< -lfmt -Wl,-flto -Wl,-O3 $(LDFLAGS)
 	-valgrind ./$@

include/trace.h

@@ -2,6 +2,14 @@
 #ifndef _TRACE_H
 #define _TRACE_H
 
+#ifdef __cplusplus
+#ifdef _TRACE_USE_FMT
+#include <utility>
+#include <fmt/format.h>
+#endif
+extern "C" {
+#endif
+
 #include <stdio.h>
 #include <stdarg.h>
 
@@ -33,5 +41,35 @@ const char* trace_name_of(enum trace_level lv);
 extern const char* const _TRACE_CONTROL_ENV_NAME;
 extern const char* const _trace_level_descriptions[_TRACE_LEVEL_NUM];
 
+#ifdef __cplusplus
+}
+#ifdef _TRACE_USE_FMT
+namespace Trace {
+
+	//TODO: How to get caller info?
+	template<trace_level Level, size_t N, typename... Args>
+	inline constexpr void printf(const char (&msg)[N], Args&&... pack) {
+		if (Level >= trace_max_level()) { fmt::vprint(stderr, msg, fmt::make_format_args(std::forward<Args>(pack)...)); std::putc('\n', stderr); };
+	}
+#define _TRACE_L(level, name) template<size_t N, typename... Args> \
+				inline constexpr void name(const char (&msg)[N], Args&&... pack) \
+				{ ::Trace::printf<TRACE_LEVEL_ ## level >(msg, std::forward<Args>(pack)...); }
+	_TRACE_L(DEBUG, Debug);
+	_TRACE_L(DEBUG, Trace);
+	
+	_TRACE_L(INFO, Info);
+	_TRACE_L(WARN, Warn);
+	_TRACE_L(ERROR, Error);
+	template<size_t N, typename... Args>
+	[[noreturn]]
+	inline constexpr void Fatal(const char (&msg)[N], Args&&... pack)
+	{ ::Trace::printf<TRACE_LEVEL_FATAL >(msg, std::forward<Args>(pack)...); 
+		::std::terminate();
+	}
+
+#undef _TRACE_L
+}
+#endif
+#endif
 
 #endif /* _TRACE_H */

src/test/main.cpp

@@ -0,0 +1,12 @@
+#include <trace.h>
+
+int main()
+{
+	Trace::printf<TRACE_LEVEL_DEBUG>("hello world");
+
+	Trace::Info("Info");
+	Trace::Warn("Warning: {}", 123);
+	Trace::Error("Error!: {}", "Error");
+	Trace::Fatal("Fatal error: {}", "terminating");
+	return 0;
+}