emscripten logging sink

include/spdlog/details/registry-inl.h

@@ -13,8 +13,11 @@
 #include <spdlog/pattern_formatter.h>
 
 #ifndef SPDLOG_DISABLE_DEFAULT_LOGGER
+    // Include emscripten sink on emscripten builds
+    #if defined(__EMSCRIPTEN__)
+        #include <spdlog/sinks/emscripten_sink.h>
     // support for the default stdout color logger
-    #ifdef _WIN32
+    #elif defined(_WIN32)
         #include <spdlog/sinks/wincolor_sink.h>
     #else
         #include <spdlog/sinks/ansicolor_sink.h>
@@ -33,8 +36,10 @@ namespace details {
 SPDLOG_INLINE registry::registry()
     : formatter_(new pattern_formatter()) {
 #ifndef SPDLOG_DISABLE_DEFAULT_LOGGER
-    // create default logger (ansicolor_stdout_sink_mt or wincolor_stdout_sink_mt in windows).
-    #ifdef _WIN32
+    // create default logger (ansicolor_stdout_sink_mt or wincolor_stdout_sink_mt in windows, or emscripten_sink_mt on emscripten).
+    #if defined(__EMSCRIPTEN__)
+    auto color_sink = std::make_shared<sinks::emscripten_sink_mt>();
+    #elif defined(_WIN32)
     auto color_sink = std::make_shared<sinks::wincolor_stdout_sink_mt>();
     #else
     auto color_sink = std::make_shared<sinks::ansicolor_stdout_sink_mt>();

include/spdlog/sinks/emscripten_sink.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#ifdef __EMSCRIPTEN__
+
+#include <spdlog/details/fmt_helper.h>
+#include <spdlog/details/null_mutex.h>
+#include <spdlog/details/os.h>
+#include <spdlog/details/synchronous_factory.h>
+#include <spdlog/sinks/base_sink.h>
+
+#include <emscripten/emscripten.h>
+#include <chrono>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <type_traits>
+
+
+namespace spdlog {
+namespace sinks {
+
+/*
+ * Emscripten sink
+ * (logging using emscripten_log)
+ */
+
+template<typename Mutex>
+class emscripten_sink : public base_sink <Mutex>
+{
+    void sink_it_(const details::log_msg& msg) override
+    {
+        // log_msg is a struct containing the log entry info like level, timestamp, thread id etc.
+        // msg.payload (before v1.3.0: msg.raw) contains pre formatted log
+
+        // If needed (very likely but not mandatory), the sink formats the message before sending it to its final destination:
+        memory_buf_t formatted;
+        base_sink<Mutex>::formatter_->format(msg, formatted);
+        emscripten_log(EM_LOG_CONSOLE | convert_to_emscripten_(msg.level), "%s", fmt::to_string(formatted).c_str());
+    }
+
+    void flush_() override {}
+
+private:
+    static int convert_to_emscripten_(spdlog::level::level_enum level) {
+        switch (level) {
+            case spdlog::level::trace:
+            case spdlog::level::debug:
+                return EM_LOG_DEBUG;
+            case spdlog::level::info:
+                return EM_LOG_INFO;
+            case spdlog::level::warn:
+                return EM_LOG_WARN;
+            case spdlog::level::err:
+            case spdlog::level::critical:
+                return EM_LOG_ERROR;
+            default:
+                return 0;
+        }
+    }
+};
+
+using emscripten_sink_mt = emscripten_sink<std::mutex>;
+using emscripten_sink_st = emscripten_sink<details::null_mutex>;
+
+}  // namespace sinks
+
+}  // namespace spdlog
+
+#endif  // __EMSCRIPTEN__