1 files changed, 114 insertions, 0 deletions
diff --git a/include/cru/common/Logger.h b/include/cru/common/Logger.h
new file mode 100644
index 00000000..25875651
--- /dev/null
+++ b/include/cru/common/Logger.h
@@ -0,0 +1,114 @@
+#pragma once
+#include "Base.h"
+
+#include "String.h"
+#include "Format.h"
+
+#include <list>
+#include <memory>
+
+namespace cru::log {
+
+enum class LogLevel { Debug, Info, Warn, Error };
+
+struct CRU_BASE_API ILogSource : virtual Interface {
+  // Write the string s. LogLevel is just a helper. It has no effect on the
+  // content to write.
+  virtual void Write(LogLevel level, StringView s) = 0;
+};
+
+class CRU_BASE_API Logger : public Object {
+ public:
+  static Logger* GetInstance();
+
+ public:
+  Logger() = default;
+
+  CRU_DELETE_COPY(Logger)
+  CRU_DELETE_MOVE(Logger)
+
+  ~Logger() override = default;
+
+ public:
+  void AddSource(std::unique_ptr<ILogSource> source);
+  void RemoveSource(ILogSource* source);
+
+ public:
+  void Log(LogLevel level, StringView message);
+  void Log(LogLevel level, StringView tag, StringView message);
+
+ private:
+  std::list<std::unique_ptr<ILogSource>> sources_;
+};
+
+// TODO: Remove argument evaluation in Debug.
+template <typename... TArgs>
+void Debug([[maybe_unused]] TArgs&&... args) {
+#ifdef CRU_DEBUG
+  Logger::GetInstance()->Log(LogLevel::Debug,
+                             Format(std::forward<TArgs>(args)...));
+#endif
+}
+
+template <typename... TArgs>
+void Info(TArgs&&... args) {
+  Logger::GetInstance()->Log(LogLevel::Info,
+                             Format(std::forward<TArgs>(args)...));
+}
+
+template <typename... TArgs>
+void Warn(TArgs&&... args) {
+  Logger::GetInstance()->Log(LogLevel::Warn,
+                             Format(std::forward<TArgs>(args)...));
+}
+
+template <typename... TArgs>
+void Error(TArgs&&... args) {
+  Logger::GetInstance()->Log(LogLevel::Error,
+                             Format(std::forward<TArgs>(args)...));
+}
+
+// TODO: Remove argument evaluation in Debug.
+template <typename... TArgs>
+void TagDebug([[maybe_unused]] StringView tag,
+              [[maybe_unused]] TArgs&&... args) {
+#ifdef CRU_DEBUG
+  Logger::GetInstance()->Log(LogLevel::Debug, tag,
+                             Format(std::forward<TArgs>(args)...));
+#endif
+}
+
+template <typename... TArgs>
+void TagInfo(StringView tag, TArgs&&... args) {
+  Logger::GetInstance()->Log(LogLevel::Info, tag,
+                             Format(std::forward<TArgs>(args)...));
+}
+
+template <typename... TArgs>
+void TagWarn(StringView tag, TArgs&&... args) {
+  Logger::GetInstance()->Log(LogLevel::Warn, tag,
+                             Format(std::forward<TArgs>(args)...));
+}
+
+template <typename... TArgs>
+void TagError(StringView tag, TArgs&&... args) {
+  Logger::GetInstance()->Log(LogLevel::Error, tag,
+                             Format(std::forward<TArgs>(args)...));
+}
+
+class StdioLogSource : public Object, public virtual ILogSource {
+ public:
+  explicit StdioLogSource(bool use_lock = false);
+
+  CRU_DELETE_COPY(StdioLogSource)
+  CRU_DELETE_MOVE(StdioLogSource)
+
+  ~StdioLogSource() override;
+
+ public:
+  void Write(LogLevel level, StringView s) override;
+
+ private:
+  bool use_lock_;
+};
+}  // namespace cru::log