[build] move logging to util

1 files changed, 80 insertions, 0 deletions

diff --git a/include/mbgl/util/logging.hpp b/include/mbgl/util/logging.hpp
new file mode 100644
index 0000000000..d072673e76
--- /dev/null
+++ b/include/mbgl/util/logging.hpp
@@ -0,0 +1,80 @@
+#pragma once
+
+#include <mbgl/util/event.hpp>
+
+#include <mbgl/util/noncopyable.hpp>
+
+#include <memory>
+#include <string>
+
+namespace mbgl {
+
+class Log {
+public:
+    class Observer : private util::noncopyable {
+    public:
+        virtual ~Observer() = default;
+
+        // When an observer is set, this function will be called for every log
+        // message. Returning true will consume the message.
+        virtual bool onRecord(EventSeverity severity, Event event, int64_t code, const std::string &msg) = 0;
+    };
+
+    class NullObserver : public Observer {
+        bool onRecord(EventSeverity, Event, int64_t, const std::string&) override {
+            return true;
+        }
+    };
+
+    static void setObserver(std::unique_ptr<Observer> Observer);
+    static std::unique_ptr<Observer> removeObserver();
+
+private:
+    template <typename T, size_t N>
+    constexpr static bool includes(const T e, const T (&l)[N], const size_t i = 0) {
+        return i < N && (l[i] == e || includes(e, l, i + 1));
+    }
+
+public:
+    template <typename ...Args>
+    static void Debug(Event event, Args&& ...args) {
+        Record(EventSeverity::Debug, event, ::std::forward<Args>(args)...);
+    }
+
+    template <typename ...Args>
+    static void Info(Event event, Args&& ...args) {
+        Record(EventSeverity::Info, event, ::std::forward<Args>(args)...);
+    }
+
+    template <typename ...Args>
+    static void Warning(Event event, Args&& ...args) {
+        Record(EventSeverity::Warning, event, ::std::forward<Args>(args)...);
+    }
+
+    template <typename ...Args>
+    static void Error(Event event, Args&& ...args) {
+        Record(EventSeverity::Error, event, ::std::forward<Args>(args)...);
+    }
+
+    template <typename ...Args>
+    static void Record(EventSeverity severity, Event event, Args&& ...args) {
+        if (!includes(severity, disabledEventSeverities) &&
+            !includes(event, disabledEvents) &&
+            !includes({ severity, event }, disabledEventPermutations)) {
+                record(severity, event, ::std::forward<Args>(args)...);
+        }
+    }
+
+private:
+    static void record(EventSeverity severity, Event event, const std::string &msg);
+    static void record(EventSeverity severity, Event event, const char* format, ...);
+    static void record(EventSeverity severity, Event event, int64_t code);
+    static void record(EventSeverity severity, Event event, int64_t code, const std::string &msg);
+
+    // This method is the data sink that must be implemented by each platform we
+    // support. It should ideally output the error message in a human readable
+    // format to the developer.
+    static void platformRecord(EventSeverity severity, const std::string &msg);
+};
+
+} // namespace mbgl