[ion] Add an event journal

It's pretty much just two callbacks that one can hook into to get some
events in or out of Ion.

It adds a couple useless checks and pointers to any build and could be
hidden behind a feature flag, but the extra weight is minimal.

ion/include/ion/events.h

@@ -53,6 +53,15 @@ enum class ShiftAlphaStatus {
 // Timeout is decremented
 Event getEvent(int * timeout);
 
+class Journal {
+public:
+  virtual void pushEvent(Event e) = 0;
+  virtual Event popEvent() = 0;
+};
+
+void replayFrom(Journal * l);
+void logTo(Journal * l);
+
 ShiftAlphaStatus shiftAlphaStatus();
 void setShiftAlphaStatus(ShiftAlphaStatus s);
 void removeShift();

ion/src/shared/events_keyboard.cpp

@@ -50,7 +50,11 @@ void resetLongRepetition() {
   ComputeAndSetRepetionFactor(sEventRepetitionCount);
 }
 
-Event getEvent(int * timeout) {
+static Keyboard::Key keyFromState(Keyboard::State state) {
+  return static_cast<Keyboard::Key>(63 - __builtin_clzll(state));
+}
+
+static inline Event innerGetEvent(int * timeout) {
   assert(*timeout > delayBeforeRepeat);
   assert(*timeout > delayBetweenRepeat);
   int time = 0;
@@ -114,5 +118,27 @@ Event getEvent(int * timeout) {
   }
 }
 
+static Journal * sSourceJournal = nullptr;
+static Journal * sDestinationJournal = nullptr;
+void replayFrom(Journal * l) { sSourceJournal = l; }
+void logTo(Journal * l) { sDestinationJournal = l; }
+
+Event getEvent(int * timeout) {
+  if (sSourceJournal != nullptr) {
+    Event e = sSourceJournal->popEvent();
+    if (e == None) {
+      sSourceJournal = nullptr;
+    } else {
+      return e;
+    }
+  }
+  Event e = innerGetEvent(timeout);
+  if (sDestinationJournal != nullptr && e != None) {
+    sDestinationJournal->pushEvent(e);
+  }
+  return e;
+}
+
+
 }
 }