refactor app code (#93)

Tactility/Private/app/AppInstance.h

@@ -0,0 +1,66 @@
+#pragma once
+
+#include "app/App.h"
+#include "app/Manifest.h"
+#include "Bundle.h"
+#include "Mutex.h"
+
+namespace tt::app {
+
+typedef enum {
+    StateInitial, // App is being activated in loader
+    StateStarted, // App is in memory
+    StateShowing, // App view is created
+    StateHiding,  // App view is destroyed
+    StateStopped  // App is not in memory
+} State;
+
+/**
+ * Thread-safe app instance.
+ */
+class AppInstance : public App {
+
+private:
+
+    Mutex mutex = Mutex(MutexTypeNormal);
+    const Manifest& manifest;
+    State state = StateInitial;
+    Flags flags = { .showStatusbar = true };
+    /** @brief Optional parameters to start the app with
+     * When these are stored in the app struct, the struct takes ownership.
+     * Do not mutate after app creation.
+     */
+    tt::Bundle parameters;
+    /** @brief @brief Contextual data related to the running app's instance
+     * The app can attach its data to this.
+     * The lifecycle is determined by the on_start and on_stop methods in the AppManifest.
+     * These manifest methods can optionally allocate/free data that is attached here.
+     */
+    void* _Nullable data = nullptr;
+
+public:
+
+    AppInstance(const Manifest& manifest) :
+        manifest(manifest) {}
+
+    AppInstance(const Manifest& manifest, const Bundle& parameters) :
+        manifest(manifest),
+        parameters(parameters) {}
+
+    ~AppInstance() {}
+
+    void setState(State state);
+    State getState() const;
+
+    const Manifest& getManifest() const;
+
+    Flags getFlags() const;
+    void setFlags(Flags flags);
+
+    _Nullable void* getData() const;
+    void setData(void* data);
+
+    const Bundle& getParameters() const;
+};
+
+} // namespace

Tactility/Private/service/loader/Loader_i.h

@@ -1,11 +1,13 @@
 #pragma once
 
 #include "app/Manifest.h"
+#include "app/AppInstance.h"
 #include "MessageQueue.h"
 #include "Pubsub.h"
 #include "Thread.h"
 #include "service/gui/ViewPort.h"
 #include "service/loader/Loader.h"
+#include <stack>
 
 #ifdef ESP_PLATFORM
 #include "freertos/FreeRTOS.h"
@@ -108,8 +110,7 @@ struct Loader {
     PubSub* pubsub_external;
     MessageQueue queue = MessageQueue(1, sizeof(LoaderMessage));
     Mutex* mutex;
-    int8_t app_stack_index;
-    app::App app_stack[APP_STACK_SIZE];
+    std::stack<app::AppInstance*> app_stack;
 };
 
 } // namespace