InputManager: Switch InputEventHandler to std::variant

pcsx2/Frontend/InputManager.cpp

@@ -25,6 +25,7 @@
 #include <mutex>
 #include <sstream>
 #include <unordered_map>
+#include <variant>
 #include <vector>
 
 // ------------------------------------------------------------------------
@@ -45,102 +46,7 @@ enum : u32
 // This class acts as an adapter to convert from normalized values to
 // binary values when the callback is a binary/button handler. That way
 // you don't need to convert float->bool in your callbacks.
-
+using InputEventHandler = std::variant<InputAxisEventHandler, InputButtonEventHandler>;
-class InputEventHandler
-{
-public:
-	InputEventHandler()
-	{
-		new (&u.button) InputButtonEventHandler;
-		is_axis = false;
-	}
-
-	InputEventHandler(InputButtonEventHandler button)
-	{
-		new (&u.button) InputButtonEventHandler(std::move(button));
-		is_axis = false;
-	}
-
-	InputEventHandler(InputAxisEventHandler axis)
-	{
-		new (&u.axis) InputAxisEventHandler(std::move(axis));
-		is_axis = true;
-	}
-
-	InputEventHandler(const InputEventHandler& copy)
-	{
-		if (copy.is_axis)
-			new (&u.axis) InputAxisEventHandler(copy.u.axis);
-		else
-			new (&u.button) InputButtonEventHandler(copy.u.button);
-		is_axis = copy.is_axis;
-	}
-
-	InputEventHandler(InputEventHandler&& move)
-	{
-		if (move.is_axis)
-			new (&u.axis) InputAxisEventHandler(std::move(move.u.axis));
-		else
-			new (&u.button) InputButtonEventHandler(std::move(move.u.button));
-		is_axis = move.is_axis;
-	}
-
-	~InputEventHandler()
-	{
-		// call the right destructor... :D
-		if (is_axis)
-			u.axis.InputAxisEventHandler::~InputAxisEventHandler();
-		else
-			u.button.InputButtonEventHandler::~InputButtonEventHandler();
-	}
-
-	InputEventHandler& operator=(const InputEventHandler& copy)
-	{
-		InputEventHandler::~InputEventHandler();
-
-		if (copy.is_axis)
-			new (&u.axis) InputAxisEventHandler(copy.u.axis);
-		else
-			new (&u.button) InputButtonEventHandler(copy.u.button);
-		is_axis = copy.is_axis;
-		return *this;
-	}
-
-	InputEventHandler& operator=(InputEventHandler&& move)
-	{
-		InputEventHandler::~InputEventHandler();
-
-		if (move.is_axis)
-			new (&u.axis) InputAxisEventHandler(std::move(move.u.axis));
-		else
-			new (&u.button) InputButtonEventHandler(std::move(move.u.button));
-		is_axis = move.is_axis;
-		return *this;
-	}
-
-	__fi bool IsAxis() const { return is_axis; }
-
-	__fi void Invoke(float value) const
-	{
-		if (is_axis)
-			u.axis(value);
-		else
-			u.button(value > 0.0f);
-	}
-
-private:
-	union HandlerUnion
-	{
-		// constructor/destructor needs to be declared
-		HandlerUnion() {}
-		~HandlerUnion() {}
-
-		InputButtonEventHandler button;
-		InputAxisEventHandler axis;
-	} u;
-
-	bool is_axis;
-};
 
 // ------------------------------------------------------------------------
 // Binding Type
@@ -194,6 +100,8 @@ namespace InputManager
 	static void AddBindings(const std::vector<std::string>& bindings, const InputEventHandler& handler);
 	static bool ParseBindingAndGetSource(const std::string_view& binding, InputBindingKey* key, InputSource** source);
 
+	static bool IsAxisHandler(const InputEventHandler& handler);
+
 	static void AddHotkeyBindings(SettingsInterface& si);
 	static void AddPadBindings(SettingsInterface& si, u32 pad, const char* default_type);
 	static void UpdateContinuedVibration();
@@ -639,6 +547,11 @@ bool InputManager::HasAnyBindingsForKey(InputBindingKey key)
 	return (s_binding_map.find(key.MaskDirection()) != s_binding_map.end());
 }
 
+bool InputManager::IsAxisHandler(const InputEventHandler& handler)
+{
+	return std::holds_alternative<InputAxisEventHandler>(handler);
+}
+
 bool InputManager::InvokeEvents(InputBindingKey key, float value)
 {
 	if (DoEventHook(key, value))
@@ -658,7 +571,7 @@ bool InputManager::InvokeEvents(InputBindingKey key, float value)
 	for (auto it = range.first; it != range.second; ++it)
 	{
 		InputBinding* binding = it->second.get();
-		if (binding->handler.IsAxis())
+		if (IsAxisHandler(binding->handler))
 			continue;
 
 		// find the key which matches us
@@ -702,7 +615,7 @@ bool InputManager::InvokeEvents(InputBindingKey key, float value)
 
 			// Don't register the key press when we're part of a longer chord. That way,
 			// the state won't change, and it won't get the released event either.
-			if (longest_hotkey_binding && new_state && !binding->handler.IsAxis() &&
+			if (longest_hotkey_binding && new_state && !IsAxisHandler(binding->handler) &&
 				binding->num_keys != longest_hotkey_binding->num_keys)
 			{
 				continue;
@@ -719,11 +632,18 @@ bool InputManager::InvokeEvents(InputBindingKey key, float value)
                                                                                                         0.0f);
 
 			// axes are fired regardless of a state change, unless they're zero
+			// (but going from not-zero to zero will still fire, because of the full state)
 			// for buttons, we can use the state of the last chord key, because it'll be 1 on press,
 			// and 0 on release (when the full state changes).
-			if (prev_full_state != new_full_state || (binding->handler.IsAxis() && value_to_pass > 0.0f))
+			if (IsAxisHandler(binding->handler))
 			{
-				binding->handler.Invoke(value_to_pass);
+				if (prev_full_state != new_full_state || value_to_pass >= 0.0f)
+					std::get<InputAxisEventHandler>(binding->handler)(value_to_pass);
+			}
+			else
+			{
+				if (prev_full_state != new_full_state)
+					std::get<InputButtonEventHandler>(binding->handler)(value_to_pass > 0.0f);
 			}
 
 			// bail out, since we shouldn't have the same key twice in the chord