1 files changed, 157 insertions, 0 deletions
diff --git a/include/libcamera/base/signal.h b/include/libcamera/base/signal.h
new file mode 100644
index 00000000..bbff1495
--- /dev/null
+++ b/include/libcamera/base/signal.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * Signal & slot implementation
+ */
+
+#pragma once
+
+#include <functional>
+#include <list>
+#include <type_traits>
+
+#include <libcamera/base/bound_method.h>
+
+namespace libcamera {
+
+class Object;
+
+class SignalBase
+{
+public:
+	void disconnect(Object *object);
+
+protected:
+	using SlotList = std::list<BoundMethodBase *>;
+
+	void connect(BoundMethodBase *slot);
+	void disconnect(std::function<bool(SlotList::iterator &)> match);
+
+	SlotList slots();
+
+private:
+	SlotList slots_;
+};
+
+template<typename... Args>
+class Signal : public SignalBase
+{
+public:
+	~Signal()
+	{
+		disconnect();
+	}
+
+#ifndef __DOXYGEN__
+	template<typename T, typename R, std::enable_if_t<std::is_base_of<Object, T>::value> * = nullptr>
+	void connect(T *obj, R (T::*func)(Args...),
+		     ConnectionType type = ConnectionTypeAuto)
+	{
+		Object *object = static_cast<Object *>(obj);
+		SignalBase::connect(new BoundMethodMember<T, R, Args...>(obj, object, func, type));
+	}
+
+	template<typename T, typename R, std::enable_if_t<!std::is_base_of<Object, T>::value> * = nullptr>
+#else
+	template<typename T, typename R>
+#endif
+	void connect(T *obj, R (T::*func)(Args...))
+	{
+		SignalBase::connect(new BoundMethodMember<T, R, Args...>(obj, nullptr, func));
+	}
+
+#ifndef __DOXYGEN__
+	template<typename T, typename Func,
+		 std::enable_if_t<std::is_base_of<Object, T>::value
+#if __cplusplus >= 201703L
+				  && std::is_invocable_v<Func, Args...>
+#endif
+				  > * = nullptr>
+	void connect(T *obj, Func func, ConnectionType type = ConnectionTypeAuto)
+	{
+		Object *object = static_cast<Object *>(obj);
+		SignalBase::connect(new BoundMethodFunctor<T, void, Func, Args...>(obj, object, func, type));
+	}
+
+	template<typename T, typename Func,
+		 std::enable_if_t<!std::is_base_of<Object, T>::value
+#if __cplusplus >= 201703L
+				  && std::is_invocable_v<Func, Args...>
+#endif
+				  > * = nullptr>
+#else
+	template<typename T, typename Func>
+#endif
+	void connect(T *obj, Func func)
+	{
+		SignalBase::connect(new BoundMethodFunctor<T, void, Func, Args...>(obj, nullptr, func));
+	}
+
+	template<typename R>
+	void connect(R (*func)(Args...))
+	{
+		SignalBase::connect(new BoundMethodStatic<R, Args...>(func));
+	}
+
+	void disconnect()
+	{
+		SignalBase::disconnect([]([[maybe_unused]] SlotList::iterator &iter) {
+			return true;
+		});
+	}
+
+	template<typename T>
+	void disconnect(T *obj)
+	{
+		SignalBase::disconnect([obj](SlotList::iterator &iter) {
+			return (*iter)->match(obj);
+		});
+	}
+
+	template<typename T, typename R>
+	void disconnect(T *obj, R (T::*func)(Args...))
+	{
+		SignalBase::disconnect([obj, func](SlotList::iterator &iter) {
+			BoundMethodArgs<R, Args...> *slot =
+				static_cast<BoundMethodArgs<R, Args...> *>(*iter);
+
+			if (!slot->match(obj))
+				return false;
+
+			/*
+			 * If the object matches the slot, the slot is
+			 * guaranteed to be a member slot, so we can safely
+			 * cast it to BoundMethodMember<T, Args...> to match
+			 * func.
+			 */
+			return static_cast<BoundMethodMember<T, R, Args...> *>(slot)->match(func);
+		});
+	}
+
+	template<typename R>
+	void disconnect(R (*func)(Args...))
+	{
+		SignalBase::disconnect([func](SlotList::iterator &iter) {
+			BoundMethodArgs<R, Args...> *slot =
+				static_cast<BoundMethodArgs<R, Args...> *>(*iter);
+
+			if (!slot->match(nullptr))
+				return false;
+
+			return static_cast<BoundMethodStatic<R, Args...> *>(slot)->match(func);
+		});
+	}
+
+	void emit(Args... args)
+	{
+		/*
+		 * Make a copy of the slots list as the slot could call the
+		 * disconnect operation, invalidating the iterator.
+		 */
+		for (BoundMethodBase *slot : slots())
+			static_cast<BoundMethodArgs<void, Args...> *>(slot)->activate(args...);
+	}
+};
+
+} /* namespace libcamera */