core/util: move DropEmitter to utils and add generic accessor macros

src/core/util.hpp

@@ -0,0 +1,81 @@
+#pragma once
+
+// NOLINTBEGIN
+#define DROP_EMIT(object, func)                                                                    \
+	DropEmitter(object, static_cast<void (*)(typeof(object))>([](typeof(object) o) { o->func(); }))
+
+#define DROP_EMIT_IF(cond, object, func) (cond) ? DROP_EMIT(object, func) : DropEmitter()
+
+#define DEFINE_DROP_EMIT_IF(cond, object, func) DropEmitter func = DROP_EMIT_IF(cond, object, func)
+
+#define DROP_EMIT_SET(object, local, member, signal)                                               \
+	auto signal = DropEmitter();                                                                     \
+	if (local == object->member) {                                                                   \
+		object->member = local;                                                                        \
+		signal = DROP_EMIT(object, signal);                                                            \
+	}
+
+// generic accessor declarations
+
+#define GDECL_GETTER(type, name) [[nodiscard]] type name() const
+
+#define GDEF_GETTER(class, type, member, name)                                                     \
+	type class::name() const { return this->member; }
+
+#define GDECL_SETTER(type, name) DropEmitter name(type value)
+
+#define GDEF_SETTER(class, type, member, name, signal)                                             \
+	DropEmitter class ::name(type value) {                                                           \
+		if (value == this->member) return DropEmitter();                                               \
+		this->member = value;                                                                          \
+		return DROP_EMIT(this, signal);                                                                \
+	}
+
+#define GDECL_MEMBER(type, getter, setter)                                                         \
+	GDECL_GETTER(type, getter)                                                             \
+	GDECL_SETTER(type, setter)
+
+#define GDEF_MEMBER(class, type, member, getter, setter, signal)                                   \
+	GDEF_GETTER(class, type, member, getter)                                               \
+	GDEF_SETTER(class, type, member, setter, signal)
+
+#define GDEF_MEMBER_S(class, type, lower, upper)                                         \
+	GDEF_MEMBER(class, type, m##upper, lower, set##upper, lower##Changed)
+
+// NOLINTEND
+
+class DropEmitter {
+public:
+	Q_DISABLE_COPY(DropEmitter);
+	template <class O>
+	DropEmitter(O* object, void (*signal)(O*))
+	    : object(object)
+	    , signal(*reinterpret_cast<void (*)(void*)>(signal)) {} // NOLINT
+
+	DropEmitter() = default;
+
+	DropEmitter(DropEmitter&& other) noexcept: object(other.object), signal(other.signal) {
+		other.object = nullptr;
+	}
+
+	~DropEmitter() { this->call(); }
+
+	DropEmitter& operator=(DropEmitter&& other) noexcept {
+		this->object = other.object;
+		this->signal = other.signal;
+		other.object = nullptr;
+		return *this;
+	}
+
+	explicit operator bool() const noexcept { return this->object; }
+
+	void call() {
+		if (!this->object) return;
+		this->signal(this->object);
+		this->object = nullptr;
+	}
+
+private:
+	void* object = nullptr;
+	void (*signal)(void*) = nullptr;
+};