Rule of Five for event::sdl_handler

This fixes the default implementations of widget's copy constructor and copy
assignment, which was root cause of the regression in 4139b43 (#4215).

This reverts commit f46ed66.

src/events.cpp

@@ -87,6 +87,14 @@ void context::add_handler(sdl_handler* ptr)
 	staging_handlers.push_back(ptr);
 }
 
+bool context::has_handler(const sdl_handler* ptr) const
+{
+	if(handlers.cend() != std::find(handlers.cbegin(), handlers.cend(), ptr)) {
+		return true;
+	}
+	return staging_handlers.cend() != std::find(staging_handlers.cbegin(), staging_handlers.cend(), ptr);
+}
+
 bool context::remove_handler(sdl_handler* ptr)
 {
 	static int depth = 0;
@@ -235,6 +243,49 @@ sdl_handler::sdl_handler(const bool auto_join)
 	}
 }
 
+sdl_handler::sdl_handler(const sdl_handler &that)
+	: has_joined_(that.has_joined_)
+	, has_joined_global_(that.has_joined_global_)
+{
+	if(has_joined_global_) {
+		assert(!event_contexts.empty());
+		event_contexts.front().add_handler(this);
+	} else if(has_joined_) {
+		bool found_context = false;
+		for(auto &context : boost::adaptors::reverse(event_contexts)) {
+			if(context.has_handler(&that)) {
+				found_context = true;
+				context.add_handler(this);
+				break;
+			}
+		}
+
+		if (!found_context) {
+			throw std::logic_error("Copy-constructing a sdl_handler that has_joined_ but can't be found by searching contexts");
+		}
+	}
+}
+
+sdl_handler &sdl_handler::operator=(const sdl_handler &that)
+{
+	if(that.has_joined_global_) {
+		join_global();
+	} else if(that.has_joined_) {
+		for(auto &context : boost::adaptors::reverse(event_contexts)) {
+			if(context.has_handler(&that)) {
+				join(context);
+				break;
+			}
+		}
+	} else if(has_joined_) {
+		leave();
+	} else if(has_joined_global_) {
+		leave_global();
+	}
+
+	return *this;
+}
+
 sdl_handler::~sdl_handler()
 {
 	if(has_joined_) {
@@ -282,8 +333,7 @@ void sdl_handler::join_same(sdl_handler* parent)
 	}
 
 	for(auto& context : boost::adaptors::reverse(event_contexts)) {
-		handler_list& handlers = context.handlers;
-		if(std::find(handlers.begin(), handlers.end(), parent) != handlers.end()) {
+		if(context.has_handler(parent)) {
 			join(context);
 			return;
 		}

src/events.hpp

@@ -51,6 +51,8 @@ class context
 	context(const context&) = delete;
 
 	void add_handler(sdl_handler* ptr);
+	/** Returns true if @a ptr is found in either the handlers or staging_handlers lists */
+	bool has_handler(const sdl_handler* ptr) const;
 	bool remove_handler(sdl_handler* ptr);
 	void cycle_focus();
 	void set_focus(const sdl_handler* ptr);
@@ -95,8 +97,19 @@ friend class context;
 
 	virtual bool has_joined() { return has_joined_;}
 	virtual bool has_joined_global() { return has_joined_global_;}
+
+	/**
+	 * Moving would require two instances' context membership to be handled,
+	 * it's simpler to delete these and require the two instances to be
+	 * separately constructed / destructed.
+	 */
+	sdl_handler &operator=(sdl_handler &&) = delete;
+	sdl_handler(sdl_handler &&) = delete;
+
 protected:
 	sdl_handler(const bool auto_join=true);
+	sdl_handler(const sdl_handler &);
+	sdl_handler &operator=(const sdl_handler &);
 	virtual ~sdl_handler();
 	virtual std::vector<sdl_handler*> handler_members()
 	{

src/widgets/widget.cpp

@@ -30,27 +30,6 @@ namespace gui {
 
 bool widget::mouse_lock_ = false;
 
-widget::widget(const widget& o)
-	: events::sdl_handler()
-	, focus_(o.focus_)
-	, video_(o.video_)
-	, restorer_(o.restorer_)
-	, rect_(o.rect_)
-	, needs_restore_(o.needs_restore_)
-	, state_(o.state_)
-	, hidden_override_(o.hidden_override_)
-	, enabled_(o.enabled_)
-	, clip_(o.clip_)
-	, clip_rect_(o.clip_rect_)
-	, volatile_(o.volatile_)
-	, help_text_(o.help_text_)
-	, tooltip_text_(o.tooltip_text_)
-	, help_string_(o.help_string_)
-	, id_(o.id_)
-	, mouse_lock_local_(o.mouse_lock_local_)
-{
-}
-
 widget::widget(CVideo& video, const bool auto_join)
 	: events::sdl_handler(auto_join), focus_(true), video_(&video), rect_(EmptyRect), needs_restore_(false),
 	  state_(UNINIT), hidden_override_(false), enabled_(true), clip_(false),

src/widgets/widget.hpp

@@ -69,7 +69,6 @@ class widget : public events::sdl_handler
 	virtual void process_tooltip_string(int mousex, int mousey);
 
 protected:
-	widget(const widget& o);
 	widget(CVideo& video, const bool auto_join=true);
 	virtual ~widget();