From 982f6785f541879c86a2f386fbdd4057e960b12c Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 6 Oct 2021 00:03:35 +0300
Subject: [PATCH] Redesign Collection's creator and notify mechanisms to be
 more generic

They now allow any functors, including lambdas.
---
 source/collection.cpp |  2 +-
 source/collection.h   | 82 ++++++++-----------------------------------
 2 files changed, 16 insertions(+), 68 deletions(-)

diff --git a/source/collection.cpp b/source/collection.cpp
index c168d8a..8b29585 100644
--- a/source/collection.cpp
+++ b/source/collection.cpp
@@ -21,7 +21,7 @@ void Collection::add_var(const string &name, const CollectionItemTypeBase *type,
 {
 	insert_unique(items, name, var);
 	if(type)
-		type->notify_item(*this, name, var);
+		type->notify_item(name, var);
 }
 
 const Variant &Collection::get_var(const string &name, const CollectionItemTypeBase *type)
diff --git a/source/collection.h b/source/collection.h
index 98b359e..fb9470d 100644
--- a/source/collection.h
+++ b/source/collection.h
@@ -364,7 +364,7 @@ public:
 	virtual bool can_create() const = 0;
 	virtual void create_item(Collection &, const std::string &) const = 0;
 	virtual void load_item(Collection &, Parser &, const std::string &) const = 0;
-	virtual void notify_item(Collection &, const std::string &, const Variant &) const = 0;
+	virtual void notify_item(const std::string &, const Variant &) const = 0;
 
 	template<typename T>
 	bool can_extract() const
@@ -394,46 +394,6 @@ template<typename T>
 class CollectionItemType: public CollectionItemTypeBase
 {
 private:
-	struct CreatorBase
-	{
-		virtual ~CreatorBase() { }
-
-		virtual T *create(Collection &, const std::string &) const = 0;
-	};
-
-	template<typename C>
-	struct Creator: CreatorBase
-	{
-		typedef T *(C::*FuncPtr)(const std::string &);
-
-		FuncPtr func;
-
-		Creator(FuncPtr f): func(f) { }
-
-		virtual T *create(Collection &coll, const std::string &name) const
-		{ return (dynamic_cast<C &>(coll).*func)(name); }
-	};
-
-	struct NotifyeeBase
-	{
-		virtual ~NotifyeeBase() { }
-
-		virtual void notify(Collection &, const std::string &, T &) const = 0;
-	};
-
-	template<typename C>
-	struct Notifyee: NotifyeeBase
-	{
-		typedef void (C::*FuncPtr)(const std::string &, T &);
-
-		FuncPtr func;
-
-		Notifyee(FuncPtr f): func(f) { }
-
-		virtual void notify(Collection &coll, const std::string &name, T &item) const
-		{ (dynamic_cast<C &>(coll).*func)(name, item); }
-	};
-
 	template<typename B>
 	struct Extractor: CollectionItemTypeBase::Extractor<B>
 	{
@@ -441,21 +401,10 @@ private:
 		{ return *var.value<RefPtr<T> >(); }
 	};
 
-	CreatorBase *creat;
-	std::vector<NotifyeeBase *> notif;
+	std::function<T *(const std::string &)> create_func;
+	std::vector<std::function<void(const std::string &, T &)>> notify_funcs;
 
 public:
-	CollectionItemType():
-		creat(0)
-	{ }
-
-	~CollectionItemType()
-	{
-		delete creat;
-		for(NotifyeeBase *n: notif)
-			delete n;
-	}
-
 	/** Sets a datafile keyword for this item type.  The Collection's loader
 	will accept a statement with this keyword and a single string argument - the
 	item's name. */
@@ -481,11 +430,10 @@ public:
 	type.  It must return the created object, or null if it could not be
 	created.  It's also permissible to load the item via other means and then
 	return null. */
-	template<typename C>
-	CollectionItemType &creator(T *(C::*func)(const std::string &))
+	template<typename F>
+	CollectionItemType &creator(F func)
 	{
-		delete creat;
-		creat = new Creator<C>(func);
+		create_func = func;
 		return *this;
 	}
 
@@ -497,10 +445,10 @@ public:
 		return *this;
 	}
 
-	template<typename C>
-	CollectionItemType &notify(void (C::*func)(const std::string &, T &))
+	template<typename F>
+	CollectionItemType &notify(F func)
 	{
-		notif.push_back(new Notifyee<C>(func));
+		notify_funcs.emplace_back(func);
 		return *this;
 	}
 
@@ -514,13 +462,13 @@ public:
 	{ }
 
 	virtual bool can_create() const
-	{ return creat!=0; }
+	{ return static_cast<bool>(create_func); }
 
 	virtual void create_item(Collection &coll, const std::string &name) const
 	{
-		if(!creat)
+		if(!create_func)
 			throw std::runtime_error("no creator");
-		T *obj = creat->create(coll, name);
+		T *obj = create_func(name);
 		if(obj)
 			coll.add(name, obj);
 	}
@@ -530,11 +478,11 @@ public:
 		throw std::runtime_error("this type cannot be loaded");
 	}
 
-	virtual void notify_item(Collection &coll, const std::string &name, const Variant &var) const
+	virtual void notify_item(const std::string &name, const Variant &var) const
 	{
 		RefPtr<T> obj = var.value<RefPtr<T> >();
-		for(NotifyeeBase *n: notif)
-			n->notify(coll, name, *obj);
+		for(const auto &n: notify_funcs)
+			n(name, *obj);
 	}
 };
 
-- 
2.45.2