From fbf76ed98dbd2cca6785efe2dd489d717fa5dce6 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 25 Apr 2021 14:07:56 +0300
Subject: [PATCH] Add a mechanism for collections to be notified when an item
 is added

---
 source/collection.cpp |  7 +++++++
 source/collection.h   | 44 +++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/source/collection.cpp b/source/collection.cpp
index 6d73063..f86adf6 100644
--- a/source/collection.cpp
+++ b/source/collection.cpp
@@ -16,6 +16,13 @@ Collection::~Collection()
 		delete *i;
 }
 
+void Collection::add_var(const string &name, const CollectionItemTypeBase *type, const Variant &var)
+{
+	insert_unique(items, name, var);
+	if(type)
+		type->notify_item(*this, name, var);
+}
+
 const Variant &Collection::get_var(const string &name, const CollectionItemTypeBase *type)
 {
 	const Variant *var = find_var(name, type);
diff --git a/source/collection.h b/source/collection.h
index 0cd799a..aa3c18a 100644
--- a/source/collection.h
+++ b/source/collection.h
@@ -104,10 +104,11 @@ public:
 		if(!item)
 			throw std::invalid_argument("Collection::add(item)");
 
-		RefPtr<typename RemoveConst<T>::Type> ptr(item);
+		typedef typename RemoveConst<T>::Type NCT;
+		RefPtr<NCT> ptr(item);
 		try
 		{
-			insert_unique(items, name, ptr);
+			add_var(name, get_type<NCT>(name), ptr);
 		}
 		catch(...)
 		{
@@ -153,6 +154,7 @@ public:
 	}
 
 private:
+	void add_var(const std::string &, const CollectionItemTypeBase *, const Variant &);
 	const Variant &get_var(const std::string &, const CollectionItemTypeBase *);
 	const Variant *find_var(const std::string &, const CollectionItemTypeBase *);
 
@@ -363,6 +365,7 @@ 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;
 
 	template<typename T>
 	bool can_extract() const
@@ -412,6 +415,26 @@ private:
 		{ 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>
 	{
@@ -420,6 +443,7 @@ private:
 	};
 
 	CreatorBase *creat;
+	std::vector<NotifyeeBase *> notif;
 
 public:
 	CollectionItemType():
@@ -429,6 +453,8 @@ public:
 	~CollectionItemType()
 	{
 		delete creat;
+		for(typename std::vector<NotifyeeBase *>::const_iterator i=notif.begin(); i!=notif.end(); ++i)
+			delete *i;
 	}
 
 	/** Sets a datafile keyword for this item type.  The Collection's loader
@@ -472,6 +498,13 @@ public:
 		return *this;
 	}
 
+	template<typename C>
+	CollectionItemType &notify(void (C::*func)(const std::string &, T &))
+	{
+		notif.push_back(new Notifyee<C>(func));
+		return *this;
+	}
+
 	virtual bool is_same_type(const CollectionItemTypeBase &other) const
 	{ return dynamic_cast<const CollectionItemType<T> *>(&other); }
 
@@ -497,6 +530,13 @@ public:
 	{
 		throw std::runtime_error("this type cannot be loaded");
 	}
+
+	virtual void notify_item(Collection &coll, const std::string &name, const Variant &var) const
+	{
+		RefPtr<T> obj = var.value<RefPtr<T> >();
+		for(typename std::vector<NotifyeeBase *>::const_iterator i=notif.begin(); i!=notif.end(); ++i)
+			(*i)->notify(coll, name, *obj);
+	}
 };
 
 
-- 
2.43.0