X-Git-Url: http://git.tdb.fi/?p=libs%2Fdatafile.git;a=blobdiff_plain;f=source%2Fcollection.h;h=0d2dc6be2fd7a6c4043ff4db18bfdc32a04bb270;hp=d5853f2ea6cb4a3fba658dd5912e148f419cb8e4;hb=9b1656018f783eb4aad2fbdc1de1404691e89bb1;hpb=bcbe8b90de68e18260313b8f0e8a8dd9c7661903

diff --git a/source/collection.h b/source/collection.h
index d5853f2..0d2dc6b 100644
--- a/source/collection.h
+++ b/source/collection.h
@@ -45,6 +45,11 @@ method for details.
 
 Collections can have sources for loading objects on demand.  Automatic loading
 only works on a non-const Collection.  See class CollectionSource for details.
+
+A fallback collection can be designated as another way of loading items that
+are not present.  Items retrieted from the fallback collection are shared
+between the collections, and are only deleted when all collections in the chain
+have been destroyed.
 */
 class Collection
 {
@@ -75,7 +80,6 @@ public:
 		}
 	};
 
-protected:
 	template<typename T, bool = NeedsCollection<typename T::Loader>::value>
 	class ItemLoader;
 
@@ -87,11 +91,12 @@ private:
 	TypeList types;
 	ItemMap items;
 	SourceList sources;
+	Collection *fallback;
 
 	Collection(const Collection &);
 	Collection &operator=(const Collection &);
 public:
-	Collection() { }
+	Collection();
 	virtual ~Collection();
 
 	/** Adds an object into the collection.  The name must not pre-exist.  The
@@ -119,7 +124,7 @@ public:
 	template<typename T>
 	T &get(const std::string &name) const
 	{
-		return extract<T>(get_item(items, name));
+		return extract<typename RemoveConst<T>::Type>(get_item(items, name));
 	}
 
 	/** Gets a typed object from the collection.  If the name is not found,
@@ -128,7 +133,8 @@ public:
 	template<typename T>
 	T &get(const std::string &name)
 	{
-		return extract<T>(get_var(name, get_type<T>()));
+		typedef typename RemoveConst<T>::Type NCT;
+		return extract<NCT>(get_var(name, get_type<NCT>()));
 	}
 
 private:
@@ -247,6 +253,7 @@ protected:
 	template<typename T>
 	CollectionItemType<T> &add_type();
 
+private:
 	/// Returns the descriptor for a type, or null if one isn't defined.
 	template<typename T>
 	CollectionItemTypeBase *get_type() const;
@@ -254,11 +261,20 @@ protected:
 	/// Returns the descriptor for an item, or null if it's of an unknown type.
 	CollectionItemTypeBase *get_type_for_item(const Variant &) const;
 
+protected:
 	void add_source(CollectionSource &);
 
+	IO::Seekable *open_from_sources(const std::string &);
+
+private:
 	void gather_names_from_sources(std::list<std::string> &, const CollectionItemTypeBase &) const;
 
 	void load_items_from_sources(const CollectionItemTypeBase &);
+
+protected:
+	/** Sets a fallback collection, which will be consulted if an item is not
+	found. */
+	void set_fallback(Collection *);
 };
 
 template<typename T>
@@ -306,6 +322,7 @@ public:
 	const std::string &get_keyword() const { return kwd; }
 	void add_suffix(const std::string &);
 	bool match_name(const std::string &) const;
+	virtual bool is_same_type(const CollectionItemTypeBase &) const = 0;
 	virtual bool check_item_type(const Variant &) const = 0;
 	virtual void add_to_loader(Collection::Loader &) const = 0;
 	virtual bool can_create() const = 0;
@@ -420,6 +437,9 @@ public:
 		return *this;
 	}
 
+	virtual bool is_same_type(const CollectionItemTypeBase &other) const
+	{ return dynamic_cast<const CollectionItemType<T> *>(&other); }
+
 	virtual bool check_item_type(const Variant &var) const
 	{ return var.check_type<RefPtr<T> >(); }
 
@@ -452,14 +472,12 @@ public:
 template<typename T>
 T &Collection::extract(const Variant &var) const
 {
-	typedef RefPtr<typename RemoveConst<T>::Type> RPNCT;
-
-	if(!var.check_type<RPNCT>())
+	if(!var.check_type<RefPtr<T> >())
 		if(CollectionItemTypeBase *type = get_type_for_item(var))
 			if(T *item = type->extract<T>(var))
 				return *item;
 
-	return *var.value<RPNCT>();
+	return *var.value<RefPtr<T> >();
 }
 
 template<typename T>
@@ -474,7 +492,7 @@ template<typename T>
 CollectionItemTypeBase *Collection::get_type() const
 {
 	for(TypeList::const_iterator j=types.begin(); j!=types.end(); ++j)
-		if(dynamic_cast<CollectionItemType<typename RemoveConst<T>::Type> *>(*j))
+		if(dynamic_cast<CollectionItemType<T> *>(*j))
 			return *j;
 	for(TypeList::const_iterator j=types.begin(); j!=types.end(); ++j)
 		if((*j)->can_extract<T>())