Helper struct to determine whether a Loader has a Collection typedef.
*/
template<typename T>
-struct NeedsCollection
+struct NeedsCollection: public Sfinae
{
- struct Yes { char c[2]; };
- struct No { char c; };
-
template<typename U>
static Yes f(typename U::Collection *);
template<typename U>
static No f(...);
- enum { value = (sizeof(f<T>(0))==sizeof(Yes)) };
+ enum { value = Evaluate<sizeof(f<T>(0))>::value };
};
class CollectionItemTypeBase;
Collections can have sources for loading objects on demand. Automatic loading
only works on a non-const Collection. See class CollectionSource for details.
+
+As a last resort, a fallback collection can be designated for 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
{
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
CollectionItemTypeBase *get_type_for_item(const Variant &) const;
protected:
+ /** Adds a source for automatically loading items. Sources are consulted
+ in the order they are added. */
void add_source(CollectionSource &);
+public:
+ /** Opens a raw resource, without interpreting it as object data. Null is
+ returned if no such file is found. The caller must dispose of the returned
+ object when done with it. */
+ IO::Seekable *open_raw(const std::string &) const;
+
+protected:
+ IO::Seekable *open_from_sources(const std::string &n) { return open_raw(n); }
+
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>
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;
Creator(FuncPtr f): func(f) { }
virtual T *create(Collection &coll, const std::string &name) const
- { return (static_cast<C &>(coll).*func)(name); }
+ { return (dynamic_cast<C &>(coll).*func)(name); }
};
template<typename B>
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> >(); }