/**
A collection of objects that can be loaded from a datafile. Each object is
identified by a name, which must be unique across the entire collection.
+
+While this class can be instantiated by itself and used for storing objects,
+loading requires that a subclass defines the supported types. See the add_type
+method for details.
*/
class Collection
{
public:
/**
- Loads objects into a Collection.
+ Loads objects into a Collection. Automatically picks up keywords from
+ defined item types.
*/
class Loader: public DataFile::Loader
{
template<typename T> friend class CollectionItemType;
private:
- template<typename T, typename S, bool = NeedsCollection<T>::value >
+ template<typename T, typename S, bool = NeedsCollection<typename T::Loader>::value>
struct Add;
Collection &coll;
template<typename T, typename S, typename C>
void coll_item(const std::string &n)
{
- RefPtr<T> it=new T;
+ RefPtr<T> it = new T;
load_sub(*it, dynamic_cast<C &>(coll));
coll.add<S>(n, it.get());
it.release();
template<typename T, typename S>
void item(const std::string &n)
{
- RefPtr<T> it=new T;
+ RefPtr<T> it = new T;
load_sub(*it);
coll.add<S>(n, it.get());
it.release();
}
-
- template<typename, typename, bool> friend class ItemKeyword;
};
private:
Collection() { }
virtual ~Collection();
- /**
- Adds an object into the collection. If a name collision occurs, an
- exception is thrown. The collection takes ownership of the object.
- */
+ /** Adds an object into the collection. The name must not pre-exist. The
+ collection takes ownership of the object. */
template<typename T>
void add(const std::string &name, T *item)
{
}
}
- /**
- Gets an object of a specific type from the collection.
- */
+ /// Gets a typed object from the collection.
template<typename T>
T &get(const std::string &name) const
{
return *get_item(items, name).value<RefPtr<NCT> >();
}
- /**
- Gets an object of a specific type from the collection. If the name is not
- found in the collection and there is a creator for the item type, it is
- invoked.
- */
+ /** Gets a typed object from the collection. If the name is not found in
+ and a creator for the item type is defined, it is invoked. */
template<typename T>
T &get(const std::string &);
- /**
- Returns a list of the names of objects of a specific type in the collection.
- */
+ /// Returns a list of the names of objects of one type in the collection.
template<typename T>
std::list<std::string> get_names() const
{
return result;
}
- /**
- Returns a list of objects of a specific type in the collection.
- */
+ /// Returns a list of objects of one type in the collection.
template<typename T>
std::list<T *> get_list() const
{
return result;
}
- /**
- Checks whether a name exists in the collection. Does not care about the
- type of the object.
- */
+ /** Checks whether a name exists in the collection. Does not care about the
+ type of the object. */
bool contains(const std::string &n) const;
- /**
- Returns the name of an item in the collection.
- */
+ /// Returns the name of an item in the collection.
template<typename T>
const std::string &get_name(T *d) const
{
}
protected:
+ /** Adds a type to the collection. The returned descriptor object reference
+ can be used to define how objects of that type can be loaded. */
template<typename T>
CollectionItemType<T> &add_type();
};
};
+/**
+Describes a type of item that can be loaded by a Collection. These are created
+by Collection::add_type.
+*/
template<typename T>
class CollectionItemType: public CollectionItemTypeBase
{
{ Collection::Loader::Add<T, S>::add(loader, kwd); }
};
- CreatorBase *creator;
+ CreatorBase *creat;
StoreBase *store;
public:
CollectionItemType():
- creator(0), store(new Store<T>)
+ creat(0), store(new Store<T>)
{ tag = new Tag<T>; }
~CollectionItemType()
{
- delete creator;
+ delete creat;
delete store;
}
+ /** 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. */
CollectionItemType &keyword(const std::string &k)
{
kwd = k;
return *this;
}
+ /** Attaches a creator function to this item type. If an item is not found
+ in the Collection, the creator function for its type is called to create it.
+ The function must be a member of the Collection subclass containing the
+ 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 &create(T *(C::*func)(const std::string &))
+ CollectionItemType &creator(T *(C::*func)(const std::string &))
{
- delete creator;
- creator = new Creator<C>(func);
+ delete creat;
+ creat = new Creator<C>(func);
return *this;
}
+ /** Specifies the storage type for items of this type. It must be a base
+ class of the actual type. */
template<typename S>
CollectionItemType &store_as()
{
{ store->add_to_loader(loader, kwd); }
virtual bool can_create() const
- { return creator!=0; }
+ { return creat!=0; }
virtual void create_item(Collection &coll, const std::string &name) const
{
- if(!creator)
+ if(!creat)
throw std::runtime_error("no creator");
- T *obj = creator->create(coll, name);
- store->store(coll, name, obj);
+ T *obj = creat->create(coll, name);
+ if(obj)
+ store->store(coll, name, obj);
}
};
projects / libs / datafile.git / blobdiff