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
{
}
};
-protected:
template<typename T, bool = NeedsCollection<typename T::Loader>::value>
class ItemLoader;
private:
typedef std::map<std::string, Variant> ItemMap;
typedef std::list<CollectionItemTypeBase *> TypeList;
- typedef std::list<CollectionSource *> SourceList;
+ typedef std::list<const CollectionSource *> SourceList;
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
if(!item)
throw std::invalid_argument("Collection::add(item)");
- insert_unique(items, name, RefPtr<typename RemoveConst<T>::Type>(item));
+ RefPtr<typename RemoveConst<T>::Type> ptr(item);
+ try
+ {
+ insert_unique(items, name, ptr);
+ }
+ catch(...)
+ {
+ // Avoid deleting the object
+ ptr.release();
+ throw;
+ }
}
/// Gets a typed object from the collection.
template<typename T>
T &get(const std::string &name) const
{
- return *get_item(items, name).value<RefPtr<typename RemoveConst<T>::Type> >();
+ return extract<typename RemoveConst<T>::Type>(get_item(items, name));
}
/** Gets a typed object from the collection. If the name is not found,
automatic creation with the type's creator function (if defined) or from
sources (if present) is attempted. */
template<typename T>
- T &get(const std::string &);
+ T &get(const std::string &name)
+ {
+ typedef typename RemoveConst<T>::Type NCT;
+ return extract<NCT>(get_var(name, get_type<NCT>()));
+ }
private:
+ const Variant &get_var(const std::string &, const CollectionItemTypeBase *);
+
template<typename T>
- void collect_items(std::list<T *> *objects, std::list<std::string> *names, std::list<std::string> *future_names) const
+ T &extract(const Variant &var) const;
+
+ template<typename T>
+ std::list<T *> extract_list(const std::list<const Variant *> &vars) const
{
- typedef RefPtr<typename RemoveConst<T>::Type> RPNCT;
+ std::list<T *> result;
+ for(std::list<const Variant *>::const_iterator i=vars.begin(); i!=vars.end(); ++i)
+ result.push_back(&extract<T>(**i));
+ return result;
+ }
- for(ItemMap::const_iterator i=items.begin(); i!=items.end(); ++i)
- if(i->second.check_type<RPNCT>())
- {
- if(objects)
- objects->push_back(i->second.value<RPNCT>().get());
- if(names)
- names->push_back(i->first);
- }
-
- if(future_names)
- if(CollectionItemTypeBase *type = get_type<T>())
- {
- for(SourceList::const_iterator i=sources.begin(); i!=sources.end(); ++i)
- {
- std::list<std::string> available_names = (*i)->get_names(*type);
- for(std::list<std::string>::iterator j=available_names.begin(); j!=available_names.end(); ++j)
- if(!items.count(*j))
- future_names->push_back(*j);
- }
- }
+ void gather_items(std::list<const Variant *> *, std::list<std::string> *, const CollectionItemTypeBase &, bool) const;
+
+ template<typename T>
+ void gather_items(std::list<const Variant *> *vars, std::list<std::string> *names, const CollectionItemTypeBase *type, bool include_sources) const
+ {
+ if(type || (type = get_type<T>()))
+ gather_items(vars, names, *type, include_sources);
+ else
+ gather_items(vars, names, CollectionItemType<T>(), false);
}
public:
template<typename T>
std::list<std::string> get_names() const
{
- std::list<std::string> result;
- collect_items<T>(0, &result, 0);
- return result;
+ std::list<std::string> names;
+ gather_items<typename RemoveConst<T>::Type>(0, &names, 0, false);
+ return names;
}
/** Returns a list of the names of objects of one type in the collection or
template<typename T>
std::list<std::string> get_names()
{
- std::list<std::string> result;
- collect_items<T>(0, &result, &result);
- return result;
+ std::list<std::string> names;
+ gather_items<typename RemoveConst<T>::Type>(0, &names, 0, true);
+ return names;
}
/// Returns a list of objects of one type in the collection.
template<typename T>
std::list<T *> get_list() const
{
- std::list<T *> result;
- collect_items<T>(&result, 0, 0);
- return result;
+ std::list<const Variant *> vars;
+ gather_items<typename RemoveConst<T>::Type>(&vars, 0, 0, false);
+ return extract_list<T>(vars);
}
/** Returns a list of objects of one type, loading them from sources if
template<typename T>
std::list<T *> get_list()
{
- std::list<T *> result;
- std::list<std::string> future;
- collect_items<T>(&result, 0, &future);
- for(std::list<std::string>::iterator i=future.begin(); i!=future.end(); ++i)
- result.push_back(&get<T>(*i));
- return result;
+ CollectionItemTypeBase *type = get_type<typename RemoveConst<T>::Type>();
+ if(type)
+ load_items_from_sources(*type);
+
+ std::list<const Variant *> vars;
+ gather_items<typename RemoveConst<T>::Type>(&vars, 0, type, true);
+ return extract_list<T>(vars);
}
private:
+ unsigned get_status(const std::string &, const CollectionItemTypeBase &) const;
+
template<typename T>
unsigned get_status(const std::string &name) const
{
- ItemMap::const_iterator i = items.find(name);
- if(i==items.end())
- {
- if(CollectionItemTypeBase *type = get_type<T>())
- {
- for(SourceList::const_iterator j=sources.begin(); j!=sources.end(); ++j)
- if((*j)->is_loadable(*type, name))
- return 2;
- }
- return 0;
- }
+ // XXX Should go through all applicable types
+ if(CollectionItemTypeBase *type = get_type<T>())
+ return get_status(name, *type);
- typedef RefPtr<typename RemoveConst<T>::Type> RPNCT;
- if(!i->second.check_type<RPNCT>())
- return 0;
-
- return 1;
+ ItemMap::const_iterator i = items.find(name);
+ return (i!=items.end() && i->second.check_type<RefPtr<T> >());
}
public:
/// Checks whether a typed object exists in the collection.
template<typename T>
bool contains(const std::string &name) const
- { return get_status<T>(name)==1; }
+ { return get_status<typename RemoveConst<T>::Type>(name)==1; }
/** Checks whether a typed object exists in the collection or is loadable
from a source. */
template<typename T>
bool contains(const std::string &name)
- { return get_status<T>(name)>0; }
+ { return get_status<typename RemoveConst<T>::Type>(name)>0; }
/// Returns the name of an item in the collection.
template<typename T>
template<typename T>
CollectionItemType<T> &add_type();
- /** Returns the descriptor for a type, or null if one isn't defined. */
+private:
+ /// Returns the descriptor for a type, or null if one isn't defined.
template<typename T>
CollectionItemTypeBase *get_type() const;
- void add_source(CollectionSource &);
+ /// Gets a descriptor with the same type as another descriptor.
+ CollectionItemTypeBase *get_type(const CollectionItemTypeBase &) const;
+
+ /// Returns the descriptor for an item, or null if it's of an unknown type.
+ 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(const 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 *);
+
+ Collection *get_fallback() const { return fallback; }
};
template<typename T>
class CollectionItemTypeBase
{
protected:
- class TagBase
+ struct ExtractorBase
{
- protected:
- TagBase() { }
- public:
- virtual ~TagBase() { }
+ virtual ~ExtractorBase() { }
};
template<typename T>
- class Tag: public TagBase
- { };
+ struct Extractor: ExtractorBase
+ {
+ virtual T &extract(const Variant &) const = 0;
+ };
std::string kwd;
std::vector<std::string> suffixes;
- TagBase *tag;
+ std::vector<ExtractorBase *> extractors;
- CollectionItemTypeBase();
+ CollectionItemTypeBase() { }
public:
virtual ~CollectionItemTypeBase();
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;
virtual void create_item(Collection &, const std::string &) const = 0;
virtual void load_item(Collection &, Parser &, const std::string &) const = 0;
template<typename T>
- bool check_type() const
- { return dynamic_cast<Tag<T> *>(tag); }
+ bool can_extract() const
+ {
+ for(std::vector<ExtractorBase *>::const_iterator i=extractors.begin(); i!=extractors.end(); ++i)
+ if(dynamic_cast<Extractor<T> *>(*i))
+ return true;
+ return false;
+ }
+
+ template<typename T>
+ T *extract(const Variant &var) const
+ {
+ for(std::vector<ExtractorBase *>::const_iterator i=extractors.begin(); i!=extractors.end(); ++i)
+ if(Extractor<T> *ex = dynamic_cast<Extractor<T> *>(*i))
+ return &ex->extract(var);
+ return 0;
+ }
};
class CollectionItemType: public CollectionItemTypeBase
{
private:
- class CreatorBase
+ struct CreatorBase
{
- protected:
- CreatorBase() { }
- public:
virtual ~CreatorBase() { }
virtual T *create(Collection &, const std::string &) const = 0;
};
template<typename C>
- class Creator: public CreatorBase
+ struct Creator: CreatorBase
{
- public:
typedef T *(C::*FuncPtr)(const std::string &);
- private:
FuncPtr func;
- public:
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); }
};
- class StoreBase
+ template<typename B>
+ struct Extractor: CollectionItemTypeBase::Extractor<B>
{
- protected:
- StoreBase() { }
- public:
- virtual ~StoreBase() { }
-
- virtual void store(Collection &, const std::string &, T *) = 0;
-
- virtual void add_to_loader(Collection::Loader &, const std::string &) = 0;
- };
-
- template<typename S>
- class Store: public StoreBase
- {
- public:
- virtual void store(Collection &coll, const std::string &name, T *obj)
- { coll.add(name, static_cast<S *>(obj)); }
-
- virtual void add_to_loader(Collection::Loader &loader, const std::string &kwd)
- { loader.add(kwd, &Collection::Loader::item<T, S>); }
+ virtual B &extract(const Variant &var) const
+ { return *var.value<RefPtr<T> >(); }
};
CreatorBase *creat;
- StoreBase *store;
public:
CollectionItemType():
- creat(0), store(new Store<T>)
- { tag = new Tag<T>; }
+ creat(0)
+ { }
~CollectionItemType()
{
delete creat;
- delete store;
}
/** Sets a datafile keyword for this item type. The Collection's loader
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()
+ /** Makes items of this type available through a base class. */
+ template<typename B>
+ CollectionItemType &base()
{
- delete tag;
- tag = new Tag<S>;
- delete store;
- store = new Store<S>;
+ extractors.push_back(new Extractor<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> >(); }
+
virtual void add_to_loader(Collection::Loader &loader) const
- { store->add_to_loader(loader, kwd); }
+ { loader.add(kwd, &Collection::Loader::item<T, T>); }
virtual bool can_create() const
{ return creat!=0; }
throw std::runtime_error("no creator");
T *obj = creat->create(coll, name);
if(obj)
- store->store(coll, name, obj);
+ coll.add(name, obj);
}
virtual void load_item(Collection &coll, Parser &parser, const std::string &name) const
RefPtr<T> obj = new T;
Collection::ItemLoader<T> ldr(*obj, coll);
ldr.load(parser);
- store->store(coll, name, obj.get());
+ coll.add(name, obj.get());
obj.release();
}
};
template<typename T>
-T &Collection::get(const std::string &name)
+T &Collection::extract(const Variant &var) const
{
- typedef RefPtr<typename RemoveConst<T>::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;
- ItemMap::iterator i = items.find(name);
- if(i!=items.end())
- return *i->second.value<RPNCT>();
-
- if(CollectionItemTypeBase *type = get_type<T>())
- {
- bool loaded = false;
- if(type->can_create())
- {
- type->create_item(*this, name);
- loaded = items.count(name);
- }
- for(SourceList::iterator j=sources.begin(); (!loaded && j!=sources.end()); ++j)
- {
- (*j)->load(*this, *type, name);
- loaded = items.count(name);
- }
- }
-
- return *get_item(items, name).value<RPNCT>();
+ return *var.value<RefPtr<T> >();
}
template<typename T>
CollectionItemTypeBase *Collection::get_type() const
{
for(TypeList::const_iterator j=types.begin(); j!=types.end(); ++j)
- if((*j)->check_type<typename RemoveConst<T>::Type>())
+ if(dynamic_cast<CollectionItemType<T> *>(*j))
+ return *j;
+ for(TypeList::const_iterator j=types.begin(); j!=types.end(); ++j)
+ if((*j)->can_extract<T>())
return *j;
return 0;
}
projects / libs / datafile.git / blobdiff