X-Git-Url: http://git.tdb.fi/?p=libs%2Fdatafile.git;a=blobdiff_plain;f=source%2Fcollection.h;h=06b8e348cbe3d2a7e16ce2735971802efa73a863;hp=2d346d9a4557a72325a18ae6f89c232e5f629681;hb=43b8dee0bf05dee1b4a07cc001fae0c81ec53a2f;hpb=35d0da96bad97214376f18d15078e6d731e6f219

diff --git a/source/collection.h b/source/collection.h
index 2d346d9..06b8e34 100644
--- a/source/collection.h
+++ b/source/collection.h
@@ -1,11 +1,15 @@
 #ifndef MSP_DATAFILE_COLLECTION_H_
 #define MSP_DATAFILE_COLLECTION_H_
 
-#include <msp/core/meta.h>
 #include <msp/core/maputils.h>
+#include <msp/core/meta.h>
 #include <msp/core/refptr.h>
+#include "collectionsource.h"
 #include "loader.h"
 
+/* XXX This file is a big mess with too many things in it.  However, the
+dependencies between those things make it difficult to split up. */
+
 namespace Msp {
 namespace DataFile {
 
@@ -13,122 +17,48 @@ namespace DataFile {
 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 { result=(sizeof(f<T>(0))==sizeof(Yes)) };
+	enum { value = Evaluate<sizeof(f<T>(0))>::value };
 };
 
+class CollectionItemTypeBase;
+
+template<typename T>
+class CollectionItemType;
+
 /**
 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.
-*/
-class Collection
-{
-public:
-	class Loader;
-
-private:
-	/* XXX I don't really like sticking all this stuff in here, but there's some
-	   complex inter-class relationships, especially between ItemKeyword and
-	   Collection::Loader. */
-
-	struct ItemBase
-	{
-		virtual ~ItemBase() { }
-	};
-
-	template<typename T>
-	struct Item: public ItemBase
-	{
-		T *data;
-
-		Item(T *d): data(d) { }
-		~Item() { delete data; }
-	};
-
-	/**
-	Used to store keywords for types that can be loaded.
-	*/
-	struct ItemKeywordBase
-	{
-		virtual ~ItemKeywordBase() { }
-		virtual void add_to_loader(Loader &) const { };
-	};
-
-	template<typename T, typename S, bool need_coll=NeedsCollection<typename T::Loader>::result>
-	struct ItemKeyword: public ItemKeywordBase
-	{
-		std::string keyword;
-
-		ItemKeyword(const std::string &kw): keyword(kw) { }
-
-		void add_to_loader(Loader &ldr) const
-		{ ldr.add(keyword, &Loader::item<T, S>); }
-	};
-
-	template<typename T, typename S>
-	struct ItemKeyword<T, S, true>: public ItemKeywordBase
-	{
-		std::string keyword;
-
-		ItemKeyword(const std::string &kw): keyword(kw) { }
-
-		virtual void add_to_loader(Loader &ldr) const
-		{ ldr.add(keyword, &Loader::coll_item<T, S, typename T::Loader::Collection>); }
-	};
-
-	/**
-	Used to store types that can be created automatically.
-	*/
-	struct ItemCreatorBase
-	{
-		virtual ~ItemCreatorBase() { }
-
-		template<typename S>
-		bool create(Collection &coll, const std::string &name, S *&ptr)
-		{
-			ItemCreatorBridge<S> *creator=dynamic_cast<ItemCreatorBridge<S> *>(this);
-			if(creator)
-			{
-				ptr=creator->create(coll, name);
-				return true;
-			}
-			return false;
-		}
-	};
 
-	template<typename S>
-	struct ItemCreatorBridge: public ItemCreatorBase
-	{
-		virtual S *create(Collection &, const std::string &) const = 0;
-	};
-
-	template<typename T, typename S, typename C>
-	struct ItemCreator: public ItemCreatorBridge<S>
-	{
-		typedef T *(C::*fCreate)(const std::string &);
+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.
 
-		fCreate create_func;
-
-		ItemCreator(fCreate cf): create_func(cf) { }
-		virtual S *create(Collection &coll, const std::string &name) const
-		{ return (dynamic_cast<C &>(coll).*create_func)(name); }
-	};
+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
+{
 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:
 		Collection &coll;
 
@@ -136,183 +66,451 @@ public:
 		Loader(Collection &);
 		Collection &get_object() const { return coll; }
 	private:
-		template<typename T, typename S, typename C>
-		void coll_item(const std::string &n)
-		{
-			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;
-			load_sub(*it);
+			RefPtr<T> it = new T;
+			ItemLoader<T> ldr(*it, coll);
+			load_sub_with(ldr);
 			coll.add<S>(n, it.get());
 			it.release();
 		}
-
-		template<typename, typename, bool> friend class ItemKeyword;
 	};
 
+	template<typename T, bool = NeedsCollection<typename T::Loader>::value>
+	class ItemLoader;
+
 private:
-	typedef std::map<std::string, ItemBase *> ItemMap;
-	typedef std::list<ItemKeywordBase *> ItemKeywordSeq;
-	typedef std::list<ItemCreatorBase *> ItemCreatorSeq;
+	typedef std::map<std::string, Variant> ItemMap;
+	typedef std::list<CollectionItemTypeBase *> TypeList;
+	typedef std::list<const CollectionSource *> SourceList;
 
+	TypeList types;
 	ItemMap items;
-	ItemKeywordSeq keywords;
-	ItemCreatorSeq creators;
+	SourceList sources;
+	Collection *fallback;
 
 	Collection(const Collection &);
 	Collection &operator=(const Collection &);
 public:
-	Collection() { }
+	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 *d)
+	void add(const std::string &name, T *item)
 	{
-		typedef typename RemoveConst<T>::Type NCT;
+		if(!item)
+			throw std::invalid_argument("Collection::add(item)");
 
-		RefPtr<Item<NCT> > i=new Item<NCT>(d);
-		insert_unique(items, i.get());
-		i.release();
+		RefPtr<typename RemoveConst<T>::Type> ptr(item);
+		try
+		{
+			insert_unique(items, name, ptr);
+		}
+		catch(...)
+		{
+			// Avoid deleting the object
+			ptr.release();
+			throw;
+		}
 	}
 
-	/**
-	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
+	T &get(const std::string &name) const
 	{
-		typedef typename RemoveConst<T>::Type NCT;
-
-		ItemBase *i=get_item(items, name);
-
-		const Item<NCT> *item=dynamic_cast<const Item<NCT> *>(i);
-		if(!item)
-			throw TypeError("Type mismatch on item '"+name+"'");
-
-		return item->data;
+		return extract<typename RemoveConst<T>::Type>(get_item(items, name));
 	}
 
-	/**
-	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,
+	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 &name)
+	T &get(const std::string &name)
 	{
 		typedef typename RemoveConst<T>::Type NCT;
+		return extract<NCT>(get_var(name, get_type<NCT>()));
+	}
 
-		if(!items.count(name))
-		{
-			for(ItemCreatorSeq::iterator j=creators.begin(); j!=creators.end(); ++j)
-			{
-				NCT *d=0;
-				if((*j)->create(*this, name, d))
-				{
-					// We already know that the item didn't exist yet
-					items[name]=new Item<NCT>(d);
-					return d;
-				}
-			}
-		}
+private:
+	const Variant &get_var(const std::string &, const CollectionItemTypeBase *);
 
-		ItemBase *i=get_item(items, name);
+	template<typename T>
+	T &extract(const Variant &var) const;
 
-		const Item<NCT> *item=dynamic_cast<const Item<NCT> *>(i);
-		if(!item)
-			throw TypeError("Type mismatch on item '"+name+"'");
+	template<typename T>
+	std::list<T *> extract_list(const std::list<const Variant *> &vars) const
+	{
+		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;
+	}
 
-		return item->data;
+	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);
 	}
 
-	/**
-	Returns a list of the names of objects of a specific type in the collection.
-	*/
+public:
+	/// Returns a list of the names of objects of one type in the collection.
 	template<typename T>
 	std::list<std::string> get_names() const
 	{
-		std::list<std::string> result;
-		for(ItemMap::const_iterator i=items.begin(); i!=items.end(); ++i)
-			if(dynamic_cast<const Item<typename RemoveConst<T>::Type> *>(i->second))
-				result.push_back(i->first);
-		return result;
+		std::list<std::string> names;
+		gather_items<typename RemoveConst<T>::Type>(0, &names, 0, false);
+		return names;
 	}
 
-	/**
-	Returns a list of objects of a specific type in the collection.
-	*/
+	/** Returns a list of the names of objects of one type in the collection or
+	available from sources. */
+	template<typename T>
+	std::list<std::string> get_names()
+	{
+		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
 	{
-		typedef typename RemoveConst<T>::Type NCT;
+		std::list<const Variant *> vars;
+		gather_items<typename RemoveConst<T>::Type>(&vars, 0, 0, false);
+		return extract_list<T>(vars);
+	}
 
-		std::list<T *> result;
-		for(ItemMap::const_iterator i=items.begin(); i!=items.end(); ++i)
-			if(Item<NCT> *item=dynamic_cast<Item<NCT> *>(i->second))
-				result.push_back(item->data);
-		return result;
+	/** Returns a list of objects of one type, loading them from sources if
+	necessary. */
+	template<typename T>
+	std::list<T *> get_list()
+	{
+		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);
 	}
 
-	/**
-	Checks whether a name exists in the collection.  Does not care about the
-	type of the object.
-	*/
-	bool contains(const std::string &n) const;
+private:
+	unsigned get_status(const std::string &, const CollectionItemTypeBase &) const;
 
-	/**
-	Returns the name of an item in the collection.
-	*/
+	template<typename T>
+	unsigned get_status(const std::string &name) const
+	{
+		// XXX Should go through all applicable types
+		if(CollectionItemTypeBase *type = get_type<T>())
+			return get_status(name, *type);
+
+		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<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<typename RemoveConst<T>::Type>(name)>0; }
+
+	/// Returns the name of an item in the collection.
 	template<typename T>
 	const std::string &get_name(T *d) const
 	{
-		typedef typename RemoveConst<T>::Type NCT;
+		typedef RefPtr<typename RemoveConst<T>::Type> RPNCT;
 
 		for(ItemMap::const_iterator i=items.begin(); i!=items.end(); ++i)
-			if(Item<NCT> *item=dynamic_cast<Item<NCT> *>(i->second))
-				if(item->data==d)
+			if(i->second.check_type<RPNCT>())
+				if(i->second.value<RPNCT>().get()==d)
 					return i->first;
 	
-		throw KeyError("Item not found in collection");
+		// XXX Need better exception class
+		throw std::runtime_error("Item not found in collection");
 	}
 
 protected:
-	/**
-	Adds a type that can be loaded from datafiles.
-	*/
+	/** 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>
-	void add_keyword(const std::string &keyword)
-	{ add_keyword<T, T>(keyword); }
+	CollectionItemType<T> &add_type();
 
-	/**
-	Adds a type that can be loaded from datafiles, with different storage type.
-	*/
-	template<typename T, typename S>
-	void add_keyword(const std::string &keyword)
-	{ keywords.push_back(new ItemKeyword<T, S>(keyword)); }
+private:
+	/// Returns the descriptor for a type, or null if one isn't defined.
+	template<typename T>
+	CollectionItemTypeBase *get_type() const;
 
-	/**
-	Adds a type that can be created automatically.
-	*/
-	template<typename T, typename C>
-	void add_creator(T *(C::*func)(const std::string &))
-	{ add_creator<T, T, C>(func); }
+	/// 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 Collection::ItemLoader<T, false>: public T::Loader
+{
+public:
+	ItemLoader(T &o, Collection &):
+		T::Loader(o)
+	{ }
+};
+
+template<typename T>
+class Collection::ItemLoader<T, true>: public T::Loader
+{
+public:
+	ItemLoader(T &o, Collection &c):
+		T::Loader(o, dynamic_cast<typename T::Loader::Collection &>(c))
+	{ }
+};
+
+
+class CollectionItemTypeBase
+{
+protected:
+	struct ExtractorBase
+	{
+		virtual ~ExtractorBase() { }
+	};
+
+	template<typename T>
+	struct Extractor: ExtractorBase
+	{
+		virtual T &extract(const Variant &) const = 0;
+	};
+
+	std::string kwd;
+	std::vector<std::string> suffixes;
+	std::vector<ExtractorBase *> extractors;
+
+	CollectionItemTypeBase() { }
+public:
+	virtual ~CollectionItemTypeBase();
+
+	void set_keyword(const std::string &);
+	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 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;
+	}
+};
+
+
+/**
+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
+{
+private:
+	struct CreatorBase
+	{
+		virtual ~CreatorBase() { }
+
+		virtual T *create(Collection &, const std::string &) const = 0;
+	};
+
+	template<typename C>
+	struct Creator: CreatorBase
+	{
+		typedef T *(C::*FuncPtr)(const std::string &);
+
+		FuncPtr func;
+
+		Creator(FuncPtr f): func(f) { }
+
+		virtual T *create(Collection &coll, const std::string &name) const
+		{ return (dynamic_cast<C &>(coll).*func)(name); }
+	};
+
+	template<typename B>
+	struct Extractor: CollectionItemTypeBase::Extractor<B>
+	{
+		virtual B &extract(const Variant &var) const
+		{ return *var.value<RefPtr<T> >(); }
+	};
+
+	CreatorBase *creat;
+
+public:
+	CollectionItemType():
+		creat(0)
+	{ }
+
+	~CollectionItemType()
+	{
+		delete creat;
+	}
+
+	/** 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)
+	{
+		set_keyword(k);
+		return *this;
+	}
+
+	/** Adds a suffix that is used to match names when looking for future
+	objects.  There is no implied separator; a name matches if it ends with the
+	suffix.  If a keyword is defined before any suffixes, then "."+keyword is
+	added as a suffix. */
+	CollectionItemType &suffix(const std::string &s)
+	{
+		add_suffix(s);
+		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 &creator(T *(C::*func)(const std::string &))
+	{
+		delete creat;
+		creat = new Creator<C>(func);
+		return *this;
+	}
+
+	/** Makes items of this type available through a base class. */
+	template<typename B>
+	CollectionItemType &base()
+	{
+		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
+	{ loader.add(kwd, &Collection::Loader::item<T, T>); }
+
+	virtual bool can_create() const
+	{ return creat!=0; }
+
+	virtual void create_item(Collection &coll, const std::string &name) const
+	{
+		if(!creat)
+			throw std::runtime_error("no creator");
+		T *obj = creat->create(coll, name);
+		if(obj)
+			coll.add(name, obj);
+	}
 
-	template<typename T, typename S, typename C>
-	void add_creator(T *(C::*func)(const std::string &))
-	{ creators.push_back(new ItemCreator<T, S, C>(func)); }
+	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);
+		coll.add(name, obj.get());
+		obj.release();
+	}
 };
 
+
+template<typename T>
+T &Collection::extract(const Variant &var) const
+{
+	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<RefPtr<T> >();
+}
+
+template<typename T>
+CollectionItemType<T> &Collection::add_type()
+{
+	CollectionItemType<T> *type = new CollectionItemType<T>;
+	types.push_back(type);
+	return *type;
+}
+
+template<typename T>
+CollectionItemTypeBase *Collection::get_type() const
+{
+	for(TypeList::const_iterator j=types.begin(); j!=types.end(); ++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>())
+			return *j;
+	return 0;
+}
+
 } // namespace DataFile
 } // namespace Msp