X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Fcollection.h;h=d0e8a1a8bb9b25c636ab23a8c1e4bbdcfa5c04a7;hb=HEAD;hp=3a3b90e57398ec3ff99221b09f85143a37330f02;hpb=e39534940056cdbec16c0d09d43e5375e2bbaf1c;p=libs%2Fdatafile.git

diff --git a/source/collection.h b/source/collection.h
index 3a3b90e..c8470dd 100644
--- a/source/collection.h
+++ b/source/collection.h
@@ -1,279 +1,555 @@
-/* $Id$
-
-This file is part of libmspdatafile
-Copyright © 2006  Mikko Rasa, Mikkosoft Productions
-Distributed under the LGPL
-*/
-
 #ifndef MSP_DATAFILE_COLLECTION_H_
 #define MSP_DATAFILE_COLLECTION_H_
 
+#include <type_traits>
+#include <msp/core/attributes.h>
+#include <msp/core/maputils.h>
+#include <msp/core/noncopyable.h>
 #include <msp/core/refptr.h>
+#include "collectionsource.h"
 #include "loader.h"
+#include "meta.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 {
 
-/**
-Helper struct to determine whether a Loader has a Collection typedef.
-*/
+class CollectionItemTypeBase;
+
 template<typename T>
-struct NeedsCollection
-{
-	struct Yes { char c[2]; };
-	struct No { char c; };
+class CollectionItemType;
 
-	template<typename U>
-	static Yes f(typename U::Collection *);
-	template<typename U>
-	static No f(...);
+template<typename T>
+class LoadableCollectionItemType;
 
-	enum { result=(sizeof(f<T>(0))==sizeof(Yes)) };
-};
+template<typename T, bool = HasLoader<T>::value>
+struct CollectionItemTypeChooser;
+
+template<typename T>
+struct CollectionItemTypeChooser<T, true>
+{ typedef LoadableCollectionItemType<T> Type; };
+
+template<typename T>
+struct CollectionItemTypeChooser<T, false>
+{ typedef CollectionItemType<T> Type; };
 
 /**
 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.
+
+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
+class Collection: private NonCopyable
 {
 public:
-	class Loader;
+	/**
+	Loads objects into a Collection.  Automatically picks up keywords from
+	defined item types.
+	*/
+	class Loader: public DataFile::Loader
+	{
+		template<typename T> friend class LoadableCollectionItemType;
+
+	private:
+		Collection &coll;
+
+	public:
+		Loader(Collection &);
+		Collection &get_object() const { return coll; }
+	private:
+		template<typename T, typename S>
+		void item(const std::string &n)
+		{
+			RefPtr<T> it = new T;
+			ItemLoader<T> ldr(*it, coll);
+			load_sub_with(ldr);
+			coll.add<S>(n, it.get());
+			it.release();
+		}
+	};
+
+	template<typename T, bool = NeedsCollection<typename T::Loader>::value>
+	class ItemLoader;
 
 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. */
+	typedef std::map<std::string, Variant> ItemMap;
+
+	std::vector<CollectionItemTypeBase *> types;
+	ItemMap items;
+	std::vector<const CollectionSource *> sources;
+	Collection *fallback = nullptr;
 
-	struct ItemBase
+public:
+	virtual ~Collection();
+
+	/** 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)
 	{
-		virtual ~ItemBase() { }
-	};
+		if(!item)
+			throw std::invalid_argument("Collection::add(item)");
+
+		typedef typename std::remove_cv<T>::type NCT;
+		RefPtr<NCT> ptr(item);
+		try
+		{
+			add_var(name, get_type<NCT>(name), ptr);
+		}
+		catch(...)
+		{
+			// Avoid deleting the object
+			ptr.release();
+			throw;
+		}
+	}
 
+	/// Gets a typed object from the collection.
 	template<typename T>
-	struct Item: public ItemBase
+	T &get(const std::string &name) const
 	{
-		T *data;
+		return extract<typename std::remove_cv<T>::type>(get_item(items, name));
+	}
 
-		Item(T *d): data(d) { }
-		~Item() { delete data; }
-	};
+	/** 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)
+	{
+		typedef typename std::remove_cv<T>::type NCT;
+		return extract<NCT>(get_var(name, get_type<NCT>(name)));
+	}
 
-	/**
-	Used to store keywords for types that can be loaded.
-	*/
-	struct ItemKeywordBase
+	/** Finds a typed object in the collection.  Returns null if the name does
+	not exist.  Throws if the name exists but the object is of an incorrect
+	type. */
+	template<typename T>
+	T *find(const std::string &name) const
 	{
-		virtual void add_to_loader(Loader &) const { };
-	};
+		ItemMap::const_iterator i = items.find(name);
+		return (i!=items.end() ? extract<typename std::remove_cv<T>::type>(i->second) : 0);
+	}
 
-	template<typename T, typename S, bool need_coll=NeedsCollection<typename T::Loader>::result>
-	struct ItemKeyword: public ItemKeywordBase
+	template<typename T>
+	T *find(const std::string &name)
 	{
-		std::string keyword;
+		typedef typename std::remove_cv<T>::type NCT;
+		const Variant *var = find_var(name, get_type<NCT>(name));
+		return (var ? &extract<NCT>(*var) : 0);
+	}
 
-		ItemKeyword(const std::string &kw): keyword(kw) { }
+private:
+	void add_var(const std::string &, const CollectionItemTypeBase *, const Variant &);
+	const Variant &get_var(const std::string &, const CollectionItemTypeBase *);
+	const Variant *find_var(const std::string &, const CollectionItemTypeBase *);
 
-		void add_to_loader(Loader &ldr) const
-		{ ldr.add(keyword, &Loader::item<T, S>); }
-	};
+	template<typename T>
+	T &extract(const Variant &var) const;
 
-	template<typename T, typename S>
-	struct ItemKeyword<T, S, true>: public ItemKeywordBase
+	template<typename T>
+	std::list<T *> extract_list(const std::vector<const Variant *> &vars) const
 	{
-		std::string keyword;
+		std::list<T *> result;
+		for(const Variant *v: vars)
+			result.push_back(&extract<T>(*v));
+		return result;
+	}
 
-		ItemKeyword(const std::string &kw): keyword(kw) { }
+	void gather_items(std::vector<const Variant *> *, std::list<std::string> *, const CollectionItemTypeBase &, bool) const;
 
-		virtual void add_to_loader(Loader &ldr) const
-		{ ldr.add(keyword, &Loader::coll_item<T, S, typename T::Loader::Collection>); }
-	};
+	template<typename T>
+	void gather_items(std::vector<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);
+	}
 
-	/**
-	Used to store types that can be created automatically.
-	*/
-	struct ItemCreatorBase
+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
 	{
-		virtual ~ItemCreatorBase() { }
+		std::list<std::string> names;
+		gather_items<typename std::remove_cv<T>::type>(0, &names, 0, false);
+		return names;
+	}
 
-		template<typename S>
-		S *create(Collection &coll, const std::string &name)
-		{
-			ItemCreatorBridge<S> *creator=dynamic_cast<ItemCreatorBridge<S> *>(this);
-			if(creator)
-				return creator->create(coll, name);
-			return 0;
-		}
-	};
+	/** 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 std::remove_cv<T>::type>(0, &names, 0, true);
+		return names;
+	}
 
-	template<typename S>
-	struct ItemCreatorBridge: public ItemCreatorBase
+	/// Returns a list of objects of one type in the collection.
+	template<typename T>
+	std::list<T *> get_list() const
 	{
-		virtual S *create(Collection &, const std::string &) const =0;
-	};
+		std::vector<const Variant *> vars;
+		gather_items<typename std::remove_cv<T>::type>(&vars, 0, 0, false);
+		return extract_list<T>(vars);
+	}
 
-	template<typename T, typename S, typename C>
-	struct ItemCreator: public ItemCreatorBridge<S>
+	/** Returns a list of objects of one type, loading them from sources if
+	necessary. */
+	template<typename T>
+	std::list<T *> get_list()
 	{
-		typedef T *(C::*fCreate)(const std::string &);
+		CollectionItemTypeBase *type = get_type<typename std::remove_cv<T>::type>();
+		if(type)
+			load_items_from_sources(*type);
 
-		fCreate create_func;
+		std::vector<const Variant *> vars;
+		gather_items<typename std::remove_cv<T>::type>(&vars, 0, type, true);
+		return extract_list<T>(vars);
+	}
 
-		ItemCreator(fCreate cf): create_func(cf) { }
-		virtual S *create(Collection &coll, const std::string &name) const
-		{ return (dynamic_cast<C &>(coll).*create_func)(name); }
-	};
+private:
+	unsigned get_status(const std::string &, const CollectionItemTypeBase &) const;
+
+	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:
-	/**
-	Loads objects into a Collection.
-	*/
-	class Loader: public DataFile::Loader
+	/// Checks whether a typed object exists in the collection.
+	template<typename T>
+	bool contains(const std::string &name) const
+	{ return get_status<typename std::remove_cv<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 std::remove_cv<T>::type>(name)>0; }
+
+	/// Returns the name of an item in the collection.
+	template<typename T>
+	const std::string &get_name(T *d) const
 	{
-	private:
-		Collection &coll;
+		typedef RefPtr<typename std::remove_cv<T>::type> RPNCT;
+
+		for(const auto &kvp: items)
+			if(kvp.second.check_type<RPNCT>())
+				if(kvp.second.value<RPNCT>().get()==d)
+					return kvp.first;
+	
+		// XXX Need better exception class
+		throw std::runtime_error("Item not found in collection");
+	}
 
-	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();
-		}
+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>
+	typename CollectionItemTypeChooser<T>::Type &add_type();
 
-		template<typename T, typename S>
-		void item(const std::string &n)
-		{
-			RefPtr<T> it=new T;
-			load_sub(*it);
-			coll.add<S>(n, it.get());
-			it.release();
-		}
+	/** Returns a mutable reference to an existing type descriptor.  This can be
+	used to e.g. override the creator function of a type added by a base class. */
+	template<typename T>
+	typename CollectionItemTypeChooser<T>::Type &modify_type();
 
-		template<typename, typename, bool> friend class ItemKeyword;
-	};
+private:
+	/** Returns the descriptor for a type, or null if one isn't defined.  An
+	optional name can be given to prioritize matching types. */
+	template<typename T>
+	CollectionItemTypeBase *get_type(const std::string & = std::string()) const;
+
+	/// 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;
 
 private:
-	typedef std::map<std::string, ItemBase *> ItemMap;
-	typedef std::list<ItemKeywordBase *> ItemKeywordSeq;
-	typedef std::list<ItemCreatorBase *> ItemCreatorSeq;
+	void gather_names_from_sources(std::list<std::string> &, const CollectionItemTypeBase &) const;
 
-	ItemMap items;
-	ItemKeywordSeq keywords;
-	ItemCreatorSeq creators;
+	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:
-	virtual ~Collection();
+	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() = default;
+	};
 
-	/**
-	Adds an object into the collection.  If a name collision occurs, an
-	exception is thrown.  The collection takes ownership of the object.
-	*/
 	template<typename T>
-	void add(const std::string &name, T *d)
+	struct Extractor: ExtractorBase
 	{
-		if(items.count(name))
-			throw KeyError("Duplicate key '"+name+"' in collection");
+		virtual T &extract(const Variant &) const = 0;
+	};
 
-		items[name]=new Item<T>(d);
+	std::string kwd;
+	std::vector<std::string> suffixes;
+	std::vector<ExtractorBase *> extractors;
+
+	CollectionItemTypeBase() = default;
+public:
+	virtual ~CollectionItemTypeBase();
+
+protected:
+	void set_keyword(const std::string &);
+	void add_suffix(const std::string &);
+public:
+	const std::string &get_keyword() const { return kwd; }
+	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;
+	virtual void notify_item(const std::string &, const Variant &) const = 0;
+
+	template<typename T>
+	bool can_extract() const
+	{
+		for(ExtractorBase *e: extractors)
+			if(dynamic_cast<Extractor<T> *>(e))
+				return true;
+		return false;
 	}
 
-	/**
-	Gets an object of a specific type from the collection.
-	*/
 	template<typename T>
-	T &get(const std::string &name) const
+	T *extract(const Variant &var) const
 	{
-		ItemMap::const_iterator i=items.find(name);
-		if(i==items.end())
-			throw KeyError("Item '"+name+"' not found in collection");
+		for(ExtractorBase *e: extractors)
+			if(Extractor<T> *ex = dynamic_cast<Extractor<T> *>(e))
+				return &ex->extract(var);
+		return 0;
+	}
+};
 
-		const Item<T> *item=dynamic_cast<const Item<T> *>(i->second);
-		if(!item)
-			throw TypeError("Item '"+name+"' is not of correct type");
 
-		return *item->data;
+/**
+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:
+	template<typename B>
+	struct Extractor: CollectionItemTypeBase::Extractor<B>
+	{
+		B &extract(const Variant &var) const override
+		{ return *var.value<RefPtr<T> >(); }
+	};
+
+	std::function<T *(const std::string &)> create_func;
+	std::vector<std::function<void(const std::string &, T &)>> notify_funcs;
+
+public:
+	/** 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 loadable
+	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;
 	}
 
-	/**
-	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.
-	*/
-	template<typename T>
-	T &get(const std::string &name)
+	/** 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 F>
+	CollectionItemType &creator(F func)
 	{
-		ItemMap::const_iterator i=items.find(name);
-		if(i==items.end())
-		{
-			for(ItemCreatorSeq::iterator j=creators.begin(); j!=creators.end(); ++j)
-				if(T *d=(*j)->create<T>(*this, name))
-				{
-					// We already know that the item didn't exist yet
-					items[name]=new Item<T>(d);
-					return *d;
-				}
-			throw KeyError("Item '"+name+"' not found in collection");
-		}
+		create_func = func;
+		return *this;
+	}
 
-		const Item<T> *item=dynamic_cast<const Item<T> *>(i->second);
-		if(!item)
-			throw TypeError("Item '"+name+"' is not of correct type");
+	/** Makes items of this type available through a base class. */
+	template<typename B>
+	CollectionItemType &base()
+	{
+		extractors.push_back(new Extractor<B>);
+		return *this;
+	}
 
-		return *item->data;
+	template<typename F>
+	CollectionItemType &notify(F func)
+	{
+		notify_funcs.emplace_back(func);
+		return *this;
 	}
 
-	/**
-	Returns a list of the names of objects of a specific type in the collection.
-	*/
-	template<typename T>
-	std::list<std::string> get_names() const
+	bool is_same_type(const CollectionItemTypeBase &other) const override
+	{ return dynamic_cast<const CollectionItemType<T> *>(&other); }
+
+	bool check_item_type(const Variant &var) const override
+	{ return var.check_type<RefPtr<T> >(); }
+
+	void add_to_loader(Collection::Loader &) const override
+	{ }
+
+	bool can_create() const override
+	{ return static_cast<bool>(create_func); }
+
+	void create_item(Collection &coll, const std::string &name) const override
 	{
-		std::list<std::string> result;
-		for(ItemMap::const_iterator i=items.begin(); i!=items.end(); ++i)
-			if(dynamic_cast<const Item<T> *>(i->second))
-				result.push_back(i->first);
-		return result;
+		if(!create_func)
+			throw std::runtime_error("no creator");
+		T *obj = create_func(name);
+		if(obj)
+			coll.add(name, obj);
 	}
 
-	/**
-	Checks whether a name exists in the collection.  Does not care about the
-	type of the object.
-	*/
-	bool contains(const std::string &n) const;
+	void load_item(Collection &, Parser &, const std::string &) const override
+	{
+		throw std::runtime_error("this type cannot be loaded");
+	}
 
-protected:
-	/**
-	Adds a type that can be loaded from datafiles.
-	*/
-	template<typename T>
-	void add_keyword(const std::string &keyword)
-	{ add_keyword<T, T>(keyword); }
+	void notify_item(const std::string &name, const Variant &var) const override
+	{
+		RefPtr<T> obj = var.value<RefPtr<T> >();
+		for(const auto &n: notify_funcs)
+			n(name, *obj);
+	}
+};
 
-	/**
-	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)); }
 
-	/**
-	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); }
+template<typename T>
+class LoadableCollectionItemType: public CollectionItemType<T>
+{
+public:
+	void add_to_loader(Collection::Loader &loader) const override
+	{ loader.add(this->kwd, &Collection::Loader::item<T, T>); }
 
-	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)); }
+	void load_item(Collection &coll, Parser &parser, const std::string &name) const override
+	{
+		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>
+typename CollectionItemTypeChooser<T>::Type &Collection::add_type()
+{
+	typename CollectionItemTypeChooser<T>::Type *type = new typename CollectionItemTypeChooser<T>::Type;
+	types.push_back(type);
+	return *type;
+}
+
+template<typename T>
+typename CollectionItemTypeChooser<T>::Type &Collection::modify_type()
+{
+	for(CollectionItemTypeBase *t: types)
+		if(CollectionItemType<T> *tt = dynamic_cast<CollectionItemType<T> *>(t))
+			return *tt;
+
+	throw std::logic_error("type not found in collection");
+}
+
+template<typename T>
+CollectionItemTypeBase *Collection::get_type(const std::string &name) const
+{
+	for(CollectionItemTypeBase *t: types)
+		if(dynamic_cast<CollectionItemType<T> *>(t))
+			return t;
+	CollectionItemTypeBase *type = nullptr;
+	for(CollectionItemTypeBase *t: types)
+		if(t->can_extract<T>())
+		{
+			if(!name.empty() && t->match_name(name))
+				return t;
+			type = t;
+		}
+	return type;
+}
+
 } // namespace DataFile
 } // namespace Msp