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Collection.h

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00001 #ifndef TAGCOLL_COLLECTION_H
00002 #define TAGCOLL_COLLECTION_H
00003 
00008 /*
00009  * Copyright (C) 2003,2004,2005  Enrico Zini <enrico@debian.org>
00010  *
00011  * This library is free software; you can redistribute it and/or
00012  * modify it under the terms of the GNU Lesser General Public
00013  * License as published by the Free Software Foundation; either
00014  * version 2.1 of the License, or (at your option) any later version.
00015  *
00016  * This library is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00019  * Lesser General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU Lesser General Public
00022  * License along with this library; if not, write to the Free Software
00023  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
00024  */
00025 
00026 #include <tagcoll/Consumer.h>
00027 
00028 namespace Tagcoll
00029 {
00030 template<typename, typename> class PatchList;
00031 
00039 template<typename ITEM, typename TAG>
00040 class Collection : public Consumer<ITEM, TAG>
00041 {
00042 protected:
00043     /*
00044      * Implementation note: to avoid problems with classes implementing only
00045      * some of the virtual methods, they are given different names.  The common
00046      * 'comsume' methods are just inlined calls to the right virtual functions,
00047      * and are a way of keeping the unoverridden methods from being hidden.
00048      */
00049 
00050     void consumeItemUntagged(const ITEM&) {}
00051     void consumeItemsUntagged(const OpSet<ITEM>&) {}
00052 
00059     virtual OpSet<ITEM> getItemsHavingTag(const TAG& tag) const = 0;
00060 
00067     virtual OpSet<ITEM> getItemsHavingTags(const OpSet<TAG>& tags) const
00068     {
00069         if (tags.empty())
00070             return OpSet<ITEM>();
00071 
00072         typename OpSet<TAG>::const_iterator i = tags.begin();
00073         OpSet<ITEM> res = getItemsHavingTag(*i);
00074 
00075         for ( ; i != tags.end(); i++)
00076             res ^= getItemsHavingTag(*i);
00077 
00078         return res;
00079 
00080     }
00081 
00091     virtual OpSet<TAG> getTagsOfItem(const ITEM& item) const = 0;
00092 
00102     virtual OpSet<TAG> getTagsOfItems(const OpSet<ITEM>& items) const
00103     {
00104         OpSet<TAG> res;
00105         for (typename OpSet<ITEM>::const_iterator i = items.begin();
00106                 i != items.end(); i++)
00107             res += getTagsOfItem(*i);
00108         return res;
00109     }
00110 
00111 public:
00112     virtual ~Collection() {}
00113     
00122     virtual bool hasTag(const TAG& tag) const
00123     {
00124         return !getItems(tag).empty();
00125     }
00126 
00130     OpSet<TAG> getTags(const ITEM& item) const { return getTagsOfItem(item); }
00131 
00135     OpSet<TAG> getTags(const OpSet<ITEM>& items) const { return getTagsOfItems(items); }
00136 
00140     OpSet<ITEM> getItems(const TAG& tag) const { return getItemsHavingTag(tag); }
00141 
00145     OpSet<ITEM> getItems(const OpSet<TAG>& tags) const { return getItemsHavingTags(tags); }
00146 
00159     virtual void applyChange(const PatchList<ITEM, TAG>& change) = 0;
00160 
00164     virtual OpSet<ITEM> getTaggedItems() const = 0;
00165 
00169     virtual OpSet<TAG> getAllTags() const = 0;
00170 
00174     virtual int getCardinality(const TAG& tag) const
00175     {
00176         return getItemsHavingTag(tag).size();
00177     }
00178 
00192     virtual OpSet<TAG> getCompanionTags(const OpSet<TAG>& tags) const
00193     {
00194         return getTagsOfItems(getItemsHavingTags(tags)) - tags;
00195     }
00196 
00228     virtual OpSet<ITEM> getRelatedItems(const OpSet<TAG>& tags, int maxdistance = 1) const
00229     {
00230         OpSet<ITEM> packages;
00231         OpSet<ITEM> res;
00232 
00233         // First get a list of packages that have a non-empty intersection with `tags'
00234         for (typename OpSet<TAG>::const_iterator i = tags.begin(); i != tags.end(); i++)
00235             packages += getItemsHavingTag(*i);
00236 
00237         // Then keep only those within the given distance
00238         for (typename OpSet<ITEM>::const_iterator i = packages.begin(); i != packages.end(); i++)
00239         {
00240             int dist = tags.distance(getTagsOfItem(*i));
00241             if (dist >= 0 && dist <= maxdistance)
00242                 res += *i;
00243         }
00244 
00245         return res;
00246     }
00247 
00251     virtual void output(Consumer<ITEM, TAG>& consumer) const = 0;
00252 
00257     virtual void outputHavingTags(const OpSet<TAG>& tags, Consumer<ITEM, TAG>& consumer) const
00258     {
00259         OpSet<ITEM> items = getItemsHavingTags(tags);
00260         for (typename OpSet<ITEM>::const_iterator i = items.begin();
00261                 i != items.end(); i++)
00262             consumer.consume(*i, getTagsOfItem(*i));
00263     }
00264 };
00265 
00266 };
00267 
00268 // vim:set ts=4 sw=4:
00269 #endif

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