ReadonlyCollection.h

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00001 #ifndef TAGCOLL_READONLY_COLLECTION_H
00002 #define TAGCOLL_READONLY_COLLECTION_H
00003 
00008 /*
00009  * Copyright (C) 2003,2004,2005,2006  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 {
00037 template<typename ITEM, typename TAG>
00038 class ReadonlyCollection
00039 {
00040 protected:
00047     virtual OpSet<ITEM> getItemsHavingTag(const TAG& tag) const = 0;
00048 
00055     virtual OpSet<ITEM> getItemsHavingTags(const OpSet<TAG>& tags) const
00056     {
00057         if (tags.empty())
00058             return OpSet<ITEM>();
00059 
00060         typename OpSet<TAG>::const_iterator i = tags.begin();
00061         OpSet<ITEM> res = getItemsHavingTag(*i);
00062 
00063         for ( ; i != tags.end(); i++)
00064             res ^= getItemsHavingTag(*i);
00065 
00066         return res;
00067 
00068     }
00069 
00079     virtual OpSet<TAG> getTagsOfItem(const ITEM& item) const = 0;
00080 
00090     virtual OpSet<TAG> getTagsOfItems(const OpSet<ITEM>& items) const
00091     {
00092         OpSet<TAG> res;
00093         for (typename OpSet<ITEM>::const_iterator i = items.begin();
00094                 i != items.end(); i++)
00095             res += getTagsOfItem(*i);
00096         return res;
00097     }
00098 
00099 public:
00100     virtual ~ReadonlyCollection() {}
00101     
00110     virtual bool hasTag(const TAG& tag) const
00111     {
00112         return !getItems(tag).empty();
00113     }
00114 
00118     OpSet<TAG> getTags(const ITEM& item) const { return getTagsOfItem(item); }
00119 
00123     OpSet<TAG> getTags(const OpSet<ITEM>& items) const { return getTagsOfItems(items); }
00124 
00128     OpSet<ITEM> getItems(const TAG& tag) const { return getItemsHavingTag(tag); }
00129 
00133     OpSet<ITEM> getItems(const OpSet<TAG>& tags) const { return getItemsHavingTags(tags); }
00134 
00138     virtual OpSet<ITEM> getTaggedItems() const = 0;
00139 
00143     virtual OpSet<TAG> getAllTags() const = 0;
00144 
00148     virtual int getCardinality(const TAG& tag) const
00149     {
00150         return getItemsHavingTag(tag).size();
00151     }
00152 
00166     virtual OpSet<TAG> getCompanionTags(const OpSet<TAG>& tags) const
00167     {
00168         return getTagsOfItems(getItemsHavingTags(tags)) - tags;
00169     }
00170 
00202     virtual OpSet<ITEM> getRelatedItems(const OpSet<TAG>& tags, int maxdistance = 1) const
00203     {
00204         OpSet<ITEM> packages;
00205         OpSet<ITEM> res;
00206 
00207         // First get a list of packages that have a non-empty intersection with `tags'
00208         for (typename OpSet<TAG>::const_iterator i = tags.begin(); i != tags.end(); i++)
00209             packages += getItemsHavingTag(*i);
00210 
00211         // Then keep only those within the given distance
00212         for (typename OpSet<ITEM>::const_iterator i = packages.begin(); i != packages.end(); i++)
00213         {
00214             int dist = tags.distance(getTagsOfItem(*i));
00215             if (dist >= 0 && dist <= maxdistance)
00216                 res += *i;
00217         }
00218 
00219         return res;
00220     }
00221 
00225     virtual void output(Consumer<ITEM, TAG>& consumer) const = 0;
00226 
00231     virtual void outputHavingTags(const OpSet<TAG>& tags, Consumer<ITEM, TAG>& consumer) const
00232     {
00233         OpSet<ITEM> items = getItemsHavingTags(tags);
00234         for (typename OpSet<ITEM>::const_iterator i = items.begin();
00235                 i != items.end(); i++)
00236             consumer.consume(*i, getTagsOfItem(*i));
00237     }
00238 };
00239 
00240 };
00241 
00242 // vim:set ts=4 sw=4:
00243 #endif

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