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TagcollReverser.h

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00001 #ifndef TAGCOLL_TAGCOLLREVERSER_H
00002 #define TAGCOLL_TAGCOLLREVERSER_H
00003 
00004 /*
00005  * "Reverse" a tagged collection, associating items to tags instead of tags to
00006  * items
00007  *
00008  * Copyright (C) 2003  Enrico Zini <enrico@debian.org>
00009  *
00010  * This library is free software; you can redistribute it and/or
00011  * modify it under the terms of the GNU Lesser General Public
00012  * License as published by the Free Software Foundation; either
00013  * version 2.1 of the License, or (at your option) any later version.
00014  *
00015  * This library is distributed in the hope that it will be useful,
00016  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018  * Lesser General Public License for more details.
00019  *
00020  * You should have received a copy of the GNU Lesser General Public
00021  * License along with this library; if not, write to the Free Software
00022  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
00023  */
00024 
00025 #pragma interface
00026 
00027 #include <tagcoll/TagcollConsumer.h>
00028 
00029 #include <string>
00030 #include <map>
00031 
00032 namespace Tagcoll
00033 {
00034 
00035 // TagcollConsumer that builds a tagged collection 
00036 template<class ITEM = std::string, class TAG = std::string>
00037 class TagcollReverser : public TagcollConsumer<ITEM, TAG>
00038 {
00039 protected:
00040     std::map< TAG, OpSet<ITEM> > tagged;
00041     OpSet<ITEM> untagged;
00042     ITEM untagged_name;
00043 
00044 public:
00045     virtual ~TagcollReverser() throw () {}
00046 
00047     // Set the item name to use when reversing untagged items.  If not set,
00048     // untagged items won't be included in the reversed collection
00049     void setUntaggedItemName(const ITEM& item) throw ()
00050     {
00051         untagged_name = item;
00052     }
00053 
00054     virtual void consume(const ITEM& item) throw ()
00055     {
00056         untagged += item;
00057     }
00058     
00059     virtual void consume(const ITEM& item, const OpSet<TAG>& tags) throw ()
00060     {
00061         for (typename OpSet<ITEM>::const_iterator i = tags.begin();
00062                 i != tags.end(); i++)
00063             tagged[*i] += item;
00064     }
00065 
00066     // Send the reversed data to a consumer
00067     void output(TagcollConsumer<TAG, ITEM>& consumer) throw ()
00068     {
00069         if (untagged_name.size() > 0)
00070             if (untagged.empty())
00071                 consumer.consume(untagged_name);
00072             else
00073                 consumer.consume(untagged_name, untagged);
00074         
00075         for (typename std::map< TAG, OpSet<ITEM> >::const_iterator i = tagged.begin();
00076                 i != tagged.end(); i++)
00077             if (i->second.empty())
00078                 consumer.consume(i->first);
00079             else
00080                 consumer.consume(i->first, i->second);
00081     }
00082 };
00083 
00084 };
00085 
00086 // vim:set ts=4 sw=4:
00087 #endif

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