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/*
* Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; version 2 of the
* License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
//! This is a generic algorithm for incrementally building any kind of list
//! with the least ammount of changes.
//! It was written primarily for updating menus and toolbars without having
//! to recreate them from scratch, but can also be used for other similar tasks.
//! The algorithm works in 2 stages, one to find out the differences and the
//! other to apply the differences.
//! Pre-conditions:
//! - no duplicate items must be possible
//! - there must be a 1:1 mapping between items from the 2 lists
#ifndef _INCREMENTAL_LIST_UPDATER_H_
#define _INCREMENTAL_LIST_UPDATER_H_
namespace bec {
template<class DestIterator, class DestRef, class SourceIterator>
class IncrementalListUpdater
{
public:
typedef DestIterator dest_iterator;
typedef DestRef dest_ref;
typedef SourceIterator source_iterator;
virtual ~IncrementalListUpdater() {}
virtual dest_iterator get_dest_iterator()= 0;
virtual source_iterator get_source_iterator()= 0;
virtual dest_iterator increment_dest(dest_iterator &iter)= 0;
virtual source_iterator increment_source(source_iterator &iter)= 0;
virtual bool has_more_dest(dest_iterator iter)= 0;
virtual bool has_more_source(source_iterator iter)= 0;
virtual bool items_match(dest_iterator diter, source_iterator siter)= 0;
virtual dest_ref get_dest(dest_iterator iter)= 0;
virtual void update(dest_ref dest_item, source_iterator source_item)= 0;
// begin adding items to the begginning of the dest list
virtual dest_iterator begin_adding()= 0;
virtual dest_iterator add(dest_iterator &iter, source_iterator source_item)= 0;
virtual dest_iterator add(dest_iterator &iter, dest_ref item)= 0;
// end adding items to the dest item, stuff after the last item added must be removed
virtual void end_adding(dest_iterator iter)= 0;
virtual void execute()
{
// find location of items in the source list in the dest list
for (source_iterator src_item= get_source_iterator(); has_more_source(src_item); increment_source(src_item))
{
// bool found= false;
for (dest_iterator item= get_dest_iterator(); has_more_dest(item); increment_dest(item))
{
if (items_match(item, src_item))
{
source_mapping[src_item]= get_dest(item);
// found= true;
break;
}
}
}
dest_iterator iter= begin_adding();
// go through source items and reorder or insert new items
for (source_iterator src_item= get_source_iterator(); has_more_source(src_item); increment_source(src_item))
{
if (dest_exists(src_item))
{
dest_ref dest= get_dest_for_source(src_item);
update(dest, src_item);
iter= add(iter, dest);
}
else
{
iter= add(iter, src_item);
}
}
end_adding(iter);
}
protected:
std::map<source_iterator, dest_ref> source_mapping;
bool dest_exists(source_iterator item)
{
return source_mapping.find(item) != source_mapping.end();
}
dest_ref get_dest_for_source(source_iterator item)
{
return source_mapping[item];
}
};
};
#endif
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