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/** \brief dynamic_list_impl.h */ // -*-c++-*-
// Copyright (C) 2010 Daniel Burrows
//
// 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; either version 2 of the
// License, or (at your option) any later version.
//
// 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; see the file COPYING. If not, write to
// the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
#ifndef DYNAMIC_LIST_IMPL_H
#define DYNAMIC_LIST_IMPL_H
#include "dynamic_list.h"
#include <boost/enable_shared_from_this.hpp>
#include <boost/make_shared.hpp>
#include <boost/shared_ptr.hpp>
#include <vector>
namespace aptitude
{
namespace util
{
/** \brief A basic implementation of the dynamic_list interface. */
template<typename T>
class dynamic_list_impl
: public writable_dynamic_list<T>,
public boost::enable_shared_from_this<dynamic_list_impl<T> >
{
typedef std::vector<T> collection;
collection entries;
public:
dynamic_list_impl();
/** \brief Retrieve the size of this list. */
std::size_t size();
/** \brief Get the idxth element of this list.
*
* \param idx A nonnegative integer less than size(), giving
* the index within this list of the desired
* element.
*/
T get_at(std::size_t idx);
/** \brief Create an empty list. */
static boost::shared_ptr<dynamic_list_impl> create();
void insert(const T &t, std::size_t position);
void remove(std::size_t position);
void move(std::size_t from, std::size_t to);
};
template<typename T>
dynamic_list_impl<T>::dynamic_list_impl()
{
}
template<typename T>
boost::shared_ptr<dynamic_list_impl<T> >
dynamic_list_impl<T>::create()
{
return boost::make_shared<dynamic_list_impl>();
}
template<typename T>
std::size_t dynamic_list_impl<T>::size()
{
return entries.size();
}
template<typename T>
T dynamic_list_impl<T>::get_at(std::size_t idx)
{
return entries[idx];
}
template<typename T>
void dynamic_list_impl<T>::insert(const T &t, std::size_t position)
{
entries.insert(entries.begin() + position, t);
this->signal_inserted(t, position);
}
template<typename T>
void dynamic_list_impl<T>::remove(std::size_t position)
{
T val = entries[position];
entries.erase(entries.begin() + position);
this->signal_removed(val, position);
}
template<typename T>
void dynamic_list_impl<T>::move(std::size_t from, std::size_t to)
{
// Don't do anything at all, don't even emit a signal, if a
// value is being moved to the same location that it already
// occupies.
if(from == to)
return;
// Simple approach: insert the value at its new location, then
// delete it from its old location.
// Defensive copy in case inserting into a vector from itself
// does anything weird. Pure paranoia.
T val = entries[from];
// If from < to, then we need to insert one entry farther than
// the target location, since the entry will shift left when we
// remove its old location.
const std::size_t idx_to_insert = from < to ? to + 1 : to;
entries.insert(entries.begin() + idx_to_insert, val);
// Note that if to < from, we just changed the index of the
// source of the move! Fix it up.
const std::size_t idx_to_delete = to < from ? from + 1 : from;
entries.erase(entries.begin() + idx_to_delete);
this->signal_moved(val, from, to);
}
}
}
#endif // DYNAMIC_LIST_IMPL_H
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