/*
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 *
 *  Point Cloud Library (PCL) - www.pointclouds.org
 *  Copyright (c) 2010-2011, Willow Garage, Inc.
 *  Copyright (c) 2012-, Open Perception, Inc.
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 *     with the distribution.
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 * $Id: file_grabber.h 8413 2013-01-15 08:37:39Z sdmiller $
 *
 */

#pragma once

#include <pcl/point_cloud.h>

namespace pcl
{
  /** \brief FileGrabber provides a container-style interface for grabbers which operate on fixed-size input
    * \author Stephen Miller
    * \ingroup io
    */
  template <typename PointT>
  class PCL_EXPORTS FileGrabber
  {
  public:

    /** \brief Empty destructor */
    virtual ~FileGrabber () {}

    /** \brief operator[] Returns the idx-th cloud in the dataset, without bounds checking.
     *  Note that in the future, this could easily be modified to do caching
     *  \param[in] idx The frame to load
     */
    virtual const typename pcl::PointCloud<PointT>::ConstPtr
    operator[] (std::size_t idx) const = 0;

    /** \brief size Returns the number of clouds currently loaded by the grabber */
    virtual std::size_t
    size () const = 0;
    
    /** \brief at Returns the idx-th cloud in the dataset, with bounds checking
     *  \param[in] idx The frame to load
     */
    virtual const typename pcl::PointCloud<PointT>::ConstPtr
    at (std::size_t idx) const
    {
      if (idx >= size ())
      {
        // Throw error 
        throw pcl::IOException ("[pcl::FileGrabber] Attempted to access element which is out of bounds!");
      }
      return (operator[] (idx));
    }
  };
}