room_util.h

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/**
 * This file is part of ArmarX.
 *
 * ArmarX is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * ArmarX 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, see <http://www.gnu.org/licenses/>.
 *
 * @author     Fabian Reister ( fabian dot reister at kit dot edu )
 * @date       2025
 * @copyright  http://www.gnu.org/licenses/gpl-2.0.txt
 *             GNU General Public License
 */
 
#pragma once
 
#include <vector>
 
#include <range/v3/range/conversion.hpp>
#include <range/v3/view/filter.hpp>
 
#include <armarx/navigation/algorithms/Room.h>
 
namespace armarx::navigation::algorithms
{
    /**
     * @brief Filter a collection of objects by whether their projected position lies inside a room.
     *
     * This function applies a projection callable to each object in @p objects and retains those
     * objects for which the room reports the projected value as inside (via Room::isInside).
     * The relative order of the returned elements matches the order in @p objects.
     *
     * @tparam T     Type of elements stored in @p objects. Must be CopyConstructible or MoveConstructible
     *               since selected elements are returned by value in a new std::vector<T>.
     * @tparam Proj  Callable type for the projection. Must be Invocable with an argument of type
     *               const T& (or T) and return a value accepted by
     *               armarx::navigation::algorithms::Room::isInside.
     *
     * @param room    Reference to an armarx::navigation::algorithms::Room used for the inside-test.
     * @param objects Constant reference to the input vector of objects to be filtered.
     * @param proj    Projection callable applied to each object to obtain the value checked by room.isInside.
     *
     * @returns A std::vector<T> containing copies of the objects for which
     *          room.isInside(proj(obj)) returns true. If no objects satisfy the predicate, an empty
     *          vector is returned.
     *
     * @complexity Linear in objects.size(): each element is projected and tested once.
     *
     * @exceptionsafety Any exceptions thrown by @p proj or Room::isInside propagate to the caller.
     *
     * @note This implementation relies on C++ ranges utilities (ranges::views::filter and ranges::to_vector).
     */
    template <typename T, typename Proj>
    std::vector<T>
    filterByRoom(const armarx::navigation::algorithms::Room& room,
                 const std::vector<T>& objects,
                 Proj proj)
    {
        namespace r = ::ranges;
        namespace rv = r::views;
 
        return objects |
               rv::filter([&room, &proj](const T& obj) { return room.isInside(proj(obj)); }) |
               r::to_vector;
    }
 
} // namespace armarx::navigation::algorithms