/****************************************************************************
 *   This file is part of the aGrUM/pyAgrum library.                        *
 *                                                                          *
 *   Copyright (c) 2005-2026 by                                             *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
 *                                                                          *
 *   The aGrUM/pyAgrum library is free software; you can redistribute it    *
 *   and/or modify it under the terms of either :                           *
 *                                                                          *
 *    - the GNU Lesser General Public License as published by               *
 *      the Free Software Foundation, either version 3 of the License,      *
 *      or (at your option) any later version,                              *
 *    - the MIT license (MIT),                                              *
 *    - or both in dual license, as here.                                   *
 *                                                                          *
 *   (see https://agrum.gitlab.io/articles/dual-licenses-lgplv3mit.html)    *
 *                                                                          *
 *   This aGrUM/pyAgrum library is distributed in the hope that it will be  *
 *   useful, but WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,          *
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 *   FOR A PARTICULAR PURPOSE  AND NONINFRINGEMENT. IN NO EVENT SHALL THE   *
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 *   See LICENCES for more details.                                         *
 *                                                                          *
 *   SPDX-FileCopyrightText: Copyright 2005-2026                            *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
 *   SPDX-License-Identifier: LGPL-3.0-or-later OR MIT                      *
 *                                                                          *
 *   Contact  : info_at_agrum_dot_org                                       *
 *   homepage : http://agrum.gitlab.io                                      *
 *   gitlab   : https://gitlab.com/agrumery/agrum                           *
 *                                                                          *
 ****************************************************************************/


/**
 * @file
 * @brief exists aggregator
 *
 * @author Pierre-Henri WUILLEMIN(_at_LIP6) & Christophe GONZALES(_at_AMU)
 */

#ifndef GUM_EXISTS_AGGREGATOR_H
#define GUM_EXISTS_AGGREGATOR_H

#include <agrum/base/multidim/aggregators/multiDimAggregator.h>

namespace gum {

  namespace aggregator {
    // =========================================================================
    // ===                     GUM_EXISTS_AGGREGATOR                         ===
    // =========================================================================
    /**
     * @class Exists
     * @headerfile exists.h <agrum/base/multidim/aggregator/exists.h>
     * @ingroup multidim_agg_group
     *
     * @brief exists aggregator
     *
     * @see MultiDimAggregator for more details of implementations
     *
     * Note that a <tt>Exists(i)</tt> aggregator should have a binary
     * aggregator variable since only 0 and 1 indexes are adressed...
     */
    template < GUM_Numeric GUM_SCALAR >
    class Exists final: public MultiDimAggregator< GUM_SCALAR > {
      public:
      Exists(Idx value);
      Exists(const Exists< GUM_SCALAR >& from);
      ~Exists() override;

      /**
       * This method creates a clone of this object, withouth its content
       * (including variable), you must use this method if you want to ensure
       * that the generated object has the same type than the object containing
       * the called newFactory()
       *
       * For example :
       * @code
       *   MultiDimArray<double> y;
       *   MultiDimContainer<double>* x = y.newFactory();
       * @endcode
       *
       * Then x is a MultiDimArray<double>*
       *
       * @warning you must desallocate by yourself the memory
       * @return an empty clone of this object with the same type
       */
      [[nodiscard]] MultiDimContainer< GUM_SCALAR >* newFactory() const override;

      std::string           aggregatorName() const override;
      std::optional< Idx >  value() const override;

      protected:
      Idx neutralElt_() const override;
      Idx fold_(const DiscreteVariable& v, Idx i1, Idx i2, bool& stop_iteration) const override;

      private:
      Idx _value_;
    };


#ifndef GUM_NO_EXTERN_TEMPLATE_CLASS
    extern template class Exists< double >;
#endif


  }   // namespace aggregator
}   // namespace gum

#include <agrum/base/multidim/aggregators/exists_tpl.h>

#endif   // GUM_EXISTS_AGGREGATOR_H
