completeProjectionRegister4MultiDim.h

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/**
 *
 *   Copyright (c) 2005-2021 by Pierre-Henri WUILLEMIN(@LIP6) & Christophe GONZALES(@AMU)
 *   info_at_agrum_dot_org
 *
 *  This library is free software: you can redistribute it and/or modify
 *  it under the terms of 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.
 *
 *  This library 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */


/**
 * @file
 * @brief A container for registering complete projection functions on
 * multiDimImplementations, i.e., projections over all variables
 *
 * @author Christophe GONZALES(@AMU) and Pierre-Henri WUILLEMIN(@LIP6)
 */

#ifndef GUM_COMPLETE_PROJECTION_REGISTER_4_MULTI_DIM_H
#define GUM_COMPLETE_PROJECTION_REGISTER_4_MULTI_DIM_H

#include <iostream>
#include <string>
#include <utility>

#include <agrum/tools/core/hashTable.h>
#include <agrum/tools/core/set.h>
#include <agrum/tools/multidim/instantiation.h>
#include <agrum/tools/variables/discreteVariable.h>

namespace gum {

  // the base object used by the projections
  template < typename GUM_SCALAR >
  class MultiDimImplementation;

  // ===========================================================================
  // ===             GUM_MULTI_DIM_COMPLETE_PROJECTION_REGISTER              ===
  // ===========================================================================

  // clang-format off
  /**
   * @class CompleteProjectionRegister4MultiDim
   * @headerfile completeProjectionRegister4MultiDim.h agrum/multdim/operators/completeProjectionRegister4MultiDim.h
   * @ingroup multidim_op_group
   *
   * @brief A container for registering complete projection functions on
   * multiDimImplementations, i.e., functions projecting tables over all their
   * variables.
   *
   */
  // clang-format on
  template < typename GUM_SCALAR >
  class CompleteProjectionRegister4MultiDim {
    public:
    /// the type of functions used by the register
    typedef GUM_SCALAR (*CompleteProjectionPtr)(const MultiDimImplementation< GUM_SCALAR >*,
                                                Instantiation* instantiation);

    // =========================================================================
    /// @name Accessors / Modifiers
    // =========================================================================
    /// @{

    /**
     * @brief Adds a new entry into the register.
     *
     * This method inserts a new function (\e newFunction) taking a multiDim of
     * type \e type_multidim (which actually inherit from
     * MultiDimImplementation) and, possibly, a pointer on an instantiation in
     * arguments.  This new function's purpose is to achieve the projection
     * described by \e projection_name. For instance, if projection_name is
     * "max", "min", "sum" or "product", the new function performs the usual
     * algebraic operations.
     *
     * @param projection_name describes the name of the operation performed by
     * newFunction. Usual operation names are "min", "max", "sum", "product"
     * @param type_multidim the \e real type of the multiDim taken in argument
     * by function \e newFunction.
     *
     * @param newFunction a pointer to the new function to register. Note that
     * although \e newFunction actually performs an operation on multiDims of
     * type \e type_multidim, it should be declared as taking in argument two
     * MultiDimImplementations. This constraint is imposed by the C++ typing
     * system.
     */
    void insert(const std::string&    projection_name,
                const std::string&    type_multidim,
                CompleteProjectionPtr newFunction);

    /**
     * @brief Removes a given entry from the register.
     *
     * removes the function, if any, that performs the projection described by
     * \e projection_name, and that takes in argument a multiDim of type \e
     * type_multidim
     *
     * @param projection_name describes the name of the projection performed by
     * the function to remove. Usual projection names are "min", "max", "sum",
     * "product"
     *
     * @param type_multidim the \e real type of the multiDim taken in argument
     * by the function to remove
     */
    void erase(const std::string& projection_name, const std::string& type_multidim);

    /**
     * @brief Indicates whether a given entry exists in the register.
     *
     * Indicates if the register contains a function that performs the
     * projection described by \e projection_name, and that takes in argument a
     * multiDim of type \e type_multidim.
     *
     * @param projection_name describes the name of the projection performed by
     * the function we look for. Usual projection names are "min", "max",
     * "sum", "product".
     *
     * @param type_multidim the \e real type of the multiDim taken in argument
     * by the function we look for.
     */
    bool exists(const std::string& projection_name, const std::string& type_multidim) const;

    /**
     * @brief returns the specialized projection operator assigned to a given
     * type of MultiDimImplementation
     *
     * returns the function, if any, that performs the projection described by
     * \e projection_name, and that takes in argument a multiDim of type \e
     * type_multidim
     *
     * @param projection_name describes the name of the projection performed by
     * the function we look for. Usual projection names are "min", "max",
     * "sum", "product"
     *
     * @param type_multidim the \e real type of the multiDim taken in argument
     * by the function we look for @throws NotFound exception is thrown if the
     * operator we look for does not exist within this register.
     */
    CompleteProjectionPtr get(const std::string& projection_name,
                              const std::string& type_multidim) const;

    /// @}

    // =========================================================================
    /// @name Named Constructors
    // =========================================================================
    /// @{

    /**
     * @brief A named constructor that constructs one and only one Register per
     * data type.
     *
     * Note that this constructor prevents the famous init order fiasco.
     */
    static CompleteProjectionRegister4MultiDim& Register();

    /// @}

    private:
    // =========================================================================
    /// @name Constructors / Destructors
    // =========================================================================
    /// @{

    /// Default constructor: creates an empty register
    CompleteProjectionRegister4MultiDim();

    /// copy operator: never to be used
    CompleteProjectionRegister4MultiDim(const CompleteProjectionRegister4MultiDim&);

    /// Destructor
    ~CompleteProjectionRegister4MultiDim();

    /// @}

    /// The set of associations for a given projection type
    typedef HashTable< std::string, CompleteProjectionPtr > CompleteProjectionSet;

    /**
     * @brief A mapping from the types of MultiDimImplementations to
     * projection operators.
     *
     * In this type, the strings represent the very types of the
     * MultiDimImplementations that will be combined. Hence, to a subtype of
     * MultiDimImplementation is associated a function to project this subtype
     * of hypermatrix (the CompleteProjectionPtr)
     */
    HashTable< std::string, CompleteProjectionSet* > _set_;
  };

  /// A function to more easily register new projection functions in MultiDims
  /// @ingroup multidim_op_group
  template < typename GUM_SCALAR >
  void registerCompleteProjection(
     const std::string& projection_name,
     const std::string& type_multidim,
     typename CompleteProjectionRegister4MultiDim< GUM_SCALAR >::CompleteProjectionPtr function);

} /* namespace gum */

// always include the implementations
#include <agrum/tools/multidim/utils/operators/completeProjectionRegister4MultiDim_tpl.h>

#endif /* GUM_COMPLETE_PROJECTION_REGISTER_MULTI_DIM_H */