/* ----------------------------------------------------------------------------

 * GTSAM Copyright 2010, Georgia Tech Research Corporation,
 * Atlanta, Georgia 30332-0415
 * All Rights Reserved
 * Authors: Frank Dellaert, et al. (see THANKS for the full author list)

 * See LICENSE for the license information

 * -------------------------------------------------------------------------- */

/**
 * @file Group.h
 *
 * @brief Concept check class for variable types with Group properties
 * @date Nov 5, 2011
 * @author Alex Cunningham
 */

#pragma once

#include <gtsam/global_includes.h>

namespace gtsam {

/**
 * This concept check enforces a Group structure on a variable type,
 * in which we require the existence of basic algebraic operations.
 */
template<class T>
class GroupConcept {
private:
  static T concept_check(const T& t) {
    /** assignment */
    T t2 = t;

    /** identity */
    T identity = T::identity();

    /** compose with another object */
    T compose_ret = identity.compose(t2);

    /** invert the object and yield a new one */
    T inverse_ret = compose_ret.inverse();

    return inverse_ret;
  }
};

} // \namespace gtsam

/**
 * Macros for using the GroupConcept
 *  - An instantiation for use inside unit tests
 *  - A typedef for use inside generic algorithms
 *
 * NOTE: intentionally not in the gtsam namespace to allow for classes not in
 * the gtsam namespace to be more easily enforced as testable
 */
#define GTSAM_CONCEPT_GROUP_INST(T) template class gtsam::GroupConcept<T>;
#define GTSAM_CONCEPT_GROUP_TYPE(T) typedef gtsam::GroupConcept<T> _gtsam_GroupConcept_##T;