include/ceres/sized_cost_function.h

// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
//   used to endorse or promote products derived from this software without
//   specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: keir@google.com (Keir Mierle)
//
// A convenience class for cost functions which are statically sized.
// Compared to the dynamically-sized base class, this reduces boilerplate.
//
// The kNumResiduals template parameter can be a constant such as 2 or 5, or it
// can be ceres::DYNAMIC. If kNumResiduals is ceres::DYNAMIC, then subclasses
// are responsible for calling set_num_residuals() at runtime.

#ifndef CERES_PUBLIC_SIZED_COST_FUNCTION_H_
#define CERES_PUBLIC_SIZED_COST_FUNCTION_H_

#include "ceres/cost_function.h"
#include "ceres/types.h"
#include "glog/logging.h"
#include "internal/parameter_dims.h"

namespace ceres {

template <int kNumResiduals, int... Ns>
class SizedCostFunction : public CostFunction {
 public:
  static_assert(kNumResiduals > 0 || kNumResiduals == DYNAMIC,
                "Cost functions must have at least one residual block.");
  static_assert(internal::StaticParameterDims<Ns...>::kIsValid,
                "Invalid parameter block dimension detected. Each parameter "
                "block dimension must be bigger than zero.");

  using ParameterDims = internal::StaticParameterDims<Ns...>;

  SizedCostFunction() {
    set_num_residuals(kNumResiduals);
    *mutable_parameter_block_sizes() = std::vector<int32_t>{Ns...};
  }

  // Subclasses must implement Evaluate().
};

}  // namespace ceres

#endif  // CERES_PUBLIC_SIZED_COST_FUNCTION_H_