| // Ceres Solver - A fast non-linear least squares minimizer |
| // Copyright 2018 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: jodebo_beck@gmx.de (Johannes Beck) |
| // |
| // This class mimics std::integer_sequence. That is the reason to follow the |
| // naming convention of the stl and not the google one. Once Ceres switches |
| // to c++ 14 this class can be removed. |
| |
| #ifndef CERES_PUBLIC_INTERNAL_INTEGER_SEQUENCE_H_ |
| #define CERES_PUBLIC_INTERNAL_INTEGER_SEQUENCE_H_ |
| |
| #if __cplusplus >= 201402L |
| // We have at least c++ 14 support. Use integer_sequence from the standard. |
| // Sometimes the STL implementation uses a compiler intrinsic to generate |
| // the sequences which will speed up compilation. |
| #include <utility> |
| |
| namespace ceres { |
| namespace internal { |
| template <typename T, T... Ns> |
| using integer_sequence = std::integer_sequence<T, Ns...>; |
| |
| template <typename T, T N> |
| using make_integer_sequence = std::make_integer_sequence<T, N>; |
| |
| } // namespace internal |
| } // namespace ceres |
| #else |
| |
| namespace ceres { |
| namespace internal { |
| |
| template <typename T, T... Ns> |
| struct integer_sequence { |
| using value_type = T; |
| }; |
| |
| // Implementation of make_integer_sequence. |
| // |
| // Recursively instantiate make_integer_sequence_impl until Ns |
| // contains the sequence 0, 1, ..., Total-1. |
| // |
| // Example for Total = 4: |
| // T CurIdx, Total, Ns... |
| // make_integer_sequence_impl<int, 0, 4 > |
| // make_integer_sequence_impl<int, 1, 4, 0 > |
| // make_integer_sequence_impl<int, 2, 4, 0, 1 > |
| // make_integer_sequence_impl<int, 3, 4, 0, 1, 2 > |
| // make_integer_sequence_impl<int, 4, 4, 0, 1, 2, 3> |
| // ^^^^^^^^^^ |
| // resulting sequence. |
| // |
| // The implemented algorithm has linear complexity for simplicity. A O(log(N)) |
| // implementation can be found e.g. here: |
| // https://stackoverflow.com/questions/17424477/implementation-c14-make-integer-sequence |
| template <typename T, T CurIdx, T Total, T... Ns> |
| struct make_integer_sequence_impl { |
| using type = typename make_integer_sequence_impl<T, CurIdx + 1, Total, Ns..., |
| CurIdx>::type; |
| }; |
| |
| // End of 'recursion' when CurIdx reaches Total. All indices 0, 1, ..., N-1 are |
| // contained in Ns. The final integer_sequence is created here. |
| template <typename T, T Total, T... Ns> |
| struct make_integer_sequence_impl<T, Total, Total, Ns...> { |
| using type = integer_sequence<T, Ns...>; |
| }; |
| |
| // A helper alias template to simplify creation of integer_sequence with 0, 1, |
| // ..., N-1 as Ns: |
| template <typename T, T N> |
| using make_integer_sequence = |
| typename make_integer_sequence_impl<T, 0, N>::type; |
| |
| } // namespace internal |
| } // namespace ceres |
| |
| #endif |
| |
| #endif // CERES_PUBLIC_INTERNAL_INTEGER_SEQUENCE_H_ |