omp_chunk.hpp

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// Copyright (c) 2019-2024 Simons Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0.txt
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Authors: Thomas Hahn, Olivier Parcollet, Nils Wentzell

 
#pragma once
 
#include "./itertools.hpp"
 
#include <omp.h>
 
namespace itertools {

  template <typename R> auto omp_chunk(R &&rg) {
    auto total_size           = itertools::distance(std::cbegin(rg), std::cend(rg));
    auto [start_idx, end_idx] = chunk_range(0, total_size, omp_get_num_threads(), omp_get_thread_num());
    return itertools::slice(std::forward<R>(rg), start_idx, end_idx);
  }
 
} // namespace itertools