array_adapter.hpp

Go to the documentation of this file.

// Copyright (c) 2020--present, The Simons Foundation
// This file is part of TRIQS/nda and is licensed under the Apache License, Version 2.0.
// SPDX-License-Identifier: Apache-2.0
// See LICENSE in the root of this distribution for details.

 
#pragma once
 
#include "./concepts.hpp"
#include "./stdutil/array.hpp"
 
#include <array>
#include <type_traits>
 
namespace nda {


  template <int R, typename F>
  class array_adapter {
    static_assert(CallableWithLongs<F, R>, "Error in nda::array_adapter: Lambda should be callable with R integers");
 
    // Shape of the array.
    std::array<long, R> myshape;
 
    // Callable object.
    F f;
 
    public:
    template <typename Int>
    array_adapter(std::array<Int, R> const &shape, F f) : myshape(stdutil::make_std_array<long>(shape)), f(f) {}

    [[nodiscard]] auto const &shape() const { return myshape; }

    [[nodiscard]] long size() const { return stdutil::product(myshape); }

    template <typename... Ints>
    auto operator()(long i0, Ints... is) const {
      static_assert((std::is_convertible_v<Ints, long> and ...), "Error in nda::array_adapter: Arguments must be convertible to long");
      return f(i0, is...);
    }
  };
 
  // Class template argument deduction guides.
  template <auto R, typename Int, typename F>
  array_adapter(std::array<Int, R>, F) -> array_adapter<R, F>;


  template <int R, typename F>
  inline constexpr char get_algebra<array_adapter<R, F>> = 'A';
 
} // namespace nda