expression_template_tools.hpp

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// Copyright (c) 2013-2018 Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
// Copyright (c) 2013-2018 Centre national de la recherche scientifique (CNRS)
// Copyright (c) 2018-2023 Simons Foundation
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You may obtain a copy of the License at
//     https://www.gnu.org/licenses/gpl-3.0.txt
//
// Authors: Olivier Parcollet, Nils Wentzell

 
#pragma once
 
#include "./macros.hpp"
 
#include <complex>
#include <type_traits>
#include <utility>
 
namespace triqs::utility {


  template <class T> struct remove_rvalue_ref {
    using type = T;
  };
  template <class T> struct remove_rvalue_ref<T &> {
    using type = T const &;
  };
  template <class T> struct remove_rvalue_ref<T &&> {
    using type = T;
  };

  template <class T> using remove_rvalue_ref_t = typename remove_rvalue_ref<T>::type;

  namespace tags {

    struct plus {};

    struct minus {};

    struct multiplies {};

    struct divides {};
 
  } // namespace tags

  template <typename Tag> struct operation;
 
  // Spezialization of triqs::utility::operation for plus operation: returns `l + r`.
  template <> struct operation<tags::plus> {
    static const char name = '+';
    template <typename L, typename R> auto operator()(L &&l, R &&r) const DECL_AND_RETURN(std::forward<L>(l) + std::forward<R>(r))
  };
 
  // Spezialization of triqs::utility::operation for minus operation: returns `l - r`.
  template <> struct operation<tags::minus> {
    static const char name = '-';
    template <typename L, typename R> auto operator()(L &&l, R &&r) const DECL_AND_RETURN(std::forward<L>(l) - std::forward<R>(r))
  };
 
  // Spezialization of triqs::utility::operation for multiplies operation: returns `l * r`.
  template <> struct operation<tags::multiplies> {
    static const char name = '*';
    template <typename L, typename R> auto operator()(L &&l, R &&r) const DECL_AND_RETURN(std::forward<L>(l) * std::forward<R>(r))
  };
 
  // Spezialization of triqs::utility::operation for divides operation: returns `l / r`.
  template <> struct operation<tags::divides> {
    static const char name = '/';
    template <typename L, typename R> auto operator()(L &&l, R &&r) const DECL_AND_RETURN(std::forward<L>(l) / std::forward<R>(r))
  };

  template <typename T> struct is_in_ZRC : std::is_arithmetic<T> {};
  template <> struct is_in_ZRC<bool> : std::true_type {};
  template <typename T> struct is_in_ZRC<std::complex<T>> : std::true_type {};
  template <typename T> struct is_in_ZRC<T &> : is_in_ZRC<T> {};
  template <typename T> struct is_in_ZRC<T &&> : is_in_ZRC<T> {};
  template <typename T> struct is_in_ZRC<const T> : is_in_ZRC<T> {};

  template <typename A, typename B> struct type_of_mult {
    using type = decltype(std::declval<std::remove_reference_t<A>>() * std::declval<std::remove_reference_t<B>>());
  };

 
} // namespace triqs::utility