variant_extensions.hpp

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// Copyright (c) 2018 Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
// Copyright (c) 2018 Centre national de la recherche scientifique (CNRS)
// Copyright (c) 2018-2020 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: Igor Krivenko, Nils Wentzell

 
#pragma once
 
#include <nda/stdutil/array.hpp>
 
#include <sstream>
#include <string>
#include <variant>
#include <vector>
 
namespace triqs::utility {

  template <typename... Fs> struct overloaded : Fs... {
    using Fs::operator()...;
  };
 
} // namespace triqs::utility
 
namespace std {


  template <typename T, typename... Ts> std::ostream &operator<<(std::ostream &os, std::variant<T, Ts...> const &v) {
    visit([&os](auto const &x) { os << x; }, v);
    return os;
  }

  template <typename T, typename... Ts> std::ostream &operator<<(std::ostream &os, std::vector<std::variant<T, Ts...>> const &vec) {
    int u = 0;
    for (auto const &i : vec) {
      if (u++) os << ",";
      os << i;
    }
    return os;
  }

  inline string to_string(string const &str) { return str; }

  template <typename T, typename... Ts> inline string to_string(variant<T, Ts...> const &var) {
    stringstream ss;
    ss << var;
    return ss.str();
  }

 
} // namespace std