Reaktoro  v2.11.0
A unified framework for modeling chemically reactive systems
Enumerate.hpp
1 // Reaktoro is a unified framework for modeling chemically reactive systems.
2 //
3 // Copyright © 2014-2024 Allan Leal
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public License
16 // along with this library. If not, see <http://www.gnu.org/licenses/>.
17 
18 //===================================================================
19 // REFERENCE:
20 //-------------------------------------------------------------------
21 // https://www.reedbeta.com/blog/python-like-enumerate-in-cpp17/
22 //===================================================================
23 
24 #pragma once
25 #include <tuple>
26 
27 template <typename T,
28  typename TIter = decltype(std::begin(std::declval<T>())),
29  typename = decltype(std::end(std::declval<T>()))>
30 constexpr auto enumerate(T && iterable)
31 {
32  struct iterator
33  {
34  size_t i;
35  TIter iter;
36  bool operator != (const iterator& other) const { return iter != other.iter; }
37  void operator ++ () { ++i; ++iter; }
38  auto operator * () const { return std::tie(i, *iter); }
39  };
40 
41  struct iterable_wrapper
42  {
43  T iterable;
44  auto begin() { return iterator{ 0, std::begin(iterable) }; }
45  auto end() { return iterator{ 0, std::end(iterable) }; }
46  };
47  return iterable_wrapper{ std::forward<T>(iterable) };
48 }