Thrill  0.1
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
vmap_foreach_with_index.hpp
Go to the documentation of this file.
1 /*******************************************************************************
2  * tlx/meta/vmap_foreach_with_index.hpp
3  *
4  * Part of tlx - http://panthema.net/tlx
5  *
6  * Copyright (C) 2016-2017 Timo Bingmann <[email protected]>
7  *
8  * All rights reserved. Published under the Boost Software License, Version 1.0
9  ******************************************************************************/
10 
11 #ifndef TLX_META_VMAP_FOREACH_WITH_INDEX_HEADER
12 #define TLX_META_VMAP_FOREACH_WITH_INDEX_HEADER
13 
14 #include <tuple>
15 #include <utility>
16 
18 
19 namespace tlx {
20 
21 //! \addtogroup tlx_meta
22 //! \{
23 
24 /******************************************************************************/
25 // Variadic Template Expander: run a generic templated functor (like a generic
26 // lambda) for each of the variadic template parameters, and collect the return
27 // values in a generic std::tuple.
28 //
29 // Called with func(StaticIndex<> index, Argument arg).
30 
31 namespace meta_detail {
32 
33 //! helper for vmap_foreach_with_index: base case
34 template <size_t Index, typename Functor, typename Arg>
35 auto vmap_foreach_with_index_impl(Functor&& f, Arg&& arg) {
36  return std::make_tuple(
37  std::forward<Functor>(f)(StaticIndex<Index>(), std::forward<Arg>(arg)));
38 }
39 
40 //! helper for vmap_foreach_with_index: general recursive case
41 template <size_t Index, typename Functor, typename Arg, typename... MoreArgs>
42 auto vmap_foreach_with_index_impl(Functor&& f, Arg&& arg, MoreArgs&& ... rest) {
43  auto x =
44  std::forward<Functor>(f)(StaticIndex<Index>(), std::forward<Arg>(arg));
45  return std::tuple_cat(
46  std::make_tuple(std::move(x)),
47  vmap_foreach_with_index_impl<Index + 1>(
48  std::forward<Functor>(f), std::forward<MoreArgs>(rest) ...));
49 }
50 
51 } // namespace meta_detail
52 
53 //! Call a generic functor (like a generic lambda) for each variadic template
54 //! argument together with its zero-based index.
55 template <typename Functor, typename... Args>
56 auto vmap_foreach_with_index(Functor&& f, Args&& ... args) {
57  return meta_detail::vmap_foreach_with_index_impl<0>(
58  std::forward<Functor>(f), std::forward<Args>(args) ...);
59 }
60 
61 //! \}
62 
63 } // namespace tlx
64 
65 #endif // !TLX_META_VMAP_FOREACH_WITH_INDEX_HEADER
66 
67 /******************************************************************************/
list x
Definition: gen_data.py:39
auto vmap_foreach_with_index_impl(Functor &&f, Arg &&arg)
helper for vmap_foreach_with_index: base case
auto vmap_foreach_with_index(Functor &&f, Args &&...args)