From bfb15475525462a4ecc30c5309ab28dd153be3c3 Mon Sep 17 00:00:00 2001
From: Simon Praetorius <simon.praetorius@tu-dresden.de>
Date: Sun, 29 Nov 2020 23:58:44 +0100
Subject: [PATCH] add enumerate algorithm andremove exclusive_scan

---
 amdis/common/Algorithm.hpp | 105 +++++++++++++++++++------------------
 1 file changed, 55 insertions(+), 50 deletions(-)

diff --git a/amdis/common/Algorithm.hpp b/amdis/common/Algorithm.hpp
index 7805a66f..c7d209dd 100644
--- a/amdis/common/Algorithm.hpp
+++ b/amdis/common/Algorithm.hpp
@@ -2,66 +2,71 @@
 
 #include <algorithm>
 #include <functional>
+#include <iterator>
+#include <tuple>
+#include <type_traits>
 #include <utility>
 
-namespace AMDiS
+namespace AMDiS {
+
+/// \brief Split a sequence `[first,last)` by the separators `sep` and pass the tokens as
+/// begin-end iterator pair to the provided functor `f = void(InputIterator, InputIterator)`
+template <class InputIter, class Tp, class BinaryFunc>
+void split(InputIter first, InputIter last, Tp sep, BinaryFunc f)
 {
-  /// \brief Split a sequence `[first,last)` by the separators `sep` and pass the tokens as
-  /// begin-end iterator pair to the provided functor `f = void(InputIterator, InputIterator)`
-  template <class InputIter, class Tp, class BinaryFunc>
-  void split(InputIter first, InputIter last, Tp sep, BinaryFunc f)
-  {
-    if (first == last)
-      return;
+  if (first == last)
+    return;
 
-    while (true) {
-      InputIter found = std::find(first, last, sep);
-      f(first, found);
-      if (found == last)
-        break;
-      first = ++found;
-    }
+  while (true) {
+    InputIter found = std::find(first, last, sep);
+    f(first, found);
+    if (found == last)
+      break;
+    first = ++found;
   }
+}
 
-  /// \brief Split a sequence `[first,last)` by any of the separators `[s_first, s_last)` and pass the tokens as
-  /// begin-end iterator pair to the provided functor `f = void(InputIterator, InputIterator)`
-  template <class InputIter, class SeparaterIter, class BinaryFunc>
-  void split(InputIter first, InputIter last, SeparaterIter s_first, SeparaterIter s_last, BinaryFunc f)
-  {
-    if (first == last)
-      return;
+/// \brief Split a sequence `[first,last)` by any of the separators `[s_first, s_last)` and pass the tokens as
+/// begin-end iterator pair to the provided functor `f = void(InputIterator, InputIterator)`
+template <class InputIter, class SeparaterIter, class BinaryFunc>
+void split(InputIter first, InputIter last, SeparaterIter s_first, SeparaterIter s_last, BinaryFunc f)
+{
+  if (first == last)
+    return;
 
-    while (true) {
-      InputIter found = std::find_first_of(first, last, s_first, s_last);
-      f(first, found);
-      if (found == last)
-        break;
-      first = ++found;
-    }
+  while (true) {
+    InputIter found = std::find_first_of(first, last, s_first, s_last);
+    f(first, found);
+    if (found == last)
+      break;
+    first = ++found;
   }
+}
 
-  /// \brief Output the cumulative sum of one range to a second range
-  // NOTE: backport of std::exclusive_scan from c++17
-  template <class InputIter, class OutputIter, class Tp, class BinaryOperation>
-  OutputIter exclusive_scan(InputIter first, InputIter last,
-                            OutputIter result, Tp init, BinaryOperation binary_op)
+/// \brief Provide python-like indexing iterator that returns a pair of [i,element]
+// see: http://reedbeta.com/blog/python-like-enumerate-in-cpp17
+template <class Range,
+  class Iter = decltype(std::begin(std::declval<Range>())),
+  class      = decltype(std::end(std::declval<Range>()))>
+constexpr auto enumerate(Range&& range)
+{
+  struct iterator
   {
-    while (first != last) {
-      auto v = init;
-      init = binary_op(init, *first);
-      ++first;
-      *result++ = std::move(v);
-    }
-    return result;
-  }
+    typename std::iterator_traits<Iter>::difference_type i;
+    Iter iter;
+    bool operator!=(iterator const& other) const { return iter != other.iter; }
+    void operator++() { ++i; ++iter; }
+    auto operator*() const { return std::tie(i, *iter); }
+  };
 
-  /// \brief Output the cumulative sum of one range to a second range
-  // NOTE: backport of std::exclusive_scan from c++17
-  template <class InputIter, class OutputIter, class Tp>
-  inline OutputIter exclusive_scan(InputIter first, InputIter last,
-                                   OutputIter result, Tp init)
+  struct range_wrapper
   {
-    return AMDiS::exclusive_scan(first, last, result, std::move(init), std::plus<>());
-  }
+    Range range;
+    auto begin() { return iterator{0, std::begin(range)}; }
+    auto end() { return iterator{0, std::end(range)}; }
+  };
+
+  return range_wrapper{std::forward<Range>(range)};
+}
 
-}
\ No newline at end of file
+} // end namepace AMDiS
-- 
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