From 6582744db5a014857b7a914815b147e88adead81 Mon Sep 17 00:00:00 2001
From: Maxwell Pirtle <maxwellpirtle@gmail.com>
Date: Mon, 6 Mar 2023 14:41:24 +0100
Subject: [PATCH] Write LazyPowerSet in terms of iterator_wrapper

---
 src/xbt/utils/iter/LazyPowerset.hpp      | 35 +++++-------------------
 src/xbt/utils/iter/iterator_wrapping.hpp |  8 +++---
 2 files changed, 11 insertions(+), 32 deletions(-)

diff --git a/src/xbt/utils/iter/LazyPowerset.hpp b/src/xbt/utils/iter/LazyPowerset.hpp
index 76d348353d..5d4a07edd2 100644
--- a/src/xbt/utils/iter/LazyPowerset.hpp
+++ b/src/xbt/utils/iter/LazyPowerset.hpp
@@ -6,39 +6,18 @@
 #ifndef XBT_UTILS_LAZY_POWER_SET_HPP
 #define XBT_UTILS_LAZY_POWER_SET_HPP
 
+#include "src/xbt/utils/iter/iterator_wrapping.hpp"
 #include "src/xbt/utils/iter/powerset.hpp"
 
 namespace simgrid::xbt {
 
-template <class Iterable> class LazyPowerset;
-template <class Iterable> LazyPowerset<Iterable> make_powerset_iter(const Iterable& container);
-
-/**
- * @brief A container which "contains" all subsets of
- * size `k` of some other container `WrapperContainer`
- *
- * @note: You should not store instances of this class directly,
- * as it acts more like a simply wrapping around another iterable
- * type to make it more convenient to iterate over subsets of
- * some iterable type.
- *
- * @class Iterable: The container from which
- * the subsets "contained" by this container are derived
- */
-template <class Iterable> class LazyPowerset final {
-public:
-  auto begin() const { return powerset_iterator<typename Iterable::const_iterator>(iterable.begin(), iterable.end()); }
-  auto end() const { return powerset_iterator<typename Iterable::const_iterator>(); }
-
-private:
-  const Iterable& iterable;
-  LazyPowerset(const Iterable& iterable) : iterable(iterable) {}
-  template <class IterableType> friend LazyPowerset<IterableType> make_powerset_iter(const IterableType& iterable);
-};
-
-template <class Iterable> LazyPowerset<Iterable> make_powerset_iter(const Iterable& container)
+template <class Iterable, class... Args>
+using LazyPowerset = iterator_wrapping<powerset_iterator<typename Iterable::const_iterator>, Args...>;
+
+template <class Iterable> constexpr auto make_powerset_iter(const Iterable& container)
 {
-  return LazyPowerset<Iterable>(container);
+  return make_iterator_wrapping<powerset_iterator<typename Iterable::const_iterator>>(container.begin(),
+                                                                                      container.end());
 }
 
 } // namespace simgrid::xbt
diff --git a/src/xbt/utils/iter/iterator_wrapping.hpp b/src/xbt/utils/iter/iterator_wrapping.hpp
index e4a4ea95c7..c6d2c9572a 100644
--- a/src/xbt/utils/iter/iterator_wrapping.hpp
+++ b/src/xbt/utils/iter/iterator_wrapping.hpp
@@ -43,10 +43,10 @@ private:
   iterator_wrapping(Args&&... begin_iteration) : m_args(std::forward<ref_or_value_t<Args>>(begin_iteration)...) {}
 
   template <typename IteratorType, typename... Arguments>
-  friend iterator_wrapping<IteratorType, Arguments...> make_iterator_wrapping(Arguments&&... args);
+  friend constexpr iterator_wrapping<IteratorType, Arguments...> make_iterator_wrapping(Arguments&&... args);
 
   template <typename IteratorType, typename... Arguments>
-  friend iterator_wrapping<IteratorType, Arguments...> make_iterator_wrapping_explicit(Arguments... args);
+  friend constexpr iterator_wrapping<IteratorType, Arguments...> make_iterator_wrapping_explicit(Arguments... args);
 
 public:
   iterator_wrapping(const iterator_wrapping&)            = delete;
@@ -62,13 +62,13 @@ public:
 };
 
 template <typename Iterator, typename... Args>
-iterator_wrapping<Iterator, Args...> make_iterator_wrapping(Args&&... args)
+constexpr iterator_wrapping<Iterator, Args...> make_iterator_wrapping(Args&&... args)
 {
   return iterator_wrapping<Iterator, Args...>(std::forward<Args>(args)...);
 }
 
 template <typename Iterator, typename... Args>
-iterator_wrapping<Iterator, Args...> make_iterator_wrapping_explicit(Args... args)
+constexpr iterator_wrapping<Iterator, Args...> make_iterator_wrapping_explicit(Args... args)
 {
   return iterator_wrapping<Iterator, Args...>(std::forward<Args>(args)...);
 }
-- 
2.20.1