Implement forward_like

lackhole · Aug 11, 2024 · 5ebb4a4 · 5ebb4a4
1 parent d95b6e8
commit 5ebb4a4
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Showing 4 changed files with 33 additions and 6 deletions.
diff --git a/include/preview/__functional/bind_back.h b/include/preview/__functional/bind_back.h
@@ -11,7 +11,7 @@
 #include "preview/__functional/invoke.h"
 #include "preview/__type_traits/conjunction.h"
 #include "preview/__type_traits/is_invocable.h"
-#include "preview/__type_traits/copy_cvref.h"
+#include "preview/__utility/forward_like.h"
 
 namespace preview {
 namespace detail {
@@ -23,11 +23,11 @@ class bind_partial_back : bind_partial<bind_partial_back<FD, BoundArgs...>, FD,
 
   template<typename Self, typename... CallArgs>
   struct bind_invocable
-      : is_invocable<copy_cvref_t<Self, FD>, CallArgs..., copy_cvref_t<Self, BoundArgs>...> {};
+      : is_invocable<forward_like_t<Self, FD>, CallArgs..., forward_like_t<Self, BoundArgs>...> {};
 
   template<typename Self, typename... CallArgs>
   struct bind_nothrow_invocable
-      : is_nothrow_invocable<copy_cvref_t<Self, FD>, CallArgs..., copy_cvref_t<Self, BoundArgs>...> {};
+      : is_nothrow_invocable<forward_like_t<Self, FD>, CallArgs..., forward_like_t<Self, BoundArgs>...> {};
 
   template<typename F, typename BoundArgsTuple, std::size_t...I, typename... CallArgs>
   static constexpr decltype(auto) call(F&& f, BoundArgsTuple&& tup, std::index_sequence<I...>, CallArgs&&... call_args)

diff --git a/include/preview/__functional/bind_front.h b/include/preview/__functional/bind_front.h
@@ -10,7 +10,7 @@
 #include "preview/__functional/invoke.h"
 #include "preview/__type_traits/conjunction.h"
 #include "preview/__type_traits/is_invocable.h"
-#include "preview/__type_traits/copy_cvref.h"
+#include "preview/__utility/forward_like.h"
 
 namespace preview {
 namespace detail {
@@ -22,11 +22,11 @@ class bind_partial_front : bind_partial<bind_partial_front<FD, BoundArgs...>, FD
 
   template<typename Self, typename... CallArgs>
   struct bind_invocable
-      : is_invocable<copy_cvref_t<Self, FD>, copy_cvref_t<Self, BoundArgs>..., CallArgs...> {};
+      : is_invocable<forward_like_t<Self, FD>, forward_like_t<Self, BoundArgs>..., CallArgs...> {};
 
   template<typename Self, typename... CallArgs>
   struct bind_nothrow_invocable
-      : is_nothrow_invocable<copy_cvref_t<Self, FD>, copy_cvref_t<Self, BoundArgs>..., CallArgs...> {};
+      : is_nothrow_invocable<forward_like_t<Self, FD>, forward_like_t<Self, BoundArgs>..., CallArgs...> {};
 
   template<typename F, typename BoundArgsTuple, std::size_t...I, typename... CallArgs>
   static constexpr decltype(auto) call(F&& f, BoundArgsTuple&& tup, std::index_sequence<I...>, CallArgs&&... call_args)

diff --git a/include/preview/__utility/forward_like.h b/include/preview/__utility/forward_like.h
@@ -0,0 +1,26 @@
+//
+// Created by yonggyulee on 2024. 8. 10.
+//
+
+#ifndef PREVIEW_UTILITY_FORWARD_LIKE_H_
+#define PREVIEW_UTILITY_FORWARD_LIKE_H_
+
+#include <type_traits>
+
+#include "preview/__type_traits/copy_cvref.h"
+
+namespace preview {
+
+template<typename T, typename U>
+constexpr auto&& forward_like(U&& x) noexcept {
+  using CU = copy_const_t<std::remove_reference_t<T>, std::remove_reference_t<U>>;
+  using RU = std::conditional_t<std::is_rvalue_reference<T>::value, std::remove_reference_t<CU>&&, CU&>;
+  return static_cast<RU>(x);
+}
+
+template<typename T, typename U>
+using forward_like_t = decltype(preview::forward_like<T>(std::declval<U>()));
+
+} // namespace preview
+
+#endif // PREVIEW_UTILITY_FORWARD_LIKE_H_
diff --git a/include/preview/utility.h b/include/preview/utility.h
@@ -9,6 +9,7 @@
 #include "preview/__utility/cmp.h"
 #include "preview/__utility/compressed_pair.h"
 #include "preview/__utility/cxx20_rel_ops.h"
+#include "preview/__utility/forward_like.h"
 #include "preview/__utility/in_place.h"
 #include "preview/__utility/in_range.h"
 #include "preview/__utility/integer_sequence.h"