Added std::make_integer_sequence.

cute-engineering · Jul 4, 2024 · 78db9ea · 78db9ea
1 parent b600649
commit 78db9ea
Show file tree

Hide file tree

Showing 2 changed files with 21 additions and 18 deletions.
diff --git a/src/ce-stdcpp/type_traits b/src/ce-stdcpp/type_traits
@@ -4,7 +4,7 @@ namespace std {
 
 template <typename T> inline constexpr bool is_array_v = __is_array(T);
 
-/* --- Remove Reference --- */
+// MARK: Remove Reference ------------------------------------------------------
 
 template <typename T> struct remove_reference {
   using type = T;
@@ -21,7 +21,7 @@ template <typename T> struct remove_reference<T &&> {
 template <typename T>
 using remove_reference_t = typename remove_reference<T>::type;
 
-/* --- Remove Const --- */
+// MARK: Remove Reference ------------------------------------------------------
 
 template <typename T> struct remove_const {
   using type = T;
@@ -33,7 +33,7 @@ template <typename T> struct remove_const<T const> {
 
 template <typename T> using remove_const_t = typename remove_const<T>::type;
 
-/* --- Remove Volatile --- */
+// MARK: Remove Volatile -------------------------------------------------------
 
 template <typename T> struct remove_volatile {
   using type = T;
@@ -46,7 +46,7 @@ template <typename T> struct remove_volatile<T volatile> {
 template <typename T>
 using remove_volatile_t = typename remove_volatile<T>::type;
 
-/* --- Remove CVR --- */
+// MARK: Remove CVR ------------------------------------------------------------
 
 template <typename T> struct remove_cv {
   using type = remove_volatile_t<remove_const_t<T>>;

diff --git a/src/ce-stdcpp/utility b/src/ce-stdcpp/utility
@@ -33,24 +33,27 @@ template <typename T> constexpr void swap(T &lhs, T &rhs) {
   rhs = std::move(tmp);
 }
 
-template <size_t... Ints> struct index_sequence {
-  using type = index_sequence;
-  using value_type = size_t;
-  static constexpr size_t size() noexcept { return sizeof...(Ints); }
+// MARK: Integer Sequence ------------------------------------------------------
+
+template <typename I, I... Seq> class integer_sequence {};
+
+template <typename I, I X, I N, I... Seq> struct _make_seq_helper {
+  using type = typename _make_seq_helper<I, X + 1, N, Seq..., X>::type;
+};
+
+template <typename I, I N, I... Seq> struct _make_seq_helper<I, N, N, Seq...> {
+  using type = integer_sequence<I, Seq...>;
 };
 
-template <class Sequence1, class Sequence2> struct _merge_and_renumber;
+template <typename I, I N>
+using make_integer_sequence = typename _make_seq_helper<I, 0, N>::type;
 
-template <size_t... I1, size_t... I2>
-struct _merge_and_renumber<index_sequence<I1...>, index_sequence<I2...>>
-    : index_sequence<I1..., (sizeof...(I1) + I2)...> {};
+// MARK: Index Sequence --------------------------------------------------------
 
-template <size_t N>
-struct make_index_sequence
-    : _merge_and_renumber<typename make_index_sequence<N / 2>::type,
-                          typename make_index_sequence<N - N / 2>::type> {};
+template <size_t... Seq>
+using index_sequence = integer_sequence<size_t, Seq...>;
 
-template <> struct make_index_sequence<0> : index_sequence<> {};
-template <> struct make_index_sequence<1> : index_sequence<0> {};
+template <size_t N>
+using make_index_sequence = make_integer_sequence<size_t, N>;
 
 } // namespace std