From 0336a5ab33388a514676372e3a3da6875a41ae0c Mon Sep 17 00:00:00 2001
From: sha512sum <linuxnyasha@tutanota.com>
Date: Tue, 9 Jul 2024 00:49:57 +0000
Subject: [PATCH] Add Enumerate, TakeFrom, PushTo, Erase functions

---
 include/utempl/type_list.hpp | 19 +++++++++++++++++++
 include/utempl/utils.hpp     |  9 +++++++++
 2 files changed, 28 insertions(+)

diff --git a/include/utempl/type_list.hpp b/include/utempl/type_list.hpp
index bb1c075..1268963 100644
--- a/include/utempl/type_list.hpp
+++ b/include/utempl/type_list.hpp
@@ -97,4 +97,23 @@ consteval auto Size(TypeList<Ts...>) -> std::size_t {
   return sizeof...(Ts);
 };
 
+template <std::size_t N, std::size_t From = 0, typename... Ts>
+consteval auto TakeFrom(TypeList<Ts...> list)
+  requires(N + From <= sizeof...(Ts))
+{
+  return [&]<std::size_t... Is>(std::index_sequence<Is...>) -> TypeList<decltype(Get<Is + From>(list))...> {
+    return {};
+  }(std::make_index_sequence<N>());
+};
+
+template <typename T, std::size_t N, typename... Ts>
+consteval auto PushTo(TypeList<Ts...> list) {
+  return TakeFrom<N>(list) + kType<T> + TakeFrom<sizeof...(Ts) - N, N>(list);
+};
+
+template <std::size_t N, typename... Ts>
+consteval auto Erase(TypeList<Ts...> list) {
+  return TakeFrom<N>(list) + TakeFrom<sizeof...(Ts) - N - 1, N + 1>(list);
+};
+
 }  // namespace utempl
diff --git a/include/utempl/utils.hpp b/include/utempl/utils.hpp
index 34d3d86..e3a78f4 100644
--- a/include/utempl/utils.hpp
+++ b/include/utempl/utils.hpp
@@ -597,4 +597,13 @@ inline constexpr auto Generate(T&& value) {
   } | kSeq<N>;
 };
 
+template <TupleLike Tuple>
+constexpr auto Enumerate(Tuple&& tuple) {
+  return Unpack(std::forward<Tuple>(tuple), [](auto&&... vs) {
+    return [&](auto... is) {
+      return MakeTuple<Tuple>(std::pair{*is, std::forward<decltype(vs)>(vs)}...);
+    } | kSeq<sizeof...(vs)>;
+  });
+};
+
 }  // namespace utempl