From 074645d82efb7aea5598e15294dbce74534470f3 Mon Sep 17 00:00:00 2001
From: Megvii Engine Team <megengine@megvii.com>
Date: Tue, 21 Jul 2020 20:11:39 +0800
Subject: [PATCH] feat(core): add array_skip

GitOrigin-RevId: ae0d12fbb8325e06b23be6cf7985897988e44c50
---
 src/core/include/megbrain/utils/metahelper_basic.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/core/include/megbrain/utils/metahelper_basic.h b/src/core/include/megbrain/utils/metahelper_basic.h
index c00048ac..f2a98434 100644
--- a/src/core/include/megbrain/utils/metahelper_basic.h
+++ b/src/core/include/megbrain/utils/metahelper_basic.h
@@ -99,6 +99,13 @@ namespace metahelper_detail {
             return else_(if_constexpr_identity{});
         }
     };
+
+    template <size_t skip, typename T, size_t isize, size_t... I>
+    decltype(auto) array_skip_impl(const std::array<T, isize>& arr,
+                                   std::index_sequence<I...>) {
+        static_assert(isize > skip, "invalid argument `skip`");
+        return std::forward_as_tuple(arr[I + skip]...);
+    }
 } // namespace metahelper_detail
 
 //! construct index_sequence<0..N-1>
@@ -344,6 +351,12 @@ decltype(auto) if_constexpr(Then&& then) {
     return if_constexpr<Cond>(std::forward<Then>(then), [](auto) {});
 }
 
+template <size_t skip, typename T, size_t isize>
+decltype(auto) array_skip(const std::array<T, isize>& arr) {
+    return metahelper_detail::array_skip_impl<skip>(
+            arr, std::make_index_sequence<isize - skip>{});
+}
+
 } // namespace mgb
 
 // vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}