From d84b69ace982bd0366ca026e26422986825d1f5e Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Thu, 8 Feb 2024 18:52:45 -0500
Subject: [PATCH] AK: Add to_array()

This is useful if you want an array with an explicit type but still
want its size to be inferred.
---
 AK/Array.h             | 15 +++++++++++++++
 Tests/AK/TestArray.cpp |  9 +++++++++
 2 files changed, 24 insertions(+)

diff --git a/AK/Array.h b/AK/Array.h
index a8c5629f2af..0b43544f9ce 100644
--- a/AK/Array.h
+++ b/AK/Array.h
@@ -162,9 +162,24 @@ constexpr auto iota_array(T const offset = {})
     return Detail::integer_sequence_generate_array<T>(offset, MakeIntegerSequence<T, N>());
 }
 
+namespace Detail {
+template<typename T, size_t N, size_t... Is>
+constexpr auto to_array_impl(T (&&a)[N], IndexSequence<Is...>) -> Array<T, sizeof...(Is)>
+{
+    return { { a[Is]... } };
+}
+}
+
+template<typename T, size_t N>
+constexpr auto to_array(T (&&a)[N])
+{
+    return Detail::to_array_impl(move(a), MakeIndexSequence<N>());
+}
+
 }
 
 #if USING_AK_GLOBALLY
 using AK::Array;
 using AK::iota_array;
+using AK::to_array;
 #endif
diff --git a/Tests/AK/TestArray.cpp b/Tests/AK/TestArray.cpp
index 24c687fc278..12f8ce35753 100644
--- a/Tests/AK/TestArray.cpp
+++ b/Tests/AK/TestArray.cpp
@@ -46,3 +46,12 @@ TEST_CASE(first_index_of)
     EXPECT(array.first_index_of(7) == 7u);
     EXPECT(!array.first_index_of(42).has_value());
 }
+
+TEST_CASE(to_array)
+{
+    constexpr auto array = to_array<u8>({ 0, 2, 1 });
+    static_assert(array.size() == 3);
+    static_assert(array[0] == 0);
+    static_assert(array[1] == 2);
+    static_assert(array[2] == 1);
+}