From 892470a91228e01d973230cd76327bbf5187319e Mon Sep 17 00:00:00 2001
From: Sam Atkins <atkinssj@serenityos.org>
Date: Fri, 21 Apr 2023 11:21:47 +0100
Subject: [PATCH] AK: Add Array::contains_slow() and ::first_index_of(), with
 tests :^)

---
 AK/Array.h             | 15 +++++++++++++++
 Tests/AK/TestArray.cpp | 18 ++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/AK/Array.h b/AK/Array.h
index 3bb11998a3..52ffa5560e 100644
--- a/AK/Array.h
+++ b/AK/Array.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <AK/Iterator.h>
+#include <AK/Optional.h>
 #include <AK/Span.h>
 #include <AK/StdLibExtras.h>
 #include <AK/TypedTransfer.h>
@@ -119,6 +120,20 @@ struct Array {
         return value;
     }
 
+    bool contains_slow(T const& value) const
+    {
+        return first_index_of(value).has_value();
+    }
+
+    Optional<size_t> first_index_of(T const& value) const
+    {
+        for (size_t i = 0; i < Size; ++i) {
+            if (__data[i] == value)
+                return i;
+        }
+        return {};
+    }
+
     Conditional<Size == 0, Detail::EmptyArrayStorage<T>, T[Size]> __data;
 };
 
diff --git a/Tests/AK/TestArray.cpp b/Tests/AK/TestArray.cpp
index 12aefe5455..24c687fc27 100644
--- a/Tests/AK/TestArray.cpp
+++ b/Tests/AK/TestArray.cpp
@@ -28,3 +28,21 @@ TEST_CASE(compile_time_iterable)
     constexpr Array<int, 8> array = { 0, 1, 2, 3, 4, 5, 6, 7 };
     static_assert(constexpr_sum(array) == 28);
 }
+
+TEST_CASE(contains_slow)
+{
+    constexpr Array<int, 8> array = { 0, 1, 2, 3, 4, 5, 6, 7 };
+    EXPECT(array.contains_slow(0));
+    EXPECT(array.contains_slow(4));
+    EXPECT(array.contains_slow(7));
+    EXPECT(!array.contains_slow(42));
+}
+
+TEST_CASE(first_index_of)
+{
+    constexpr Array<int, 8> array = { 0, 1, 2, 3, 4, 5, 6, 7 };
+    EXPECT(array.first_index_of(0) == 0u);
+    EXPECT(array.first_index_of(4) == 4u);
+    EXPECT(array.first_index_of(7) == 7u);
+    EXPECT(!array.first_index_of(42).has_value());
+}