AK: Implement take_all_matching(predicate) API in HashTable

Author: https://github.com/IdanHo
Commit: 5097e72174
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5766
Reviewed-by: https://github.com/trflynn89 ✅

AK/HashTable.h

@@ -478,6 +478,25 @@ public:
         return has_removed_anything;
     }
 
+    template<typename TUnaryPredicate>
+    Vector<T> take_all_matching(TUnaryPredicate const& predicate)
+    {
+        Vector<T> values;
+        for (size_t i = 0; i < m_capacity; ++i) {
+            auto& bucket = m_buckets[i];
+            if (bucket.state == BucketState::Free || !predicate(*bucket.slot()))
+                continue;
+
+            values.append(move(*bucket.slot()));
+            delete_bucket(bucket);
+
+            // If a bucket was shifted up, reevaluate this bucket index
+            if (bucket.state != BucketState::Free)
+                --i;
+        }
+        return values;
+    }
+
     T take_last()
     requires(IsOrdered)
     {

Tests/AK/TestHashTable.cpp

@@ -131,6 +131,38 @@ TEST_CASE(remove_all_matching)
     EXPECT_EQ(ints.remove_all_matching([&](int) { return true; }), false);
 }
 
+TEST_CASE(take_all_matching)
+{
+    HashTable<int> ints;
+
+    ints.set(1);
+    ints.set(2);
+    ints.set(3);
+    ints.set(4);
+
+    EXPECT_EQ(ints.size(), 4u);
+
+    auto first_values = ints.take_all_matching([&](int value) { return value > 2; });
+    EXPECT_EQ(first_values.size(), 2u);
+    EXPECT(first_values.contains_slow(3));
+    EXPECT(first_values.contains_slow(4));
+    EXPECT(ints.take_all_matching([&](int) { return false; }).is_empty());
+
+    EXPECT_EQ(ints.size(), 2u);
+
+    EXPECT(ints.contains(1));
+    EXPECT(ints.contains(2));
+
+    auto second_values = ints.take_all_matching([&](int) { return true; });
+    EXPECT_EQ(second_values.size(), 2u);
+    EXPECT(second_values.contains_slow(1));
+    EXPECT(second_values.contains_slow(2));
+
+    EXPECT(ints.is_empty());
+
+    EXPECT(ints.take_all_matching([&](int) { return true; }).is_empty());
+}
+
 TEST_CASE(case_insensitive)
 {
     HashTable<ByteString, CaseInsensitiveStringTraits> casetable;