AK: Add HashTable::remove_all_matching(predicate)

This removes all matching entries from a table in a single pass.

AK/HashTable.h

@@ -384,7 +384,7 @@ public:
         return false;
     }
 
-    void remove(Iterator iterator)
+    Iterator remove(Iterator iterator)
     {
         VERIFY(iterator.m_bucket);
         auto& bucket = *iterator.m_bucket;
@@ -394,6 +394,9 @@ public:
         if constexpr (!IsOrdered)
             VERIFY(!bucket.end);
 
+        auto next_iterator = iterator;
+        ++next_iterator;
+
         bucket.slot()->~T();
         bucket.used = false;
         bucket.deleted = true;
@@ -411,6 +414,19 @@ public:
             else
                 m_collection_data.tail = bucket.previous;
         }
+
+        return next_iterator;
+    }
+
+    template<typename TUnaryPredicate>
+    void remove_all_matching(TUnaryPredicate predicate)
+    {
+        for (auto it = begin(); it != end();) {
+            if (predicate(*it))
+                it = remove(it);
+            else
+                ++it;
+        }
     }
 
 private:

Tests/AK/TestHashTable.cpp

@@ -84,6 +84,26 @@ TEST_CASE(table_remove)
     EXPECT(strings.find("Two") != strings.end());
 }
 
+TEST_CASE(table_remove_all_matching)
+{
+    HashTable<int> ints;
+
+    ints.set(1);
+    ints.set(2);
+    ints.set(3);
+    ints.set(4);
+
+    EXPECT_EQ(ints.size(), 4u);
+
+    ints.remove_all_matching([&](int value) { return value > 2; });
+
+    EXPECT_EQ(ints.size(), 2u);
+
+    ints.remove_all_matching([&](int) { return true; });
+
+    EXPECT(ints.is_empty());
+}
+
 TEST_CASE(case_insensitive)
 {
     HashTable<String, CaseInsensitiveStringTraits> casetable;