AK: Add Vector::prepend(Vector&&).

Also included a good boy unit test.

AK/Tests/TestVector.cpp

@@ -65,4 +65,37 @@ TEST_CASE(strings_insert_ordered)
     EXPECT_EQ(strings[3], "ghi");
 }
 
+TEST_CASE(prepend_vector)
+{
+    Vector<int> ints;
+    ints.append(1);
+    ints.append(2);
+    ints.append(3);
+
+    Vector<int> more_ints;
+    more_ints.append(4);
+    more_ints.append(5);
+    more_ints.append(6);
+
+    ints.prepend(move(more_ints));
+
+    EXPECT_EQ(ints.size(), 6);
+    EXPECT_EQ(more_ints.size(), 0);
+
+    EXPECT_EQ(ints[0], 4);
+    EXPECT_EQ(ints[1], 5);
+    EXPECT_EQ(ints[2], 6);
+    EXPECT_EQ(ints[3], 1);
+    EXPECT_EQ(ints[4], 2);
+    EXPECT_EQ(ints[5], 3);
+
+    ints.prepend(move(more_ints));
+    EXPECT_EQ(ints.size(), 6);
+    EXPECT_EQ(more_ints.size(), 0);
+
+    more_ints.prepend(move(ints));
+    EXPECT_EQ(more_ints.size(), 6);
+    EXPECT_EQ(ints.size(), 0);
+}
+
 TEST_MAIN(Vector)

AK/Vector.h

@@ -349,6 +349,31 @@ public:
         ++m_size;
     }
 
+    void prepend(Vector&& other)
+    {
+        if (other.is_empty())
+            return;
+
+        if (is_empty()) {
+            *this = move(other);
+            return;
+        }
+
+        auto other_size = other.size();
+        grow_capacity(size() + other_size);
+
+        for (int i = size() + other_size - 1; i > other.size(); --i) {
+            new (slot(i)) T(move(at(i - other_size)));
+            at(i - other_size).~T();
+        }
+
+        Vector tmp = move(other);
+        for (int i = 0; i < tmp.size(); ++i)
+            new (slot(i)) T(move(tmp.at(i)));
+
+        m_size += other_size;
+    }
+
     void append(const T* values, int count)
     {
         if (!count)