Fix for LinkedHashSet::swap.

R=erik.corry@gmail.com
BUG=

Review URL: https://codereview.chromium.org/474943002

git-svn-id: svn://svn.chromium.org/blink/trunk@180257 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/wtf/LinkedHashSet.h

@@ -499,7 +499,7 @@ template<typename T, typename U, typename V, typename W>
 inline void LinkedHashSet<T, U, V, W>::swap(LinkedHashSet& other)
 {
     m_impl.swap(other.m_impl);
-    swap(m_anchor, other.m_anchor);
+    swapAnchor(m_anchor, other.m_anchor);
 }
 
 template<typename T, typename U, typename V, typename Allocator>
@@ -667,8 +667,32 @@ inline void LinkedHashSet<T, U, V, W>::remove(ValuePeekInType value)
     remove(find(value));
 }
 
+inline void swapAnchor(LinkedHashSetNodeBase& a, LinkedHashSetNodeBase& b)
+{
+    ASSERT(a.m_prev && a.m_next && b.m_prev && b.m_next);
+    swap(a.m_prev, b.m_prev);
+    swap(a.m_next, b.m_next);
+    if (b.m_next == &a) {
+        ASSERT(b.m_prev == &a);
+        b.m_next = &b;
+        b.m_prev = &b;
+    } else {
+        b.m_next->m_prev = &b;
+        b.m_prev->m_next = &b;
+    }
+    if (a.m_next == &b) {
+        ASSERT(a.m_prev == &b);
+        a.m_next = &a;
+        a.m_prev = &a;
+    } else {
+        a.m_next->m_prev = &a;
+        a.m_prev->m_next = &a;
+    }
+}
+
 inline void swap(LinkedHashSetNodeBase& a, LinkedHashSetNodeBase& b)
 {
+    ASSERT(a.m_next != &a && b.m_next != &b);
     swap(a.m_prev, b.m_prev);
     swap(a.m_next, b.m_next);
     if (b.m_next) {

third_party/WebKit/Source/wtf/ListHashSetTest.cpp

@@ -656,4 +656,66 @@ TEST(ListHashSetTest, WithOwnPtr)
     EXPECT_EQ(ptr2, ownPtr2);
 }
 
+template<typename Set>
+void swapTestHelper()
+{
+    int num = 10;
+    Set set0;
+    Set set1;
+    Set set2;
+    for (int i = 0; i < num; ++i) {
+        set1.add(i + 1);
+        set2.add(num - i);
+    }
+
+    typename Set::iterator it1 = set1.begin();
+    typename Set::iterator it2 = set2.begin();
+    for (int i = 0; i < num; ++i, ++it1, ++it2) {
+        EXPECT_EQ(*it1, i + 1);
+        EXPECT_EQ(*it2, num - i);
+    }
+    EXPECT_EQ(set0.begin(), set0.end());
+    EXPECT_EQ(it1, set1.end());
+    EXPECT_EQ(it2, set2.end());
+
+    // Shift sets: 2->1, 1->0, 0->2
+    set1.swap(set2); // Swap with non-empty sets.
+    set0.swap(set2); // Swap with an empty set.
+
+    it1 = set0.begin();
+    it2 = set1.begin();
+    for (int i = 0; i < num; ++i, ++it1, ++it2) {
+        EXPECT_EQ(*it1, i + 1);
+        EXPECT_EQ(*it2, num - i);
+    }
+    EXPECT_EQ(it1, set0.end());
+    EXPECT_EQ(it2, set1.end());
+    EXPECT_EQ(set2.begin(), set2.end());
+
+    int removedIndex = num >> 1;
+    set0.remove(removedIndex + 1);
+    set1.remove(num - removedIndex);
+
+    it1 = set0.begin();
+    it2 = set1.begin();
+    for (int i = 0; i < num; ++i, ++it1, ++it2) {
+        if (i == removedIndex)
+            ++i;
+        EXPECT_EQ(*it1, i + 1);
+        EXPECT_EQ(*it2, num - i);
+    }
+    EXPECT_EQ(it1, set0.end());
+    EXPECT_EQ(it2, set1.end());
+}
+
+TEST(ListHashSetTest, Swap)
+{
+    swapTestHelper<ListHashSet<int> >();
+}
+
+TEST(LinkedHashSetTest, Swap)
+{
+    swapTestHelper<LinkedHashSet<int> >();
+}
+
 } // namespace