external/webkit r30707

1 files changed, 108 insertions, 0 deletions

diff --git a/WebCore/platform/TreeShared.h b/WebCore/platform/TreeShared.h
new file mode 100644
index 0000000..aaa26aa
--- /dev/null
+++ b/WebCore/platform/TreeShared.h
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef TreeShared_h
+#define TreeShared_h
+
+#include <wtf/Assertions.h>
+#include <wtf/Noncopyable.h>
+
+namespace WebCore {
+
+template<class T> class TreeShared : Noncopyable {
+public:
+    TreeShared()
+        : m_refCount(0)
+        , m_parent(0)
+    {
+#ifndef NDEBUG
+        m_deletionHasBegun = false;
+        m_inRemovedLastRefFunction = false;
+#endif
+    }
+    TreeShared(T* parent)
+        : m_refCount(0)
+        , m_parent(0)
+    {
+#ifndef NDEBUG
+        m_deletionHasBegun = false;
+        m_inRemovedLastRefFunction = false;
+#endif
+    }
+    virtual ~TreeShared()
+    {
+        ASSERT(m_deletionHasBegun);
+    }
+
+    void ref()
+    {
+        ASSERT(!m_deletionHasBegun);
+        ASSERT(!m_inRemovedLastRefFunction);
+        ++m_refCount;
+    }
+
+    void deref()
+    {
+        ASSERT(!m_deletionHasBegun);
+        ASSERT(!m_inRemovedLastRefFunction);
+        if (--m_refCount <= 0 && !m_parent) {
+#ifndef NDEBUG
+            m_inRemovedLastRefFunction = true;
+#endif
+            removedLastRef();
+        }
+    }
+
+    bool hasOneRef() const
+    {
+        ASSERT(!m_deletionHasBegun);
+        ASSERT(!m_inRemovedLastRefFunction);
+        return m_refCount == 1;
+    }
+
+    int refCount() const
+    {
+        return m_refCount;
+    }
+
+    void setParent(T* parent) { m_parent = parent; }
+    T* parent() const { return m_parent; }
+
+#ifndef NDEBUG
+    bool m_deletionHasBegun;
+    bool m_inRemovedLastRefFunction;
+#endif
+
+private:
+    virtual void removedLastRef()
+    {
+#ifndef NDEBUG
+        m_deletionHasBegun = true;
+#endif
+        delete this;
+    }
+
+    int m_refCount;
+    T* m_parent;
+};
+
+}
+
+#endif // TreeShared.h