WIP: WebLayer::addAnimation should transfer the ownership of WebAnimation instance.

public/platform/WebPassOwnPtr.h

+/*
+ * Copyright (C) 2013 Intel Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1.  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef WebPassOwnPtr_h
+#define WebPassOwnPtr_h
+
+#include "WebCommon.h"
+
+#if INSIDE_WEBKIT
+#include "wtf/OwnPtr.h"
+#include "wtf/PassOwnPtr.h"
+using WTF::EnableIf;
+using WTF::IsPointerConvertible;
+#endif
+
+namespace WebKit {
+
+// It exists to help transfer the ownership of either OwnPtr or PassOwnPtr from Blink to Chromium.
+//
+// A typical usage is as follows:
+// in Blink side
+//   OwnPtr<WebAnimation> animation;
+//   WebLayer layer;
+//   layer->addAnimation(animation);
+//
+// in Chromium side
+//   bool WebAnimation::addAnimation(WebPassOwnPtr<WebAnimation> pop_animation) {
+//     scoped_ptr<WebAnimation> animation(pop_animation.leakPtr());
+//     ...
+//   }
+template <typename T>
+class WebPassOwnPtr {
+public:
+    WebPassOwnPtr() : m_ptr(0) { }
+    ~WebPassOwnPtr() { delete m_ptr; }

[jamesr, 2013/09/24 17:52:10]

you can't do this without ~T(), which will make it really hard to use this type
in practice.  WebPrivatePtr<> and WebPrivateOwnPtr<> get around this by
exporting a reset() function and requiring (with an ASSERTion) that this is
called before the destructor

[dshwang, 2013/09/24 18:23:22]

Could you explain why it cannot work in detail or let me know relevant document
or link? This class works very well in my machine. It transfer ownership of
WebAnimation and delete WebAnimation correctly.

In addition, we can not use reset() mechanism because it is defined under
INSIDE_WEBKIT guard.
#if INSIDE_WEBKIT
    void reset(T* ptr)
    {
        delete m_ptr;
        m_ptr = ptr;
    }
#endif

+    WebPassOwnPtr(const WebPassOwnPtr& o) : m_ptr(o.leakPtr()) { }
+
+    T* leakPtr() const
+    {
+        T* ptr = m_ptr;
+        m_ptr = 0;
+        return ptr;
+    }
+    bool operator!() const { return !m_ptr; }
+
+#if INSIDE_WEBKIT
+    explicit WebPassOwnPtr(T* ptr)
+        : m_ptr(ptr)
+    {
+        COMPILE_ASSERT(sizeof(T) > 0, TypeMustBeComplete);
+    }
+
+    template<typename U> WebPassOwnPtr(const OwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
+    template<typename U> WebPassOwnPtr(const PassOwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
+
+    T* get() const { return m_ptr; }
+    T* operator->() const
+    {
+        WEBKIT_ASSERT(m_ptr);
+        return m_ptr;
+    }
+#endif // INSIDE_WEBKIT
+
+private:
+    WebPassOwnPtr& operator=(const WebPassOwnPtr&);
+
+    mutable T* m_ptr;
+};
+
+#if INSIDE_WEBKIT
+template<typename T> template<typename U> inline WebPassOwnPtr<T>::WebPassOwnPtr(const OwnPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
+    : m_ptr(o.leakPtr())
+{
+}
+
+template<typename T> template<typename U> inline WebPassOwnPtr<T>::WebPassOwnPtr(const PassOwnPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
+    : m_ptr(o.leakPtr())
+{
+}
+#endif
+
+} // namespace WebKit
+
+#endif