[WIP]Add WebPrivateHeapPtr and use it for speech platform layer.

public/platform/WebPrivateHeapPtr.h

+/*
+ * Copyright (c) 2014, Opera Software ASA. All rights reserved.

[haraken, 2014/02/17 09:04:57]

Can you use the 4-line copyright?

+ *
+ * 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.
+ * 3. Neither the name of Opera Software ASA nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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 WebPrivateHeapPtr_h
+#define WebPrivateHeapPtr_h
+
+#include "WebCommon.h"
+
+#if INSIDE_BLINK

[haraken, 2014/02/17 09:04:57]

What's the difference between INSIDE_BLINK and BLINK_IMPLEMENTATION ?

[sof, 2014/02/17 10:22:26]

Good question; I can't discern a pattern within this directory, but the former
is more common.

If one is considered preferable for new files, please let me know & I'll adapt.

[tkent, 2014/02/17 23:42:46]

INSIDE_BLINK means that it's in either of webkit.dll, blink_common.dll,
blink_heap.dll, or blink_platform.dll.
BLINK_IMPLEMENTATION means that it's in webkit.dll.  We have other macros like
BLINK_COMMON_IMPLEMENTATION, HEAP_IMPLEMENTATION, and
BLINK_PLATFORM_IMPLEMENTATION.

INSIDE_BLINK is appropriate here because it's ok to refer to Handle.h and
PassRefPtr.h in any Blink DLLs.

[sof, 2014/02/18 10:14:17]

Excellent clarification & info, many thanks :)

On that last point, would it be acceptable to let public/WebPrivatePtr.h
#include heap/Handle.h? (cf. https://codereview.chromium.org/168963003/#msg30
... well, it's not WebWillBePrivateGarbageCollectedPtr.h any longer, but
WebPrivatePtr.h)

+#include "heap/Handle.h"
+#include "wtf/PassRefPtr.h"
+#endif
+
+namespace blink {
+
+// A version of WebPrivatePtr that holds a heap-residing object,
+// but without exposing how that is done within Blink. If no
+// heap support (i.e., no Oilpan), WebPrivateHeapPtr is equal
+// to WebPrivatePtr and the object will be reference counted.

[haraken, 2014/02/17 09:04:57]

"heap" is ambiguous. We want to use "garbage-collected heap" or "oilpan" for
clarity.

+//
+// See WebPrivatePtr.h comment for how to make use of WebPrivateHeapPtr;
+// same pattern applies, but for one detail. Instead of declaring & defining,
+//
+//    #if INSIDE_BLINK
+//        WebFoo(const WTF::PassRefPtr<WebCore::Foo>&);
+//    #endif
+//
+// provide
+//
+//    #if INSIDE_BLINK
+//        WebFoo(const WTF::PassRefPtrWillBeRawPtr<WebCore::Foo>&);
+//    #endif
+//
+template <typename T>
+class WebPrivateHeapPtr {
+public:
+    WebPrivateHeapPtr() : m_ptr(0) { }
+    ~WebPrivateHeapPtr()
+    {
+        // We don't destruct the object pointed by m_ptr here because we don't
+        // want to expose destructors of core classes to embedders. We should
+        // call reset() manually in destructors of classes with WebPrivateHeapPtr
+        // members.
+        BLINK_ASSERT(!m_ptr);
+    }
+
+    bool isNull() const { return !m_ptr; }
+
+#if INSIDE_BLINK
+    WebPrivateHeapPtr(const PassRefPtrWillBeRawPtr<T>& p)
+# if !ENABLE(OILPAN)
+        : m_ptr(p.leakRef())
+# endif
+    {
+# if ENABLE(OILPAN)
+        assign(new WebCore::Persistent<T>(p));

[haraken, 2014/02/17 09:04:57]

How about calling 'new Persistent' in assign? assign can take a raw pointer.

[sof, 2014/02/17 09:23:21]

Yes, let's do that.

+# endif
+    }
+
+    void reset()
+    {
+# if ENABLE(OILPAN)
+        if (this->m_ptr) {
+            delete reinterpret_cast<WebCore::Persistent<T>*>(this->m_ptr);
+            this->m_ptr = 0;
+        }
+# else
+        assign(0);
+# endif
+    }
+
+    WebPrivateHeapPtr<T>& operator=(const WebPrivateHeapPtr<T>& other)
+    {
+# if ENABLE(OILPAN)
+        assign(new WebCore::Persistent<T>(other.get()));
+# else
+        T* p = other.m_ptr;
+        if (p)
+            p->ref();
+        assign(p);
+# endif
+        return *this;
+    }
+
+    WebPrivateHeapPtr<T>& operator=(WebPrivateHeapPtr<T>& other)
+    {
+        assign(new WebCore::Persistent<T>(other.get()));
+        return *this;
+    }
+
+    WebPrivateHeapPtr<T>& operator=(const PassRefPtrWillBeRawPtr<T>& p)
+    {
+# if ENABLE(OILPAN)
+        assign(new WebCore::Persistent<T>(p));
+# else
+        assign(p.leakRef());
+# endif
+        return *this;
+    }
+
+    T* get() const
+    {
+# if ENABLE(OILPAN)
+        if (!m_ptr)
+            return 0;
+        return (reinterpret_cast<WebCore::Persistent<T> * >(m_ptr))->get();
+# else
+        return m_ptr;
+# endif
+    }
+
+    T* operator->() const
+    {
+        ASSERT(m_ptr);
+# if ENABLE(OILPAN)
+        return (reinterpret_cast<WebCore::Persistent<T> * >(m_ptr))->get();
+# else
+        return m_ptr;
+# endif
+    }
+#endif
+
+private:
+#if INSIDE_BLINK
+# if ENABLE(OILPAN)
+    void assign(WebCore::Persistent<T>* p)
+    {
+        reset();
+        m_ptr = reinterpret_cast<T*>(p);
+    }
+# else
+    void assign(T* p)
+    {
+        // p is already ref'd for us by the caller
+        if (m_ptr)
+            m_ptr->deref();
+        m_ptr = p;
+    }
+# endif
+#else
+    // Disable the assignment operator; we define it above for when
+    // INSIDE_BLINK is set, but we need to make sure that it is not
+    // used outside there; the compiler-provided version won't handle reference
+    // counting properly.
+    WebPrivateHeapPtr<T>& operator=(const WebPrivateHeapPtr<T>& other);
+#endif
+    // Disable the copy constructor; classes that contain a WebPrivateHeapPtr
+    // should implement their copy constructor using assign().
+    WebPrivateHeapPtr(const WebPrivateHeapPtr<T>&);
+
+    T* m_ptr;
+};
+
+} // namespace blink
+
+#endif