2009-11-13 Vitaly Repeshko <vitalyr@chromium.org>

[WebKit-https.git] / WebCore / bindings / v8 / V8Proxy.h

diff --git a/WebCore/bindings/v8/V8Proxy.h b/WebCore/bindings/v8/V8Proxy.h
index 99ae1f28cbdcd6965d56cf4c50542d57d52e7991..e299d628b7e19f6052f60890a176e48eef68fc8f 100644 (file)
--- a/WebCore/bindings/v8/V8Proxy.h
+++ b/WebCore/bindings/v8/V8Proxy.h
@@ -177,6 +177,33 @@ namespace WebCore {
 #if ENABLE(SVG)
         static void setSVGContext(void*, SVGElement*);
         static SVGElement* svgContext(void*);
+
+        // These helper functions are required in case we are given a PassRefPtr
+        // to a (possibly) newly created object and must prevent its reference
+        // count from dropping to zero as would happen in code like
+        //
+        //   V8Proxy::setSVGContext(imp->getNewlyCreatedObject().get(), context);
+        //   foo(imp->getNewlyCreatedObject().get());
+        //
+        // In the above two lines each time getNewlyCreatedObject() is called it
+        // creates a new object because we don't ref() it. (So our attemts to
+        // associate a context with it fail.) Such code should be rewritten to
+        //
+        //   foo(V8Proxy::withSVGContext(imp->getNewlyCreatedObject(), context).get());
+        //
+        // where PassRefPtr::~PassRefPtr() is invoked only after foo() is
+        // called.
+        template <typename T>
+        static PassRefPtr<T> withSVGContext(PassRefPtr<T> object, SVGElement* context)
+        {
+            setSVGContext(object.get(), context);
+            return object;
+        }
+        static void* withSVGContext(void* object, SVGElement* context)
+        {
+            setSVGContext(object, context);
+            return object;
+        }
 #endif
 
         void setEventHandlerLineNumber(int lineNumber) { m_handlerLineNumber = lineNumber; }