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#ifndef V8IsolatedContext_h

#define V8IsolatedContext_h

#include "IsolatedWorld.h"

#include "ScriptSourceCode.h" // for WebCore::ScriptSourceCode

#include "V8DOMWindow.h"

#include "V8Proxy.h"

#include "V8Utilities.h"

#include <v8.h>

namespace WebCore {

class V8Proxy;

// V8IsolatedContext

//

// V8IsolatedContext represents a isolated execution environment for

// JavaScript.  Each isolated world executes in parallel with the main

// JavaScript world.  An isolated world has access to the same DOM data

// structures as the main world but none of the JavaScript pointers.

//

// It is an error to ever share a JavaScript pointer between two isolated

// worlds or between an isolated world and the main world.  Because

// isolated worlds have access to the DOM, they need their own DOM wrappers

// to avoid having pointers to the main world's DOM wrappers (which are

// JavaScript objects).

class V8IsolatedContext {

public:

    // Creates an isolated world. To destroy it, call destroy().

    // This will delete the isolated world when the context it owns is GC'd.

    V8IsolatedContext(V8Proxy* proxy, int extensionGroup);

    ~V8IsolatedContext();

    // Call this to destroy the isolated world. It will be deleted sometime

    // after this call, once all script references to the world's context

    // have been dropped.

    void destroy();

    // Returns the isolated world associated with

    // v8::Context::GetEntered().  Because worlds are isolated, the entire

    // JavaScript call stack should be from the same isolated world.

    // Returns 0 if the entered context is from the main world.

    //

    // FIXME: Consider edge cases with DOM mutation events that might

    // violate this invariant.

    //

    static V8IsolatedContext* getEntered()

    {

        // This is a temporary performance optimization.   Essentially,

        // GetHiddenValue is too slow for this code path.  We need to get the

        // V8 team to add a real property to v8::Context for isolated worlds.

        // Until then, we optimize the common case of not having any isolated

        // worlds at all.

        if (!IsolatedWorld::count())

            return 0;

        if (!v8::Context::InContext())

            return 0;

        return reinterpret_cast<V8IsolatedContext*>(getGlobalObject(v8::Context::GetEntered())->GetPointerFromInternalField(V8DOMWindow::enteredIsolatedWorldIndex));

    }

    v8::Handle<v8::Context> context() { return m_context->get(); }

    PassRefPtr<SharedPersistent<v8::Context> > sharedContext() { return m_context; }

    IsolatedWorld* world() const { return m_world.get(); }

private:

    static v8::Handle<v8::Object> getGlobalObject(v8::Handle<v8::Context> context)

    {

        return v8::Handle<v8::Object>::Cast(context->Global()->GetPrototype());

    }

    // Called by the garbage collector when our JavaScript context is about

    // to be destroyed.

    static void contextWeakReferenceCallback(v8::Persistent<v8::Value> object, void* isolatedContext);

    // The underlying v8::Context. This object is keep on the heap as

    // long as |m_context| has not been garbage collected.

    RefPtr<SharedPersistent<v8::Context> > m_context;

    RefPtr<IsolatedWorld> m_world;

};

} // namespace WebCore

#endif // V8IsolatedContext_h