michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef nsXBLMaybeCompiled_h__
michael@0: #define nsXBLMaybeCompiled_h__
michael@0: 
michael@0: #include "js/GCAPI.h"
michael@0: 
michael@0: /*
michael@0:  * A union containing either a pointer representing uncompiled source or a
michael@0:  * JSObject* representing the compiled result.  The class is templated on the
michael@0:  * source object type.
michael@0:  *
michael@0:  * The purpose of abstracting this as a separate class is to allow it to be
michael@0:  * wrapped in a JS::Heap<T> to correctly handle post-barriering of the JSObject
michael@0:  * pointer, when present.
michael@0:  */
michael@0: template <class UncompiledT>
michael@0: class nsXBLMaybeCompiled
michael@0: {
michael@0: public:
michael@0:   nsXBLMaybeCompiled() : mUncompiled(BIT_UNCOMPILED) {}
michael@0: 
michael@0:   nsXBLMaybeCompiled(UncompiledT* uncompiled)
michael@0:     : mUncompiled(reinterpret_cast<uintptr_t>(uncompiled) | BIT_UNCOMPILED) {}
michael@0: 
michael@0:   nsXBLMaybeCompiled(JSObject* compiled) : mCompiled(compiled) {}
michael@0: 
michael@0:   bool IsCompiled() const
michael@0:   {
michael@0:     return !(mUncompiled & BIT_UNCOMPILED);
michael@0:   }
michael@0: 
michael@0:   UncompiledT* GetUncompiled() const
michael@0:   {
michael@0:     MOZ_ASSERT(!IsCompiled(), "Attempt to get compiled function as uncompiled");
michael@0:     uintptr_t unmasked = mUncompiled & ~BIT_UNCOMPILED;
michael@0:     return reinterpret_cast<UncompiledT*>(unmasked);
michael@0:   }
michael@0: 
michael@0:   JSObject* GetJSFunction() const
michael@0:   {
michael@0:     MOZ_ASSERT(IsCompiled(), "Attempt to get uncompiled function as compiled");
michael@0:     if (mCompiled) {
michael@0:       JS::ExposeObjectToActiveJS(mCompiled);
michael@0:     }
michael@0:     return mCompiled;
michael@0:   }
michael@0: 
michael@0:   // This is appropriate for use in tracing methods, etc.
michael@0:   JSObject* GetJSFunctionPreserveColor() const
michael@0:   {
michael@0:     MOZ_ASSERT(IsCompiled(), "Attempt to get uncompiled function as compiled");
michael@0:     return mCompiled;
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   JSObject*& UnsafeGetJSFunction()
michael@0:   {
michael@0:     MOZ_ASSERT(IsCompiled(), "Attempt to get uncompiled function as compiled");
michael@0:     return mCompiled;
michael@0:   }
michael@0: 
michael@0:   enum { BIT_UNCOMPILED = 1 << 0 };
michael@0: 
michael@0:   union
michael@0:   {
michael@0:     // An pointer that represents the function before being compiled, with
michael@0:     // BIT_UNCOMPILED set.
michael@0:     uintptr_t mUncompiled;
michael@0: 
michael@0:     // The JS object for the compiled result.
michael@0:     JSObject* mCompiled;
michael@0:   };
michael@0: 
michael@0:   friend class js::GCMethods<nsXBLMaybeCompiled<UncompiledT> >;
michael@0: };
michael@0: 
michael@0: /* Add support for JS::Heap<nsXBLMaybeCompiled>. */
michael@0: namespace js {
michael@0: 
michael@0: template <class UncompiledT>
michael@0: struct GCMethods<nsXBLMaybeCompiled<UncompiledT> > : public GCMethods<JSObject *>
michael@0: {
michael@0:   typedef struct GCMethods<JSObject *> Base;
michael@0: 
michael@0:   static nsXBLMaybeCompiled<UncompiledT> initial() { return nsXBLMaybeCompiled<UncompiledT>(); }
michael@0: 
michael@0:   static bool poisoned(nsXBLMaybeCompiled<UncompiledT> function)
michael@0:   {
michael@0:     return function.IsCompiled() && Base::poisoned(function.GetJSFunction());
michael@0:   }
michael@0: 
michael@0:   static bool needsPostBarrier(nsXBLMaybeCompiled<UncompiledT> function)
michael@0:   {
michael@0:     return function.IsCompiled() && Base::needsPostBarrier(function.GetJSFunction());
michael@0:   }
michael@0: 
michael@0: #ifdef JSGC_GENERATIONAL
michael@0:   static void postBarrier(nsXBLMaybeCompiled<UncompiledT>* functionp)
michael@0:   {
michael@0:     Base::postBarrier(&functionp->UnsafeGetJSFunction());
michael@0:   }
michael@0: 
michael@0:   static void relocate(nsXBLMaybeCompiled<UncompiledT>* functionp)
michael@0:   {
michael@0:     Base::relocate(&functionp->UnsafeGetJSFunction());
michael@0:   }
michael@0: #endif
michael@0: };
michael@0: 
michael@0: template <class UncompiledT>
michael@0: class HeapBase<nsXBLMaybeCompiled<UncompiledT> >
michael@0: {
michael@0:   const JS::Heap<nsXBLMaybeCompiled<UncompiledT> >& wrapper() const {
michael@0:     return *static_cast<const JS::Heap<nsXBLMaybeCompiled<UncompiledT> >*>(this);
michael@0:   }
michael@0: 
michael@0:   JS::Heap<nsXBLMaybeCompiled<UncompiledT> >& wrapper() {
michael@0:     return *static_cast<JS::Heap<nsXBLMaybeCompiled<UncompiledT> >*>(this);
michael@0:   }
michael@0: 
michael@0:   const nsXBLMaybeCompiled<UncompiledT>* extract() const {
michael@0:     return wrapper().address();
michael@0:   }
michael@0: 
michael@0:   nsXBLMaybeCompiled<UncompiledT>* extract() {
michael@0:     return wrapper().unsafeGet();
michael@0:   }
michael@0: 
michael@0: public:
michael@0:   bool IsCompiled() const { return extract()->IsCompiled(); }
michael@0:   UncompiledT* GetUncompiled() const { return extract()->GetUncompiled(); }
michael@0:   JSObject* GetJSFunction() const { return extract()->GetJSFunction(); }
michael@0:   JSObject* GetJSFunctionPreserveColor() const { return extract()->GetJSFunctionPreserveColor(); }
michael@0: 
michael@0:   void SetUncompiled(UncompiledT* source) {
michael@0:     wrapper().set(nsXBLMaybeCompiled<UncompiledT>(source));
michael@0:   }
michael@0: 
michael@0:   void SetJSFunction(JSObject* function) {
michael@0:     wrapper().set(nsXBLMaybeCompiled<UncompiledT>(function));
michael@0:   }
michael@0: 
michael@0:   JS::Heap<JSObject*>& AsHeapObject()
michael@0:   {
michael@0:     MOZ_ASSERT(extract()->IsCompiled());
michael@0:     return *reinterpret_cast<JS::Heap<JSObject*>*>(this);
michael@0:   }
michael@0: };
michael@0: 
michael@0: } /* namespace js */
michael@0: 
michael@0: #endif // nsXBLMaybeCompiled_h__