C++ NativeIterator类代码示例

void
JSCompartment::sweep(FreeOp *fop, bool releaseTypes)
{
    JS_ASSERT(!activeAnalysis);

    /* This function includes itself in PHASE_SWEEP_TABLES. */
    sweepCrossCompartmentWrappers();

    {
        gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_TABLES);

        /* Remove dead references held weakly by the compartment. */

        sweepBaseShapeTable();
        sweepInitialShapeTable();
        sweepNewTypeObjectTable(newTypeObjects);
        sweepNewTypeObjectTable(lazyTypeObjects);
        sweepCallsiteClones();

        if (global_ && IsObjectAboutToBeFinalized(global_.unsafeGet()))
            global_ = NULL;

#ifdef JS_ION
        if (ionCompartment_)
            ionCompartment_->sweep(fop);
#endif

        /*
         * JIT code increments activeUseCount for any RegExpShared used by jit
         * code for the lifetime of the JIT script. Thus, we must perform
         * sweeping after clearing jit code.
         */
        regExps.sweep(rt);

        if (debugScopes)
            debugScopes->sweep(rt);

        /* Finalize unreachable (key,value) pairs in all weak maps. */
        WeakMapBase::sweepCompartment(this);
    }

    if (!zone()->isPreservingCode()) {
        JS_ASSERT(!types.constrainedOutputs);
        gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_DISCARD_ANALYSIS);
        gcstats::AutoPhase ap2(rt->gcStats, gcstats::PHASE_FREE_TI_ARENA);
        rt->freeLifoAlloc.transferFrom(&analysisLifoAlloc);
    } else {
        gcstats::AutoPhase ap2(rt->gcStats, gcstats::PHASE_DISCARD_ANALYSIS);
        types.sweepShapes(fop);
    }

    NativeIterator *ni = enumerators->next();
    while (ni != enumerators) {
        JSObject *iterObj = ni->iterObj();
        NativeIterator *next = ni->next();
        if (gc::IsObjectAboutToBeFinalized(&iterObj))
            ni->unlink();
        ni = next;
    }
}

static JSObject* Reify(JSContext* cx, JS::Compartment* origin,
                       HandleObject iter) {
  // Ensure iterator gets closed.
  auto autoCloseIterator = mozilla::MakeScopeExit([=] { CloseIterator(iter); });

  NativeIterator* ni = iter->as<PropertyIteratorObject>().getNativeIterator();
  RootedObject obj(cx, ni->objectBeingIterated());

  // Wrap iteratee.
  if (!origin->wrap(cx, &obj)) {
    return nullptr;
  }

  // Wrap the elements in the iterator's snapshot.
  size_t length = ni->numKeys();
  AutoIdVector keys(cx);
  if (length > 0) {
    if (!keys.reserve(length)) {
      return nullptr;
    }
    RootedId id(cx);
    RootedValue v(cx);
    for (size_t i = 0; i < length; ++i) {
      v.setString(ni->propertiesBegin()[i]);
      if (!ValueToId<CanGC>(cx, v, &id)) {
        return nullptr;
      }
      cx->markId(id);
      keys.infallibleAppend(id);
    }
  }

  // Return iterator in current compartment.
  return EnumeratedIdVectorToIterator(cx, obj, keys);
}

void
js::UnwindIteratorForUncatchableException(JSObject* obj)
{
    if (obj->is<PropertyIteratorObject>()) {
        NativeIterator* ni = obj->as<PropertyIteratorObject>().getNativeIterator();
        ni->unlink();
    }
}

static void
iterator_trace(JSTracer *trc, JSObject *obj)
{
    NativeIterator *ni = obj->getNativeIterator();

    if (ni)
        ni->mark(trc);
}

void
JSCompartment::sweepNativeIterators()
{
    /* Sweep list of native iterators. */
    NativeIterator* ni = enumerators->next();
    while (ni != enumerators) {
        JSObject* iterObj = ni->iterObj();
        NativeIterator* next = ni->next();
        if (gc::IsAboutToBeFinalizedUnbarriered(&iterObj))
            ni->unlink();
        ni = next;
    }
}

static bool
Reify(JSContext *cx, JSCompartment *origin, Value *vp)
{
    Rooted<PropertyIteratorObject*> iterObj(cx, &vp->toObject().asPropertyIterator());
    NativeIterator *ni = iterObj->getNativeIterator();

    AutoCloseIterator close(cx, iterObj);

    /* Wrap the iteratee. */
    RootedObject obj(cx, ni->obj);
    if (!origin->wrap(cx, obj.address()))
        return false;

    /*
     * Wrap the elements in the iterator's snapshot.
     * N.B. the order of closing/creating iterators is important due to the
     * implicit cx->enumerators state.
     */
    size_t length = ni->numKeys();
    bool isKeyIter = ni->isKeyIter();
    AutoIdVector keys(cx);
    if (length > 0) {
        if (!keys.reserve(length))
            return false;
        for (size_t i = 0; i < length; ++i) {
            jsid id;
            if (!ValueToId(cx, StringValue(ni->begin()[i]), &id))
                return false;
            keys.infallibleAppend(id);
            if (!origin->wrapId(cx, &keys[i]))
                return false;
        }
    }

    close.clear();
    if (!CloseIterator(cx, iterObj))
        return false;

    RootedValue value(cx, *vp);

    if (isKeyIter) {
        if (!VectorToKeyIterator(cx, obj, ni->flags, keys, &value))
            return false;
    } else {
        if (!VectorToValueIterator(cx, obj, ni->flags, keys, &value))
            return false;
    }

    *vp = value;
    return true;
}

static inline PropertyIteratorObject*
VectorToKeyIterator(JSContext* cx, HandleObject obj, AutoIdVector& keys, uint32_t numGuards)
{
    if (obj->isSingleton() && !JSObject::setIteratedSingleton(cx, obj))
        return nullptr;
    MarkObjectGroupFlags(cx, obj, OBJECT_FLAG_ITERATED);

    Rooted<PropertyIteratorObject*> iterobj(cx, NewPropertyIteratorObject(cx));
    if (!iterobj)
        return nullptr;

    NativeIterator* ni = NativeIterator::allocateIterator(cx, numGuards, keys.length());
    if (!ni)
        return nullptr;

    iterobj->setNativeIterator(ni);
    ni->init(obj, iterobj, numGuards, 0);
    if (!ni->initProperties(cx, iterobj, keys))
        return nullptr;

    if (numGuards) {
        // Fill in the guard array from scratch. Also recompute the guard key
        // as we might have reshaped the object (see for instance the
        // setIteratedSingleton call above) or GC might have moved shapes and
        // groups in memory.
        JSObject* pobj = obj;
        size_t ind = 0;
        uint32_t key = 0;
        do {
            ReceiverGuard guard(pobj);
            ni->guard_array[ind++].init(guard);
            key = mozilla::AddToHash(key, guard.hash());

            // The one caller of this method that passes |numGuards > 0|, does
            // so only if the entire chain consists of cacheable objects (that
            // necessarily have static prototypes).
            pobj = pobj->staticPrototype();
        } while (pobj);
        ni->guard_key = key;
        MOZ_ASSERT(ind == numGuards);
    }

    RegisterEnumerator(cx, ni);
    return iterobj;
}

static bool
Reify(JSContext *cx, JSCompartment *origin, Value *vp)
{
    JSObject *iterObj = &vp->toObject();
    NativeIterator *ni = iterObj->getNativeIterator();

    AutoCloseIterator close(cx, iterObj);

    /* Wrap the iteratee. */
    JSObject *obj = ni->obj;
    if (!origin->wrap(cx, &obj))
        return false;

    /*
     * Wrap the elements in the iterator's snapshot.
     * N.B. the order of closing/creating iterators is important due to the
     * implicit cx->enumerators state.
     */
    size_t length = ni->numKeys();
    bool isKeyIter = ni->isKeyIter();
    AutoIdVector keys(cx);
    if (length > 0) {
        if (!keys.resize(length))
            return false;
        for (size_t i = 0; i < length; ++i) {
            jsid id;
            if (!ValueToId(cx, StringValue(ni->begin()[i]), &id))
                return false;
            id = js_CheckForStringIndex(id);
            keys[i] = id;
            if (!origin->wrapId(cx, &keys[i]))
                return false;
        }
    }

    close.clear();
    if (!js_CloseIterator(cx, iterObj))
        return false;

    if (isKeyIter)
        return VectorToKeyIterator(cx, obj, ni->flags, keys, vp);
    return VectorToValueIterator(cx, obj, ni->flags, keys, vp); 
}

static JSObject*
Reify(JSContext* cx, JSCompartment* origin, HandleObject objp)
{
    Rooted<PropertyIteratorObject*> iterObj(cx, &objp->as<PropertyIteratorObject>());
    NativeIterator* ni = iterObj->getNativeIterator();

    RootedObject obj(cx, ni->obj);
    {
        AutoCloseIterator close(cx, iterObj);

        /* Wrap the iteratee. */
        if (!origin->wrap(cx, &obj))
            return nullptr;

        /*
         * Wrap the elements in the iterator's snapshot.
         * N.B. the order of closing/creating iterators is important due to the
         * implicit cx->enumerators state.
         */
        size_t length = ni->numKeys();
        AutoIdVector keys(cx);
        if (length > 0) {
            if (!keys.reserve(length))
                return nullptr;
            RootedId id(cx);
            RootedValue v(cx);
            for (size_t i = 0; i < length; ++i) {
                v.setString(ni->begin()[i]);
                if (!ValueToId<CanGC>(cx, v, &id))
                    return nullptr;
                cx->markId(id);
                keys.infallibleAppend(id);
            }
        }

        close.clear();
        CloseIterator(iterObj);

        obj = EnumeratedIdVectorToIterator(cx, obj, keys);
    }
    return obj;
}

// Mainly used for .. in over null/undefined
JSObject*
js::NewEmptyPropertyIterator(JSContext* cx)
{
    Rooted<PropertyIteratorObject*> iterobj(cx, NewPropertyIteratorObject(cx));
    if (!iterobj)
        return nullptr;

    AutoIdVector keys(cx); // Empty
    NativeIterator* ni = NativeIterator::allocateIterator(cx, 0, keys.length());
    if (!ni)
        return nullptr;

    iterobj->setNativeIterator(ni);
    ni->init(nullptr, iterobj, 0, 0);
    if (!ni->initProperties(cx, iterobj, keys))
        return nullptr;

    RegisterEnumerator(cx, ni);
    return iterobj;
}

static bool
Reify(JSContext* cx, JSCompartment* origin, MutableHandleObject objp)
{
    Rooted<PropertyIteratorObject*> iterObj(cx, &objp->as<PropertyIteratorObject>());
    NativeIterator* ni = iterObj->getNativeIterator();

    AutoCloseIterator close(cx, iterObj);

    /* Wrap the iteratee. */
    RootedObject obj(cx, ni->obj);
    if (!origin->wrap(cx, &obj))
        return false;

    /*
     * Wrap the elements in the iterator's snapshot.
     * N.B. the order of closing/creating iterators is important due to the
     * implicit cx->enumerators state.
     */
    size_t length = ni->numKeys();
    AutoIdVector keys(cx);
    if (length > 0) {
        if (!keys.reserve(length))
            return false;
        for (size_t i = 0; i < length; ++i) {
            RootedId id(cx);
            RootedValue v(cx, StringValue(ni->begin()[i]));
            if (!ValueToId<CanGC>(cx, v, &id))
                return false;
            keys.infallibleAppend(id);
        }
    }

    close.clear();
    MOZ_ALWAYS_TRUE(CloseIterator(cx, iterObj));

    return EnumeratedIdVectorToIterator(cx, obj, ni->flags, keys, objp);
}

static bool
Reify(JSContext *cx, JSCompartment *origin, Value *vp)
{
    JSObject *iterObj = &vp->toObject();
    NativeIterator *ni = iterObj->getNativeIterator();

    /* Wrap the iteratee. */
    JSObject *obj = ni->obj;
    if (!origin->wrap(cx, &obj))
        return false;

    /*
     * Wrap the elements in the iterator's snapshot.
     * N.B. the order of closing/creating iterators is important due to the
     * implicit cx->enumerators state.
     */

    if (ni->isKeyIter()) {
        size_t length = ni->numKeys();
        AutoIdVector keys(cx);
        if (length > 0) {
            if (!keys.resize(length))
                return false;
            for (size_t i = 0; i < length; ++i) {
                keys[i] = ni->beginKey()[i];
                if (!origin->wrapId(cx, &keys[i]))
                    return false;
            }
        }

        return js_CloseIterator(cx, iterObj) &&
               VectorToKeyIterator(cx, obj, ni->flags, keys, vp);
    }

    size_t length = ni->numValues();
    AutoValueVector vals(cx);
    if (length > 0) {
        if (!vals.resize(length))
            return false;
        for (size_t i = 0; i < length; ++i) {
            vals[i] = ni->beginValue()[i];
            if (!origin->wrap(cx, &vals[i]))
                return false;
        }

    }

    return js_CloseIterator(cx, iterObj) &&
           VectorToValueIterator(cx, obj, ni->flags, vals, vp);
}

static bool
SuppressDeletedPropertyHelper(JSContext* cx, HandleObject obj, StringPredicate predicate)
{
    NativeIterator* enumeratorList = cx->compartment()->enumerators;
    NativeIterator* ni = enumeratorList->next();

    while (ni != enumeratorList) {
      again:
        if (ni->obj == obj && ni->props_cursor < ni->props_end) {
            /* Check whether id is still to come. */
            GCPtrFlatString* props_cursor = ni->current();
            GCPtrFlatString* props_end = ni->end();
            for (GCPtrFlatString* idp = props_cursor; idp < props_end; ++idp) {
                if (predicate(*idp)) {
                    /*
                     * Check whether another property along the prototype chain
                     * became visible as a result of this deletion.
                     */
                    RootedObject proto(cx);
                    if (!GetPrototype(cx, obj, &proto))
                        return false;
                    if (proto) {
                        RootedId id(cx);
                        RootedValue idv(cx, StringValue(*idp));
                        if (!ValueToId<CanGC>(cx, idv, &id))
                            return false;

                        Rooted<PropertyDescriptor> desc(cx);
                        if (!GetPropertyDescriptor(cx, proto, id, &desc))
                            return false;

                        if (desc.object()) {
                            if (desc.enumerable())
                                continue;
                        }
                    }

                    /*
                     * If GetPropertyDescriptorById above removed a property from
                     * ni, start over.
                     */
                    if (props_end != ni->props_end || props_cursor != ni->props_cursor)
                        goto again;

                    /*
                     * No property along the prototype chain stepped in to take the
                     * property's place, so go ahead and delete id from the list.
                     * If it is the next property to be enumerated, just skip it.
                     */
                    if (idp == props_cursor) {
                        ni->incCursor();
                    } else {
                        for (GCPtrFlatString* p = idp; p + 1 != props_end; p++)
                            *p = *(p + 1);
                        ni->props_end = ni->end() - 1;

                        /*
                         * This invokes the pre barrier on this element, since
                         * it's no longer going to be marked, and ensures that
                         * any existing remembered set entry will be dropped.
                         */
                        *ni->props_end = nullptr;
                    }

                    /* Don't reuse modified native iterators. */
                    ni->flags |= JSITER_UNREUSABLE;

                    if (predicate.matchesAtMostOne())
                        break;
                }
            }
        }
        ni = ni->next();
    }
    return true;
}