/* * Copyright (C) 2013 Apple Inc. All rights reserved. * * 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. * * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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 PrototypeMap_h #define PrototypeMap_h #include "WeakGCMap.h" #include <wtf/TriState.h> namespace JSC { class JSObject; class Structure; // Tracks the canonical structure an object should be allocated with when inheriting from a given prototype. class PrototypeMap { public: JS_EXPORT_PRIVATE Structure* emptyObjectStructureForPrototype(JSObject*, unsigned inlineCapacity); void clearEmptyObjectStructureForPrototype(JSObject*, unsigned inlineCapacity); void addPrototype(JSObject*); TriState isPrototype(JSObject*) const; // Returns a conservative estimate. private: WeakGCMap<JSObject*, JSObject> m_prototypes; typedef WeakGCMap<std::pair<JSObject*, unsigned>, Structure> StructureMap; StructureMap m_structures; }; inline TriState PrototypeMap::isPrototype(JSObject* object) const { if (!m_prototypes.contains(object)) return FalseTriState; // We know that 'object' was used as a prototype at one time, so be // conservative and say that it might still be so. (It would be expensive // to find out for sure, and we don't know of any cases where being precise // would improve performance.) return MixedTriState; } } // namespace JSC #endif // PrototypeMap_h