/* * 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. */ #include "config.h" #include "PrototypeMap.h" #include "JSGlobalObject.h" #include "Operations.h" namespace JSC { void PrototypeMap::addPrototype(JSObject* object) { m_prototypes.add(object, object); // Note that this method makes the somewhat odd decision to not check if this // object currently has indexed accessors. We could do that check here, and if // indexed accessors were found, we could tell the global object to have a bad // time. But we avoid this, to allow the following to be always fast: // // 1) Create an object. // 2) Give it a setter or read-only property that happens to have a numeric name. // 3) Allocate objects that use this object as a prototype. // // This avoids anyone having a bad time. Even if the instance objects end up // having indexed storage, the creation of indexed storage leads to a prototype // chain walk that detects the presence of indexed setters and then does the // right thing. As a result, having a bad time only happens if you add an // indexed setter (or getter, or read-only field) to an object that is already // used as a prototype. } Structure* PrototypeMap::emptyObjectStructureForPrototype(JSObject* prototype, unsigned inlineCapacity) { StructureMap::AddResult addResult = m_structures.add(std::make_pair(prototype, inlineCapacity), nullptr); if (!addResult.isNewEntry) { ASSERT(isPrototype(prototype)); return addResult.iterator->value.get(); } addPrototype(prototype); Structure* structure = JSFinalObject::createStructure( prototype->globalObject()->vm(), prototype->globalObject(), prototype, inlineCapacity); addResult.iterator->value = structure; return structure; } void PrototypeMap::clearEmptyObjectStructureForPrototype(JSObject* object, unsigned inlineCapacity) { m_structures.remove(std::make_pair(object, inlineCapacity)); } } // namespace JSC