runtime/ClonedArguments.h

   1 /*
   2  * Copyright (C) 2015 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef ClonedArguments_h
  27 #define ClonedArguments_h
  28
  29 #include "ArgumentsMode.h"
  30 #include "JSObject.h"
  31
  32 namespace JSC {
  33
  34 // This is an Arguments-class object that we create when you do function.arguments, or you say
  35 // "arguments" inside a function in strict mode. It behaves almpst entirely like an ordinary
  36 // JavaScript object. All of the arguments values are simply copied from the stack (possibly via
  37 // some sophisticated ValueRecovery's if an optimizing compiler is in play) and the appropriate
  38 // properties of the object are populated. The only reason why we need a special class is to make
  39 // the object claim to be "Arguments" from a toString standpoint, and to avoid materializing the
  40 // caller/callee/@@iterator properties unless someone asks for them.
  41 class ClonedArguments : public JSNonFinalObject {
  42 public:
  43     typedef JSNonFinalObject Base;
  44     static const unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | OverridesGetPropertyNames;
  45
  46 private:
  47     ClonedArguments(VM&, Structure*);
  48
  49 public:
  50     static ClonedArguments* createEmpty(VM&, Structure*, JSFunction* callee);
  51     static ClonedArguments* createEmpty(ExecState*, JSFunction* callee);
  52     static ClonedArguments* createWithInlineFrame(ExecState* myFrame, ExecState* targetFrame, InlineCallFrame*, ArgumentsMode);
  53     static ClonedArguments* createWithMachineFrame(ExecState* myFrame, ExecState* targetFrame, ArgumentsMode);
  54     static ClonedArguments* createByCopyingFrom(ExecState*, Structure*, Register* argumentsStart, unsigned length, JSFunction* callee);
  55
  56     static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype);
  57
  58     static void visitChildren(JSCell*, SlotVisitor&);
  59
  60     DECLARE_INFO;
  61
  62 private:
  63     static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
  64     static void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
  65     static void put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
  66     static bool deleteProperty(JSCell*, ExecState*, PropertyName);
  67     static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
  68
  69     bool specialsMaterialized() const { return !m_callee; }
  70     void materializeSpecials(ExecState*);
  71     void materializeSpecialsIfNecessary(ExecState*);
  72
  73     WriteBarrier<JSFunction> m_callee; // Set to nullptr when we materialize all of our special properties.
  74 };
  75
  76 } // namespace JSC
  77
  78 #endif // ClonedArguments_h
  79