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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
/* JSClass definition and its component types, plus related interfaces. */
#ifndef js_Class_h
#define js_Class_h
#include "mozilla/DebugOnly.h"
#include "jstypes.h"
#include "js/CallArgs.h"
#include "js/Id.h"
#include "js/TypeDecls.h"
* A JSClass acts as a vtable for JS objects that allows JSAPI clients to
* control various aspects of the behavior of an object like property lookup.
* js::Class is an engine-private extension that allows more control over
* object behavior and, e.g., allows custom slow layout.
struct JSAtomState;
struct JSFreeOp;
struct JSFunctionSpec;
namespace js {
struct Class;
class FreeOp;
class Shape;
// This is equal to JSFunction::class_. Use it in places where you don't want
// to #include jsfun.h.
extern JS_FRIEND_DATA(const js::Class* const) FunctionClassPtr;
} // namespace js
namespace JS {
template <typename T>
class AutoVectorRooter;
typedef AutoVectorRooter<jsid> AutoIdVector;
* The answer to a successful query as to whether an object is an Array per
* ES6's internal |IsArray| operation (as exposed by |Array.isArray|).
enum class IsArrayAnswer
* ES6 7.2.2.
* Returns false on failure, otherwise returns true and sets |*isArray|
* indicating whether the object passes ECMAScript's IsArray test. This is the
* same test performed by |Array.isArray|.
* This is NOT the same as asking whether |obj| is an Array or a wrapper around
* one. If |obj| is a proxy created by |Proxy.revocable()| and has been
* revoked, or if |obj| is a proxy whose target (at any number of hops) is a
* revoked proxy, this method throws a TypeError and returns false.
extern JS_PUBLIC_API(bool)
IsArray(JSContext* cx, HandleObject obj, bool* isArray);
* Identical to IsArray above, but the nature of the object (if successfully
* determined) is communicated via |*answer|. In particular this method
* returns true and sets |*answer = IsArrayAnswer::RevokedProxy| when called on
* a revoked proxy.
* Most users will want the overload above, not this one.
extern JS_PUBLIC_API(bool)
IsArray(JSContext* cx, HandleObject obj, IsArrayAnswer* answer);
* Per ES6, the [[DefineOwnProperty]] internal method has three different
* possible outcomes:
* - It can throw an exception (which we indicate by returning false).
* - It can return true, indicating unvarnished success.
* - It can return false, indicating "strict failure". The property could
* not be defined. It's an error, but no exception was thrown.
* It's not just [[DefineOwnProperty]]: all the mutating internal methods have
* the same three outcomes. (The other affected internal methods are [[Set]],
* [[Delete]], [[SetPrototypeOf]], and [[PreventExtensions]].)
* If you think this design is awful, you're not alone. But as it's the
* standard, we must represent these boolean "success" values somehow.
* ObjectOpSuccess is the class for this. It's like a bool, but when it's false
* it also stores an error code.
* Typical usage:
* ObjectOpResult result;
* if (!DefineProperty(cx, obj, id, ..., result))
* return false;
* if (!result)
* return result.reportError(cx, obj, id);
* Users don't have to call ``; another possible ending is:
* argv.rval().setBoolean(bool(result));
* return true;
class ObjectOpResult
* code_ is either one of the special codes OkCode or Uninitialized, or
* an error code. For now the error codes are private to the JS engine;
* they're defined in js/src/js.msg.
* code_ is uintptr_t (rather than uint32_t) for the convenience of the
* JITs, which would otherwise have to deal with either padding or stack
* alignment on 64-bit platforms.
uintptr_t code_;
enum SpecialCodes : uintptr_t {
OkCode = 0,
Uninitialized = uintptr_t(-1)
ObjectOpResult() : code_(Uninitialized) {}
/* Return true if succeed() was called. */
bool ok() const {
MOZ_ASSERT(code_ != Uninitialized);
return code_ == OkCode;
explicit operator bool() const { return ok(); }
/* Set this ObjectOpResult to true and return true. */
bool succeed() {
code_ = OkCode;
return true;
* Set this ObjectOpResult to false with an error code.
* Always returns true, as a convenience. Typical usage will be:
* if (funny condition)
* return;
* The true return value indicates that no exception is pending, and it
* would be OK to ignore the failure and continue.
bool fail(uint32_t msg) {
MOZ_ASSERT(msg != OkCode);
code_ = msg;
return true;
JS_PUBLIC_API(bool) failCantRedefineProp();
JS_PUBLIC_API(bool) failReadOnly();
JS_PUBLIC_API(bool) failGetterOnly();
JS_PUBLIC_API(bool) failCantDelete();
JS_PUBLIC_API(bool) failCantSetInterposed();
JS_PUBLIC_API(bool) failCantDefineWindowElement();
JS_PUBLIC_API(bool) failCantDeleteWindowElement();
JS_PUBLIC_API(bool) failCantDeleteWindowNamedProperty();
JS_PUBLIC_API(bool) failCantPreventExtensions();
JS_PUBLIC_API(bool) failCantSetProto();
JS_PUBLIC_API(bool) failNoNamedSetter();
JS_PUBLIC_API(bool) failNoIndexedSetter();
uint32_t failureCode() const {
return uint32_t(code_);
* Report an error or warning if necessary; return true to proceed and
* false if an error was reported. Call this when failure should cause
* a warning if extraWarnings are enabled.
* The precise rules are like this:
* - If ok(), then we succeeded. Do nothing and return true.
* - Otherwise, if |strict| is true, or if cx has both extraWarnings and
* werrorOption enabled, throw a TypeError and return false.
* - Otherwise, if cx has extraWarnings enabled, emit a warning and
* return true.
* - Otherwise, do nothing and return true.
bool checkStrictErrorOrWarning(JSContext* cx, HandleObject obj, HandleId id, bool strict) {
if (ok())
return true;
return reportStrictErrorOrWarning(cx, obj, id, strict);
* The same as checkStrictErrorOrWarning(cx, id, strict), except the
* operation is not associated with a particular property id. This is
* used for [[PreventExtensions]] and [[SetPrototypeOf]]. failureCode()
* must not be an error that has "{0}" in the error message.
bool checkStrictErrorOrWarning(JSContext* cx, HandleObject obj, bool strict) {
return ok() || reportStrictErrorOrWarning(cx, obj, strict);
/* Throw a TypeError. Call this only if !ok(). */
bool reportError(JSContext* cx, HandleObject obj, HandleId id) {
return reportStrictErrorOrWarning(cx, obj, id, true);
* The same as reportError(cx, obj, id), except the operation is not
* associated with a particular property id.
bool reportError(JSContext* cx, HandleObject obj) {
return reportStrictErrorOrWarning(cx, obj, true);
/* Helper function for checkStrictErrorOrWarning's slow path. */
JS_PUBLIC_API(bool) reportStrictErrorOrWarning(JSContext* cx, HandleObject obj, HandleId id, bool strict);
JS_PUBLIC_API(bool) reportStrictErrorOrWarning(JSContext* cx, HandleObject obj, bool strict);
* Convenience method. Return true if ok() or if strict is false; otherwise
* throw a TypeError and return false.
bool checkStrict(JSContext* cx, HandleObject obj, HandleId id) {
return checkStrictErrorOrWarning(cx, obj, id, true);
* Convenience method. The same as checkStrict(cx, id), except the
* operation is not associated with a particular property id.
bool checkStrict(JSContext* cx, HandleObject obj) {
return checkStrictErrorOrWarning(cx, obj, true);
} // namespace JS
// JSClass operation signatures.
* Get a property named by id in obj. Note the jsid id type -- id may
* be a string (Unicode property identifier) or an int (element index). The
* *vp out parameter, on success, is the new property value after the action.
typedef bool
(* JSGetterOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
JS::MutableHandleValue vp);
/** Add a property named by id to obj. */
typedef bool
(* JSAddPropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::HandleValue v);
* Set a property named by id in obj, treating the assignment as strict
* mode code if strict is true. Note the jsid id type -- id may be a string
* (Unicode property identifier) or an int (element index). The *vp out
* parameter, on success, is the new property value after the
* set.
typedef bool
(* JSSetterOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
JS::MutableHandleValue vp, JS::ObjectOpResult& result);
* Delete a property named by id in obj.
* If an error occurred, return false as per normal JSAPI error practice.
* If no error occurred, but the deletion attempt wasn't allowed (perhaps
* because the property was non-configurable), call and
* return true. This will cause |delete obj[id]| to evaluate to false in
* non-strict mode code, and to throw a TypeError in strict mode code.
* If no error occurred and the deletion wasn't disallowed (this is *not* the
* same as saying that a deletion actually occurred -- deleting a non-existent
* property, or an inherited property, is allowed -- it's just pointless),
* call result.succeed() and return true.
typedef bool
(* JSDeletePropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
JS::ObjectOpResult& result);
* The type of ObjectOps::enumerate. This callback overrides a portion of
* SpiderMonkey's default [[Enumerate]] internal method. When an ordinary object
* is enumerated, that object and each object on its prototype chain is tested
* for an enumerate op, and those ops are called in order. The properties each
* op adds to the 'properties' vector are added to the set of values the for-in
* loop will iterate over. All of this is nonstandard.
* An object is "enumerated" when it's the target of a for-in loop or
* JS_Enumerate(). The callback's job is to populate 'properties' with the
* object's property keys. If `enumerableOnly` is true, the callback should only
* add enumerable properties.
typedef bool
(* JSNewEnumerateOp)(JSContext* cx, JS::HandleObject obj, JS::AutoIdVector& properties,
bool enumerableOnly);
* The old-style JSClass.enumerate op should define all lazy properties not
* yet reflected in obj.
typedef bool
(* JSEnumerateOp)(JSContext* cx, JS::HandleObject obj);
* The type of ObjectOps::funToString. This callback allows an object to
* provide a custom string to use when Function.prototype.toString is invoked on
* that object. A null return value means OOM.
typedef JSString*
(* JSFunToStringOp)(JSContext* cx, JS::HandleObject obj, unsigned indent);
* Resolve a lazy property named by id in obj by defining it directly in obj.
* Lazy properties are those reflected from some peer native property space
* (e.g., the DOM attributes for a given node reflected as obj) on demand.
* JS looks for a property in an object, and if not found, tries to resolve
* the given id. *resolvedp should be set to true iff the property was
* was defined on |obj|.
typedef bool
(* JSResolveOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
bool* resolvedp);
* A class with a resolve hook can optionally have a mayResolve hook. This hook
* must have no side effects and must return true for a given id if the resolve
* hook may resolve this id. This is useful when we're doing a "pure" lookup: if
* mayResolve returns false, we know we don't have to call the effectful resolve
* hook.
* maybeObj, if non-null, is the object on which we're doing the lookup. This
* can be nullptr: during JIT compilation we sometimes know the Class but not
* the object.
typedef bool
(* JSMayResolveOp)(const JSAtomState& names, jsid id, JSObject* maybeObj);
* Finalize obj, which the garbage collector has determined to be unreachable
* from other live objects or from GC roots. Obviously, finalizers must never
* store a reference to obj.
typedef void
(* JSFinalizeOp)(JSFreeOp* fop, JSObject* obj);
/** Finalizes external strings created by JS_NewExternalString. */
struct JSStringFinalizer {
void (*finalize)(const JSStringFinalizer* fin, char16_t* chars);
* Check whether v is an instance of obj. Return false on error or exception,
* true on success with true in *bp if v is an instance of obj, false in
* *bp otherwise.
typedef bool
(* JSHasInstanceOp)(JSContext* cx, JS::HandleObject obj, JS::MutableHandleValue vp,
bool* bp);
* Function type for trace operation of the class called to enumerate all
* traceable things reachable from obj's private data structure. For each such
* thing, a trace implementation must call one of the JS_Call*Tracer variants
* on the thing.
* JSTraceOp implementation can assume that no other threads mutates object
* state. It must not change state of the object or corresponding native
* structures. The only exception for this rule is the case when the embedding
* needs a tight integration with GC. In that case the embedding can check if
* the traversal is a part of the marking phase through calling
* JS_IsGCMarkingTracer and apply a special code like emptying caches or
* marking its native structures.
typedef void
(* JSTraceOp)(JSTracer* trc, JSObject* obj);
typedef JSObject*
(* JSWeakmapKeyDelegateOp)(JSObject* obj);
typedef void
(* JSObjectMovedOp)(JSObject* obj, const JSObject* old);
/* js::Class operation signatures. */
namespace js {
typedef bool
(* LookupPropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
JS::MutableHandleObject objp, JS::MutableHandle<Shape*> propp);
typedef bool
(* DefinePropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
JS::Handle<JSPropertyDescriptor> desc,
JS::ObjectOpResult& result);
typedef bool
(* HasPropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id, bool* foundp);
typedef bool
(* GetPropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleValue receiver, JS::HandleId id,
JS::MutableHandleValue vp);
typedef bool
(* SetPropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::HandleValue v,
JS::HandleValue receiver, JS::ObjectOpResult& result);
typedef bool
(* GetOwnPropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
JS::MutableHandle<JSPropertyDescriptor> desc);
typedef bool
(* DeletePropertyOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id,
JS::ObjectOpResult& result);
typedef bool
(* WatchOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::HandleObject callable);
typedef bool
(* UnwatchOp)(JSContext* cx, JS::HandleObject obj, JS::HandleId id);
class JS_FRIEND_API(ElementAdder)
enum GetBehavior {
// Check if the element exists before performing the Get and preserve
// holes.
// Perform a Get operation, like obj[index] in JS.
// Only one of these is used.
JS::RootedObject resObj_;
JS::Value* vp_;
uint32_t index_;
mozilla::DebugOnly<uint32_t> length_;
GetBehavior getBehavior_;
ElementAdder(JSContext* cx, JSObject* obj, uint32_t length, GetBehavior behavior)
: resObj_(cx, obj), vp_(nullptr), index_(0), length_(length), getBehavior_(behavior)
ElementAdder(JSContext* cx, JS::Value* vp, uint32_t length, GetBehavior behavior)
: resObj_(cx), vp_(vp), index_(0), length_(length), getBehavior_(behavior)
GetBehavior getBehavior() const { return getBehavior_; }
bool append(JSContext* cx, JS::HandleValue v);
void appendHole();
typedef bool
(* GetElementsOp)(JSContext* cx, JS::HandleObject obj, uint32_t begin, uint32_t end,
ElementAdder* adder);
typedef void
(* FinalizeOp)(FreeOp* fop, JSObject* obj);
#define JS_CLASS_MEMBERS(FinalizeOpType) \
const char* name; \
uint32_t flags; \
/* Function pointer members (may be null). */ \
JSAddPropertyOp addProperty; \
JSDeletePropertyOp delProperty; \
JSGetterOp getProperty; \
JSSetterOp setProperty; \
JSEnumerateOp enumerate; \
JSResolveOp resolve; \
JSMayResolveOp mayResolve; \
FinalizeOpType finalize; \
JSNative call; \
JSHasInstanceOp hasInstance; \
JSNative construct; \
JSTraceOp trace
/** Callback for the creation of constructor and prototype objects. */
typedef JSObject* (*ClassObjectCreationOp)(JSContext* cx, JSProtoKey key);
/** Callback for custom post-processing after class initialization via ClassSpec. */
typedef bool (*FinishClassInitOp)(JSContext* cx, JS::HandleObject ctor,
JS::HandleObject proto);
struct ClassSpec
// All properties except flags should be accessed through accessor.
ClassObjectCreationOp createConstructor_;
ClassObjectCreationOp createPrototype_;
const JSFunctionSpec* constructorFunctions_;
const JSPropertySpec* constructorProperties_;
const JSFunctionSpec* prototypeFunctions_;
const JSPropertySpec* prototypeProperties_;
FinishClassInitOp finishInit_;
uintptr_t flags;
static const size_t ParentKeyWidth = JSCLASS_CACHED_PROTO_WIDTH;
static const uintptr_t ParentKeyMask = (1 << ParentKeyWidth) - 1;
static const uintptr_t DontDefineConstructor = 1 << ParentKeyWidth;
static const uintptr_t IsDelegated = 1 << (ParentKeyWidth + 1);
bool defined() const { return !!createConstructor_; }
bool delegated() const {
return (flags & IsDelegated);
bool dependent() const {
return (flags & ParentKeyMask);
JSProtoKey parentKey() const {
static_assert(JSProto_Null == 0, "zeroed key must be null");
return JSProtoKey(flags & ParentKeyMask);
bool shouldDefineConstructor() const {
return !(flags & DontDefineConstructor);
const ClassSpec* delegatedClassSpec() const {
return reinterpret_cast<ClassSpec*>(createConstructor_);
ClassObjectCreationOp createConstructorHook() const {
if (delegated())
return delegatedClassSpec()->createConstructorHook();
return createConstructor_;
ClassObjectCreationOp createPrototypeHook() const {
if (delegated())
return delegatedClassSpec()->createPrototypeHook();
return createPrototype_;
const JSFunctionSpec* constructorFunctions() const {
if (delegated())
return delegatedClassSpec()->constructorFunctions();
return constructorFunctions_;
const JSPropertySpec* constructorProperties() const {
if (delegated())
return delegatedClassSpec()->constructorProperties();
return constructorProperties_;
const JSFunctionSpec* prototypeFunctions() const {
if (delegated())
return delegatedClassSpec()->prototypeFunctions();
return prototypeFunctions_;
const JSPropertySpec* prototypeProperties() const {
if (delegated())
return delegatedClassSpec()->prototypeProperties();
return prototypeProperties_;
FinishClassInitOp finishInitHook() const {
if (delegated())
return delegatedClassSpec()->finishInitHook();
return finishInit_;
struct ClassExtension
* isWrappedNative is true only if the class is an XPCWrappedNative.
* WeakMaps use this to override the wrapper disposal optimization.
bool isWrappedNative;
* If an object is used as a key in a weakmap, it may be desirable for the
* garbage collector to keep that object around longer than it otherwise
* would. A common case is when the key is a wrapper around an object in
* another compartment, and we want to avoid collecting the wrapper (and
* removing the weakmap entry) as long as the wrapped object is alive. In
* that case, the wrapped object is returned by the wrapper's
* weakmapKeyDelegateOp hook. As long as the wrapper is used as a weakmap
* key, it will not be collected (and remain in the weakmap) until the
* wrapped object is collected.
JSWeakmapKeyDelegateOp weakmapKeyDelegateOp;
* Optional hook called when an object is moved by a compacting GC.
* There may exist weak pointers to an object that are not traced through
* when the normal trace APIs are used, for example objects in the wrapper
* cache. This hook allows these pointers to be updated.
* Note that this hook can be called before JS_NewObject() returns if a GC
* is triggered during construction of the object. This can happen for
* global objects for example.
JSObjectMovedOp objectMovedOp;
inline ClassObjectCreationOp DELEGATED_CLASSSPEC(const ClassSpec* spec) {
return reinterpret_cast<ClassObjectCreationOp>(const_cast<ClassSpec*>(spec));
#define JS_NULL_CLASS_SPEC {nullptr,nullptr,nullptr,nullptr,nullptr,nullptr}
#define JS_NULL_CLASS_EXT {false,nullptr}
struct ObjectOps
LookupPropertyOp lookupProperty;
DefinePropertyOp defineProperty;
HasPropertyOp hasProperty;
GetPropertyOp getProperty;
SetPropertyOp setProperty;
GetOwnPropertyOp getOwnPropertyDescriptor;
DeletePropertyOp deleteProperty;
WatchOp watch;
UnwatchOp unwatch;
GetElementsOp getElements;
JSNewEnumerateOp enumerate;
JSFunToStringOp funToString;
{nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, \
nullptr, nullptr, nullptr, nullptr}
} // namespace js
// Classes, objects, and properties.
typedef void (*JSClassInternal)();
struct JSClass {
void* reserved[23];
#define JSCLASS_HAS_PRIVATE (1<<0) // objects have private slot
#define JSCLASS_DELAY_METADATA_CALLBACK (1<<1) // class's initialization code
// will call
// SetNewObjectMetadata itself
#define JSCLASS_PRIVATE_IS_NSISUPPORTS (1<<3) // private is (nsISupports*)
#define JSCLASS_IS_DOMJSCLASS (1<<4) // objects are DOM
// Bit 5 is unused.
#define JSCLASS_EMULATES_UNDEFINED (1<<6) // objects of this class act
// like the value undefined,
// in some contexts
#define JSCLASS_USERBIT1 (1<<7) // Reserved for embeddings.
// To reserve slots fetched and stored via JS_Get/SetReservedSlot, bitwise-or
// JSCLASS_HAS_RESERVED_SLOTS(n) into the initializer for JSClass.flags, where
// n is a constant in [1, 255]. Reserved slots are indexed from 0 to n-1.
#define JSCLASS_RESERVED_SLOTS_SHIFT 8 // room for 8 flags below */
#define JSCLASS_RESERVED_SLOTS_WIDTH 8 // and 16 above this field */
#define JSCLASS_RESERVED_SLOTS(clasp) (((clasp)->flags \
// Reserved for embeddings.
// Bits 26 through 31 are reserved for the CACHED_PROTO_KEY mechanism, see
// below.
// ECMA-262 requires that most constructors used internally create objects
// with "the original Foo.prototype value" as their [[Prototype]] (__proto__)
// member initial value. The "original ... value" verbiage is there because
// in ECMA-262, global properties naming class objects are read/write and
// deleteable, for the most part.
// Implementing this efficiently requires that global objects have classes
// with the following flags. Failure to use JSCLASS_GLOBAL_FLAGS was
// previously allowed, but is now an ES5 violation and thus unsupported.
// JSCLASS_GLOBAL_APPLICATION_SLOTS is the number of slots reserved at
// the beginning of every global object's slots for use by the
// application.
(((clasp)->flags & JSCLASS_IS_GLOBAL) \
// Fast access to the original value of each standard class's prototype.
#define JSCLASS_CACHED_PROTO_KEY(clasp) ((JSProtoKey) \
(((clasp)->flags \
// Initializer for unused members of statically initialized JSClass structs.
#define JSCLASS_NO_INTERNAL_MEMBERS {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
namespace js {
struct Class
ClassSpec spec;
ClassExtension ext;
ObjectOps ops;
* Objects of this class aren't native objects. They don't have Shapes that
* describe their properties and layout. Classes using this flag must
* provide their own property behavior, either by being proxy classes (do
* this) or by overriding all the ObjectOps except getElements, watch and
* unwatch (don't do this).
static const uint32_t NON_NATIVE = JSCLASS_INTERNAL_FLAG2;
bool isNative() const {
return !(flags & NON_NATIVE);
bool hasPrivate() const {
return !!(flags & JSCLASS_HAS_PRIVATE);
bool emulatesUndefined() const {
bool isJSFunction() const {
return this == js::FunctionClassPtr;
bool nonProxyCallable() const {
return isJSFunction() || call;
bool isProxy() const {
return flags & JSCLASS_IS_PROXY;
bool isDOMClass() const {
bool shouldDelayMetadataCallback() const {
static size_t offsetOfFlags() { return offsetof(Class, flags); }
static_assert(offsetof(JSClass, name) == offsetof(Class, name),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, flags) == offsetof(Class, flags),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, addProperty) == offsetof(Class, addProperty),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, delProperty) == offsetof(Class, delProperty),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, getProperty) == offsetof(Class, getProperty),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, setProperty) == offsetof(Class, setProperty),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, enumerate) == offsetof(Class, enumerate),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, resolve) == offsetof(Class, resolve),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, mayResolve) == offsetof(Class, mayResolve),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, finalize) == offsetof(Class, finalize),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, call) == offsetof(Class, call),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, construct) == offsetof(Class, construct),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, hasInstance) == offsetof(Class, hasInstance),
"Class and JSClass must be consistent");
static_assert(offsetof(JSClass, trace) == offsetof(Class, trace),
"Class and JSClass must be consistent");
static_assert(sizeof(JSClass) == sizeof(Class),
"Class and JSClass must be consistent");
static MOZ_ALWAYS_INLINE const JSClass*
Jsvalify(const Class* c)
return (const JSClass*)c;
static MOZ_ALWAYS_INLINE const Class*
Valueify(const JSClass* c)
return (const Class*)c;
* Enumeration describing possible values of the [[Class]] internal property
* value of objects.
enum ESClassValue {
ESClass_Object, ESClass_Array, ESClass_Number, ESClass_String,
ESClass_Boolean, ESClass_RegExp, ESClass_ArrayBuffer, ESClass_SharedArrayBuffer,
ESClass_Date, ESClass_Set, ESClass_Map,
/** None of the above. */
/* Fills |vp| with the unboxed value for boxed types, or undefined otherwise. */
inline bool
Unbox(JSContext* cx, JS::HandleObject obj, JS::MutableHandleValue vp);
#ifdef DEBUG
HasObjectMovedOp(JSObject* obj);
} /* namespace js */
#endif /* js_Class_h */