Add m-esr52 at 52.6.0

1 files changed, 995 insertions, 0 deletions

diff --git a/js/public/Class.h b/js/public/Class.h
new file mode 100644
index 000000000..3b5023875
--- /dev/null
+++ b/js/public/Class.h
@@ -0,0 +1,995 @@
+/* -*- 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 http://mozilla.org/MPL/2.0/. */
+
+/* JSClass definition and its component types, plus related interfaces. */
+
+#ifndef js_Class_h
+#define js_Class_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 {
+
+class 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
+{
+    Array,
+    NotArray,
+    RevokedProxy
+};
+
+/**
+ * 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 `result.report()`; another possible ending is:
+ *
+ *     argv.rval().setBoolean(bool(result));
+ *     return true;
+ */
+class ObjectOpResult
+{
+  private:
+    /**
+     * 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_;
+
+  public:
+    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 result.fail(JSMSG_CANT_DO_THE_THINGS);
+     *
+     * 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 {
+        MOZ_ASSERT(!ok());
+        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 result.fail() 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 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)(JS::Zone* zone, 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 JS::TraceEdge on the thing's
+ * location.
+ *
+ * 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<JS::PropertyDescriptor> 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<JS::PropertyDescriptor> 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)
+{
+  public:
+    enum GetBehavior {
+        // Check if the element exists before performing the Get and preserve
+        // holes.
+        CheckHasElemPreserveHoles,
+
+        // Perform a Get operation, like obj[index] in JS.
+        GetElement
+    };
+
+  private:
+    // Only one of these is used.
+    JS::RootedObject resObj_;
+    JS::Value* vp_;
+
+    uint32_t index_;
+#ifdef DEBUG
+    uint32_t length_;
+#endif
+    GetBehavior getBehavior_;
+
+  public:
+    ElementAdder(JSContext* cx, JSObject* obj, uint32_t length, GetBehavior behavior)
+      : resObj_(cx, obj), vp_(nullptr), index_(0),
+#ifdef DEBUG
+        length_(length),
+#endif
+        getBehavior_(behavior)
+    {}
+    ElementAdder(JSContext* cx, JS::Value* vp, uint32_t length, GetBehavior behavior)
+      : resObj_(cx), vp_(vp), index_(0),
+#ifdef DEBUG
+        length_(length),
+#endif
+        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);
+
+// The special treatment of |finalize| and |trace| is necessary because if we
+// assign either of those hooks to a local variable and then call it -- as is
+// done with the other hooks -- the GC hazard analysis gets confused.
+#define JS_CLASS_MEMBERS(ClassOpsType, FreeOpType) \
+    const char* name; \
+    uint32_t flags; \
+    const ClassOpsType* cOps; \
+    \
+    JSAddPropertyOp    getAddProperty() const { return cOps ? cOps->addProperty : nullptr; } \
+    JSDeletePropertyOp getDelProperty() const { return cOps ? cOps->delProperty : nullptr; } \
+    JSGetterOp         getGetProperty() const { return cOps ? cOps->getProperty : nullptr; } \
+    JSSetterOp         getSetProperty() const { return cOps ? cOps->setProperty : nullptr; } \
+    JSEnumerateOp      getEnumerate()   const { return cOps ? cOps->enumerate   : nullptr; } \
+    JSResolveOp        getResolve()     const { return cOps ? cOps->resolve     : nullptr; } \
+    JSMayResolveOp     getMayResolve()  const { return cOps ? cOps->mayResolve  : nullptr; } \
+    JSNative           getCall()        const { return cOps ? cOps->call        : nullptr; } \
+    JSHasInstanceOp    getHasInstance() const { return cOps ? cOps->hasInstance : nullptr; } \
+    JSNative           getConstruct()   const { return cOps ? cOps->construct   : nullptr; } \
+    \
+    bool hasFinalize() const { return cOps && cOps->finalize; } \
+    bool hasTrace()    const { return cOps && cOps->trace;    } \
+    \
+    bool isTrace(JSTraceOp trace) const { return cOps && cOps->trace == trace; } \
+    \
+    void doFinalize(FreeOpType* fop, JSObject* obj) const { \
+        MOZ_ASSERT(cOps && cOps->finalize); \
+        cOps->finalize(fop, obj); \
+    } \
+    void doTrace(JSTracer* trc, JSObject* obj) const { \
+        MOZ_ASSERT(cOps && cOps->trace); \
+        cOps->trace(trc, obj); \
+    }
+
+struct ClassOps
+{
+    /* Function pointer members (may be null). */
+    JSAddPropertyOp     addProperty;
+    JSDeletePropertyOp  delProperty;
+    JSGetterOp          getProperty;
+    JSSetterOp          setProperty;
+    JSEnumerateOp       enumerate;
+    JSResolveOp         resolve;
+    JSMayResolveOp      mayResolve;
+    FinalizeOp          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);
+
+const size_t JSCLASS_CACHED_PROTO_WIDTH = 6;
+
+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 ProtoKeyWidth = JSCLASS_CACHED_PROTO_WIDTH;
+
+    static const uintptr_t ProtoKeyMask = (1 << ProtoKeyWidth) - 1;
+    static const uintptr_t DontDefineConstructor = 1 << ProtoKeyWidth;
+    static const uintptr_t IsDelegated = 1 << (ProtoKeyWidth + 1);
+
+    bool defined() const { return !!createConstructor_; }
+
+    bool delegated() const {
+        return (flags & IsDelegated);
+    }
+
+    // The ProtoKey this class inherits from.
+    JSProtoKey inheritanceProtoKey() const {
+        MOZ_ASSERT(defined());
+        static_assert(JSProto_Null == 0, "zeroed key must be null");
+
+        // Default: Inherit from Object.
+        if (!(flags & ProtoKeyMask))
+            return JSProto_Object;
+
+        return JSProtoKey(flags & ProtoKeyMask);
+    }
+
+    bool shouldDefineConstructor() const {
+        MOZ_ASSERT(defined());
+        return !(flags & DontDefineConstructor);
+    }
+
+    const ClassSpec* delegatedClassSpec() const {
+        MOZ_ASSERT(delegated());
+        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
+{
+    /**
+     * 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
+#define JS_NULL_CLASS_EXT   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;
+};
+
+#define JS_NULL_OBJECT_OPS nullptr
+
+} // namespace js
+
+// Classes, objects, and properties.
+
+typedef void (*JSClassInternal)();
+
+struct JSClassOps
+{
+    /* Function pointer members (may be null). */
+    JSAddPropertyOp     addProperty;
+    JSDeletePropertyOp  delProperty;
+    JSGetterOp          getProperty;
+    JSSetterOp          setProperty;
+    JSEnumerateOp       enumerate;
+    JSResolveOp         resolve;
+    JSMayResolveOp      mayResolve;
+    JSFinalizeOp        finalize;
+    JSNative            call;
+    JSHasInstanceOp     hasInstance;
+    JSNative            construct;
+    JSTraceOp           trace;
+};
+
+#define JS_NULL_CLASS_OPS nullptr
+
+struct JSClass {
+    JS_CLASS_MEMBERS(JSClassOps, JSFreeOp);
+
+    void* reserved[3];
+};
+
+#define JSCLASS_HAS_PRIVATE             (1<<0)  // objects have private slot
+#define JSCLASS_DELAY_METADATA_BUILDER  (1<<1)  // class's initialization code
+                                                // will call
+                                                // SetNewObjectMetadata itself
+#define JSCLASS_IS_WRAPPED_NATIVE       (1<<2)  // class is an XPCWrappedNative.
+                                                // WeakMaps use this to override
+                                                // the wrapper disposal
+                                                // mechanism.
+#define JSCLASS_PRIVATE_IS_NSISUPPORTS  (1<<3)  // private is (nsISupports*)
+#define JSCLASS_IS_DOMJSCLASS           (1<<4)  // objects are DOM
+#define JSCLASS_HAS_XRAYED_CONSTRUCTOR  (1<<5)  // if wrapped by an xray
+                                                // wrapper, the builtin
+                                                // class's constructor won't
+                                                // be unwrapped and invoked.
+                                                // Instead, the constructor is
+                                                // resolved in the caller's
+                                                // compartment and invoked
+                                                // with a wrapped newTarget.
+                                                // The constructor has to
+                                                // detect and handle this
+                                                // situation.
+                                                // See PromiseConstructor for
+                                                // details.
+#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_MASK     JS_BITMASK(JSCLASS_RESERVED_SLOTS_WIDTH)
+#define JSCLASS_HAS_RESERVED_SLOTS(n)   (((n) & JSCLASS_RESERVED_SLOTS_MASK)  \
+                                         << JSCLASS_RESERVED_SLOTS_SHIFT)
+#define JSCLASS_RESERVED_SLOTS(clasp)   (((clasp)->flags                      \
+                                          >> JSCLASS_RESERVED_SLOTS_SHIFT)    \
+                                         & JSCLASS_RESERVED_SLOTS_MASK)
+
+#define JSCLASS_HIGH_FLAGS_SHIFT        (JSCLASS_RESERVED_SLOTS_SHIFT +       \
+                                         JSCLASS_RESERVED_SLOTS_WIDTH)
+
+#define JSCLASS_IS_ANONYMOUS            (1<<(JSCLASS_HIGH_FLAGS_SHIFT+0))
+#define JSCLASS_IS_GLOBAL               (1<<(JSCLASS_HIGH_FLAGS_SHIFT+1))
+#define JSCLASS_INTERNAL_FLAG2          (1<<(JSCLASS_HIGH_FLAGS_SHIFT+2))
+#define JSCLASS_INTERNAL_FLAG3          (1<<(JSCLASS_HIGH_FLAGS_SHIFT+3))
+
+#define JSCLASS_IS_PROXY                (1<<(JSCLASS_HIGH_FLAGS_SHIFT+4))
+
+#define JSCLASS_SKIP_NURSERY_FINALIZE   (1<<(JSCLASS_HIGH_FLAGS_SHIFT+5))
+
+// Reserved for embeddings.
+#define JSCLASS_USERBIT2                (1<<(JSCLASS_HIGH_FLAGS_SHIFT+6))
+#define JSCLASS_USERBIT3                (1<<(JSCLASS_HIGH_FLAGS_SHIFT+7))
+
+#define JSCLASS_BACKGROUND_FINALIZE     (1<<(JSCLASS_HIGH_FLAGS_SHIFT+8))
+#define JSCLASS_FOREGROUND_FINALIZE     (1<<(JSCLASS_HIGH_FLAGS_SHIFT+9))
+
+// 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.
+#define JSCLASS_GLOBAL_APPLICATION_SLOTS 5
+#define JSCLASS_GLOBAL_SLOT_COUNT                                             \
+    (JSCLASS_GLOBAL_APPLICATION_SLOTS + JSProto_LIMIT * 2 + 39)
+#define JSCLASS_GLOBAL_FLAGS_WITH_SLOTS(n)                                    \
+    (JSCLASS_IS_GLOBAL | JSCLASS_HAS_RESERVED_SLOTS(JSCLASS_GLOBAL_SLOT_COUNT + (n)))
+#define JSCLASS_GLOBAL_FLAGS                                                  \
+    JSCLASS_GLOBAL_FLAGS_WITH_SLOTS(0)
+#define JSCLASS_HAS_GLOBAL_FLAG_AND_SLOTS(clasp)                              \
+  (((clasp)->flags & JSCLASS_IS_GLOBAL)                                       \
+   && JSCLASS_RESERVED_SLOTS(clasp) >= JSCLASS_GLOBAL_SLOT_COUNT)
+
+// Fast access to the original value of each standard class's prototype.
+#define JSCLASS_CACHED_PROTO_SHIFT      (JSCLASS_HIGH_FLAGS_SHIFT + 10)
+#define JSCLASS_CACHED_PROTO_MASK       JS_BITMASK(js::JSCLASS_CACHED_PROTO_WIDTH)
+#define JSCLASS_HAS_CACHED_PROTO(key)   (uint32_t(key) << JSCLASS_CACHED_PROTO_SHIFT)
+#define JSCLASS_CACHED_PROTO_KEY(clasp) ((JSProtoKey)                         \
+                                         (((clasp)->flags                     \
+                                           >> JSCLASS_CACHED_PROTO_SHIFT)     \
+                                          & JSCLASS_CACHED_PROTO_MASK))
+
+// 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}
+#define JSCLASS_NO_OPTIONAL_MEMBERS     0,0,0,0,0,JSCLASS_NO_INTERNAL_MEMBERS
+
+namespace js {
+
+struct Class
+{
+    JS_CLASS_MEMBERS(js::ClassOps, FreeOp);
+    const ClassSpec* spec;
+    const ClassExtension* ext;
+    const ObjectOps* oOps;
+
+    /*
+     * 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 {
+        return flags & JSCLASS_EMULATES_UNDEFINED;
+    }
+
+    bool isJSFunction() const {
+        return this == js::FunctionClassPtr;
+    }
+
+    bool nonProxyCallable() const {
+        MOZ_ASSERT(!isProxy());
+        return isJSFunction() || getCall();
+    }
+
+    bool isProxy() const {
+        return flags & JSCLASS_IS_PROXY;
+    }
+
+    bool isDOMClass() const {
+        return flags & JSCLASS_IS_DOMJSCLASS;
+    }
+
+    bool shouldDelayMetadataBuilder() const {
+        return flags & JSCLASS_DELAY_METADATA_BUILDER;
+    }
+
+    bool isWrappedNative() const {
+        return flags & JSCLASS_IS_WRAPPED_NATIVE;
+    }
+
+    static size_t offsetOfFlags() { return offsetof(Class, flags); }
+
+    bool specDefined()         const { return spec ? spec->defined()   : false; }
+    JSProtoKey specInheritanceProtoKey()
+                               const { return spec ? spec->inheritanceProtoKey() : JSProto_Null; }
+    bool specShouldDefineConstructor()
+                               const { return spec ? spec->shouldDefineConstructor() : true; }
+    ClassObjectCreationOp specCreateConstructorHook()
+                               const { return spec ? spec->createConstructorHook()   : nullptr; }
+    ClassObjectCreationOp specCreatePrototypeHook()
+                               const { return spec ? spec->createPrototypeHook()     : nullptr; }
+    const JSFunctionSpec* specConstructorFunctions()
+                               const { return spec ? spec->constructorFunctions()    : nullptr; }
+    const JSPropertySpec* specConstructorProperties()
+                               const { return spec ? spec->constructorProperties()   : nullptr; }
+    const JSFunctionSpec* specPrototypeFunctions()
+                               const { return spec ? spec->prototypeFunctions()      : nullptr; }
+    const JSPropertySpec* specPrototypeProperties()
+                               const { return spec ? spec->prototypeProperties()     : nullptr; }
+    FinishClassInitOp specFinishInitHook()
+                               const { return spec ? spec->finishInitHook()          : nullptr; }
+
+    JSWeakmapKeyDelegateOp extWeakmapKeyDelegateOp()
+                               const { return ext ? ext->weakmapKeyDelegateOp        : nullptr; }
+    JSObjectMovedOp extObjectMovedOp()
+                               const { return ext ? ext->objectMovedOp               : nullptr; }
+
+    LookupPropertyOp getOpsLookupProperty() const { return oOps ? oOps->lookupProperty : nullptr; }
+    DefinePropertyOp getOpsDefineProperty() const { return oOps ? oOps->defineProperty : nullptr; }
+    HasPropertyOp    getOpsHasProperty()    const { return oOps ? oOps->hasProperty    : nullptr; }
+    GetPropertyOp    getOpsGetProperty()    const { return oOps ? oOps->getProperty    : nullptr; }
+    SetPropertyOp    getOpsSetProperty()    const { return oOps ? oOps->setProperty    : nullptr; }
+    GetOwnPropertyOp getOpsGetOwnPropertyDescriptor()
+                                            const { return oOps ? oOps->getOwnPropertyDescriptor
+                                                                                     : nullptr; }
+    DeletePropertyOp getOpsDeleteProperty() const { return oOps ? oOps->deleteProperty : nullptr; }
+    WatchOp          getOpsWatch()          const { return oOps ? oOps->watch          : nullptr; }
+    UnwatchOp        getOpsUnwatch()        const { return oOps ? oOps->unwatch        : nullptr; }
+    GetElementsOp    getOpsGetElements()    const { return oOps ? oOps->getElements    : nullptr; }
+    JSNewEnumerateOp getOpsEnumerate()      const { return oOps ? oOps->enumerate      : nullptr; }
+    JSFunToStringOp  getOpsFunToString()    const { return oOps ? oOps->funToString    : nullptr; }
+};
+
+static_assert(offsetof(JSClassOps, addProperty) == offsetof(ClassOps, addProperty),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, delProperty) == offsetof(ClassOps, delProperty),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, getProperty) == offsetof(ClassOps, getProperty),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, setProperty) == offsetof(ClassOps, setProperty),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, enumerate) == offsetof(ClassOps, enumerate),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, resolve) == offsetof(ClassOps, resolve),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, mayResolve) == offsetof(ClassOps, mayResolve),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, finalize) == offsetof(ClassOps, finalize),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, call) == offsetof(ClassOps, call),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, construct) == offsetof(ClassOps, construct),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, hasInstance) == offsetof(ClassOps, hasInstance),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(offsetof(JSClassOps, trace) == offsetof(ClassOps, trace),
+              "ClassOps and JSClassOps must be consistent");
+static_assert(sizeof(JSClassOps) == sizeof(ClassOps),
+              "ClassOps and JSClassOps must be consistent");
+
+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, cOps) == offsetof(Class, cOps),
+              "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 class ESClass {
+    Object,
+    Array,
+    Number,
+    String,
+    Boolean,
+    RegExp,
+    ArrayBuffer,
+    SharedArrayBuffer,
+    Date,
+    Set,
+    Map,
+    Promise,
+    MapIterator,
+    SetIterator,
+    Arguments,
+    Error,
+
+    /** None of the above. */
+    Other
+};
+
+/* Fills |vp| with the unboxed value for boxed types, or undefined otherwise. */
+bool
+Unbox(JSContext* cx, JS::HandleObject obj, JS::MutableHandleValue vp);
+
+#ifdef DEBUG
+JS_FRIEND_API(bool)
+HasObjectMovedOp(JSObject* obj);
+#endif
+
+}  /* namespace js */
+
+#endif  /* js_Class_h */