264 lines
9.6 KiB
C++
264 lines
9.6 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_dom_DOMJSProxyHandler_h
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#define mozilla_dom_DOMJSProxyHandler_h
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#include "mozilla/Attributes.h"
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#include "mozilla/Likely.h"
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#include "jsapi.h"
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#include "js/Proxy.h"
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#include "nsString.h"
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#define DOM_PROXY_OBJECT_SLOT js::PROXY_PRIVATE_SLOT
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namespace mozilla {
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namespace dom {
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enum {
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/**
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* DOM proxies have an extra slot for the expando object at index
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* JSPROXYSLOT_EXPANDO.
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*
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* The expando object is a plain JSObject whose properties correspond to
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* "expandos" (custom properties set by the script author).
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*
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* The exact value stored in the JSPROXYSLOT_EXPANDO slot depends on whether
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* the interface is annotated with the [OverrideBuiltins] extended attribute.
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*
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* If it is, the proxy is initialized with a PrivateValue, which contains a
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* pointer to a js::ExpandoAndGeneration object; this contains a pointer to
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* the actual expando object as well as the "generation" of the object. The
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* proxy handler will trace the expando object stored in the
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* js::ExpandoAndGeneration while the proxy itself is alive.
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*
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* If it is not, the proxy is initialized with an UndefinedValue. In
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* EnsureExpandoObject, it is set to an ObjectValue that points to the
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* expando object directly. (It is set back to an UndefinedValue only when
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* the object is about to die.)
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*/
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JSPROXYSLOT_EXPANDO = 0
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};
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template<typename T> struct Prefable;
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class BaseDOMProxyHandler : public js::BaseProxyHandler
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{
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public:
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explicit constexpr BaseDOMProxyHandler(const void* aProxyFamily, bool aHasPrototype = false)
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: js::BaseProxyHandler(aProxyFamily, aHasPrototype)
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{}
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// Implementations of methods that can be implemented in terms of
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// other lower-level methods.
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bool getOwnPropertyDescriptor(JSContext* cx, JS::Handle<JSObject*> proxy,
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JS::Handle<jsid> id,
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JS::MutableHandle<JS::PropertyDescriptor> desc) const override;
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virtual bool ownPropertyKeys(JSContext* cx, JS::Handle<JSObject*> proxy,
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JS::AutoIdVector &props) const override;
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virtual bool getPrototypeIfOrdinary(JSContext* cx, JS::Handle<JSObject*> proxy,
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bool* isOrdinary,
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JS::MutableHandle<JSObject*> proto) const override;
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// We override getOwnEnumerablePropertyKeys() and implement it directly
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// instead of using the default implementation, which would call
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// ownPropertyKeys and then filter out the non-enumerable ones. This avoids
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// unnecessary work during enumeration.
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virtual bool getOwnEnumerablePropertyKeys(JSContext* cx, JS::Handle<JSObject*> proxy,
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JS::AutoIdVector &props) const override;
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protected:
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// Hook for subclasses to implement shared ownPropertyKeys()/keys()
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// functionality. The "flags" argument is either JSITER_OWNONLY (for keys())
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// or JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS (for
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// ownPropertyKeys()).
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virtual bool ownPropNames(JSContext* cx, JS::Handle<JSObject*> proxy,
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unsigned flags,
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JS::AutoIdVector& props) const = 0;
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// Hook for subclasses to allow set() to ignore named props while other things
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// that look at property descriptors see them. This is intentionally not
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// named getOwnPropertyDescriptor to avoid subclasses that override it hiding
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// our public getOwnPropertyDescriptor.
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virtual bool getOwnPropDescriptor(JSContext* cx,
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JS::Handle<JSObject*> proxy,
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JS::Handle<jsid> id,
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bool ignoreNamedProps,
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JS::MutableHandle<JS::PropertyDescriptor> desc) const = 0;
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};
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class DOMProxyHandler : public BaseDOMProxyHandler
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{
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public:
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constexpr DOMProxyHandler()
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: BaseDOMProxyHandler(&family)
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{}
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bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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JS::Handle<JS::PropertyDescriptor> desc,
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JS::ObjectOpResult &result) const override
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{
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bool unused;
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return defineProperty(cx, proxy, id, desc, result, &unused);
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}
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virtual bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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JS::Handle<JS::PropertyDescriptor> desc,
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JS::ObjectOpResult &result, bool *defined) const;
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bool delete_(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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JS::ObjectOpResult &result) const override;
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bool preventExtensions(JSContext* cx, JS::Handle<JSObject*> proxy,
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JS::ObjectOpResult& result) const override;
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bool isExtensible(JSContext *cx, JS::Handle<JSObject*> proxy, bool *extensible)
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const override;
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bool set(JSContext *cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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JS::Handle<JS::Value> v, JS::Handle<JS::Value> receiver, JS::ObjectOpResult &result)
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const override;
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/*
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* If assigning to proxy[id] hits a named setter with OverrideBuiltins or
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* an indexed setter, call it and set *done to true on success. Otherwise, set
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* *done to false.
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*/
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virtual bool setCustom(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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JS::Handle<JS::Value> v, bool *done) const;
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/*
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* Get the expando object for the given DOM proxy.
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*/
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static JSObject* GetExpandoObject(JSObject* obj);
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/*
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* Clear the "external references" to this object. If you are not
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* nsWrapperCAche::ReleaseWrapper, you do NOT want to be calling this method.
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*
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* XXXbz if we nixed the DOM expando hash and just had a finalizer that
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* cleared out the value in the ExpandoAndGeneration in the shadowing case,
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* could we just get rid of this function altogether?
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*/
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static void ClearExternalRefsForWrapperRelease(JSObject* obj);
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/*
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* Clear the expando object for the given DOM proxy and return it. This
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* function will ensure that the returned object is exposed to active JS if
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* the given object is exposed.
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*
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* GetAndClearExpandoObject does not DROP or clear the preserving wrapper
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* flag.
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*/
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static JSObject* GetAndClearExpandoObject(JSObject* obj);
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/*
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* Ensure that the given proxy (obj) has an expando object, and return it.
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* Returns null on failure.
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*/
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static JSObject* EnsureExpandoObject(JSContext* cx,
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JS::Handle<JSObject*> obj);
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static const char family;
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};
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// Class used by shadowing handlers (the ones that have [OverrideBuiltins].
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// This handles tracing the expando in ExpandoAndGeneration.
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class ShadowingDOMProxyHandler : public DOMProxyHandler
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{
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virtual void trace(JSTracer* trc, JSObject* proxy) const override;
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};
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inline bool IsDOMProxy(JSObject *obj)
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{
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const js::Class* clasp = js::GetObjectClass(obj);
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return clasp->isProxy() &&
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js::GetProxyHandler(obj)->family() == &DOMProxyHandler::family;
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}
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inline const DOMProxyHandler*
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GetDOMProxyHandler(JSObject* obj)
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{
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MOZ_ASSERT(IsDOMProxy(obj));
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return static_cast<const DOMProxyHandler*>(js::GetProxyHandler(obj));
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}
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extern jsid s_length_id;
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// A return value of UINT32_MAX indicates "not an array index". Note, in
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// particular, that UINT32_MAX itself is not a valid array index in general.
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inline uint32_t
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GetArrayIndexFromId(JSContext* cx, JS::Handle<jsid> id)
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{
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// Much like js::IdIsIndex, except with a fast path for "length" and another
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// fast path for starting with a lowercase ascii char. Is that second one
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// really needed? I guess it is because StringIsArrayIndex is out of line...
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if (MOZ_LIKELY(JSID_IS_INT(id))) {
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return JSID_TO_INT(id);
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}
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if (MOZ_LIKELY(id == s_length_id)) {
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return UINT32_MAX;
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}
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if (MOZ_UNLIKELY(!JSID_IS_ATOM(id))) {
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return UINT32_MAX;
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}
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JSLinearString* str = js::AtomToLinearString(JSID_TO_ATOM(id));
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char16_t s;
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{
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JS::AutoCheckCannotGC nogc;
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if (js::LinearStringHasLatin1Chars(str)) {
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s = *js::GetLatin1LinearStringChars(nogc, str);
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} else {
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s = *js::GetTwoByteLinearStringChars(nogc, str);
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}
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}
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if (MOZ_LIKELY((unsigned)s >= 'a' && (unsigned)s <= 'z'))
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return UINT32_MAX;
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uint32_t i;
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return js::StringIsArrayIndex(str, &i) ? i : UINT32_MAX;
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}
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inline bool
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IsArrayIndex(uint32_t index)
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{
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return index < UINT32_MAX;
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}
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inline void
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FillPropertyDescriptor(JS::MutableHandle<JS::PropertyDescriptor> desc,
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JSObject* obj, bool readonly, bool enumerable = true)
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{
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desc.object().set(obj);
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desc.setAttributes((readonly ? JSPROP_READONLY : 0) |
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(enumerable ? JSPROP_ENUMERATE : 0));
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desc.setGetter(nullptr);
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desc.setSetter(nullptr);
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}
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inline void
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FillPropertyDescriptor(JS::MutableHandle<JS::PropertyDescriptor> desc,
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JSObject* obj, const JS::Value& v,
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bool readonly, bool enumerable = true)
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{
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desc.value().set(v);
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FillPropertyDescriptor(desc, obj, readonly, enumerable);
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}
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inline void
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FillPropertyDescriptor(JS::MutableHandle<JS::PropertyDescriptor> desc,
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JSObject* obj, unsigned attributes, const JS::Value& v)
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{
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desc.object().set(obj);
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desc.value().set(v);
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desc.setAttributes(attributes);
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desc.setGetter(nullptr);
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desc.setSetter(nullptr);
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}
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} // namespace dom
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} // namespace mozilla
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#endif /* mozilla_dom_DOMProxyHandler_h */
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