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https://github.com/mozilla/gecko-dev.git
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f480e9ecdf
The patch makes the following proxy changes: * The number of slots in ProxyValueArray is now dynamic and depends on the number of reserved slots we get from the Class. * "Extra slots" was renamed to "Reserved slots" to make this clearer. * All proxy Classes now have 2 reserved slots, but it should be easy to change that for proxy Classes that need more than 2 slots. * Proxies now store a pointer to these slots and this means GetReservedSlot and SetReservedSlot can be used on proxies as well. We no longer need GetReservedOrProxyPrivateSlot and SetReservedOrProxyPrivateSlot. And some changes to make DOM Proxies work with this: * We now store the C++ object in the first reserved slot (DOM_OBJECT_SLOT) instead of in the proxy's private slot. This is pretty nice because it matches what we do for non-proxy DOM objects. * We now store the expando in the proxy's private slot so I removed GetDOMProxyExpandoSlot and changed the IC code to get the expando from the private slot instead.
263 lines
9.7 KiB
C++
263 lines
9.7 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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namespace mozilla {
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namespace dom {
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/**
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* DOM proxies store the expando object in the private slot.
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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 proxy's private slot depends on whether the
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* 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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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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bool watch(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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JS::Handle<JSObject*> callable) const override;
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bool unwatch(JSContext* cx, JS::Handle<JSObject*> proxy,
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JS::Handle<jsid> id) 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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