зеркало из https://github.com/mozilla/gecko-dev.git
216 строки
8.3 KiB
C++
216 строки
8.3 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 "mozilla/Maybe.h"
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#include "mozilla/TextUtils.h"
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#include "jsapi.h"
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#include "js/Object.h" // JS::GetClass
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#include "js/Proxy.h"
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#include "js/String.h" // JS::AtomToLinearString, JS::GetLinearString{CharAt,Length}
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#include "nsString.h"
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// XXX Avoid including this (and maybe some of those above by moving inline
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// function bodies out)
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#include "jsfriendapi.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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class BaseDOMProxyHandler : public js::BaseProxyHandler {
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public:
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explicit constexpr BaseDOMProxyHandler(const void* aProxyFamily,
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bool aHasPrototype = false)
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: js::BaseProxyHandler(aProxyFamily, aHasPrototype) {}
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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(
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JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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JS::MutableHandle<Maybe<JS::PropertyDescriptor>> desc) const override;
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virtual bool ownPropertyKeys(
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JSContext* cx, JS::Handle<JSObject*> proxy,
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JS::MutableHandleVector<jsid> props) const override;
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virtual bool getPrototypeIfOrdinary(
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JSContext* cx, JS::Handle<JSObject*> proxy, 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(
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JSContext* cx, JS::Handle<JSObject*> proxy,
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JS::MutableHandleVector<jsid> 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::MutableHandleVector<jsid> 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(
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JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
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bool ignoreNamedProps,
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JS::MutableHandle<Maybe<JS::PropertyDescriptor>> desc) const = 0;
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};
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class DOMProxyHandler : public BaseDOMProxyHandler {
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public:
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constexpr DOMProxyHandler() : BaseDOMProxyHandler(&family) {}
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bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy,
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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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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,
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JS::Handle<jsid> id,
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JS::Handle<JS::PropertyDescriptor> desc,
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JS::ObjectOpResult& result, bool* done) 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,
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bool* extensible) 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,
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JS::ObjectOpResult& result) const override;
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// Use the DOMProxyExpando object for private fields, rather than the proxy
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// expando object.
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virtual bool useProxyExpandoObjectForPrivateFields() const override {
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return false;
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}
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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,
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JS::Handle<jsid> id, JS::Handle<JS::Value> v,
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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 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 JS::ExpandoAndGeneration.
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class ShadowingDOMProxyHandler : public DOMProxyHandler {
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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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return js::IsProxy(obj) &&
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js::GetProxyHandler(obj)->family() == &DOMProxyHandler::family;
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}
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inline const DOMProxyHandler* GetDOMProxyHandler(JSObject* obj) {
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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 GetArrayIndexFromId(JS::Handle<jsid> id) {
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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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// as of now, use id.get() instead of id otherwise operands mismatch error
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// occurs.
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if (MOZ_LIKELY(id.isInt())) {
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return id.toInt();
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}
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if (MOZ_LIKELY(id.get() == s_length_id)) {
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return UINT32_MAX;
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}
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if (MOZ_UNLIKELY(!id.isAtom())) {
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return UINT32_MAX;
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}
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JSLinearString* str = JS::AtomToLinearString(id.toAtom());
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if (MOZ_UNLIKELY(JS::GetLinearStringLength(str) == 0)) {
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return UINT32_MAX;
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}
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char16_t firstChar = JS::GetLinearStringCharAt(str, 0);
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if (MOZ_LIKELY(IsAsciiLowercaseAlpha(firstChar))) {
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return UINT32_MAX;
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}
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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 IsArrayIndex(uint32_t index) { return index < UINT32_MAX; }
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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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