gecko-dev/dom/bindings/DOMJSProxyHandler.h
2015-05-03 15:32:37 -04:00

235 lines
8.5 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
#ifndef mozilla_dom_DOMJSProxyHandler_h
#define mozilla_dom_DOMJSProxyHandler_h
#include "mozilla/Attributes.h"
#include "mozilla/Likely.h"
#include "jsapi.h"
#include "js/Proxy.h"
#include "nsString.h"
#define DOM_PROXY_OBJECT_SLOT js::PROXY_PRIVATE_SLOT
namespace mozilla {
namespace dom {
enum {
/**
* DOM proxies have an extra slot for the expando object at index
* JSPROXYSLOT_EXPANDO.
*
* The expando object is a plain JSObject whose properties correspond to
* "expandos" (custom properties set by the script author).
*
* The exact value stored in the JSPROXYSLOT_EXPANDO slot depends on whether
* the interface is annotated with the [OverrideBuiltins] extended attribute.
*
* If it is, the proxy is initialized with a PrivateValue, which contains a
* pointer to a js::ExpandoAndGeneration object; this contains a pointer to
* the actual expando object as well as the "generation" of the object.
*
* If it is not, the proxy is initialized with an UndefinedValue. In
* EnsureExpandoObject, it is set to an ObjectValue that points to the
* expando object directly. (It is set back to an UndefinedValue only when
* the object is about to die.)
*/
JSPROXYSLOT_EXPANDO = 0
};
template<typename T> struct Prefable;
class BaseDOMProxyHandler : public js::BaseProxyHandler
{
public:
explicit MOZ_CONSTEXPR BaseDOMProxyHandler(const void* aProxyFamily, bool aHasPrototype = false)
: js::BaseProxyHandler(aProxyFamily, aHasPrototype)
{}
// Implementations of methods that can be implemented in terms of
// other lower-level methods.
bool getOwnPropertyDescriptor(JSContext* cx, JS::Handle<JSObject*> proxy,
JS::Handle<jsid> id,
JS::MutableHandle<JSPropertyDescriptor> desc) const override;
virtual bool ownPropertyKeys(JSContext* cx, JS::Handle<JSObject*> proxy,
JS::AutoIdVector &props) const override;
virtual bool enumerate(JSContext *cx, JS::Handle<JSObject*> proxy,
JS::MutableHandle<JSObject*> objp) const override;
// We override getOwnEnumerablePropertyKeys() and implement it directly
// instead of using the default implementation, which would call
// ownPropertyKeys and then filter out the non-enumerable ones. This avoids
// unnecessary work during enumeration.
virtual bool getOwnEnumerablePropertyKeys(JSContext* cx, JS::Handle<JSObject*> proxy,
JS::AutoIdVector &props) const override;
bool watch(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
JS::Handle<JSObject*> callable) const override;
bool unwatch(JSContext* cx, JS::Handle<JSObject*> proxy,
JS::Handle<jsid> id) const override;
protected:
// Hook for subclasses to implement shared ownPropertyKeys()/keys()
// functionality. The "flags" argument is either JSITER_OWNONLY (for keys())
// or JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS (for
// ownPropertyKeys()).
virtual bool ownPropNames(JSContext* cx, JS::Handle<JSObject*> proxy,
unsigned flags,
JS::AutoIdVector& props) const = 0;
// Hook for subclasses to allow set() to ignore named props while other things
// that look at property descriptors see them. This is intentionally not
// named getOwnPropertyDescriptor to avoid subclasses that override it hiding
// our public getOwnPropertyDescriptor.
virtual bool getOwnPropDescriptor(JSContext* cx,
JS::Handle<JSObject*> proxy,
JS::Handle<jsid> id,
bool ignoreNamedProps,
JS::MutableHandle<JSPropertyDescriptor> desc) const = 0;
};
class DOMProxyHandler : public BaseDOMProxyHandler
{
public:
MOZ_CONSTEXPR DOMProxyHandler()
: BaseDOMProxyHandler(&family)
{}
bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
JS::Handle<JSPropertyDescriptor> desc,
JS::ObjectOpResult &result) const override
{
bool unused;
return defineProperty(cx, proxy, id, desc, result, &unused);
}
virtual bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
JS::Handle<JSPropertyDescriptor> desc,
JS::ObjectOpResult &result, bool *defined) const;
bool delete_(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
JS::ObjectOpResult &result) const override;
bool preventExtensions(JSContext* cx, JS::Handle<JSObject*> proxy,
JS::ObjectOpResult& result) const override;
bool isExtensible(JSContext *cx, JS::Handle<JSObject*> proxy, bool *extensible)
const override;
bool has(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
bool* bp) const override;
bool set(JSContext *cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
JS::Handle<JS::Value> v, JS::Handle<JS::Value> receiver, JS::ObjectOpResult &result)
const override;
/*
* If assigning to proxy[id] hits a named setter with OverrideBuiltins or
* an indexed setter, call it and set *done to true on success. Otherwise, set
* *done to false.
*/
virtual bool setCustom(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
JS::Handle<JS::Value> v, bool *done) const;
static JSObject* GetExpandoObject(JSObject* obj);
/* GetAndClearExpandoObject does not DROP or clear the preserving wrapper flag. */
static JSObject* GetAndClearExpandoObject(JSObject* obj);
static JSObject* EnsureExpandoObject(JSContext* cx,
JS::Handle<JSObject*> obj);
static const char family;
};
inline bool IsDOMProxy(JSObject *obj)
{
const js::Class* clasp = js::GetObjectClass(obj);
return clasp->isProxy() &&
js::GetProxyHandler(obj)->family() == &DOMProxyHandler::family;
}
inline const DOMProxyHandler*
GetDOMProxyHandler(JSObject* obj)
{
MOZ_ASSERT(IsDOMProxy(obj));
return static_cast<const DOMProxyHandler*>(js::GetProxyHandler(obj));
}
extern jsid s_length_id;
int32_t IdToInt32(JSContext* cx, JS::Handle<jsid> id);
// XXXbz this should really return uint32_t, with the maximum value
// meaning "not an index"...
inline int32_t
GetArrayIndexFromId(JSContext* cx, JS::Handle<jsid> id)
{
if (MOZ_LIKELY(JSID_IS_INT(id))) {
return JSID_TO_INT(id);
}
if (MOZ_LIKELY(id == s_length_id)) {
return -1;
}
if (MOZ_LIKELY(JSID_IS_ATOM(id))) {
JSAtom* atom = JSID_TO_ATOM(id);
char16_t s;
{
JS::AutoCheckCannotGC nogc;
if (js::AtomHasLatin1Chars(atom)) {
s = *js::GetLatin1AtomChars(nogc, atom);
} else {
s = *js::GetTwoByteAtomChars(nogc, atom);
}
}
if (MOZ_LIKELY((unsigned)s >= 'a' && (unsigned)s <= 'z'))
return -1;
uint32_t i;
JSLinearString* str = js::AtomToLinearString(JSID_TO_ATOM(id));
return js::StringIsArrayIndex(str, &i) ? i : -1;
}
return IdToInt32(cx, id);
}
inline bool
IsArrayIndex(int32_t index)
{
return index >= 0;
}
inline void
FillPropertyDescriptor(JS::MutableHandle<JSPropertyDescriptor> desc,
JSObject* obj, bool readonly, bool enumerable = true)
{
desc.object().set(obj);
desc.setAttributes((readonly ? JSPROP_READONLY : 0) |
(enumerable ? JSPROP_ENUMERATE : 0));
desc.setGetter(nullptr);
desc.setSetter(nullptr);
}
inline void
FillPropertyDescriptor(JS::MutableHandle<JSPropertyDescriptor> desc,
JSObject* obj, JS::Value v,
bool readonly, bool enumerable = true)
{
desc.value().set(v);
FillPropertyDescriptor(desc, obj, readonly, enumerable);
}
inline void
FillPropertyDescriptor(JS::MutableHandle<JSPropertyDescriptor> desc,
JSObject* obj, unsigned attributes, JS::Value v)
{
desc.object().set(obj);
desc.value().set(v);
desc.setAttributes(attributes);
desc.setGetter(nullptr);
desc.setSetter(nullptr);
}
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_DOMProxyHandler_h */