gecko-dev/dom/base/MozQueryInterface.cpp

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3.7 KiB
C++
Исходник Обычный вид История

/* -*- 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/. */
#include "ChromeUtils.h"
#include "MozQueryInterface.h"
#include <string.h>
#include "jsapi.h"
#include "xpcpublic.h"
#include "xpcjsid.h"
namespace mozilla {
namespace dom {
constexpr size_t IID_SIZE = sizeof(nsIID);
static_assert(IID_SIZE == 16,
"Size of nsID struct changed. Please ensure this code is still valid.");
static int
CompareIIDs(const nsIID& aA, const nsIID &aB)
{
return memcmp((void*)&aA.m0, (void*)&aB.m0, IID_SIZE);
}
struct IIDComparator
{
bool
LessThan(const nsIID& aA, const nsIID &aB) const
{
return CompareIIDs(aA, aB) < 0;
}
bool
Equals(const nsIID& aA, const nsIID &aB) const
{
return aA.Equals(aB);
}
};
/* static */
MozQueryInterface*
ChromeUtils::GenerateQI(const GlobalObject& aGlobal, const Sequence<OwningStringOrIID>& aInterfaces, ErrorResult& aRv)
{
JSContext* cx = aGlobal.Context();
JS::RootedObject xpcIfaces(cx);
nsTArray<nsIID> ifaces;
JS::RootedValue val(cx);
for (auto& iface : aInterfaces) {
if (iface.IsIID()) {
ifaces.AppendElement(*iface.GetAsIID()->GetID());
continue;
}
// If we have a string value, we need to look up the interface name. The
// simplest and most efficient way to do this is to just grab the "Ci"
// object from the global scope.
if (!xpcIfaces) {
JS::RootedObject global(cx, aGlobal.Get());
if (!JS_GetProperty(cx, global, "Ci", &val)) {
aRv.NoteJSContextException(cx);
return nullptr;
}
if (!val.isObject()) {
aRv.Throw(NS_ERROR_UNEXPECTED);
return nullptr;
}
xpcIfaces = &val.toObject();
}
auto& name = iface.GetAsString();
if (!JS_GetUCProperty(cx, xpcIfaces, name.get(), name.Length(), &val)) {
aRv.NoteJSContextException(cx);
return nullptr;
}
if (val.isNullOrUndefined()) {
continue;
}
if (!val.isObject()) {
aRv.Throw(NS_ERROR_INVALID_ARG);
return nullptr;
}
nsCOMPtr<nsISupports> base = xpc::UnwrapReflectorToISupports(&val.toObject());
nsCOMPtr<nsIJSID> iid = do_QueryInterface(base);
if (!iid) {
aRv.Throw(NS_ERROR_INVALID_ARG);
return nullptr;
}
ifaces.AppendElement(*iid->GetID());
}
MOZ_ASSERT(!ifaces.Contains(NS_GET_IID(nsISupports), IIDComparator()));
ifaces.AppendElement(NS_GET_IID(nsISupports));
ifaces.Sort(IIDComparator());
return new MozQueryInterface(Move(ifaces));
}
bool
MozQueryInterface::QueriesTo(const nsIID& aIID) const
{
// We use BinarySearchIf here because nsTArray::ContainsSorted requires
// twice as many comparisons.
size_t result;
return BinarySearchIf(mInterfaces, 0, mInterfaces.Length(),
[&] (const nsIID& aOther) { return CompareIIDs(aIID, aOther); },
&result);
}
void
MozQueryInterface::LegacyCall(JSContext* cx, JS::Handle<JS::Value> thisv,
nsIJSID* aIID,
JS::MutableHandle<JS::Value> aResult,
ErrorResult& aRv) const
{
if (!QueriesTo(*aIID->GetID())) {
aRv.Throw(NS_ERROR_NO_INTERFACE);
} else {
aResult.set(thisv);
}
}
bool
MozQueryInterface::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto, JS::MutableHandle<JSObject*> aReflector)
{
return MozQueryInterfaceBinding::Wrap(aCx, this, aGivenProto, aReflector);
}
} // namespace dom
} // namespace mozilla