gecko-dev/js/jetpack/Handle.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sw=4 et tw=80:
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* The Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Ben Newman <mozilla@benjamn.com> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef mozilla_jetpack_HandleParent_h
#define mozilla_jetpack_HandleParent_h
#include "mozilla/jetpack/PHandleParent.h"
#include "mozilla/jetpack/PHandleChild.h"
#include "jsapi.h"
#include "jsobj.h"
#include "jscntxt.h"
#include "mozilla/unused.h"
namespace mozilla {
namespace jetpack {
/**
* BaseType should be one of PHandleParent or PHandleChild; see the
* HandleParent and HandleChild typedefs at the bottom of this file.
*/
template <class BaseType>
class Handle
: public BaseType
{
Handle(Handle* parent)
: mParent(parent)
, mObj(NULL)
, mCx(NULL)
, mRooted(false)
{}
BaseType* AllocPHandle() {
return new Handle(this);
}
bool DeallocPHandle(BaseType* actor) {
delete actor;
return true;
}
public:
Handle()
: mParent(NULL)
, mObj(NULL)
, mCx(NULL)
, mRooted(false)
{}
~Handle() { TearDown(); }
static Handle* FromJSObject(JSContext* cx, JSObject* obj) {
// TODO Convert non-Handles to Handles somehow?
return Unwrap(cx, obj);
}
static Handle* FromJSVal(JSContext* cx, jsval val) {
if (!JSVAL_IS_OBJECT(val))
return NULL;
return Unwrap(cx, JSVAL_TO_OBJECT(val));
}
void Root() {
NS_ASSERTION(mObj && mCx, "Rooting with no object unexpected.");
if (mRooted)
return;
if (!JS_AddNamedObjectRoot(mCx, &mObj, "Jetpack Handle")) {
NS_RUNTIMEABORT("Failed to add root.");
}
mRooted = true;
}
void Unroot() {
NS_ASSERTION(mCx, "Unrooting with no JSContext unexpected.");
if (!mRooted)
return;
JS_RemoveObjectRoot(mCx, &mObj);
mRooted = false;
}
JSObject* ToJSObject(JSContext* cx) {
if (!mObj && !mCx) {
JSAutoRequest request(cx);
JSClass* clasp = const_cast<JSClass*>(&sHandle_JSClass);
JSObject* obj = JS_NewObject(cx, clasp, NULL, NULL);
if (!obj)
return NULL;
js::AutoObjectRooter root(cx, obj);
JSPropertySpec* ps = const_cast<JSPropertySpec*>(sHandle_Properties);
JSFunctionSpec* fs = const_cast<JSFunctionSpec*>(sHandle_Functions);
if (JS_SetPrivate(cx, obj, (void*)this) &&
JS_DefineProperties(cx, obj, ps) &&
JS_DefineFunctions(cx, obj, fs)) {
mObj = obj;
mCx = cx;
Root();
}
}
return mObj;
}
protected:
void ActorDestroy(typename Handle::ActorDestroyReason why) {
TearDown();
}
private:
static bool IsParent(const PHandleParent* handle) { return true; }
static bool IsParent(const PHandleChild* handle) { return false; }
void TearDown() {
if (mCx) {
JSAutoRequest ar(mCx);
if (mObj) {
mObj->setPrivate(NULL);
js::AutoObjectRooter obj(mCx, mObj);
mObj = NULL;
JSBool hasOnInvalidate;
if (JS_HasProperty(mCx, obj.object(), "onInvalidate",
&hasOnInvalidate) && hasOnInvalidate) {
js::AutoValueRooter r(mCx);
JSBool ok = JS_CallFunctionName(mCx, obj.object(), "onInvalidate", 0,
NULL, r.jsval_addr());
if (!ok)
JS_ReportPendingException(mCx);
}
// By not nulling out mContext, we prevent ToJSObject from
// reviving an invalidated/destroyed handle.
}
// Nulling out mObj effectively unroots the object, but we still
// need to remove the root, else the JS engine will complain at
// shutdown.
Unroot();
}
}
static const JSClass sHandle_JSClass;
static const JSPropertySpec sHandle_Properties[];
static const JSFunctionSpec sHandle_Functions[];
Handle* const mParent;
// Used to cache the JSObject returned by ToJSObject, which is
// otherwise a const method.
JSObject* mObj;
JSContext* mCx;
bool mRooted;
static Handle*
Unwrap(JSContext* cx, JSObject* obj) {
while (obj && obj->getJSClass() != &sHandle_JSClass)
obj = obj->getProto();
if (!obj)
return NULL;
Handle* self = static_cast<Handle*>(JS_GetPrivate(cx, obj));
NS_ASSERTION(!self || self->ToJSObject(cx) == obj,
"Wrapper and wrapped object disagree?");
return self;
}
static JSBool
GetParent(JSContext* cx, JSObject* obj, jsid, jsval* vp) {
JS_SET_RVAL(cx, vp, JSVAL_NULL);
Handle* self = Unwrap(cx, obj);
if (!self)
return JS_TRUE;
Handle* parent = self->mParent;
if (!parent)
return JS_TRUE;
JSObject* pobj = parent->ToJSObject(cx);
JS_SET_RVAL(cx, vp, OBJECT_TO_JSVAL(pobj));
return JS_TRUE;
}
static JSBool
GetIsValid(JSContext* cx, JSObject* obj, jsid, jsval* vp) {
Handle* self = Unwrap(cx, obj);
JS_SET_RVAL(cx, vp, BOOLEAN_TO_JSVAL(!!self));
return JS_TRUE;
}
static JSBool
GetIsRooted(JSContext* cx, JSObject* obj, jsid, jsval* vp) {
Handle* self = Unwrap(cx, obj);
bool rooted = self ? self->mRooted : false;
JS_SET_RVAL(cx, vp, BOOLEAN_TO_JSVAL(rooted));
return JS_TRUE;
}
static JSBool
SetIsRooted(JSContext* cx, JSObject* obj, jsid, jsval* vp) {
Handle* self = Unwrap(cx, obj);
JSBool v;
if (!JS_ValueToBoolean(cx, *vp, &v))
return JS_FALSE;
if (!self) {
if (v) {
JS_ReportError(cx, "Cannot root invalidated handle.");
return JS_FALSE;
}
return JS_TRUE;
}
if (v)
self->Root();
else
self->Unroot();
*vp = BOOLEAN_TO_JSVAL(v);
return JS_TRUE;
}
static JSBool
Invalidate(JSContext* cx, uintN argc, jsval* vp) {
if (argc > 0) {
JS_ReportError(cx, "invalidate takes zero arguments");
return JS_FALSE;
}
Handle* self = Unwrap(cx, JS_THIS_OBJECT(cx, vp));
if (self)
unused << BaseType::Send__delete__(self);
JS_SET_RVAL(cx, vp, JSVAL_VOID);
return JS_TRUE;
}
static JSBool
CreateHandle(JSContext* cx, uintN argc, jsval* vp) {
if (argc > 0) {
JS_ReportError(cx, "createHandle takes zero arguments");
return JS_FALSE;
}
Handle* self = Unwrap(cx, JS_THIS_OBJECT(cx, vp));
if (!self) {
JS_ReportError(cx, "Tried to create child from invalid handle");
return JS_FALSE;
}
BaseType* child = self->SendPHandleConstructor();
if (!child) {
JS_ReportError(cx, "Failed to construct child");
return JS_FALSE;
}
JSObject* obj = static_cast<Handle*>(child)->ToJSObject(cx);
JS_SET_RVAL(cx, vp, OBJECT_TO_JSVAL(obj));
return JS_TRUE;
}
static void
Finalize(JSContext* cx, JSObject* obj) {
Handle* self = Unwrap(cx, obj);
if (self) {
NS_ASSERTION(!self->mRooted, "Finalizing a rooted object?");
self->mCx = NULL;
self->mObj = NULL;
unused << BaseType::Send__delete__(self);
}
}
};
template <class BaseType>
const JSClass
Handle<BaseType>::sHandle_JSClass = {
"IPDL Handle", JSCLASS_HAS_PRIVATE,
JS_PropertyStub, JS_PropertyStub,
JS_PropertyStub, JS_PropertyStub,
JS_EnumerateStub, JS_ResolveStub,
JS_ConvertStub, Handle::Finalize,
JSCLASS_NO_OPTIONAL_MEMBERS
};
#define HANDLE_PROP_FLAGS (JSPROP_PERMANENT | JSPROP_SHARED)
template <class BaseType>
const JSPropertySpec
Handle<BaseType>::sHandle_Properties[] = {
{ "parent", 0, HANDLE_PROP_FLAGS | JSPROP_READONLY, GetParent, NULL },
{ "isValid", 0, HANDLE_PROP_FLAGS | JSPROP_READONLY, GetIsValid, NULL },
{ "isRooted", 0, HANDLE_PROP_FLAGS, GetIsRooted, SetIsRooted },
{ 0, 0, 0, NULL, NULL }
};
#undef HANDLE_PROP_FLAGS
#define HANDLE_FUN_FLAGS (JSPROP_READONLY | \
JSPROP_PERMANENT)
template <class BaseType>
const JSFunctionSpec
Handle<BaseType>::sHandle_Functions[] = {
JS_FN("invalidate", Invalidate, 0, HANDLE_FUN_FLAGS),
JS_FN("createHandle", CreateHandle, 0, HANDLE_FUN_FLAGS),
JS_FS_END
};
#undef HANDLE_FUN_FLAGS
// The payoff for using templates is that these two implementations are
// guaranteed to be perfectly symmetric:
typedef Handle<PHandleParent> HandleParent;
typedef Handle<PHandleChild> HandleChild;
} // namespace jetpack
} // namespace mozilla
#endif