gecko-dev/dom/public/nsDOMScriptObjectHolder.h
2006-06-13 03:07:47 +00:00

232 lines
8.3 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** 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
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Mark Hammond <mhammond@skippinet.com.au>
*
* 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 nsDOMScriptObjectHolder_h__
#define nsDOMScriptObjectHolder_h__
#include "nsIScriptRuntime.h"
#include "nsIDOMScriptObjectFactory.h"
class nsIScriptContext;
// Drop a reference to a script object when all you have is the script
// language ID.
inline nsresult NS_DropScriptObject(PRUint32 aLangID, void *aThing)
{
nsresult rv;
nsCOMPtr<nsIScriptRuntime> scriptRT;
NS_DEFINE_CID(cid, NS_DOM_SCRIPT_OBJECT_FACTORY_CID);
nsCOMPtr<nsIDOMScriptObjectFactory> factory = do_GetService(cid, &rv);
if (NS_SUCCEEDED(rv))
rv = factory->GetScriptRuntimeByID(aLangID, getter_AddRefs(scriptRT));
if (NS_SUCCEEDED(rv))
rv = scriptRT->DropScriptObject(aThing);
if (NS_FAILED(rv))
NS_ERROR("Failed to drop the script object");
return rv;
}
// Hold a reference to a script object when all you have is the script
// language ID, and you need to take a copy of the void script object.
// Must be matched by an NS_DropScriptObject
inline nsresult NS_HoldScriptObject(PRUint32 aLangID, void *aThing)
{
nsresult rv;
nsCOMPtr<nsIScriptRuntime> scriptRT;
NS_DEFINE_CID(cid, NS_DOM_SCRIPT_OBJECT_FACTORY_CID);
nsCOMPtr<nsIDOMScriptObjectFactory> factory = do_GetService(cid, &rv);
if (NS_SUCCEEDED(rv))
rv = factory->GetScriptRuntimeByID(aLangID, getter_AddRefs(scriptRT));
if (NS_SUCCEEDED(rv))
rv = scriptRT->HoldScriptObject(aThing);
if (NS_FAILED(rv))
NS_ERROR("Failed to hold the script object");
return rv;
}
// A thin class used to help with script object memory management. No virtual
// functions and a fully inline implementation should keep the cost down.
// [Note that a fully inline implementation is necessary for use by other
// languages, which do not link against the layout component module]
class nsScriptObjectHolder {
public:
// A constructor that will cause a reference to |ctx| to be stored in
// the object. Only use for short-lived object holders.
nsScriptObjectHolder(nsIScriptContext *ctx, void *aObject = nsnull) :
mObject(aObject), mContextOrLangID(NS_REINTERPRET_CAST(PtrBits, ctx)) {
NS_ASSERTION(ctx, "Must provide a valid context");
NS_ADDREF(ctx);
}
// A constructor that stores only the integer language ID - freeing the
// script object is slower in this case, but is safe for long-lived
// object holders.
nsScriptObjectHolder(PRUint32 aLangID, void *aObject = nsnull) :
mObject(aObject),
mContextOrLangID((aLangID << 1) | SOH_HAS_LANGID_BIT) {
NS_ASSERTION(aLangID != nsIProgrammingLanguage::UNKNOWN,
"Please supply a valid language ID");
}
// copy constructor
nsScriptObjectHolder(const nsScriptObjectHolder& other) :
mObject(other.mObject),
mContextOrLangID(other.mContextOrLangID)
{
if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
if (mObject) {
NS_HoldScriptObject(getScriptTypeIDFromBits(), mObject);
}
} else {
// New hold the script object and new reference on the script context.
nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
mContextOrLangID);
NS_ASSERTION(ctx, "Lost context pointer?");
NS_ADDREF(ctx);
if (mObject)
ctx->HoldScriptObject(mObject);
}
}
~nsScriptObjectHolder() {
// If we have a language ID, then we only need to NS_DropScriptObject if
// we are holding a script object.
// If we have a script context, we must always release our reference to it,
// even if we are not holding a script object.
if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
if (mObject) {
NS_DropScriptObject(getScriptTypeIDFromBits(), mObject);
}
} else {
nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
mContextOrLangID);
NS_ASSERTION(ctx, "Lost context pointer?");
if (mObject) {
ctx->DropScriptObject(mObject);
}
NS_IF_RELEASE(ctx);
}
}
// misc operators
nsScriptObjectHolder &operator=(const nsScriptObjectHolder &other) {
set(other);
return *this;
}
PRBool operator!() const {
return !mObject;
}
operator void *() const {
return mObject;
}
// Drop the script object - but *not* the nsIScriptContext nor the language
// ID.
nsresult drop() {
nsresult rv = NS_OK;
if (mObject) {
if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
rv = NS_DropScriptObject(getScriptTypeIDFromBits(), mObject);
} else {
nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
mContextOrLangID);
NS_ASSERTION(ctx, "Lost ctx pointer!");
rv = ctx->DropScriptObject(mObject);
}
mObject = nsnull;
}
return rv;
}
nsresult set(void *object) {
NS_ASSERTION(getScriptTypeID() != nsIProgrammingLanguage::UNKNOWN,
"Must know the language!");
nsresult rv = drop();
if (NS_FAILED(rv))
return rv;
if (object) {
if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
rv = NS_HoldScriptObject(getScriptTypeIDFromBits(), object);
} else {
nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
mContextOrLangID);
rv = ctx->HoldScriptObject(object);
}
// don't store the pointer if we failed to lock it.
if (NS_SUCCEEDED(rv)) {
mObject = object;
}
}
return rv;
}
nsresult set(const nsScriptObjectHolder &other) {
NS_ASSERTION(getScriptTypeID() == other.getScriptTypeID(),
"Must have identical languages!");
nsresult rv = drop();
if (NS_FAILED(rv))
return rv;
return set(other.mObject);
}
// Get the language ID.
PRUint32 getScriptTypeID() const {
if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
return getScriptTypeIDFromBits();
}
nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
mContextOrLangID);
NS_ASSERTION(ctx, "How did I lose my pointer?");
return ctx->GetScriptTypeID();
}
protected:
PRUint32 getScriptTypeIDFromBits() const {
NS_ASSERTION(mContextOrLangID & SOH_HAS_LANGID_BIT, "Not in the bits!");
return (mContextOrLangID & ~SOH_HAS_LANGID_BIT) >> 1;
}
void *mObject;
// We store either an nsIScriptContext* if this bit is clear,
// else the language ID (specifically, ((lang_id << 1) | SOH_HAS_LANGID_BIT)
// when set.
typedef PRWord PtrBits;
enum { SOH_HAS_LANGID_BIT = 0x1 };
PtrBits mContextOrLangID;
};
#endif // nsDOMScriptObjectHolder_h__