mirror of
https://github.com/mozilla/gecko-dev.git
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232 lines
8.3 KiB
C++
232 lines
8.3 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2005
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Mark Hammond <mhammond@skippinet.com.au>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef nsDOMScriptObjectHolder_h__
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#define nsDOMScriptObjectHolder_h__
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#include "nsIScriptRuntime.h"
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#include "nsIDOMScriptObjectFactory.h"
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class nsIScriptContext;
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// Drop a reference to a script object when all you have is the script
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// language ID.
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inline nsresult NS_DropScriptObject(PRUint32 aLangID, void *aThing)
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{
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nsresult rv;
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nsCOMPtr<nsIScriptRuntime> scriptRT;
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NS_DEFINE_CID(cid, NS_DOM_SCRIPT_OBJECT_FACTORY_CID);
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nsCOMPtr<nsIDOMScriptObjectFactory> factory = do_GetService(cid, &rv);
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if (NS_SUCCEEDED(rv))
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rv = factory->GetScriptRuntimeByID(aLangID, getter_AddRefs(scriptRT));
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if (NS_SUCCEEDED(rv))
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rv = scriptRT->DropScriptObject(aThing);
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if (NS_FAILED(rv))
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NS_ERROR("Failed to drop the script object");
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return rv;
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}
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// Hold a reference to a script object when all you have is the script
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// language ID, and you need to take a copy of the void script object.
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// Must be matched by an NS_DropScriptObject
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inline nsresult NS_HoldScriptObject(PRUint32 aLangID, void *aThing)
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{
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nsresult rv;
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nsCOMPtr<nsIScriptRuntime> scriptRT;
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NS_DEFINE_CID(cid, NS_DOM_SCRIPT_OBJECT_FACTORY_CID);
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nsCOMPtr<nsIDOMScriptObjectFactory> factory = do_GetService(cid, &rv);
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if (NS_SUCCEEDED(rv))
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rv = factory->GetScriptRuntimeByID(aLangID, getter_AddRefs(scriptRT));
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if (NS_SUCCEEDED(rv))
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rv = scriptRT->HoldScriptObject(aThing);
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if (NS_FAILED(rv))
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NS_ERROR("Failed to hold the script object");
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return rv;
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}
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// A thin class used to help with script object memory management. No virtual
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// functions and a fully inline implementation should keep the cost down.
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// [Note that a fully inline implementation is necessary for use by other
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// languages, which do not link against the layout component module]
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class nsScriptObjectHolder {
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public:
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// A constructor that will cause a reference to |ctx| to be stored in
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// the object. Only use for short-lived object holders.
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nsScriptObjectHolder(nsIScriptContext *ctx, void *aObject = nsnull) :
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mObject(aObject), mContextOrLangID(NS_REINTERPRET_CAST(PtrBits, ctx)) {
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NS_ASSERTION(ctx, "Must provide a valid context");
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NS_ADDREF(ctx);
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}
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// A constructor that stores only the integer language ID - freeing the
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// script object is slower in this case, but is safe for long-lived
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// object holders.
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nsScriptObjectHolder(PRUint32 aLangID, void *aObject = nsnull) :
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mObject(aObject),
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mContextOrLangID((aLangID << 1) | SOH_HAS_LANGID_BIT) {
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NS_ASSERTION(aLangID != nsIProgrammingLanguage::UNKNOWN,
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"Please supply a valid language ID");
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}
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// copy constructor
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nsScriptObjectHolder(const nsScriptObjectHolder& other) :
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mObject(other.mObject),
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mContextOrLangID(other.mContextOrLangID)
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{
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if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
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if (mObject) {
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NS_HoldScriptObject(getScriptTypeIDFromBits(), mObject);
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}
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} else {
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// New hold the script object and new reference on the script context.
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nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
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mContextOrLangID);
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NS_ASSERTION(ctx, "Lost context pointer?");
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NS_ADDREF(ctx);
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if (mObject)
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ctx->HoldScriptObject(mObject);
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}
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}
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~nsScriptObjectHolder() {
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// If we have a language ID, then we only need to NS_DropScriptObject if
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// we are holding a script object.
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// If we have a script context, we must always release our reference to it,
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// even if we are not holding a script object.
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if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
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if (mObject) {
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NS_DropScriptObject(getScriptTypeIDFromBits(), mObject);
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}
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} else {
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nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
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mContextOrLangID);
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NS_ASSERTION(ctx, "Lost context pointer?");
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if (mObject) {
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ctx->DropScriptObject(mObject);
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}
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NS_IF_RELEASE(ctx);
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}
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}
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// misc operators
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nsScriptObjectHolder &operator=(const nsScriptObjectHolder &other) {
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set(other);
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return *this;
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}
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PRBool operator!() const {
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return !mObject;
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}
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operator void *() const {
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return mObject;
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}
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// Drop the script object - but *not* the nsIScriptContext nor the language
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// ID.
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nsresult drop() {
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nsresult rv = NS_OK;
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if (mObject) {
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if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
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rv = NS_DropScriptObject(getScriptTypeIDFromBits(), mObject);
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} else {
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nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
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mContextOrLangID);
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NS_ASSERTION(ctx, "Lost ctx pointer!");
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rv = ctx->DropScriptObject(mObject);
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}
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mObject = nsnull;
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}
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return rv;
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}
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nsresult set(void *object) {
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NS_ASSERTION(getScriptTypeID() != nsIProgrammingLanguage::UNKNOWN,
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"Must know the language!");
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nsresult rv = drop();
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if (NS_FAILED(rv))
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return rv;
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if (object) {
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if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
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rv = NS_HoldScriptObject(getScriptTypeIDFromBits(), object);
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} else {
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nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
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mContextOrLangID);
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rv = ctx->HoldScriptObject(object);
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}
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// don't store the pointer if we failed to lock it.
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if (NS_SUCCEEDED(rv)) {
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mObject = object;
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}
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}
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return rv;
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}
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nsresult set(const nsScriptObjectHolder &other) {
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NS_ASSERTION(getScriptTypeID() == other.getScriptTypeID(),
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"Must have identical languages!");
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nsresult rv = drop();
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if (NS_FAILED(rv))
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return rv;
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return set(other.mObject);
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}
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// Get the language ID.
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PRUint32 getScriptTypeID() const {
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if (mContextOrLangID & SOH_HAS_LANGID_BIT) {
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return getScriptTypeIDFromBits();
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}
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nsIScriptContext *ctx = NS_REINTERPRET_CAST(nsIScriptContext *,
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mContextOrLangID);
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NS_ASSERTION(ctx, "How did I lose my pointer?");
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return ctx->GetScriptTypeID();
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}
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protected:
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PRUint32 getScriptTypeIDFromBits() const {
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NS_ASSERTION(mContextOrLangID & SOH_HAS_LANGID_BIT, "Not in the bits!");
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return (mContextOrLangID & ~SOH_HAS_LANGID_BIT) >> 1;
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}
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void *mObject;
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// We store either an nsIScriptContext* if this bit is clear,
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// else the language ID (specifically, ((lang_id << 1) | SOH_HAS_LANGID_BIT)
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// when set.
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typedef PRWord PtrBits;
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enum { SOH_HAS_LANGID_BIT = 0x1 };
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PtrBits mContextOrLangID;
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};
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#endif // nsDOMScriptObjectHolder_h__
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