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94 lines
2.5 KiB
C++
94 lines
2.5 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsDOMScriptObjectHolder_h__
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#define nsDOMScriptObjectHolder_h__
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#include "nsIScriptContext.h"
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#include "nsIDOMScriptObjectFactory.h"
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#include "jspubtd.h"
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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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template<class T>
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class NS_STACK_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<T>(nsIScriptContext *ctx, T* aObject = nullptr) :
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mObject(aObject), mContext(ctx) {
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NS_ASSERTION(ctx, "Must provide a valid context");
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}
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// copy constructor
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nsScriptObjectHolder<T>(const nsScriptObjectHolder<T>& other) :
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mObject(other.mObject),
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mContext(other.mContext)
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{
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// New hold the script object and new reference on the script context.
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if (mObject)
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mContext->HoldScriptObject(mObject);
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}
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~nsScriptObjectHolder<T>() {
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if (mObject)
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mContext->DropScriptObject(mObject);
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}
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// misc operators
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nsScriptObjectHolder<T> &operator=(const nsScriptObjectHolder<T> &other) {
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set(other);
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return *this;
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}
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bool operator!() const {
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return !mObject;
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}
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operator bool() const {
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return !!mObject;
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}
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T* get() const {
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return mObject;
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}
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// Drop the script object - but *not* the nsIScriptContext.
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nsresult drop() {
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nsresult rv = NS_OK;
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if (mObject) {
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rv = mContext->DropScriptObject(mObject);
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mObject = nullptr;
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}
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return rv;
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}
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nsresult set(T* object) {
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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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rv = mContext->HoldScriptObject(object);
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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<T> &other) {
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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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protected:
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T* mObject;
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nsCOMPtr<nsIScriptContext> mContext;
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};
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#endif // nsDOMScriptObjectHolder_h__
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