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/* Copyright (C) 2021 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_SCRIPTREQUEST
#define INCLUDED_SCRIPTREQUEST
#include "scriptinterface/ScriptForward.h"
// Ignore warnings in SM headers.
#if GCC_VERSION || CLANG_VERSION
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wunused-parameter"
# pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
#elif MSC_VERSION
# pragma warning(push, 1)
#endif
#include "js/RootingAPI.h"
#if GCC_VERSION || CLANG_VERSION
# pragma GCC diagnostic pop
#elif MSC_VERSION
# pragma warning(pop)
#endif
#include <memory>
class ScriptInterface;
/**
* Spidermonkey maintains some 'local' state via the JSContext* object.
* This object is an argument to most JSAPI functions.
* Furthermore, this state is Realm (~ global) dependent. For many reasons, including GC safety,
* The JSContext* Realm must be set up correctly when accessing it.
* 'Entering' and 'Leaving' realms must be done in a LIFO manner.
* SM recommends using JSAutoRealm, which provides an RAII option.
*
* ScriptRequest combines both of the above in a single convenient package,
* providing safe access to the JSContext*, the global object, and ensuring that the proper realm has been entered.
* Most scriptinterface/ functions will take a ScriptRequest, to ensure proper rooting. You may sometimes
* have to create one from a ScriptInterface.
*
* Be particularly careful when manipulating several script interfaces.
*/
class ScriptRequest
{
ScriptRequest() = delete;
ScriptRequest(const ScriptRequest& rq) = delete;
ScriptRequest& operator=(const ScriptRequest& rq) = delete;
public:
/**
* NB: the definitions are in scriptinterface.cpp, because these access members of the PImpled
* implementation of ScriptInterface, and that seemed more convenient.
*/
ScriptRequest(const ScriptInterface& scriptInterface);
ScriptRequest(const ScriptInterface* scriptInterface) : ScriptRequest(*scriptInterface) {}
ScriptRequest(std::shared_ptr<ScriptInterface> scriptInterface) : ScriptRequest(*scriptInterface) {}
~ScriptRequest();
/**
* Create a script request from a JSContext.
* This can be used to get the script interface in a JSNative function.
* In general, you shouldn't have to rely on this otherwise.
*/
ScriptRequest(JSContext* cx);
/**
* Return the scriptInterface active when creating this ScriptRequest.
* Note that this is multi-request safe: even if another ScriptRequest is created,
* it will point to the original scriptInterface, and thus can be used to re-enter the realm.
*/
const ScriptInterface& GetScriptInterface() const;
JS::Value globalValue() const;
// Note that JSContext actually changes behind the scenes when creating another ScriptRequest for another realm,
// so be _very_ careful when juggling between different realms.
JSContext* cx;
JS::HandleObject glob;
JS::HandleObject nativeScope;
private:
const ScriptInterface& m_ScriptInterface;
JS::Realm* m_FormerRealm;
};
#endif // INCLUDED_SCRIPTREQUEST
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