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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef js_public_ObjectWithStashedPointer_h
#define js_public_ObjectWithStashedPointer_h
#include "jstypes.h" // JS_PUBLIC_API
#include "js/RootingAPI.h" // JS::Handle
struct JS_PUBLIC_API JSContext;
class JS_PUBLIC_API JSObject;
namespace JS {
namespace detail {
using UntypedFreeFunction = void (*)(void*);
extern JS_PUBLIC_API JSObject* NewObjectWithUntypedStashedPointer(
JSContext* cx, void* ptr, UntypedFreeFunction freeFunc);
extern JS_PUBLIC_API void* ObjectGetUntypedStashedPointer(JSContext* cx,
JSObject* obj);
} // namespace detail
/**
* Convenience function for creating a JS object that has an embedder C++
* pointer stashed in it. The JS object assumes ownership of the pointer. When
* the JS object is finalized, freeFunc will be called on the pointer to free
* it.
*
* The pointer is not known to the garbage collector, and not traced. If it
* points to a GC thing, the embedder is responsible for tracing it manually.
*
* freeFunc must not call any JSAPI functions that could cause a garbage
* collection.
*/
template <typename T, typename F>
inline JSObject* NewObjectWithStashedPointer(JSContext* cx, T* ptr,
F freeFunc) {
using FreeFunction = void (*)(T*);
static_assert(std::is_convertible_v<F, FreeFunction>,
"free function is not of a compatible type");
return detail::NewObjectWithUntypedStashedPointer(
cx, ptr,
reinterpret_cast<detail::UntypedFreeFunction>(
static_cast<FreeFunction>(freeFunc)));
}
/**
* As above, but without a free function for the pointer.
*/
template <typename T>
inline JSObject* NewObjectWithStashedPointer(JSContext* cx, T* ptr) {
return detail::NewObjectWithUntypedStashedPointer(cx, ptr, nullptr);
}
/**
* Retrieve the stashed pointer from an object created using
* NewObjectWithStashedPointer().
*/
template <typename T>
inline T* ObjectGetStashedPointer(JSContext* cx, JSObject* obj) {
return static_cast<T*>(detail::ObjectGetUntypedStashedPointer(cx, obj));
}
} // namespace JS
#endif // js_public_ObjectWithStashedPointer_h
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