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