mirror of https://github.com/axmolengine/axmol.git
41 lines
1.6 KiB
C++
41 lines
1.6 KiB
C++
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#pragma once
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#include <jni/class.hpp>
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#include <jni/object.hpp>
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namespace jni
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{
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struct WeakReferenceTag { static constexpr auto Name() { return "java/lang/ref/WeakReference"; } };
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// Wraps a JNI global reference to a java.lang.ref.WeakReference, producing an ownership class
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// similar to jni::Weak<T> (JNI's weak global reference), but with more reliable promotion semantics.
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// Whereas a JNI weak global reference may still be promoted to a strong reference even during
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// finalization, leading to potential use-after-free errors, a WeakReference cannot.
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template < class T, template < RefDeletionMethod > class Deleter = DefaultRefDeleter >
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class WeakReference
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{
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private:
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Global<Object<WeakReferenceTag>, Deleter> reference;
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public:
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WeakReference(JNIEnv& env, const T& referent)
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{
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static auto& klass = Class<WeakReferenceTag>::Singleton(env);
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static auto constructor = klass.GetConstructor<Object<>>(env);
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reference = NewGlobal<Deleter>(env, klass.New(env, constructor, referent));
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}
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Local<T> get(JNIEnv& env)
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{
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if (!reference)
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{
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return Local<T>();
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}
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static auto& klass = Class<WeakReferenceTag>::Singleton(env);
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static auto get = klass.template GetMethod<Object<> ()>(env, "get");
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return Local<T>(env, reinterpret_cast<typename T::UntaggedType*>(reference.Call(env, get).release()));
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}
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};
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}
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