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91 lines
2.2 KiB
91 lines
2.2 KiB
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <cstddef>
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#include <jni.h>
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#include "nativehelper_utils.h"
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// A smart pointer that deletes a JNI local reference when it goes out of scope.
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template<typename T>
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class ScopedLocalRef {
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public:
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ScopedLocalRef(JNIEnv* env, T localRef) : mEnv(env), mLocalRef(localRef) {
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}
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ScopedLocalRef(ScopedLocalRef&& s) noexcept : mEnv(s.mEnv), mLocalRef(s.release()) {
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}
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explicit ScopedLocalRef(JNIEnv* env) : mEnv(env), mLocalRef(nullptr) {
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}
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~ScopedLocalRef() {
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reset();
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}
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void reset(T ptr = nullptr) {
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if (ptr != mLocalRef) {
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if (mLocalRef != nullptr) {
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mEnv->DeleteLocalRef(mLocalRef);
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}
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mLocalRef = ptr;
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}
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}
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T release() __attribute__((warn_unused_result)) {
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T localRef = mLocalRef;
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mLocalRef = nullptr;
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return localRef;
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}
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T get() const {
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return mLocalRef;
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}
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// We do not expose an empty constructor as it can easily lead to errors
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// using common idioms, e.g.:
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// ScopedLocalRef<...> ref;
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// ref.reset(...);
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// Move assignment operator.
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ScopedLocalRef& operator=(ScopedLocalRef&& s) noexcept {
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reset(s.release());
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mEnv = s.mEnv;
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return *this;
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}
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// Allows "if (scoped_ref == nullptr)"
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bool operator==(std::nullptr_t) const {
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return mLocalRef == nullptr;
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}
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// Allows "if (scoped_ref != nullptr)"
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bool operator!=(std::nullptr_t) const {
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return mLocalRef != nullptr;
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}
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private:
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JNIEnv* mEnv;
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T mLocalRef;
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DISALLOW_COPY_AND_ASSIGN(ScopedLocalRef);
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};
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