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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Derived from
// https://cs.android.com/android/platform/superproject/+/android-11.0.0_r1:libnativehelper/header_only_include/nativehelper/scoped_local_ref.h
#ifndef LIBNATIVEHELPER_HEADER_ONLY_INCLUDE_NATIVEHELPER_SCOPED_LOCAL_REF_H_
#define LIBNATIVEHELPER_HEADER_ONLY_INCLUDE_NATIVEHELPER_SCOPED_LOCAL_REF_H_
#include <android-base/macros.h>
#include <cstddef>
#include "jni.h"
// #include "nativehelper_utils.h"
// A smart pointer that deletes a JNI local reference when it goes out of scope.
template <typename T>
class ScopedLocalRef {
public:
ScopedLocalRef(JNIEnv* env, T localRef) : mEnv(env), mLocalRef(localRef) {}
ScopedLocalRef(ScopedLocalRef&& s) noexcept
: mEnv(s.mEnv), mLocalRef(s.release()) {}
explicit ScopedLocalRef(JNIEnv* env) : mEnv(env), mLocalRef(nullptr) {}
~ScopedLocalRef() { reset(); }
void reset(T ptr = NULL) {
if (ptr != mLocalRef) {
if (mLocalRef != NULL) {
mEnv->DeleteLocalRef(mLocalRef);
}
mLocalRef = ptr;
}
}
T release() __attribute__((warn_unused_result)) {
T localRef = mLocalRef;
mLocalRef = NULL;
return localRef;
}
T get() const { return mLocalRef; }
// We do not expose an empty constructor as it can easily lead to errors
// using common idioms, e.g.:
// ScopedLocalRef<...> ref;
// ref.reset(...);
// Move assignment operator.
ScopedLocalRef& operator=(ScopedLocalRef&& s) noexcept {
reset(s.release());
mEnv = s.mEnv;
return *this;
}
// Allows "if (scoped_ref == nullptr)"
bool operator==(std::nullptr_t) const { return mLocalRef == nullptr; }
// Allows "if (scoped_ref != nullptr)"
bool operator!=(std::nullptr_t) const { return mLocalRef != nullptr; }
private:
JNIEnv* mEnv;
T mLocalRef;
DISALLOW_COPY_AND_ASSIGN(ScopedLocalRef);
};
#endif // LIBNATIVEHELPER_HEADER_ONLY_INCLUDE_NATIVEHELPER_SCOPED_LOCAL_REF_H_
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