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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef SCOPEDLOCALREF_H_
     18 #define SCOPEDLOCALREF_H_
     19 
     20 #include <conscrypt/macros.h>
     21 #include <jni.h>
     22 
     23 #include <stddef.h>
     24 
     25 // A smart pointer that deletes a JNI local reference when it goes out of scope.
     26 template <typename T>
     27 class ScopedLocalRef {
     28 public:
     29     ScopedLocalRef(JNIEnv* env, T localRef) : mEnv(env), mLocalRef(localRef) {}
     30 
     31     ~ScopedLocalRef() {
     32         reset();
     33     }
     34 
     35     void reset(T ptr = nullptr) {
     36         if (ptr != mLocalRef) {
     37             if (mLocalRef != nullptr) {
     38                 mEnv->DeleteLocalRef(mLocalRef);
     39             }
     40             mLocalRef = ptr;
     41         }
     42     }
     43 
     44     CONSCRYPT_WARN_UNUSED
     45     T release() {
     46         T localRef = mLocalRef;
     47         mLocalRef = nullptr;
     48         return localRef;
     49     }
     50 
     51     T get() const {
     52         return mLocalRef;
     53     }
     54 
     55 private:
     56     JNIEnv* mEnv;
     57     T mLocalRef;
     58 
     59     // Disallow copy and assignment.
     60     ScopedLocalRef(const ScopedLocalRef&);
     61     void operator=(const ScopedLocalRef&);
     62 };
     63 
     64 #endif  // SCOPEDLOCALREF_H_
     65