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 SCOPED_LOCAL_REF_H_included
18#define SCOPED_LOCAL_REF_H_included
19
20#include "jni.h"
21
22#include <stddef.h>
23#include "JNIHelp.h"  // for DISALLOW_COPY_AND_ASSIGN.
24
25// A smart pointer that deletes a JNI local reference when it goes out of scope.
26template<typename T>
27class ScopedLocalRef {
28public:
29    ScopedLocalRef(JNIEnv* env, T localRef) : mEnv(env), mLocalRef(localRef) {
30    }
31
32    ~ScopedLocalRef() {
33        reset();
34    }
35
36    void reset(T ptr = NULL) {
37        if (ptr != mLocalRef) {
38            if (mLocalRef != NULL) {
39                mEnv->DeleteLocalRef(mLocalRef);
40            }
41            mLocalRef = ptr;
42        }
43    }
44
45    T release() __attribute__((warn_unused_result)) {
46        T localRef = mLocalRef;
47        mLocalRef = NULL;
48        return localRef;
49    }
50
51    T get() const {
52        return mLocalRef;
53    }
54
55private:
56    JNIEnv* const mEnv;
57    T mLocalRef;
58
59    DISALLOW_COPY_AND_ASSIGN(ScopedLocalRef);
60};
61
62#endif  // SCOPED_LOCAL_REF_H_included
63