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
24// A smart pointer that deletes a JNI local reference when it goes out of scope.
25template<typename T>
26class ScopedLocalRef {
27public:
28    ScopedLocalRef(JNIEnv* env, T localRef) : mEnv(env), mLocalRef(localRef) {
29    }
30
31    ~ScopedLocalRef() {
32        reset();
33    }
34
35    void reset(T ptr = NULL) {
36        if (ptr != mLocalRef) {
37            if (mLocalRef != NULL) {
38                mEnv->DeleteLocalRef(mLocalRef);
39            }
40            mLocalRef = ptr;
41        }
42    }
43
44    T release() __attribute__((warn_unused_result)) {
45        T localRef = mLocalRef;
46        mLocalRef = NULL;
47        return localRef;
48    }
49
50    T get() const {
51        return mLocalRef;
52    }
53
54private:
55    JNIEnv* mEnv;
56    T mLocalRef;
57
58    // Disallow copy and assignment.
59    ScopedLocalRef(const ScopedLocalRef&);
60    void operator=(const ScopedLocalRef&);
61};
62
63#endif  // SCOPED_LOCAL_REF_H_included
64