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_UTF_CHARS_H_included
18#define SCOPED_UTF_CHARS_H_included
19
20#include "JNIHelp.h"
21#include <string.h>
22
23// A smart pointer that provides read-only access to a Java string's UTF chars.
24// Unlike GetStringUTFChars, we throw NullPointerException rather than abort if
25// passed a null jstring, and c_str will return NULL.
26// This makes the correct idiom very simple:
27//
28//   ScopedUtfChars name(env, javaName);
29//   if (name.c_str() == NULL) {
30//       return NULL;
31//   }
32class ScopedUtfChars {
33public:
34    ScopedUtfChars(JNIEnv* env, jstring s)
35    : mEnv(env), mString(s)
36    {
37        if (s == NULL) {
38            mUtfChars = NULL;
39            jniThrowNullPointerException(env, NULL);
40        } else {
41            mUtfChars = env->GetStringUTFChars(s, NULL);
42        }
43    }
44
45    ~ScopedUtfChars() {
46        if (mUtfChars) {
47            mEnv->ReleaseStringUTFChars(mString, mUtfChars);
48        }
49    }
50
51    const char* c_str() const {
52        return mUtfChars;
53    }
54
55    size_t size() const {
56        return strlen(mUtfChars);
57    }
58
59    // Element access.
60    const char& operator[](size_t n) const {
61        return mUtfChars[n];
62    }
63
64private:
65    JNIEnv* mEnv;
66    jstring mString;
67    const char* mUtfChars;
68
69    // Disallow copy and assignment.
70    ScopedUtfChars(const ScopedUtfChars&);
71    void operator=(const ScopedUtfChars&);
72};
73
74#endif  // SCOPED_UTF_CHARS_H_included
75