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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 SCOPED_UTF_CHARS_H_included
     18 #define SCOPED_UTF_CHARS_H_included
     19 
     20 #include <string.h>
     21 #include <jni.h>
     22 
     23 #include "android-base/logging.h"
     24 
     25 // This file was copied with some minor modifications from libnativehelper.
     26 // As soon as libnativehelper can be compiled for Windows, this file should be
     27 // replaced with libnativehelper's implementation.
     28 class ScopedUtfChars {
     29  public:
     30   ScopedUtfChars(JNIEnv* env, jstring s) : env_(env), string_(s) {
     31     CHECK(s != nullptr);
     32     utf_chars_ = env->GetStringUTFChars(s, nullptr);
     33   }
     34 
     35   ScopedUtfChars(ScopedUtfChars&& rhs) :
     36       env_(rhs.env_), string_(rhs.string_), utf_chars_(rhs.utf_chars_) {
     37     rhs.env_ = nullptr;
     38     rhs.string_ = nullptr;
     39     rhs.utf_chars_ = nullptr;
     40   }
     41 
     42   ~ScopedUtfChars() {
     43     if (utf_chars_) {
     44       env_->ReleaseStringUTFChars(string_, utf_chars_);
     45     }
     46   }
     47 
     48   ScopedUtfChars& operator=(ScopedUtfChars&& rhs) {
     49     if (this != &rhs) {
     50       // Delete the currently owned UTF chars.
     51       this->~ScopedUtfChars();
     52 
     53       // Move the rhs ScopedUtfChars and zero it out.
     54       env_ = rhs.env_;
     55       string_ = rhs.string_;
     56       utf_chars_ = rhs.utf_chars_;
     57       rhs.env_ = nullptr;
     58       rhs.string_ = nullptr;
     59       rhs.utf_chars_ = nullptr;
     60     }
     61     return *this;
     62   }
     63 
     64   const char* c_str() const {
     65     return utf_chars_;
     66   }
     67 
     68   size_t size() const {
     69     return strlen(utf_chars_);
     70   }
     71 
     72   const char& operator[](size_t n) const {
     73     return utf_chars_[n];
     74   }
     75 
     76  private:
     77   JNIEnv* env_;
     78   jstring string_;
     79   const char* utf_chars_;
     80 
     81   DISALLOW_COPY_AND_ASSIGN(ScopedUtfChars);
     82 };
     83 
     84 #endif  // SCOPED_UTF_CHARS_H_included
     85