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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <stddef.h>
#include <string.h>
#include <jni.h>
#include "nativehelper_utils.h"
// A smart pointer that provides read-only access to a Java string's UTF chars.
// Unlike GetStringUTFChars, we throw NullPointerException rather than abort if
// passed a null jstring, and c_str will return nullptr.
// This makes the correct idiom very simple:
//
// ScopedUtfChars name(env, java_name);
// if (name.c_str() == nullptr) {
// return nullptr;
// }
class ScopedUtfChars {
public:
ScopedUtfChars(JNIEnv* env, jstring s) : env_(env), string_(s) {
if (s == nullptr) {
utf_chars_ = nullptr;
jniThrowNullPointerException(env);
} else {
utf_chars_ = env->GetStringUTFChars(s, nullptr);
}
}
ScopedUtfChars(ScopedUtfChars&& rhs) noexcept :
env_(rhs.env_), string_(rhs.string_), utf_chars_(rhs.utf_chars_) {
rhs.env_ = nullptr;
rhs.string_ = nullptr;
rhs.utf_chars_ = nullptr;
}
~ScopedUtfChars() {
if (utf_chars_) {
env_->ReleaseStringUTFChars(string_, utf_chars_);
}
}
ScopedUtfChars& operator=(ScopedUtfChars&& rhs) noexcept {
if (this != &rhs) {
// Delete the currently owned UTF chars.
this->~ScopedUtfChars();
// Move the rhs ScopedUtfChars and zero it out.
env_ = rhs.env_;
string_ = rhs.string_;
utf_chars_ = rhs.utf_chars_;
rhs.env_ = nullptr;
rhs.string_ = nullptr;
rhs.utf_chars_ = nullptr;
}
return *this;
}
const char* c_str() const {
return utf_chars_;
}
size_t size() const {
return strlen(utf_chars_);
}
const char& operator[](size_t n) const {
return utf_chars_[n];
}
private:
JNIEnv* env_;
jstring string_;
const char* utf_chars_;
DISALLOW_COPY_AND_ASSIGN(ScopedUtfChars);
};