Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2011 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 | #pragma once |
| 18 | |
| 19 | #include <stddef.h> |
| 20 | |
| 21 | #include <jni.h> |
| 22 | |
| 23 | #include "nativehelper_utils.h" |
| 24 | |
| 25 | // A smart pointer that provides access to a jchar* given a JNI jstring. |
| 26 | // Unlike GetStringChars, we throw NullPointerException rather than abort if |
| 27 | // passed a null jstring, and get will return nullptr. |
| 28 | // This makes the correct idiom very simple: |
| 29 | // |
| 30 | // ScopedStringChars name(env, java_name); |
| 31 | // if (name.get() == nullptr) { |
| 32 | // return nullptr; |
| 33 | // } |
| 34 | class ScopedStringChars { |
| 35 | public: |
| 36 | ScopedStringChars(JNIEnv* env, jstring s) : env_(env), string_(s), size_(0) { |
| 37 | if (s == nullptr) { |
| 38 | chars_ = nullptr; |
| 39 | jniThrowNullPointerException(env); |
| 40 | } else { |
| 41 | chars_ = env->GetStringChars(string_, nullptr); |
| 42 | if (chars_ != nullptr) { |
| 43 | size_ = env->GetStringLength(string_); |
| 44 | } |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | ~ScopedStringChars() { |
| 49 | if (chars_ != nullptr) { |
| 50 | env_->ReleaseStringChars(string_, chars_); |
| 51 | } |
| 52 | } |
| 53 | |
| 54 | const jchar* get() const { |
| 55 | return chars_; |
| 56 | } |
| 57 | |
| 58 | size_t size() const { |
| 59 | return size_; |
| 60 | } |
| 61 | |
| 62 | const jchar& operator[](size_t n) const { |
| 63 | return chars_[n]; |
| 64 | } |
| 65 | |
| 66 | private: |
| 67 | JNIEnv* const env_; |
| 68 | const jstring string_; |
| 69 | const jchar* chars_; |
| 70 | size_t size_; |
| 71 | |
| 72 | DISALLOW_COPY_AND_ASSIGN(ScopedStringChars); |
| 73 | }; |
| 74 | |