1 /* 2 * Copyright (C) 2016 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 AAPT_IO_IO_H 18 #define AAPT_IO_IO_H 19 20 #include <string> 21 22 namespace aapt { 23 namespace io { 24 25 // InputStream interface that mimics protobuf's ZeroCopyInputStream, 26 // with added error handling methods to better report issues. 27 class InputStream { 28 public: 29 virtual ~InputStream() = default; 30 31 // Returns a chunk of data for reading. data and size must not be nullptr. 32 // Returns true so long as there is more data to read, returns false if an error occurred 33 // or no data remains. If an error occurred, check HadError(). 34 // The stream owns the buffer returned from this method and the buffer is invalidated 35 // anytime another mutable method is called. 36 virtual bool Next(const void** data, size_t* size) = 0; 37 38 // Backup count bytes, where count is smaller or equal to the size of the last buffer returned 39 // from Next(). 40 // Useful when the last block returned from Next() wasn't fully read. 41 virtual void BackUp(size_t count) = 0; 42 43 // Returns true if this InputStream can rewind. If so, Rewind() can be called. 44 virtual bool CanRewind() const { return false; }; 45 46 // Rewinds the stream to the beginning so it can be read again. 47 // Returns true if the rewind succeeded. 48 // This does nothing if CanRewind() returns false. 49 virtual bool Rewind() { return false; } 50 51 // Returns the number of bytes that have been read from the stream. 52 virtual size_t ByteCount() const = 0; 53 54 // Returns an error message if HadError() returned true. 55 virtual std::string GetError() const { return {}; } 56 57 // Returns true if an error occurred. Errors are permanent. 58 virtual bool HadError() const = 0; 59 }; 60 61 // OutputStream interface that mimics protobuf's ZeroCopyOutputStream, 62 // with added error handling methods to better report issues. 63 class OutputStream { 64 public: 65 virtual ~OutputStream() = default; 66 67 // Returns a buffer to which data can be written to. The data written to this buffer will 68 // eventually be written to the stream. Call BackUp() if the data written doesn't occupy the 69 // entire buffer. 70 // Return false if there was an error. 71 // The stream owns the buffer returned from this method and the buffer is invalidated 72 // anytime another mutable method is called. 73 virtual bool Next(void** data, size_t* size) = 0; 74 75 // Backup count bytes, where count is smaller or equal to the size of the last buffer returned 76 // from Next(). 77 // Useful for when the last block returned from Next() wasn't fully written to. 78 virtual void BackUp(size_t count) = 0; 79 80 // Returns the number of bytes that have been written to the stream. 81 virtual size_t ByteCount() const = 0; 82 83 // Returns an error message if HadError() returned true. 84 virtual std::string GetError() const { return {}; } 85 86 // Returns true if an error occurred. Errors are permanent. 87 virtual bool HadError() const = 0; 88 }; 89 90 } // namespace io 91 } // namespace aapt 92 93 #endif /* AAPT_IO_IO_H */ 94
