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/*
* Copyright (C) 2016 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.
*/
#ifndef AAPT_IO_IO_H
#define AAPT_IO_IO_H
#include <string>
namespace aapt {
namespace io {
// InputStream interface that mimics protobuf's ZeroCopyInputStream,
// with added error handling methods to better report issues.
class InputStream {
public:
virtual ~InputStream() = default;
// Returns a chunk of data for reading. data and size must not be nullptr.
// Returns true so long as there is more data to read, returns false if an error occurred
// or no data remains. If an error occurred, check HadError().
// The stream owns the buffer returned from this method and the buffer is invalidated
// anytime another mutable method is called.
virtual bool Next(const void** data, size_t* size) = 0;
// Backup count bytes, where count is smaller or equal to the size of the last buffer returned
// from Next().
// Useful when the last block returned from Next() wasn't fully read.
virtual void BackUp(size_t count) = 0;
// Returns true if this InputStream can rewind. If so, Rewind() can be called.
virtual bool CanRewind() const { return false; };
// Rewinds the stream to the beginning so it can be read again.
// Returns true if the rewind succeeded.
// This does nothing if CanRewind() returns false.
virtual bool Rewind() { return false; }
// Returns the number of bytes that have been read from the stream.
virtual size_t ByteCount() const = 0;
// Returns an error message if HadError() returned true.
virtual std::string GetError() const { return {}; }
// Returns true if an error occurred. Errors are permanent.
virtual bool HadError() const = 0;
};
// OutputStream interface that mimics protobuf's ZeroCopyOutputStream,
// with added error handling methods to better report issues.
class OutputStream {
public:
virtual ~OutputStream() = default;
// Returns a buffer to which data can be written to. The data written to this buffer will
// eventually be written to the stream. Call BackUp() if the data written doesn't occupy the
// entire buffer.
// Return false if there was an error.
// The stream owns the buffer returned from this method and the buffer is invalidated
// anytime another mutable method is called.
virtual bool Next(void** data, size_t* size) = 0;
// Backup count bytes, where count is smaller or equal to the size of the last buffer returned
// from Next().
// Useful for when the last block returned from Next() wasn't fully written to.
virtual void BackUp(size_t count) = 0;
// Returns the number of bytes that have been written to the stream.
virtual size_t ByteCount() const = 0;
// Returns an error message if HadError() returned true.
virtual std::string GetError() const { return {}; }
// Returns true if an error occurred. Errors are permanent.
virtual bool HadError() const = 0;
};
} // namespace io
} // namespace aapt
#endif /* AAPT_IO_IO_H */
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