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100 lines
3.6 KiB
100 lines
3.6 KiB
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef AAPT_IO_IO_H
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#define AAPT_IO_IO_H
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#include <string>
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namespace aapt {
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namespace io {
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// InputStream interface that mimics protobuf's ZeroCopyInputStream,
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// with added error handling methods to better report issues.
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class InputStream {
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public:
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virtual ~InputStream() = default;
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// Returns a chunk of data for reading. data and size must not be nullptr.
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// Returns true so long as there is more data to read, returns false if an error occurred
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// or no data remains. If an error occurred, check HadError().
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// The stream owns the buffer returned from this method and the buffer is invalidated
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// anytime another mutable method is called.
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virtual bool Next(const void** data, size_t* size) = 0;
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// Backup count bytes, where count is smaller or equal to the size of the last buffer returned
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// from Next().
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// Useful when the last block returned from Next() wasn't fully read.
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virtual void BackUp(size_t count) = 0;
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// Returns true if this InputStream can rewind. If so, Rewind() can be called.
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virtual bool CanRewind() const { return false; };
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// Rewinds the stream to the beginning so it can be read again.
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// Returns true if the rewind succeeded.
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// This does nothing if CanRewind() returns false.
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virtual bool Rewind() { return false; }
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// Returns the number of bytes that have been read from the stream.
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virtual size_t ByteCount() const = 0;
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// Returns an error message if HadError() returned true.
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virtual std::string GetError() const { return {}; }
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// Returns true if an error occurred. Errors are permanent.
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virtual bool HadError() const = 0;
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};
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// A sub-InputStream interface that knows the total size of its stream.
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class KnownSizeInputStream : public InputStream {
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public:
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virtual size_t TotalSize() const = 0;
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};
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// OutputStream interface that mimics protobuf's ZeroCopyOutputStream,
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// with added error handling methods to better report issues.
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class OutputStream {
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public:
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virtual ~OutputStream() = default;
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// Returns a buffer to which data can be written to. The data written to this buffer will
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// eventually be written to the stream. Call BackUp() if the data written doesn't occupy the
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// entire buffer.
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// Return false if there was an error.
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// The stream owns the buffer returned from this method and the buffer is invalidated
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// anytime another mutable method is called.
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virtual bool Next(void** data, size_t* size) = 0;
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// Backup count bytes, where count is smaller or equal to the size of the last buffer returned
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// from Next().
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// Useful for when the last block returned from Next() wasn't fully written to.
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virtual void BackUp(size_t count) = 0;
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// Returns the number of bytes that have been written to the stream.
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virtual size_t ByteCount() const = 0;
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// Returns an error message if HadError() returned true.
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virtual std::string GetError() const { return {}; }
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// Returns true if an error occurred. Errors are permanent.
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virtual bool HadError() const = 0;
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};
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} // namespace io
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} // namespace aapt
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#endif /* AAPT_IO_IO_H */
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