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2c68c634a9
After several smaller patches to get most of the core improvements finished up, this patch is a straight move and header fixup of the source. Differential Revision: https://reviews.llvm.org/D30266 llvm-svn: 296810
79 lines
3.0 KiB
C++
79 lines
3.0 KiB
C++
//===- BinaryStream.h - Base interface for a stream of data -----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_BINARYSTREAM_H
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#define LLVM_SUPPORT_BINARYSTREAM_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/Support/BinaryStreamError.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/Error.h"
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#include <cstdint>
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namespace llvm {
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/// \brief An interface for accessing data in a stream-like format, but which
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/// discourages copying. Instead of specifying a buffer in which to copy
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/// data on a read, the API returns an ArrayRef to data owned by the stream's
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/// implementation. Since implementations may not necessarily store data in a
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/// single contiguous buffer (or even in memory at all), in such cases a it may
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/// be necessary for an implementation to cache such a buffer so that it can
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/// return it.
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class BinaryStream {
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public:
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virtual ~BinaryStream() = default;
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virtual llvm::support::endianness getEndian() const = 0;
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/// \brief Given an offset into the stream and a number of bytes, attempt to
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/// read the bytes and set the output ArrayRef to point to data owned by the
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/// stream.
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virtual Error readBytes(uint32_t Offset, uint32_t Size,
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ArrayRef<uint8_t> &Buffer) = 0;
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/// \brief Given an offset into the stream, read as much as possible without
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/// copying any data.
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virtual Error readLongestContiguousChunk(uint32_t Offset,
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ArrayRef<uint8_t> &Buffer) = 0;
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/// \brief Return the number of bytes of data in this stream.
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virtual uint32_t getLength() = 0;
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protected:
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Error checkOffset(uint32_t Offset, uint32_t DataSize) {
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if (Offset > getLength())
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return make_error<BinaryStreamError>(stream_error_code::invalid_offset);
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if (getLength() < DataSize + Offset)
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return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
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return Error::success();
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}
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};
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/// \brief A BinaryStream which can be read from as well as written to. Note
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/// that writing to a BinaryStream always necessitates copying from the input
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/// buffer to the stream's backing store. Streams are assumed to be buffered
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/// so that to be portable it is necessary to call commit() on the stream when
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/// all data has been written.
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class WritableBinaryStream : public BinaryStream {
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public:
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~WritableBinaryStream() override = default;
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/// \brief Attempt to write the given bytes into the stream at the desired
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/// offset. This will always necessitate a copy. Cannot shrink or grow the
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/// stream, only writes into existing allocated space.
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virtual Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) = 0;
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/// \brief For buffered streams, commits changes to the backing store.
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virtual Error commit() = 0;
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};
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} // end namespace llvm
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#endif // LLVM_SUPPORT_BINARYSTREAM_H
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