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//===- StreamRef.h - A copyable reference to a stream -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_DEBUGINFO_MSF_STREAMREF_H
#define LLVM_DEBUGINFO_MSF_STREAMREF_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/DebugInfo/MSF/MSFError.h"
#include "llvm/DebugInfo/MSF/StreamInterface.h"
#include "llvm/Support/Error.h"
#include <algorithm>
#include <cstdint>
namespace llvm {
namespace msf {
template <class StreamType, class RefType> class StreamRefBase {
public:
StreamRefBase() : Stream(nullptr), ViewOffset(0), Length(0) {}
StreamRefBase(const StreamType &Stream, uint32_t Offset, uint32_t Length)
: Stream(&Stream), ViewOffset(Offset), Length(Length) {}
uint32_t getLength() const { return Length; }
const StreamType *getStream() const { return Stream; }
RefType drop_front(uint32_t N) const {
if (!Stream)
return RefType();
N = std::min(N, Length);
return RefType(*Stream, ViewOffset + N, Length - N);
}
RefType keep_front(uint32_t N) const {
if (!Stream)
return RefType();
N = std::min(N, Length);
return RefType(*Stream, ViewOffset, N);
}
RefType slice(uint32_t Offset, uint32_t Len) const {
return drop_front(Offset).keep_front(Len);
}
bool operator==(const RefType &Other) const {
if (Stream != Other.Stream)
return false;
if (ViewOffset != Other.ViewOffset)
return false;
if (Length != Other.Length)
return false;
return true;
}
protected:
const StreamType *Stream;
uint32_t ViewOffset;
uint32_t Length;
};
class ReadableStreamRef
: public StreamRefBase<ReadableStream, ReadableStreamRef> {
public:
ReadableStreamRef() = default;
ReadableStreamRef(const ReadableStream &Stream)
: StreamRefBase(Stream, 0, Stream.getLength()) {}
ReadableStreamRef(const ReadableStream &Stream, uint32_t Offset,
uint32_t Length)
: StreamRefBase(Stream, Offset, Length) {}
// Use StreamRef.slice() instead.
ReadableStreamRef(const ReadableStreamRef &S, uint32_t Offset,
uint32_t Length) = delete;
Error readBytes(uint32_t Offset, uint32_t Size,
ArrayRef<uint8_t> &Buffer) const {
if (ViewOffset + Offset < Offset)
return make_error<MSFError>(msf_error_code::insufficient_buffer);
if (Size + Offset > Length)
return make_error<MSFError>(msf_error_code::insufficient_buffer);
return Stream->readBytes(ViewOffset + Offset, Size, Buffer);
}
// Given an offset into the stream, read as much as possible without copying
// any data.
Error readLongestContiguousChunk(uint32_t Offset,
ArrayRef<uint8_t> &Buffer) const {
if (Offset >= Length)
return make_error<MSFError>(msf_error_code::insufficient_buffer);
if (auto EC = Stream->readLongestContiguousChunk(Offset, Buffer))
return EC;
// This StreamRef might refer to a smaller window over a larger stream. In
// that case we will have read out more bytes than we should return, because
// we should not read past the end of the current view.
uint32_t MaxLength = Length - Offset;
if (Buffer.size() > MaxLength)
Buffer = Buffer.slice(0, MaxLength);
return Error::success();
}
};
class WritableStreamRef
: public StreamRefBase<WritableStream, WritableStreamRef> {
public:
WritableStreamRef() = default;
WritableStreamRef(const WritableStream &Stream)
: StreamRefBase(Stream, 0, Stream.getLength()) {}
WritableStreamRef(const WritableStream &Stream, uint32_t Offset,
uint32_t Length)
: StreamRefBase(Stream, Offset, Length) {}
// Use StreamRef.slice() instead.
WritableStreamRef(const WritableStreamRef &S, uint32_t Offset,
uint32_t Length) = delete;
Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) const {
if (Data.size() + Offset > Length)
return make_error<MSFError>(msf_error_code::insufficient_buffer);
return Stream->writeBytes(ViewOffset + Offset, Data);
}
Error commit() const { return Stream->commit(); }
};
} // end namespace msf
} // end namespace llvm
#endif // LLVM_DEBUGINFO_MSF_STREAMREF_H
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