llvm/lib/Support/BinaryStreamWriter.cpp
Zachary Turner 81a153c99a [BinaryStream] Support growable streams.
The existing library assumed that a stream's length would never
change.  This makes some things simpler, but it's not flexible
enough for what we need, especially for writable streams where
what you really want is for each call to write to actually append.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319070 91177308-0d34-0410-b5e6-96231b3b80d8
2017-11-27 18:48:37 +00:00

92 lines
2.9 KiB
C++

//===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/BinaryStreamWriter.h"
#include "llvm/Support/BinaryStreamError.h"
#include "llvm/Support/BinaryStreamReader.h"
#include "llvm/Support/BinaryStreamRef.h"
using namespace llvm;
BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef Ref)
: Stream(Ref) {}
BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream)
: Stream(Stream) {}
BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data,
llvm::support::endianness Endian)
: Stream(Data, Endian) {}
Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
if (auto EC = Stream.writeBytes(Offset, Buffer))
return EC;
Offset += Buffer.size();
return Error::success();
}
Error BinaryStreamWriter::writeCString(StringRef Str) {
if (auto EC = writeFixedString(Str))
return EC;
if (auto EC = writeObject('\0'))
return EC;
return Error::success();
}
Error BinaryStreamWriter::writeFixedString(StringRef Str) {
return writeBytes(arrayRefFromStringRef(Str));
}
Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {
return writeStreamRef(Ref, Ref.getLength());
}
Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint32_t Length) {
BinaryStreamReader SrcReader(Ref.slice(0, Length));
// This is a bit tricky. If we just call readBytes, we are requiring that it
// return us the entire stream as a contiguous buffer. There is no guarantee
// this can be satisfied by returning a reference straight from the buffer, as
// an implementation may not store all data in a single contiguous buffer. So
// we iterate over each contiguous chunk, writing each one in succession.
while (SrcReader.bytesRemaining() > 0) {
ArrayRef<uint8_t> Chunk;
if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
return EC;
if (auto EC = writeBytes(Chunk))
return EC;
}
return Error::success();
}
std::pair<BinaryStreamWriter, BinaryStreamWriter>
BinaryStreamWriter::split(uint32_t Off) const {
assert(getLength() >= Off);
WritableBinaryStreamRef First = Stream.drop_front(Offset);
WritableBinaryStreamRef Second = First.drop_front(Off);
First = First.keep_front(Off);
BinaryStreamWriter W1{First};
BinaryStreamWriter W2{Second};
return std::make_pair(W1, W2);
}
Error BinaryStreamWriter::padToAlignment(uint32_t Align) {
uint32_t NewOffset = alignTo(Offset, Align);
if (NewOffset > getLength())
return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
while (Offset < NewOffset)
if (auto EC = writeInteger('\0'))
return EC;
return Error::success();
}