[Support] Move Stream library from MSF -> Support.

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

1 files changed, 95 insertions, 0 deletions

diff --git a/llvm/lib/Support/BinaryStreamReader.cpp b/llvm/lib/Support/BinaryStreamReader.cpp
new file mode 100644
index 00000000000..c7a2e0ddb17
--- /dev/null
+++ b/llvm/lib/Support/BinaryStreamReader.cpp
@@ -0,0 +1,95 @@
+//===- BinaryStreamReader.cpp - Reads objects from a binary stream --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/BinaryStreamReader.h"
+
+#include "llvm/Support/BinaryStreamError.h"
+#include "llvm/Support/BinaryStreamRef.h"
+
+using namespace llvm;
+
+BinaryStreamReader::BinaryStreamReader(BinaryStreamRef S)
+    : Stream(S), Offset(0) {}
+
+Error BinaryStreamReader::readLongestContiguousChunk(
+    ArrayRef<uint8_t> &Buffer) {
+  if (auto EC = Stream.readLongestContiguousChunk(Offset, Buffer))
+    return EC;
+  Offset += Buffer.size();
+  return Error::success();
+}
+
+Error BinaryStreamReader::readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size) {
+  if (auto EC = Stream.readBytes(Offset, Size, Buffer))
+    return EC;
+  Offset += Size;
+  return Error::success();
+}
+
+Error BinaryStreamReader::readCString(StringRef &Dest) {
+  // TODO: This could be made more efficient by using readLongestContiguousChunk
+  // and searching for null terminators in the resulting buffer.
+
+  uint32_t Length = 0;
+  // First compute the length of the string by reading 1 byte at a time.
+  uint32_t OriginalOffset = getOffset();
+  const char *C;
+  while (true) {
+    if (auto EC = readObject(C))
+      return EC;
+    if (*C == '\0')
+      break;
+    ++Length;
+  }
+  // Now go back and request a reference for that many bytes.
+  uint32_t NewOffset = getOffset();
+  setOffset(OriginalOffset);
+
+  if (auto EC = readFixedString(Dest, Length))
+    return EC;
+
+  // Now set the offset back to where it was after we calculated the length.
+  setOffset(NewOffset);
+  return Error::success();
+}
+
+Error BinaryStreamReader::readFixedString(StringRef &Dest, uint32_t Length) {
+  ArrayRef<uint8_t> Bytes;
+  if (auto EC = readBytes(Bytes, Length))
+    return EC;
+  Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size());
+  return Error::success();
+}
+
+Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref) {
+  return readStreamRef(Ref, bytesRemaining());
+}
+
+Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref, uint32_t Length) {
+  if (bytesRemaining() < Length)
+    return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
+  Ref = Stream.slice(Offset, Length);
+  Offset += Length;
+  return Error::success();
+}
+
+Error BinaryStreamReader::skip(uint32_t Amount) {
+  if (Amount > bytesRemaining())
+    return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
+  Offset += Amount;
+  return Error::success();
+}
+
+uint8_t BinaryStreamReader::peek() const {
+  ArrayRef<uint8_t> Buffer;
+  auto EC = Stream.readBytes(Offset, 1, Buffer);
+  assert(!EC && "Cannot peek an empty buffer!");
+  llvm::consumeError(std::move(EC));
+  return Buffer[0];
+}