1 files changed, 130 insertions, 0 deletions
diff --git a/llvm/lib/Support/BinaryStreamRef.cpp b/llvm/lib/Support/BinaryStreamRef.cpp
new file mode 100644
index 000000000000..6bcc504ffad5
--- /dev/null
+++ b/llvm/lib/Support/BinaryStreamRef.cpp
@@ -0,0 +1,130 @@
+//===- BinaryStreamRef.cpp - ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/BinaryByteStream.h"
+
+using namespace llvm;
+using namespace llvm::support;
+
+namespace {
+
+class ArrayRefImpl : public BinaryStream {
+public:
+  ArrayRefImpl(ArrayRef<uint8_t> Data, endianness Endian) : BBS(Data, Endian) {}
+
+  llvm::support::endianness getEndian() const override {
+    return BBS.getEndian();
+  }
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) override {
+    return BBS.readBytes(Offset, Size, Buffer);
+  }
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) override {
+    return BBS.readLongestContiguousChunk(Offset, Buffer);
+  }
+  uint32_t getLength() override { return BBS.getLength(); }
+
+private:
+  BinaryByteStream BBS;
+};
+
+class MutableArrayRefImpl : public WritableBinaryStream {
+public:
+  MutableArrayRefImpl(MutableArrayRef<uint8_t> Data, endianness Endian)
+      : BBS(Data, Endian) {}
+
+  // Inherited via WritableBinaryStream
+  llvm::support::endianness getEndian() const override {
+    return BBS.getEndian();
+  }
+  Error readBytes(uint32_t Offset, uint32_t Size,
+                  ArrayRef<uint8_t> &Buffer) override {
+    return BBS.readBytes(Offset, Size, Buffer);
+  }
+  Error readLongestContiguousChunk(uint32_t Offset,
+                                   ArrayRef<uint8_t> &Buffer) override {
+    return BBS.readLongestContiguousChunk(Offset, Buffer);
+  }
+  uint32_t getLength() override { return BBS.getLength(); }
+
+  Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) override {
+    return BBS.writeBytes(Offset, Data);
+  }
+  Error commit() override { return BBS.commit(); }
+
+private:
+  MutableBinaryByteStream BBS;
+};
+}
+
+BinaryStreamRef::BinaryStreamRef(BinaryStream &Stream)
+    : BinaryStreamRefBase(Stream) {}
+BinaryStreamRef::BinaryStreamRef(BinaryStream &Stream, uint32_t Offset,
+                                 Optional<uint32_t> Length)
+    : BinaryStreamRefBase(Stream, Offset, Length) {}
+BinaryStreamRef::BinaryStreamRef(ArrayRef<uint8_t> Data, endianness Endian)
+    : BinaryStreamRefBase(std::make_shared<ArrayRefImpl>(Data, Endian), 0,
+                          Data.size()) {}
+BinaryStreamRef::BinaryStreamRef(StringRef Data, endianness Endian)
+    : BinaryStreamRef(makeArrayRef(Data.bytes_begin(), Data.bytes_end()),
+                      Endian) {}
+
+Error BinaryStreamRef::readBytes(uint32_t Offset, uint32_t Size,
+                                 ArrayRef<uint8_t> &Buffer) const {
+  if (auto EC = checkOffsetForRead(Offset, Size))
+    return EC;
+  return BorrowedImpl->readBytes(ViewOffset + Offset, Size, Buffer);
+}
+
+Error BinaryStreamRef::readLongestContiguousChunk(
+    uint32_t Offset, ArrayRef<uint8_t> &Buffer) const {
+  if (auto EC = checkOffsetForRead(Offset, 1))
+    return EC;
+
+  if (auto EC =
+          BorrowedImpl->readLongestContiguousChunk(ViewOffset + 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 = getLength() - Offset;
+  if (Buffer.size() > MaxLength)
+    Buffer = Buffer.slice(0, MaxLength);
+  return Error::success();
+}
+
+WritableBinaryStreamRef::WritableBinaryStreamRef(WritableBinaryStream &Stream)
+    : BinaryStreamRefBase(Stream) {}
+
+WritableBinaryStreamRef::WritableBinaryStreamRef(WritableBinaryStream &Stream,
+                                                 uint32_t Offset,
+                                                 Optional<uint32_t> Length)
+    : BinaryStreamRefBase(Stream, Offset, Length) {}
+
+WritableBinaryStreamRef::WritableBinaryStreamRef(MutableArrayRef<uint8_t> Data,
+                                                 endianness Endian)
+    : BinaryStreamRefBase(std::make_shared<MutableArrayRefImpl>(Data, Endian),
+                          0, Data.size()) {}
+
+
+Error WritableBinaryStreamRef::writeBytes(uint32_t Offset,
+                                          ArrayRef<uint8_t> Data) const {
+  if (auto EC = checkOffsetForWrite(Offset, Data.size()))
+    return EC;
+
+  return BorrowedImpl->writeBytes(ViewOffset + Offset, Data);
+}
+
+WritableBinaryStreamRef::operator BinaryStreamRef() const {
+  return BinaryStreamRef(*BorrowedImpl, ViewOffset, Length);
+}
+
+/// For buffered streams, commits changes to the backing store.
+Error WritableBinaryStreamRef::commit() { return BorrowedImpl->commit(); }