1 //===- StreamInterface.h - Base interface for a stream of data --*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef LLVM_DEBUGINFO_CODEVIEW_STREAMINTERFACE_H
11 #define LLVM_DEBUGINFO_CODEVIEW_STREAMINTERFACE_H
12 
13 #include "llvm/ADT/ArrayRef.h"
14 #include "llvm/Support/Error.h"
15 #include <cstdint>
16 
17 namespace llvm {
18 namespace codeview {
19 
20 /// StreamInterface abstracts the notion of a data stream.  This way, an
21 /// implementation could implement trivial reading from a contiguous memory
22 /// buffer or, as in the case of PDB files, reading from a set of possibly
23 /// discontiguous blocks.  The implementation is required to return references
24 /// to stable memory, so if this is not possible (for example in the case of
25 /// a PDB file with discontiguous blocks, it must keep its own pool of temp
26 /// storage.
27 class StreamInterface {
28 public:
~StreamInterface()29   virtual ~StreamInterface() {}
30 
31   // Given an offset into the stream and a number of bytes, attempt to read
32   // the bytes and set the output ArrayRef to point to a reference into the
33   // stream, without copying any data.
34   virtual Error readBytes(uint32_t Offset, uint32_t Size,
35                           ArrayRef<uint8_t> &Buffer) const = 0;
36 
37   // Given an offset into the stream, read as much as possible without copying
38   // any data.
39   virtual Error readLongestContiguousChunk(uint32_t Offset,
40                                            ArrayRef<uint8_t> &Buffer) const = 0;
41 
42   // Attempt to write the given bytes into the stream at the desired offset.
43   // This will always necessitate a copy.  Cannot shrink or grow the stream,
44   // only writes into existing allocated space.
45   virtual Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) const = 0;
46 
47   virtual uint32_t getLength() const = 0;
48 
49   virtual Error commit() const = 0;
50 };
51 
52 } // end namespace codeview
53 } // end namespace llvm
54 
55 #endif // LLVM_DEBUGINFO_CODEVIEW_STREAMINTERFACE_H
56