1//===--- HeaderMap.h - A file that acts like dir of symlinks ----*- 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// This file defines the HeaderMap interface.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LEX_HEADERMAP_H
15#define LLVM_CLANG_LEX_HEADERMAP_H
16
17#include "clang/Basic/LLVM.h"
18#include "llvm/ADT/Optional.h"
19#include "llvm/Support/Compiler.h"
20#include "llvm/Support/MemoryBuffer.h"
21#include <memory>
22
23namespace clang {
24
25class FileEntry;
26class FileManager;
27struct HMapBucket;
28struct HMapHeader;
29
30/// Implementation for \a HeaderMap that doesn't depend on \a FileManager.
31class HeaderMapImpl {
32  std::unique_ptr<const llvm::MemoryBuffer> FileBuffer;
33  bool NeedsBSwap;
34
35public:
36  HeaderMapImpl(std::unique_ptr<const llvm::MemoryBuffer> File, bool NeedsBSwap)
37      : FileBuffer(std::move(File)), NeedsBSwap(NeedsBSwap) {}
38
39  // Check for a valid header and extract the byte swap.
40  static bool checkHeader(const llvm::MemoryBuffer &File, bool &NeedsByteSwap);
41
42  /// If the specified relative filename is located in this HeaderMap return
43  /// the filename it is mapped to, otherwise return an empty StringRef.
44  StringRef lookupFilename(StringRef Filename,
45                           SmallVectorImpl<char> &DestPath) const;
46
47  /// Return the filename of the headermap.
48  StringRef getFileName() const;
49
50  /// Print the contents of this headermap to stderr.
51  void dump() const;
52
53private:
54  unsigned getEndianAdjustedWord(unsigned X) const;
55  const HMapHeader &getHeader() const;
56  HMapBucket getBucket(unsigned BucketNo) const;
57
58  /// Look up the specified string in the string table.  If the string index is
59  /// not valid, return None.
60  Optional<StringRef> getString(unsigned StrTabIdx) const;
61};
62
63/// This class represents an Apple concept known as a 'header map'.  To the
64/// \#include file resolution process, it basically acts like a directory of
65/// symlinks to files.  Its advantages are that it is dense and more efficient
66/// to create and process than a directory of symlinks.
67class HeaderMap : private HeaderMapImpl {
68  HeaderMap(std::unique_ptr<const llvm::MemoryBuffer> File, bool BSwap)
69      : HeaderMapImpl(std::move(File), BSwap) {}
70
71public:
72  /// This attempts to load the specified file as a header map.  If it doesn't
73  /// look like a HeaderMap, it gives up and returns null.
74  static const HeaderMap *Create(const FileEntry *FE, FileManager &FM);
75
76  /// Check to see if the specified relative filename is located in this
77  /// HeaderMap.  If so, open it and return its FileEntry.  If RawPath is not
78  /// NULL and the file is found, RawPath will be set to the raw path at which
79  /// the file was found in the file system. For example, for a search path
80  /// ".." and a filename "../file.h" this would be "../../file.h".
81  const FileEntry *LookupFile(StringRef Filename, FileManager &FM) const;
82
83  using HeaderMapImpl::lookupFilename;
84  using HeaderMapImpl::getFileName;
85  using HeaderMapImpl::dump;
86};
87
88} // end namespace clang.
89
90#endif
91