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1//===--- HeaderMap.h - A file that acts like dir of symlinks ----*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the HeaderMap interface.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_LEX_HEADERMAP_H
14#define LLVM_CLANG_LEX_HEADERMAP_H
15
16#include "clang/Basic/FileManager.h"
17#include "clang/Basic/LLVM.h"
18#include "llvm/ADT/Optional.h"
19#include "llvm/ADT/StringMap.h"
20#include "llvm/Support/Compiler.h"
21#include "llvm/Support/MemoryBuffer.h"
22#include <memory>
23
24namespace clang {
25
26struct HMapBucket;
27struct HMapHeader;
28
29/// Implementation for \a HeaderMap that doesn't depend on \a FileManager.
30class HeaderMapImpl {
31 std::unique_ptr<const llvm::MemoryBuffer> FileBuffer;
32 bool NeedsBSwap;
33 mutable llvm::StringMap<StringRef> ReverseMap;
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
53 /// Return key for specifed path.
54 StringRef reverseLookupFilename(StringRef DestPath) const;
55
56private:
57 unsigned getEndianAdjustedWord(unsigned X) const;
58 const HMapHeader &getHeader() const;
59 HMapBucket getBucket(unsigned BucketNo) const;
60
61 /// Look up the specified string in the string table. If the string index is
62 /// not valid, return None.
63 Optional<StringRef> getString(unsigned StrTabIdx) const;
64};
65
66/// This class represents an Apple concept known as a 'header map'. To the
67/// \#include file resolution process, it basically acts like a directory of
68/// symlinks to files. Its advantages are that it is dense and more efficient
69/// to create and process than a directory of symlinks.
70class HeaderMap : private HeaderMapImpl {
71 HeaderMap(std::unique_ptr<const llvm::MemoryBuffer> File, bool BSwap)
72 : HeaderMapImpl(std::move(File), BSwap) {}
73
74public:
75 /// This attempts to load the specified file as a header map. If it doesn't
76 /// look like a HeaderMap, it gives up and returns null.
77 static std::unique_ptr<HeaderMap> Create(const FileEntry *FE,
78 FileManager &FM);
79
80 using HeaderMapImpl::dump;
81 using HeaderMapImpl::getFileName;
82 using HeaderMapImpl::lookupFilename;
83 using HeaderMapImpl::reverseLookupFilename;
84};
85
86} // end namespace clang.
87
88#endif
89

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source code of clang/include/clang/Lex/HeaderMap.h