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