- //===- HeaderSearch.h - Resolve Header File Locations -----------*- C++ -*-===// 
- // 
- // 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 
- // 
- //===----------------------------------------------------------------------===// 
- // 
- // This file defines the HeaderSearch interface. 
- // 
- //===----------------------------------------------------------------------===// 
-   
- #ifndef LLVM_CLANG_LEX_HEADERSEARCH_H 
- #define LLVM_CLANG_LEX_HEADERSEARCH_H 
-   
- #include "clang/Basic/SourceLocation.h" 
- #include "clang/Basic/SourceManager.h" 
- #include "clang/Lex/DirectoryLookup.h" 
- #include "clang/Lex/HeaderMap.h" 
- #include "clang/Lex/ModuleMap.h" 
- #include "llvm/ADT/ArrayRef.h" 
- #include "llvm/ADT/DenseMap.h" 
- #include "llvm/ADT/SmallString.h" 
- #include "llvm/ADT/StringMap.h" 
- #include "llvm/ADT/StringRef.h" 
- #include "llvm/ADT/StringSet.h" 
- #include "llvm/Support/Allocator.h" 
- #include <cassert> 
- #include <cstddef> 
- #include <memory> 
- #include <string> 
- #include <utility> 
- #include <vector> 
-   
- namespace llvm { 
-   
- class Triple; 
-   
- } // namespace llvm 
-   
- namespace clang { 
-   
- class DiagnosticsEngine; 
- class DirectoryEntry; 
- class ExternalPreprocessorSource; 
- class FileEntry; 
- class FileManager; 
- class HeaderSearch; 
- class HeaderSearchOptions; 
- class IdentifierInfo; 
- class LangOptions; 
- class Module; 
- class Preprocessor; 
- class TargetInfo; 
-   
- /// The preprocessor keeps track of this information for each 
- /// file that is \#included. 
- struct HeaderFileInfo { 
-   // TODO: Whether the file was imported is not a property of the file itself. 
-   // It's a preprocessor state, move it there. 
-   /// True if this is a \#import'd file. 
-   unsigned isImport : 1; 
-   
-   /// True if this is a \#pragma once file. 
-   unsigned isPragmaOnce : 1; 
-   
-   /// Keep track of whether this is a system header, and if so, 
-   /// whether it is C++ clean or not.  This can be set by the include paths or 
-   /// by \#pragma gcc system_header.  This is an instance of 
-   /// SrcMgr::CharacteristicKind. 
-   unsigned DirInfo : 3; 
-   
-   /// Whether this header file info was supplied by an external source, 
-   /// and has not changed since. 
-   unsigned External : 1; 
-   
-   /// Whether this header is part of a module. 
-   unsigned isModuleHeader : 1; 
-   
-   /// Whether this header is part of the module that we are building. 
-   unsigned isCompilingModuleHeader : 1; 
-   
-   /// Whether this structure is considered to already have been 
-   /// "resolved", meaning that it was loaded from the external source. 
-   unsigned Resolved : 1; 
-   
-   /// Whether this is a header inside a framework that is currently 
-   /// being built. 
-   /// 
-   /// When a framework is being built, the headers have not yet been placed 
-   /// into the appropriate framework subdirectories, and therefore are 
-   /// provided via a header map. This bit indicates when this is one of 
-   /// those framework headers. 
-   unsigned IndexHeaderMapHeader : 1; 
-   
-   /// Whether this file has been looked up as a header. 
-   unsigned IsValid : 1; 
-   
-   /// The ID number of the controlling macro. 
-   /// 
-   /// This ID number will be non-zero when there is a controlling 
-   /// macro whose IdentifierInfo may not yet have been loaded from 
-   /// external storage. 
-   unsigned ControllingMacroID = 0; 
-   
-   /// If this file has a \#ifndef XXX (or equivalent) guard that 
-   /// protects the entire contents of the file, this is the identifier 
-   /// for the macro that controls whether or not it has any effect. 
-   /// 
-   /// Note: Most clients should use getControllingMacro() to access 
-   /// the controlling macro of this header, since 
-   /// getControllingMacro() is able to load a controlling macro from 
-   /// external storage. 
-   const IdentifierInfo *ControllingMacro = nullptr; 
-   
-   /// If this header came from a framework include, this is the name 
-   /// of the framework. 
-   StringRef Framework; 
-   
-   HeaderFileInfo() 
-       : isImport(false), isPragmaOnce(false), DirInfo(SrcMgr::C_User), 
-         External(false), isModuleHeader(false), isCompilingModuleHeader(false), 
-         Resolved(false), IndexHeaderMapHeader(false), IsValid(false)  {} 
-   
-   /// Retrieve the controlling macro for this header file, if 
-   /// any. 
-   const IdentifierInfo * 
-   getControllingMacro(ExternalPreprocessorSource *External); 
- }; 
-   
- /// An external source of header file information, which may supply 
- /// information about header files already included. 
- class ExternalHeaderFileInfoSource { 
- public: 
-   virtual ~ExternalHeaderFileInfoSource(); 
-   
-   /// Retrieve the header file information for the given file entry. 
-   /// 
-   /// \returns Header file information for the given file entry, with the 
-   /// \c External bit set. If the file entry is not known, return a 
-   /// default-constructed \c HeaderFileInfo. 
-   virtual HeaderFileInfo GetHeaderFileInfo(const FileEntry *FE) = 0; 
- }; 
-   
- /// This structure is used to record entries in our framework cache. 
- struct FrameworkCacheEntry { 
-   /// The directory entry which should be used for the cached framework. 
-   OptionalDirectoryEntryRef Directory; 
-   
-   /// Whether this framework has been "user-specified" to be treated as if it 
-   /// were a system framework (even if it was found outside a system framework 
-   /// directory). 
-   bool IsUserSpecifiedSystemFramework; 
- }; 
-   
- namespace detail { 
- template <bool Const, typename T> 
- using Qualified = std::conditional_t<Const, const T, T>; 
-   
- /// Forward iterator over the search directories of \c HeaderSearch. 
- template <bool IsConst> 
- struct SearchDirIteratorImpl 
-     : llvm::iterator_facade_base<SearchDirIteratorImpl<IsConst>, 
-                                  std::forward_iterator_tag, 
-                                  Qualified<IsConst, DirectoryLookup>> { 
-   /// Const -> non-const iterator conversion. 
-   template <typename Enable = std::enable_if<IsConst, bool>> 
-   SearchDirIteratorImpl(const SearchDirIteratorImpl<false> &Other) 
-       : HS(Other.HS), Idx(Other.Idx) {} 
-   
-   SearchDirIteratorImpl(const SearchDirIteratorImpl &) = default; 
-   
-   SearchDirIteratorImpl &operator=(const SearchDirIteratorImpl &) = default; 
-   
-   bool operator==(const SearchDirIteratorImpl &RHS) const { 
-     return HS == RHS.HS && Idx == RHS.Idx; 
-   } 
-   
-   SearchDirIteratorImpl &operator++() { 
-     assert(*this && "Invalid iterator."); 
-     ++Idx; 
-     return *this; 
-   } 
-   
-   Qualified<IsConst, DirectoryLookup> &operator*() const { 
-     assert(*this && "Invalid iterator."); 
-     return HS->SearchDirs[Idx]; 
-   } 
-   
-   /// Creates an invalid iterator. 
-   SearchDirIteratorImpl(std::nullptr_t) : HS(nullptr), Idx(0) {} 
-   
-   /// Checks whether the iterator is valid. 
-   explicit operator bool() const { return HS != nullptr; } 
-   
- private: 
-   /// The parent \c HeaderSearch. This is \c nullptr for invalid iterator. 
-   Qualified<IsConst, HeaderSearch> *HS; 
-   
-   /// The index of the current element. 
-   size_t Idx; 
-   
-   /// The constructor that creates a valid iterator. 
-   SearchDirIteratorImpl(Qualified<IsConst, HeaderSearch> &HS, size_t Idx) 
-       : HS(&HS), Idx(Idx) {} 
-   
-   /// Only HeaderSearch is allowed to instantiate valid iterators. 
-   friend HeaderSearch; 
-   
-   /// Enables const -> non-const conversion. 
-   friend SearchDirIteratorImpl<!IsConst>; 
- }; 
- } // namespace detail 
-   
- using ConstSearchDirIterator = detail::SearchDirIteratorImpl<true>; 
- using SearchDirIterator = detail::SearchDirIteratorImpl<false>; 
-   
- using ConstSearchDirRange = llvm::iterator_range<ConstSearchDirIterator>; 
- using SearchDirRange = llvm::iterator_range<SearchDirIterator>; 
-   
- /// Encapsulates the information needed to find the file referenced 
- /// by a \#include or \#include_next, (sub-)framework lookup, etc. 
- class HeaderSearch { 
-   friend class DirectoryLookup; 
-   
-   friend ConstSearchDirIterator; 
-   friend SearchDirIterator; 
-   
-   /// Header-search options used to initialize this header search. 
-   std::shared_ptr<HeaderSearchOptions> HSOpts; 
-   
-   /// Mapping from SearchDir to HeaderSearchOptions::UserEntries indices. 
-   llvm::DenseMap<unsigned, unsigned> SearchDirToHSEntry; 
-   
-   DiagnosticsEngine &Diags; 
-   FileManager &FileMgr; 
-   
-   /// \#include search path information.  Requests for \#include "x" search the 
-   /// directory of the \#including file first, then each directory in SearchDirs 
-   /// consecutively. Requests for <x> search the current dir first, then each 
-   /// directory in SearchDirs, starting at AngledDirIdx, consecutively.  If 
-   /// NoCurDirSearch is true, then the check for the file in the current 
-   /// directory is suppressed. 
-   std::vector<DirectoryLookup> SearchDirs; 
-   /// Whether the DirectoryLookup at the corresponding index in SearchDirs has 
-   /// been successfully used to lookup a file. 
-   std::vector<bool> SearchDirsUsage; 
-   unsigned AngledDirIdx = 0; 
-   unsigned SystemDirIdx = 0; 
-   bool NoCurDirSearch = false; 
-   
-   /// Maps HeaderMap keys to SearchDir indices. When HeaderMaps are used 
-   /// heavily, SearchDirs can start with thousands of HeaderMaps, so this Index 
-   /// lets us avoid scanning them all to find a match. 
-   llvm::StringMap<unsigned, llvm::BumpPtrAllocator> SearchDirHeaderMapIndex; 
-   
-   /// The index of the first SearchDir that isn't a header map. 
-   unsigned FirstNonHeaderMapSearchDirIdx = 0; 
-   
-   /// \#include prefixes for which the 'system header' property is 
-   /// overridden. 
-   /// 
-   /// For a \#include "x" or \#include \<x> directive, the last string in this 
-   /// list which is a prefix of 'x' determines whether the file is treated as 
-   /// a system header. 
-   std::vector<std::pair<std::string, bool>> SystemHeaderPrefixes; 
-   
-   /// The hash used for module cache paths. 
-   std::string ModuleHash; 
-   
-   /// The path to the module cache. 
-   std::string ModuleCachePath; 
-   
-   /// All of the preprocessor-specific data about files that are 
-   /// included, indexed by the FileEntry's UID. 
-   mutable std::vector<HeaderFileInfo> FileInfo; 
-   
-   /// Keeps track of each lookup performed by LookupFile. 
-   struct LookupFileCacheInfo { 
-     /// Starting search directory iterator that the cached search was performed 
-     /// from. If there is a hit and this value doesn't match the current query, 
-     /// the cache has to be ignored. 
-     ConstSearchDirIterator StartIt = nullptr; 
-   
-     /// The search directory iterator that satisfied the query. 
-     ConstSearchDirIterator HitIt = nullptr; 
-   
-     /// This is non-null if the original filename was mapped to a framework 
-     /// include via a headermap. 
-     const char *MappedName = nullptr; 
-   
-     /// Default constructor -- Initialize all members with zero. 
-     LookupFileCacheInfo() = default; 
-   
-     void reset(ConstSearchDirIterator NewStartIt) { 
-       StartIt = NewStartIt; 
-       MappedName = nullptr; 
-     } 
-   }; 
-   llvm::StringMap<LookupFileCacheInfo, llvm::BumpPtrAllocator> LookupFileCache; 
-   
-   /// Collection mapping a framework or subframework 
-   /// name like "Carbon" to the Carbon.framework directory. 
-   llvm::StringMap<FrameworkCacheEntry, llvm::BumpPtrAllocator> FrameworkMap; 
-   
-   /// Maps include file names (including the quotes or 
-   /// angle brackets) to other include file names.  This is used to support the 
-   /// include_alias pragma for Microsoft compatibility. 
-   using IncludeAliasMap = 
-       llvm::StringMap<std::string, llvm::BumpPtrAllocator>; 
-   std::unique_ptr<IncludeAliasMap> IncludeAliases; 
-   
-   /// This is a mapping from FileEntry -> HeaderMap, uniquing headermaps. 
-   std::vector<std::pair<const FileEntry *, std::unique_ptr<HeaderMap>>> HeaderMaps; 
-   
-   /// The mapping between modules and headers. 
-   mutable ModuleMap ModMap; 
-   
-   /// Describes whether a given directory has a module map in it. 
-   llvm::DenseMap<const DirectoryEntry *, bool> DirectoryHasModuleMap; 
-   
-   /// Set of module map files we've already loaded, and a flag indicating 
-   /// whether they were valid or not. 
-   llvm::DenseMap<const FileEntry *, bool> LoadedModuleMaps; 
-   
-   // A map of discovered headers with their associated include file name. 
-   llvm::DenseMap<const FileEntry *, llvm::SmallString<64>> IncludeNames; 
-   
-   /// Uniqued set of framework names, which is used to track which 
-   /// headers were included as framework headers. 
-   llvm::StringSet<llvm::BumpPtrAllocator> FrameworkNames; 
-   
-   /// Entity used to resolve the identifier IDs of controlling 
-   /// macros into IdentifierInfo pointers, and keep the identifire up to date, 
-   /// as needed. 
-   ExternalPreprocessorSource *ExternalLookup = nullptr; 
-   
-   /// Entity used to look up stored header file information. 
-   ExternalHeaderFileInfoSource *ExternalSource = nullptr; 
-   
-   /// Scan all of the header maps at the beginning of SearchDirs and 
-   /// map their keys to the SearchDir index of their header map. 
-   void indexInitialHeaderMaps(); 
-   
- public: 
-   HeaderSearch(std::shared_ptr<HeaderSearchOptions> HSOpts, 
-                SourceManager &SourceMgr, DiagnosticsEngine &Diags, 
-                const LangOptions &LangOpts, const TargetInfo *Target); 
-   HeaderSearch(const HeaderSearch &) = delete; 
-   HeaderSearch &operator=(const HeaderSearch &) = delete; 
-   
-   /// Retrieve the header-search options with which this header search 
-   /// was initialized. 
-   HeaderSearchOptions &getHeaderSearchOpts() const { return *HSOpts; } 
-   
-   FileManager &getFileMgr() const { return FileMgr; } 
-   
-   DiagnosticsEngine &getDiags() const { return Diags; } 
-   
-   /// Interface for setting the file search paths. 
-   void SetSearchPaths(std::vector<DirectoryLookup> dirs, unsigned angledDirIdx, 
-                       unsigned systemDirIdx, bool noCurDirSearch, 
-                       llvm::DenseMap<unsigned, unsigned> searchDirToHSEntry); 
-   
-   /// Add an additional search path. 
-   void AddSearchPath(const DirectoryLookup &dir, bool isAngled); 
-   
-   /// Add an additional system search path. 
-   void AddSystemSearchPath(const DirectoryLookup &dir) { 
-     SearchDirs.push_back(dir); 
-     SearchDirsUsage.push_back(false); 
-   } 
-   
-   /// Set the list of system header prefixes. 
-   void SetSystemHeaderPrefixes(ArrayRef<std::pair<std::string, bool>> P) { 
-     SystemHeaderPrefixes.assign(P.begin(), P.end()); 
-   } 
-   
-   /// Checks whether the map exists or not. 
-   bool HasIncludeAliasMap() const { return (bool)IncludeAliases; } 
-   
-   /// Map the source include name to the dest include name. 
-   /// 
-   /// The Source should include the angle brackets or quotes, the dest 
-   /// should not.  This allows for distinction between <> and "" headers. 
-   void AddIncludeAlias(StringRef Source, StringRef Dest) { 
-     if (!IncludeAliases) 
-       IncludeAliases.reset(new IncludeAliasMap); 
-     (*IncludeAliases)[Source] = std::string(Dest); 
-   } 
-   
-   /// Maps one header file name to a different header 
-   /// file name, for use with the include_alias pragma.  Note that the source 
-   /// file name should include the angle brackets or quotes.  Returns StringRef 
-   /// as null if the header cannot be mapped. 
-   StringRef MapHeaderToIncludeAlias(StringRef Source) { 
-     assert(IncludeAliases && "Trying to map headers when there's no map"); 
-   
-     // Do any filename replacements before anything else 
-     IncludeAliasMap::const_iterator Iter = IncludeAliases->find(Source); 
-     if (Iter != IncludeAliases->end()) 
-       return Iter->second; 
-     return {}; 
-   } 
-   
-   /// Set the hash to use for module cache paths. 
-   void setModuleHash(StringRef Hash) { ModuleHash = std::string(Hash); } 
-   
-   /// Set the path to the module cache. 
-   void setModuleCachePath(StringRef CachePath) { 
-     ModuleCachePath = std::string(CachePath); 
-   } 
-   
-   /// Retrieve the module hash. 
-   StringRef getModuleHash() const { return ModuleHash; } 
-   
-   /// Retrieve the path to the module cache. 
-   StringRef getModuleCachePath() const { return ModuleCachePath; } 
-   
-   /// Consider modules when including files from this directory. 
-   void setDirectoryHasModuleMap(const DirectoryEntry* Dir) { 
-     DirectoryHasModuleMap[Dir] = true; 
-   } 
-   
-   /// Forget everything we know about headers so far. 
-   void ClearFileInfo() { 
-     FileInfo.clear(); 
-   } 
-   
-   void SetExternalLookup(ExternalPreprocessorSource *EPS) { 
-     ExternalLookup = EPS; 
-   } 
-   
-   ExternalPreprocessorSource *getExternalLookup() const { 
-     return ExternalLookup; 
-   } 
-   
-   /// Set the external source of header information. 
-   void SetExternalSource(ExternalHeaderFileInfoSource *ES) { 
-     ExternalSource = ES; 
-   } 
-   
-   /// Set the target information for the header search, if not 
-   /// already known. 
-   void setTarget(const TargetInfo &Target); 
-   
-   /// Given a "foo" or \<foo> reference, look up the indicated file, 
-   /// return null on failure. 
-   /// 
-   /// \returns If successful, this returns 'UsedDir', the DirectoryLookup member 
-   /// the file was found in, or null if not applicable. 
-   /// 
-   /// \param IncludeLoc Used for diagnostics if valid. 
-   /// 
-   /// \param isAngled indicates whether the file reference is a <> reference. 
-   /// 
-   /// \param CurDir If non-null, the file was found in the specified directory 
-   /// search location.  This is used to implement \#include_next. 
-   /// 
-   /// \param Includers Indicates where the \#including file(s) are, in case 
-   /// relative searches are needed. In reverse order of inclusion. 
-   /// 
-   /// \param SearchPath If non-null, will be set to the search path relative 
-   /// to which the file was found. If the include path is absolute, SearchPath 
-   /// will be set to an empty string. 
-   /// 
-   /// \param RelativePath If non-null, will be set to the path relative to 
-   /// SearchPath at which the file was found. This only differs from the 
-   /// Filename for framework includes. 
-   /// 
-   /// \param SuggestedModule If non-null, and the file found is semantically 
-   /// part of a known module, this will be set to the module that should 
-   /// be imported instead of preprocessing/parsing the file found. 
-   /// 
-   /// \param IsMapped If non-null, and the search involved header maps, set to 
-   /// true. 
-   /// 
-   /// \param IsFrameworkFound If non-null, will be set to true if a framework is 
-   /// found in any of searched SearchDirs. Will be set to false if a framework 
-   /// is found only through header maps. Doesn't guarantee the requested file is 
-   /// found. 
-   OptionalFileEntryRef LookupFile( 
-       StringRef Filename, SourceLocation IncludeLoc, bool isAngled, 
-       ConstSearchDirIterator FromDir, ConstSearchDirIterator *CurDir, 
-       ArrayRef<std::pair<const FileEntry *, const DirectoryEntry *>> Includers, 
-       SmallVectorImpl<char> *SearchPath, SmallVectorImpl<char> *RelativePath, 
-       Module *RequestingModule, ModuleMap::KnownHeader *SuggestedModule, 
-       bool *IsMapped, bool *IsFrameworkFound, bool SkipCache = false, 
-       bool BuildSystemModule = false, bool OpenFile = true, 
-       bool CacheFailures = true); 
-   
-   /// Look up a subframework for the specified \#include file. 
-   /// 
-   /// For example, if \#include'ing <HIToolbox/HIToolbox.h> from 
-   /// within ".../Carbon.framework/Headers/Carbon.h", check to see if 
-   /// HIToolbox is a subframework within Carbon.framework.  If so, return 
-   /// the FileEntry for the designated file, otherwise return null. 
-   OptionalFileEntryRef LookupSubframeworkHeader( 
-       StringRef Filename, const FileEntry *ContextFileEnt, 
-       SmallVectorImpl<char> *SearchPath, SmallVectorImpl<char> *RelativePath, 
-       Module *RequestingModule, ModuleMap::KnownHeader *SuggestedModule); 
-   
-   /// Look up the specified framework name in our framework cache. 
-   /// \returns The DirectoryEntry it is in if we know, null otherwise. 
-   FrameworkCacheEntry &LookupFrameworkCache(StringRef FWName) { 
-     return FrameworkMap[FWName]; 
-   } 
-   
-   /// Mark the specified file as a target of a \#include, 
-   /// \#include_next, or \#import directive. 
-   /// 
-   /// \return false if \#including the file will have no effect or true 
-   /// if we should include it. 
-   bool ShouldEnterIncludeFile(Preprocessor &PP, const FileEntry *File, 
-                               bool isImport, bool ModulesEnabled, Module *M, 
-                               bool &IsFirstIncludeOfFile); 
-   
-   /// Return whether the specified file is a normal header, 
-   /// a system header, or a C++ friendly system header. 
-   SrcMgr::CharacteristicKind getFileDirFlavor(const FileEntry *File) { 
-     return (SrcMgr::CharacteristicKind)getFileInfo(File).DirInfo; 
-   } 
-   
-   /// Mark the specified file as a "once only" file due to 
-   /// \#pragma once. 
-   void MarkFileIncludeOnce(const FileEntry *File) { 
-     HeaderFileInfo &FI = getFileInfo(File); 
-     FI.isPragmaOnce = true; 
-   } 
-   
-   /// Mark the specified file as a system header, e.g. due to 
-   /// \#pragma GCC system_header. 
-   void MarkFileSystemHeader(const FileEntry *File) { 
-     getFileInfo(File).DirInfo = SrcMgr::C_System; 
-   } 
-   
-   /// Mark the specified file as part of a module. 
-   void MarkFileModuleHeader(const FileEntry *FE, 
-                             ModuleMap::ModuleHeaderRole Role, 
-                             bool isCompilingModuleHeader); 
-   
-   /// Mark the specified file as having a controlling macro. 
-   /// 
-   /// This is used by the multiple-include optimization to eliminate 
-   /// no-op \#includes. 
-   void SetFileControllingMacro(const FileEntry *File, 
-                                const IdentifierInfo *ControllingMacro) { 
-     getFileInfo(File).ControllingMacro = ControllingMacro; 
-   } 
-   
-   /// Determine whether this file is intended to be safe from 
-   /// multiple inclusions, e.g., it has \#pragma once or a controlling 
-   /// macro. 
-   /// 
-   /// This routine does not consider the effect of \#import 
-   bool isFileMultipleIncludeGuarded(const FileEntry *File); 
-   
-   /// Determine whether the given file is known to have ever been \#imported. 
-   bool hasFileBeenImported(const FileEntry *File) { 
-     const HeaderFileInfo *FI = getExistingFileInfo(File); 
-     return FI && FI->isImport; 
-   } 
-   
-   /// Determine which HeaderSearchOptions::UserEntries have been successfully 
-   /// used so far and mark their index with 'true' in the resulting bit vector. 
-   /// Note: implicit module maps don't contribute to entry usage. 
-   std::vector<bool> computeUserEntryUsage() const; 
-   
-   /// This method returns a HeaderMap for the specified 
-   /// FileEntry, uniquing them through the 'HeaderMaps' datastructure. 
-   const HeaderMap *CreateHeaderMap(const FileEntry *FE); 
-   
-   /// Get filenames for all registered header maps. 
-   void getHeaderMapFileNames(SmallVectorImpl<std::string> &Names) const; 
-   
-   /// Retrieve the name of the cached module file that should be used 
-   /// to load the given module. 
-   /// 
-   /// \param Module The module whose module file name will be returned. 
-   /// 
-   /// \returns The name of the module file that corresponds to this module, 
-   /// or an empty string if this module does not correspond to any module file. 
-   std::string getCachedModuleFileName(Module *Module); 
-   
-   /// Retrieve the name of the prebuilt module file that should be used 
-   /// to load a module with the given name. 
-   /// 
-   /// \param ModuleName The module whose module file name will be returned. 
-   /// 
-   /// \param FileMapOnly If true, then only look in the explicit module name 
-   //  to file name map and skip the directory search. 
-   /// 
-   /// \returns The name of the module file that corresponds to this module, 
-   /// or an empty string if this module does not correspond to any module file. 
-   std::string getPrebuiltModuleFileName(StringRef ModuleName, 
-                                         bool FileMapOnly = false); 
-   
-   /// Retrieve the name of the prebuilt module file that should be used 
-   /// to load the given module. 
-   /// 
-   /// \param Module The module whose module file name will be returned. 
-   /// 
-   /// \returns The name of the module file that corresponds to this module, 
-   /// or an empty string if this module does not correspond to any module file. 
-   std::string getPrebuiltImplicitModuleFileName(Module *Module); 
-   
-   /// Retrieve the name of the (to-be-)cached module file that should 
-   /// be used to load a module with the given name. 
-   /// 
-   /// \param ModuleName The module whose module file name will be returned. 
-   /// 
-   /// \param ModuleMapPath A path that when combined with \c ModuleName 
-   /// uniquely identifies this module. See Module::ModuleMap. 
-   /// 
-   /// \returns The name of the module file that corresponds to this module, 
-   /// or an empty string if this module does not correspond to any module file. 
-   std::string getCachedModuleFileName(StringRef ModuleName, 
-                                       StringRef ModuleMapPath); 
-   
-   /// Lookup a module Search for a module with the given name. 
-   /// 
-   /// \param ModuleName The name of the module we're looking for. 
-   /// 
-   /// \param ImportLoc Location of the module include/import. 
-   /// 
-   /// \param AllowSearch Whether we are allowed to search in the various 
-   /// search directories to produce a module definition. If not, this lookup 
-   /// will only return an already-known module. 
-   /// 
-   /// \param AllowExtraModuleMapSearch Whether we allow to search modulemaps 
-   /// in subdirectories. 
-   /// 
-   /// \returns The module with the given name. 
-   Module *lookupModule(StringRef ModuleName, 
-                        SourceLocation ImportLoc = SourceLocation(), 
-                        bool AllowSearch = true, 
-                        bool AllowExtraModuleMapSearch = false); 
-   
-   /// Try to find a module map file in the given directory, returning 
-   /// \c nullptr if none is found. 
-   const FileEntry *lookupModuleMapFile(const DirectoryEntry *Dir, 
-                                        bool IsFramework); 
-   
-   /// Determine whether there is a module map that may map the header 
-   /// with the given file name to a (sub)module. 
-   /// Always returns false if modules are disabled. 
-   /// 
-   /// \param Filename The name of the file. 
-   /// 
-   /// \param Root The "root" directory, at which we should stop looking for 
-   /// module maps. 
-   /// 
-   /// \param IsSystem Whether the directories we're looking at are system 
-   /// header directories. 
-   bool hasModuleMap(StringRef Filename, const DirectoryEntry *Root, 
-                     bool IsSystem); 
-   
-   /// Retrieve the module that corresponds to the given file, if any. 
-   /// 
-   /// \param File The header that we wish to map to a module. 
-   /// \param AllowTextual Whether we want to find textual headers too. 
-   ModuleMap::KnownHeader findModuleForHeader(const FileEntry *File, 
-                                              bool AllowTextual = false, 
-                                              bool AllowExcluded = false) const; 
-   
-   /// Retrieve all the modules corresponding to the given file. 
-   /// 
-   /// \ref findModuleForHeader should typically be used instead of this. 
-   ArrayRef<ModuleMap::KnownHeader> 
-   findAllModulesForHeader(const FileEntry *File) const; 
-   
-   /// Read the contents of the given module map file. 
-   /// 
-   /// \param File The module map file. 
-   /// \param IsSystem Whether this file is in a system header directory. 
-   /// \param ID If the module map file is already mapped (perhaps as part of 
-   ///        processing a preprocessed module), the ID of the file. 
-   /// \param Offset [inout] An offset within ID to start parsing. On exit, 
-   ///        filled by the end of the parsed contents (either EOF or the 
-   ///        location of an end-of-module-map pragma). 
-   /// \param OriginalModuleMapFile The original path to the module map file, 
-   ///        used to resolve paths within the module (this is required when 
-   ///        building the module from preprocessed source). 
-   /// \returns true if an error occurred, false otherwise. 
-   bool loadModuleMapFile(const FileEntry *File, bool IsSystem, 
-                          FileID ID = FileID(), unsigned *Offset = nullptr, 
-                          StringRef OriginalModuleMapFile = StringRef()); 
-   
-   /// Collect the set of all known, top-level modules. 
-   /// 
-   /// \param Modules Will be filled with the set of known, top-level modules. 
-   void collectAllModules(SmallVectorImpl<Module *> &Modules); 
-   
-   /// Load all known, top-level system modules. 
-   void loadTopLevelSystemModules(); 
-   
- private: 
-   /// Lookup a module with the given module name and search-name. 
-   /// 
-   /// \param ModuleName The name of the module we're looking for. 
-   /// 
-   /// \param SearchName The "search-name" to derive filesystem paths from 
-   /// when looking for the module map; this is usually equal to ModuleName, 
-   /// but for compatibility with some buggy frameworks, additional attempts 
-   /// may be made to find the module under a related-but-different search-name. 
-   /// 
-   /// \param ImportLoc Location of the module include/import. 
-   /// 
-   /// \param AllowExtraModuleMapSearch Whether we allow to search modulemaps 
-   /// in subdirectories. 
-   /// 
-   /// \returns The module named ModuleName. 
-   Module *lookupModule(StringRef ModuleName, StringRef SearchName, 
-                        SourceLocation ImportLoc, 
-                        bool AllowExtraModuleMapSearch = false); 
-   
-   /// Retrieve the name of the (to-be-)cached module file that should 
-   /// be used to load a module with the given name. 
-   /// 
-   /// \param ModuleName The module whose module file name will be returned. 
-   /// 
-   /// \param ModuleMapPath A path that when combined with \c ModuleName 
-   /// uniquely identifies this module. See Module::ModuleMap. 
-   /// 
-   /// \param CachePath A path to the module cache. 
-   /// 
-   /// \returns The name of the module file that corresponds to this module, 
-   /// or an empty string if this module does not correspond to any module file. 
-   std::string getCachedModuleFileNameImpl(StringRef ModuleName, 
-                                           StringRef ModuleMapPath, 
-                                           StringRef CachePath); 
-   
-   /// Retrieve a module with the given name, which may be part of the 
-   /// given framework. 
-   /// 
-   /// \param Name The name of the module to retrieve. 
-   /// 
-   /// \param Dir The framework directory (e.g., ModuleName.framework). 
-   /// 
-   /// \param IsSystem Whether the framework directory is part of the system 
-   /// frameworks. 
-   /// 
-   /// \returns The module, if found; otherwise, null. 
-   Module *loadFrameworkModule(StringRef Name, DirectoryEntryRef Dir, 
-                               bool IsSystem); 
-   
-   /// Load all of the module maps within the immediate subdirectories 
-   /// of the given search directory. 
-   void loadSubdirectoryModuleMaps(DirectoryLookup &SearchDir); 
-   
-   /// Find and suggest a usable module for the given file. 
-   /// 
-   /// \return \c true if the file can be used, \c false if we are not permitted to 
-   ///         find this file due to requirements from \p RequestingModule. 
-   bool findUsableModuleForHeader(const FileEntry *File, 
-                                  const DirectoryEntry *Root, 
-                                  Module *RequestingModule, 
-                                  ModuleMap::KnownHeader *SuggestedModule, 
-                                  bool IsSystemHeaderDir); 
-   
-   /// Find and suggest a usable module for the given file, which is part of 
-   /// the specified framework. 
-   /// 
-   /// \return \c true if the file can be used, \c false if we are not permitted to 
-   ///         find this file due to requirements from \p RequestingModule. 
-   bool findUsableModuleForFrameworkHeader( 
-       const FileEntry *File, StringRef FrameworkName, Module *RequestingModule, 
-       ModuleMap::KnownHeader *SuggestedModule, bool IsSystemFramework); 
-   
-   /// Look up the file with the specified name and determine its owning 
-   /// module. 
-   OptionalFileEntryRef 
-   getFileAndSuggestModule(StringRef FileName, SourceLocation IncludeLoc, 
-                           const DirectoryEntry *Dir, bool IsSystemHeaderDir, 
-                           Module *RequestingModule, 
-                           ModuleMap::KnownHeader *SuggestedModule, 
-                           bool OpenFile = true, bool CacheFailures = true); 
-   
-   /// Cache the result of a successful lookup at the given include location 
-   /// using the search path at \c HitIt. 
-   void cacheLookupSuccess(LookupFileCacheInfo &CacheLookup, 
-                           ConstSearchDirIterator HitIt, 
-                           SourceLocation IncludeLoc); 
-   
-   /// Note that a lookup at the given include location was successful using the 
-   /// search path at index `HitIdx`. 
-   void noteLookupUsage(unsigned HitIdx, SourceLocation IncludeLoc); 
-   
- public: 
-   /// Retrieve the module map. 
-   ModuleMap &getModuleMap() { return ModMap; } 
-   
-   /// Retrieve the module map. 
-   const ModuleMap &getModuleMap() const { return ModMap; } 
-   
-   unsigned header_file_size() const { return FileInfo.size(); } 
-   
-   /// Return the HeaderFileInfo structure for the specified FileEntry, 
-   /// in preparation for updating it in some way. 
-   HeaderFileInfo &getFileInfo(const FileEntry *FE); 
-   
-   /// Return the HeaderFileInfo structure for the specified FileEntry, 
-   /// if it has ever been filled in. 
-   /// \param WantExternal Whether the caller wants purely-external header file 
-   ///        info (where \p External is true). 
-   const HeaderFileInfo *getExistingFileInfo(const FileEntry *FE, 
-                                             bool WantExternal = true) const; 
-   
-   SearchDirIterator search_dir_begin() { return {*this, 0}; } 
-   SearchDirIterator search_dir_end() { return {*this, SearchDirs.size()}; } 
-   SearchDirRange search_dir_range() { 
-     return {search_dir_begin(), search_dir_end()}; 
-   } 
-   
-   ConstSearchDirIterator search_dir_begin() const { return quoted_dir_begin(); } 
-   ConstSearchDirIterator search_dir_nth(size_t n) const { 
-     assert(n < SearchDirs.size()); 
-     return {*this, n}; 
-   } 
-   ConstSearchDirIterator search_dir_end() const { return system_dir_end(); } 
-   ConstSearchDirRange search_dir_range() const { 
-     return {search_dir_begin(), search_dir_end()}; 
-   } 
-   
-   unsigned search_dir_size() const { return SearchDirs.size(); } 
-   
-   ConstSearchDirIterator quoted_dir_begin() const { return {*this, 0}; } 
-   ConstSearchDirIterator quoted_dir_end() const { return angled_dir_begin(); } 
-   
-   ConstSearchDirIterator angled_dir_begin() const { 
-     return {*this, AngledDirIdx}; 
-   } 
-   ConstSearchDirIterator angled_dir_end() const { return system_dir_begin(); } 
-   
-   ConstSearchDirIterator system_dir_begin() const { 
-     return {*this, SystemDirIdx}; 
-   } 
-   ConstSearchDirIterator system_dir_end() const { 
-     return {*this, SearchDirs.size()}; 
-   } 
-   
-   /// Get the index of the given search directory. 
-   unsigned searchDirIdx(const DirectoryLookup &DL) const; 
-   
-   /// Retrieve a uniqued framework name. 
-   StringRef getUniqueFrameworkName(StringRef Framework); 
-   
-   /// Retrieve the include name for the header. 
-   /// 
-   /// \param File The entry for a given header. 
-   /// \returns The name of how the file was included when the header's location 
-   /// was resolved. 
-   StringRef getIncludeNameForHeader(const FileEntry *File) const; 
-   
-   /// Suggest a path by which the specified file could be found, for use in 
-   /// diagnostics to suggest a #include. Returned path will only contain forward 
-   /// slashes as separators. MainFile is the absolute path of the file that we 
-   /// are generating the diagnostics for. It will try to shorten the path using 
-   /// MainFile location, if none of the include search directories were prefix 
-   /// of File. 
-   /// 
-   /// \param IsSystem If non-null, filled in to indicate whether the suggested 
-   ///        path is relative to a system header directory. 
-   std::string suggestPathToFileForDiagnostics(const FileEntry *File, 
-                                               llvm::StringRef MainFile, 
-                                               bool *IsSystem = nullptr); 
-   
-   /// Suggest a path by which the specified file could be found, for use in 
-   /// diagnostics to suggest a #include. Returned path will only contain forward 
-   /// slashes as separators. MainFile is the absolute path of the file that we 
-   /// are generating the diagnostics for. It will try to shorten the path using 
-   /// MainFile location, if none of the include search directories were prefix 
-   /// of File. 
-   /// 
-   /// \param WorkingDir If non-empty, this will be prepended to search directory 
-   /// paths that are relative. 
-   std::string suggestPathToFileForDiagnostics(llvm::StringRef File, 
-                                               llvm::StringRef WorkingDir, 
-                                               llvm::StringRef MainFile, 
-                                               bool *IsSystem = nullptr); 
-   
-   void PrintStats(); 
-   
-   size_t getTotalMemory() const; 
-   
- private: 
-   /// Describes what happened when we tried to load a module map file. 
-   enum LoadModuleMapResult { 
-     /// The module map file had already been loaded. 
-     LMM_AlreadyLoaded, 
-   
-     /// The module map file was loaded by this invocation. 
-     LMM_NewlyLoaded, 
-   
-     /// There is was directory with the given name. 
-     LMM_NoDirectory, 
-   
-     /// There was either no module map file or the module map file was 
-     /// invalid. 
-     LMM_InvalidModuleMap 
-   }; 
-   
-   LoadModuleMapResult loadModuleMapFileImpl(const FileEntry *File, 
-                                             bool IsSystem, 
-                                             DirectoryEntryRef Dir, 
-                                             FileID ID = FileID(), 
-                                             unsigned *Offset = nullptr); 
-   
-   /// Try to load the module map file in the given directory. 
-   /// 
-   /// \param DirName The name of the directory where we will look for a module 
-   /// map file. 
-   /// \param IsSystem Whether this is a system header directory. 
-   /// \param IsFramework Whether this is a framework directory. 
-   /// 
-   /// \returns The result of attempting to load the module map file from the 
-   /// named directory. 
-   LoadModuleMapResult loadModuleMapFile(StringRef DirName, bool IsSystem, 
-                                         bool IsFramework); 
-   
-   /// Try to load the module map file in the given directory. 
-   /// 
-   /// \param Dir The directory where we will look for a module map file. 
-   /// \param IsSystem Whether this is a system header directory. 
-   /// \param IsFramework Whether this is a framework directory. 
-   /// 
-   /// \returns The result of attempting to load the module map file from the 
-   /// named directory. 
-   LoadModuleMapResult loadModuleMapFile(DirectoryEntryRef Dir, bool IsSystem, 
-                                         bool IsFramework); 
- }; 
-   
- /// Apply the header search options to get given HeaderSearch object. 
- void ApplyHeaderSearchOptions(HeaderSearch &HS, 
-                               const HeaderSearchOptions &HSOpts, 
-                               const LangOptions &Lang, 
-                               const llvm::Triple &triple); 
-   
- } // namespace clang 
-   
- #endif // LLVM_CLANG_LEX_HEADERSEARCH_H 
-