1 files changed, 43 insertions, 29 deletions

diff --git a/include/clang/Lex/HeaderMap.h b/include/clang/Lex/HeaderMap.h
index 183361e4f8c0c..8466f1a24d52d 100644
--- a/include/clang/Lex/HeaderMap.h
+++ b/include/clang/Lex/HeaderMap.h
@@ -15,60 +15,74 @@
 #define LLVM_CLANG_LEX_HEADERMAP_H
 
 #include "clang/Basic/LLVM.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include <memory>
 
-namespace llvm {
-  class MemoryBuffer;
-}
 namespace clang {
-  class FileEntry;
-  class FileManager;
-  struct HMapBucket;
-  struct HMapHeader;
 
-/// This class represents an Apple concept known as a 'header map'.  To the
-/// \#include file resolution process, it basically acts like a directory of
-/// symlinks to files.  Its advantages are that it is dense and more efficient
-/// to create and process than a directory of symlinks.
-class HeaderMap {
-  HeaderMap(const HeaderMap &) = delete;
-  void operator=(const HeaderMap &) = delete;
+class FileEntry;
+class FileManager;
+struct HMapBucket;
+struct HMapHeader;
 
+/// Implementation for \a HeaderMap that doesn't depend on \a FileManager.
+class HeaderMapImpl {
   std::unique_ptr<const llvm::MemoryBuffer> FileBuffer;
   bool NeedsBSwap;
 
-  HeaderMap(std::unique_ptr<const llvm::MemoryBuffer> File, bool BSwap)
-      : FileBuffer(std::move(File)), NeedsBSwap(BSwap) {}
 public:
-  /// HeaderMap::Create - This attempts to load the specified file as a header
-  /// map.  If it doesn't look like a HeaderMap, it gives up and returns null.
-  static const HeaderMap *Create(const FileEntry *FE, FileManager &FM);
+  HeaderMapImpl(std::unique_ptr<const llvm::MemoryBuffer> File, bool NeedsBSwap)
+      : FileBuffer(std::move(File)), NeedsBSwap(NeedsBSwap) {}
 
-  /// LookupFile - Check to see if the specified relative filename is located in
-  /// this HeaderMap.  If so, open it and return its FileEntry.
-  /// If RawPath is not NULL and the file is found, RawPath will be set to the
-  /// raw path at which the file was found in the file system. For example,
-  /// for a search path ".." and a filename "../file.h" this would be
-  /// "../../file.h".
-  const FileEntry *LookupFile(StringRef Filename, FileManager &FM) const;
+  // Check for a valid header and extract the byte swap.
+  static bool checkHeader(const llvm::MemoryBuffer &File, bool &NeedsByteSwap);
 
   /// If the specified relative filename is located in this HeaderMap return
   /// the filename it is mapped to, otherwise return an empty StringRef.
   StringRef lookupFilename(StringRef Filename,
                            SmallVectorImpl<char> &DestPath) const;
 
-  /// getFileName - Return the filename of the headermap.
+  /// Return the filename of the headermap.
   const char *getFileName() const;
 
-  /// dump - Print the contents of this headermap to stderr.
+  /// Print the contents of this headermap to stderr.
   void dump() const;
 
 private:
   unsigned getEndianAdjustedWord(unsigned X) const;
   const HMapHeader &getHeader() const;
   HMapBucket getBucket(unsigned BucketNo) const;
-  const char *getString(unsigned StrTabIdx) const;
+
+  /// Look up the specified string in the string table.  If the string index is
+  /// not valid, return None.
+  Optional<StringRef> getString(unsigned StrTabIdx) const;
+};
+
+/// This class represents an Apple concept known as a 'header map'.  To the
+/// \#include file resolution process, it basically acts like a directory of
+/// symlinks to files.  Its advantages are that it is dense and more efficient
+/// to create and process than a directory of symlinks.
+class HeaderMap : private HeaderMapImpl {
+  HeaderMap(std::unique_ptr<const llvm::MemoryBuffer> File, bool BSwap)
+      : HeaderMapImpl(std::move(File), BSwap) {}
+
+public:
+  /// This attempts to load the specified file as a header map.  If it doesn't
+  /// look like a HeaderMap, it gives up and returns null.
+  static const HeaderMap *Create(const FileEntry *FE, FileManager &FM);
+
+  /// Check to see if the specified relative filename is located in this
+  /// HeaderMap.  If so, open it and return its FileEntry.  If RawPath is not
+  /// NULL and the file is found, RawPath will be set to the raw path at which
+  /// the file was found in the file system. For example, for a search path
+  /// ".." and a filename "../file.h" this would be "../../file.h".
+  const FileEntry *LookupFile(StringRef Filename, FileManager &FM) const;
+
+  using HeaderMapImpl::lookupFilename;
+  using HeaderMapImpl::getFileName;
+  using HeaderMapImpl::dump;
 };
 
 } // end namespace clang.