lib/Lex/PPLexerChange.cpp - platform/external/clang - Git at Google

 //===--- PPLexerChange.cpp - Handle changing lexers in the preprocessor ---===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements pieces of the Preprocessor interface that manage the
 // current lexer stack.
 //
 //===----------------------------------------------------------------------===//

 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/LexDiagnostic.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/PathV2.h"
 #include "llvm/ADT/StringSwitch.h"
 using namespace clang;

 PPCallbacks::~PPCallbacks() {}

 //===----------------------------------------------------------------------===//
 // Miscellaneous Methods.
 //===----------------------------------------------------------------------===//

 /// isInPrimaryFile - Return true if we're in the top-level file, not in a
 /// \#include.  This looks through macro expansions and active _Pragma lexers.
 bool Preprocessor::isInPrimaryFile() const {
   if (IsFileLexer())
     return IncludeMacroStack.empty();

   // If there are any stacked lexers, we're in a #include.
   assert(IsFileLexer(IncludeMacroStack[0]) &&
          "Top level include stack isn't our primary lexer?");
   for (unsigned i = 1, e = IncludeMacroStack.size(); i != e; ++i)
     if (IsFileLexer(IncludeMacroStack[i]))
       return false;
   return true;
 }

 /// getCurrentLexer - Return the current file lexer being lexed from.  Note
 /// that this ignores any potentially active macro expansions and _Pragma
 /// expansions going on at the time.
 PreprocessorLexer *Preprocessor::getCurrentFileLexer() const {
   if (IsFileLexer())
     return CurPPLexer;

   // Look for a stacked lexer.
   for (unsigned i = IncludeMacroStack.size(); i != 0; --i) {
     const IncludeStackInfo& ISI = IncludeMacroStack[i-1];
     if (IsFileLexer(ISI))
       return ISI.ThePPLexer;
   }
   return 0;
 }


 //===----------------------------------------------------------------------===//
 // Methods for Entering and Callbacks for leaving various contexts
 //===----------------------------------------------------------------------===//

 /// EnterSourceFile - Add a source file to the top of the include stack and
 /// start lexing tokens from it instead of the current buffer.
 void Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir,
                                    SourceLocation Loc) {
   assert(CurTokenLexer == 0 && "Cannot #include a file inside a macro!");
   ++NumEnteredSourceFiles;

   if (MaxIncludeStackDepth < IncludeMacroStack.size())
     MaxIncludeStackDepth = IncludeMacroStack.size();

   if (PTH) {
     if (PTHLexer *PL = PTH->CreateLexer(FID)) {
       EnterSourceFileWithPTH(PL, CurDir);
       return;
     }
   }

   // Get the MemoryBuffer for this FID, if it fails, we fail.
   bool Invalid = false;
   const llvm::MemoryBuffer *InputFile =
     getSourceManager().getBuffer(FID, Loc, &Invalid);
   if (Invalid) {
     SourceLocation FileStart = SourceMgr.getLocForStartOfFile(FID);
     Diag(Loc, diag::err_pp_error_opening_file)
       << std::string(SourceMgr.getBufferName(FileStart)) << "";
     return;
   }

   if (isCodeCompletionEnabled() &&
       SourceMgr.getFileEntryForID(FID) == CodeCompletionFile) {
     CodeCompletionFileLoc = SourceMgr.getLocForStartOfFile(FID);
     CodeCompletionLoc =
         CodeCompletionFileLoc.getLocWithOffset(CodeCompletionOffset);
   }

   EnterSourceFileWithLexer(new Lexer(FID, InputFile, *this), CurDir);
   return;
 }

 /// EnterSourceFileWithLexer - Add a source file to the top of the include stack
 ///  and start lexing tokens from it instead of the current buffer.
 void Preprocessor::EnterSourceFileWithLexer(Lexer *TheLexer,
                                             const DirectoryLookup *CurDir) {

   // Add the current lexer to the include stack.
   if (CurPPLexer || CurTokenLexer)
     PushIncludeMacroStack();

   CurLexer.reset(TheLexer);
   CurPPLexer = TheLexer;
   CurDirLookup = CurDir;
   if (CurLexerKind != CLK_LexAfterModuleImport)
     CurLexerKind = CLK_Lexer;

   // Notify the client, if desired, that we are in a new source file.
   if (Callbacks && !CurLexer->Is_PragmaLexer) {
     SrcMgr::CharacteristicKind FileType =
        SourceMgr.getFileCharacteristic(CurLexer->getFileLoc());

     Callbacks->FileChanged(CurLexer->getFileLoc(),
                            PPCallbacks::EnterFile, FileType);
   }
 }

 /// EnterSourceFileWithPTH - Add a source file to the top of the include stack
 /// and start getting tokens from it using the PTH cache.
 void Preprocessor::EnterSourceFileWithPTH(PTHLexer *PL,
                                           const DirectoryLookup *CurDir) {

   if (CurPPLexer || CurTokenLexer)
     PushIncludeMacroStack();

   CurDirLookup = CurDir;
   CurPTHLexer.reset(PL);
   CurPPLexer = CurPTHLexer.get();
   if (CurLexerKind != CLK_LexAfterModuleImport)
     CurLexerKind = CLK_PTHLexer;

   // Notify the client, if desired, that we are in a new source file.
   if (Callbacks) {
     FileID FID = CurPPLexer->getFileID();
     SourceLocation EnterLoc = SourceMgr.getLocForStartOfFile(FID);
     SrcMgr::CharacteristicKind FileType =
       SourceMgr.getFileCharacteristic(EnterLoc);
     Callbacks->FileChanged(EnterLoc, PPCallbacks::EnterFile, FileType);
   }
 }

 /// EnterMacro - Add a Macro to the top of the include stack and start lexing
 /// tokens from it instead of the current buffer.
 void Preprocessor::EnterMacro(Token &Tok, SourceLocation ILEnd,
                               MacroArgs *Args) {
   PushIncludeMacroStack();
   CurDirLookup = 0;

   if (NumCachedTokenLexers == 0) {
     CurTokenLexer.reset(new TokenLexer(Tok, ILEnd, Args, *this));
   } else {
     CurTokenLexer.reset(TokenLexerCache[--NumCachedTokenLexers]);
     CurTokenLexer->Init(Tok, ILEnd, Args);
   }
   if (CurLexerKind != CLK_LexAfterModuleImport)
     CurLexerKind = CLK_TokenLexer;
 }

 /// EnterTokenStream - Add a "macro" context to the top of the include stack,
 /// which will cause the lexer to start returning the specified tokens.
 ///
 /// If DisableMacroExpansion is true, tokens lexed from the token stream will
 /// not be subject to further macro expansion.  Otherwise, these tokens will
 /// be re-macro-expanded when/if expansion is enabled.
 ///
 /// If OwnsTokens is false, this method assumes that the specified stream of
 /// tokens has a permanent owner somewhere, so they do not need to be copied.
 /// If it is true, it assumes the array of tokens is allocated with new[] and
 /// must be freed.
 ///
 void Preprocessor::EnterTokenStream(const Token *Toks, unsigned NumToks,
                                     bool DisableMacroExpansion,
                                     bool OwnsTokens) {
   // Save our current state.
   PushIncludeMacroStack();
   CurDirLookup = 0;

   // Create a macro expander to expand from the specified token stream.
   if (NumCachedTokenLexers == 0) {
     CurTokenLexer.reset(new TokenLexer(Toks, NumToks, DisableMacroExpansion,
                                        OwnsTokens, *this));
   } else {
     CurTokenLexer.reset(TokenLexerCache[--NumCachedTokenLexers]);
     CurTokenLexer->Init(Toks, NumToks, DisableMacroExpansion, OwnsTokens);
   }
   if (CurLexerKind != CLK_LexAfterModuleImport)
     CurLexerKind = CLK_TokenLexer;
 }

 /// \brief Compute the relative path that names the given file relative to
 /// the given directory.
 static void computeRelativePath(FileManager &FM, const DirectoryEntry *Dir,
                                 const FileEntry *File,
                                 SmallString<128> &Result) {
   Result.clear();

   StringRef FilePath = File->getDir()->getName();
   StringRef Path = FilePath;
   while (!Path.empty()) {
     if (const DirectoryEntry *CurDir = FM.getDirectory(Path)) {
       if (CurDir == Dir) {
         Result = FilePath.substr(Path.size());
         llvm::sys::path::append(Result,
                                 llvm::sys::path::filename(File->getName()));
         return;
       }
     }

     Path = llvm::sys::path::parent_path(Path);
   }

   Result = File->getName();
 }

 /// HandleEndOfFile - This callback is invoked when the lexer hits the end of
 /// the current file.  This either returns the EOF token or pops a level off
 /// the include stack and keeps going.
 bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
   assert(!CurTokenLexer &&
          "Ending a file when currently in a macro!");

   // See if this file had a controlling macro.
   if (CurPPLexer) {  // Not ending a macro, ignore it.
     if (const IdentifierInfo *ControllingMacro =
           CurPPLexer->MIOpt.GetControllingMacroAtEndOfFile()) {
       // Okay, this has a controlling macro, remember in HeaderFileInfo.
       if (const FileEntry *FE =
             SourceMgr.getFileEntryForID(CurPPLexer->getFileID()))
         HeaderInfo.SetFileControllingMacro(FE, ControllingMacro);
     }
   }

   // Complain about reaching a true EOF within arc_cf_code_audited.
   // We don't want to complain about reaching the end of a macro
   // instantiation or a _Pragma.
   if (PragmaARCCFCodeAuditedLoc.isValid() &&
       !isEndOfMacro && !(CurLexer && CurLexer->Is_PragmaLexer)) {
     Diag(PragmaARCCFCodeAuditedLoc, diag::err_pp_eof_in_arc_cf_code_audited);

     // Recover by leaving immediately.
     PragmaARCCFCodeAuditedLoc = SourceLocation();
   }

   // If this is a #include'd file, pop it off the include stack and continue
   // lexing the #includer file.
   if (!IncludeMacroStack.empty()) {

     // If we lexed the code-completion file, act as if we reached EOF.
     if (isCodeCompletionEnabled() && CurPPLexer &&
         SourceMgr.getLocForStartOfFile(CurPPLexer->getFileID()) ==
             CodeCompletionFileLoc) {
       if (CurLexer) {
         Result.startToken();
         CurLexer->FormTokenWithChars(Result, CurLexer->BufferEnd, tok::eof);
         CurLexer.reset();
       } else {
         assert(CurPTHLexer && "Got EOF but no current lexer set!");
         CurPTHLexer->getEOF(Result);
         CurPTHLexer.reset();
       }

       CurPPLexer = 0;
       return true;
     }

     if (!isEndOfMacro && CurPPLexer &&
         SourceMgr.getIncludeLoc(CurPPLexer->getFileID()).isValid()) {
       // Notify SourceManager to record the number of FileIDs that were created
       // during lexing of the #include'd file.
       unsigned NumFIDs =
           SourceMgr.local_sloc_entry_size() -
           CurPPLexer->getInitialNumSLocEntries() + 1/*#include'd file*/;
       SourceMgr.setNumCreatedFIDsForFileID(CurPPLexer->getFileID(), NumFIDs);
     }

     FileID ExitedFID;
     if (Callbacks && !isEndOfMacro && CurPPLexer)
       ExitedFID = CurPPLexer->getFileID();

     // We're done with the #included file.
     RemoveTopOfLexerStack();

     // Notify the client, if desired, that we are in a new source file.
     if (Callbacks && !isEndOfMacro && CurPPLexer) {
       SrcMgr::CharacteristicKind FileType =
         SourceMgr.getFileCharacteristic(CurPPLexer->getSourceLocation());
       Callbacks->FileChanged(CurPPLexer->getSourceLocation(),
                              PPCallbacks::ExitFile, FileType, ExitedFID);
     }

     // Client should lex another token.
     return false;
   }

   // If the file ends with a newline, form the EOF token on the newline itself,
   // rather than "on the line following it", which doesn't exist.  This makes
   // diagnostics relating to the end of file include the last file that the user
   // actually typed, which is goodness.
   if (CurLexer) {
     const char *EndPos = CurLexer->BufferEnd;
     if (EndPos != CurLexer->BufferStart &&
         (EndPos[-1] == '\n' || EndPos[-1] == '\r')) {
       --EndPos;

       // Handle \n\r and \r\n:
       if (EndPos != CurLexer->BufferStart &&
           (EndPos[-1] == '\n' || EndPos[-1] == '\r') &&
           EndPos[-1] != EndPos[0])
         --EndPos;
     }

     Result.startToken();
     CurLexer->BufferPtr = EndPos;
     CurLexer->FormTokenWithChars(Result, EndPos, tok::eof);

     if (!isIncrementalProcessingEnabled())
       // We're done with lexing.
       CurLexer.reset();
   } else {
     assert(CurPTHLexer && "Got EOF but no current lexer set!");
     CurPTHLexer->getEOF(Result);
     CurPTHLexer.reset();
   }

   if (!isIncrementalProcessingEnabled())
     CurPPLexer = 0;

   // This is the end of the top-level file. 'WarnUnusedMacroLocs' has collected
   // all macro locations that we need to warn because they are not used.
   for (WarnUnusedMacroLocsTy::iterator
          I=WarnUnusedMacroLocs.begin(), E=WarnUnusedMacroLocs.end(); I!=E; ++I)
     Diag(*I, diag::pp_macro_not_used);

   // If we are building a module that has an umbrella header, make sure that
   // each of the headers within the directory covered by the umbrella header
   // was actually included by the umbrella header.
   if (Module *Mod = getCurrentModule()) {
     if (Mod->getUmbrellaHeader()) {
       SourceLocation StartLoc
         = SourceMgr.getLocForStartOfFile(SourceMgr.getMainFileID());

       if (getDiagnostics().getDiagnosticLevel(
             diag::warn_uncovered_module_header,
             StartLoc) != DiagnosticsEngine::Ignored) {
         ModuleMap &ModMap = getHeaderSearchInfo().getModuleMap();
         typedef llvm::sys::fs::recursive_directory_iterator
           recursive_directory_iterator;
         const DirectoryEntry *Dir = Mod->getUmbrellaDir();
         llvm::error_code EC;
         for (recursive_directory_iterator Entry(Dir->getName(), EC), End;
              Entry != End && !EC; Entry.increment(EC)) {
           using llvm::StringSwitch;

           // Check whether this entry has an extension typically associated with
           // headers.
           if (!StringSwitch<bool>(llvm::sys::path::extension(Entry->path()))
                  .Cases(".h", ".H", ".hh", ".hpp", true)
                  .Default(false))
             continue;

           if (const FileEntry *Header = getFileManager().getFile(Entry->path()))
             if (!getSourceManager().hasFileInfo(Header)) {
               if (!ModMap.isHeaderInUnavailableModule(Header)) {
                 // Find the relative path that would access this header.
                 SmallString<128> RelativePath;
                 computeRelativePath(FileMgr, Dir, Header, RelativePath);
                 Diag(StartLoc, diag::warn_uncovered_module_header)
                   << RelativePath;
               }
             }
         }
       }
     }
   }

   return true;
 }

 /// HandleEndOfTokenLexer - This callback is invoked when the current TokenLexer
 /// hits the end of its token stream.
 bool Preprocessor::HandleEndOfTokenLexer(Token &Result) {
   assert(CurTokenLexer && !CurPPLexer &&
          "Ending a macro when currently in a #include file!");

   if (!MacroExpandingLexersStack.empty() &&
       MacroExpandingLexersStack.back().first == CurTokenLexer.get())
     removeCachedMacroExpandedTokensOfLastLexer();

   // Delete or cache the now-dead macro expander.
   if (NumCachedTokenLexers == TokenLexerCacheSize)
     CurTokenLexer.reset();
   else
     TokenLexerCache[NumCachedTokenLexers++] = CurTokenLexer.take();

   // Handle this like a #include file being popped off the stack.
   return HandleEndOfFile(Result, true);
 }

 /// RemoveTopOfLexerStack - Pop the current lexer/macro exp off the top of the
 /// lexer stack.  This should only be used in situations where the current
 /// state of the top-of-stack lexer is unknown.
 void Preprocessor::RemoveTopOfLexerStack() {
   assert(!IncludeMacroStack.empty() && "Ran out of stack entries to load");

   if (CurTokenLexer) {
     // Delete or cache the now-dead macro expander.
     if (NumCachedTokenLexers == TokenLexerCacheSize)
       CurTokenLexer.reset();
     else
       TokenLexerCache[NumCachedTokenLexers++] = CurTokenLexer.take();
   }

   PopIncludeMacroStack();
 }

 /// HandleMicrosoftCommentPaste - When the macro expander pastes together a
 /// comment (/##/) in microsoft mode, this method handles updating the current
 /// state, returning the token on the next source line.
 void Preprocessor::HandleMicrosoftCommentPaste(Token &Tok) {
   assert(CurTokenLexer && !CurPPLexer &&
          "Pasted comment can only be formed from macro");

   // We handle this by scanning for the closest real lexer, switching it to
   // raw mode and preprocessor mode.  This will cause it to return \n as an
   // explicit EOD token.
   PreprocessorLexer *FoundLexer = 0;
   bool LexerWasInPPMode = false;
   for (unsigned i = 0, e = IncludeMacroStack.size(); i != e; ++i) {
     IncludeStackInfo &ISI = *(IncludeMacroStack.end()-i-1);
     if (ISI.ThePPLexer == 0) continue;  // Scan for a real lexer.

     // Once we find a real lexer, mark it as raw mode (disabling macro
     // expansions) and preprocessor mode (return EOD).  We know that the lexer
     // was *not* in raw mode before, because the macro that the comment came
     // from was expanded.  However, it could have already been in preprocessor
     // mode (#if COMMENT) in which case we have to return it to that mode and
     // return EOD.
     FoundLexer = ISI.ThePPLexer;
     FoundLexer->LexingRawMode = true;
     LexerWasInPPMode = FoundLexer->ParsingPreprocessorDirective;
     FoundLexer->ParsingPreprocessorDirective = true;
     break;
   }

   // Okay, we either found and switched over the lexer, or we didn't find a
   // lexer.  In either case, finish off the macro the comment came from, getting
   // the next token.
   if (!HandleEndOfTokenLexer(Tok)) Lex(Tok);

   // Discarding comments as long as we don't have EOF or EOD.  This 'comments
   // out' the rest of the line, including any tokens that came from other macros
   // that were active, as in:
   //  #define submacro a COMMENT b
   //    submacro c
   // which should lex to 'a' only: 'b' and 'c' should be removed.
   while (Tok.isNot(tok::eod) && Tok.isNot(tok::eof))
     Lex(Tok);

   // If we got an eod token, then we successfully found the end of the line.
   if (Tok.is(tok::eod)) {
     assert(FoundLexer && "Can't get end of line without an active lexer");
     // Restore the lexer back to normal mode instead of raw mode.
     FoundLexer->LexingRawMode = false;

     // If the lexer was already in preprocessor mode, just return the EOD token
     // to finish the preprocessor line.
     if (LexerWasInPPMode) return;

     // Otherwise, switch out of PP mode and return the next lexed token.
     FoundLexer->ParsingPreprocessorDirective = false;
     return Lex(Tok);
   }

   // If we got an EOF token, then we reached the end of the token stream but
   // didn't find an explicit \n.  This can only happen if there was no lexer
   // active (an active lexer would return EOD at EOF if there was no \n in
   // preprocessor directive mode), so just return EOF as our token.
   assert(!FoundLexer && "Lexer should return EOD before EOF in PP mode");
 }
	//===--- PPLexerChange.cpp - Handle changing lexers in the preprocessor ---===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file implements pieces of the Preprocessor interface that manage the
	// current lexer stack.
	//
	//===----------------------------------------------------------------------===//

	#include "clang/Lex/Preprocessor.h"
	#include "clang/Lex/HeaderSearch.h"
	#include "clang/Lex/MacroInfo.h"
	#include "clang/Lex/LexDiagnostic.h"
	#include "clang/Basic/FileManager.h"
	#include "clang/Basic/SourceManager.h"
	#include "llvm/Support/FileSystem.h"
	#include "llvm/Support/MemoryBuffer.h"
	#include "llvm/Support/PathV2.h"
	#include "llvm/ADT/StringSwitch.h"
	using namespace clang;

	PPCallbacks::~PPCallbacks() {}

	//===----------------------------------------------------------------------===//
	// Miscellaneous Methods.
	//===----------------------------------------------------------------------===//

	/// isInPrimaryFile - Return true if we're in the top-level file, not in a
	/// \#include. This looks through macro expansions and active _Pragma lexers.
	bool Preprocessor::isInPrimaryFile() const {
	if (IsFileLexer())
	return IncludeMacroStack.empty();

	// If there are any stacked lexers, we're in a #include.
	assert(IsFileLexer(IncludeMacroStack[0]) &&
	"Top level include stack isn't our primary lexer?");
	for (unsigned i = 1, e = IncludeMacroStack.size(); i != e; ++i)
	if (IsFileLexer(IncludeMacroStack[i]))
	return false;
	return true;
	}

	/// getCurrentLexer - Return the current file lexer being lexed from. Note
	/// that this ignores any potentially active macro expansions and _Pragma
	/// expansions going on at the time.
	PreprocessorLexer *Preprocessor::getCurrentFileLexer() const {
	if (IsFileLexer())
	return CurPPLexer;

	// Look for a stacked lexer.
	for (unsigned i = IncludeMacroStack.size(); i != 0; --i) {
	const IncludeStackInfo& ISI = IncludeMacroStack[i-1];
	if (IsFileLexer(ISI))
	return ISI.ThePPLexer;
	}
	return 0;
	}


	//===----------------------------------------------------------------------===//
	// Methods for Entering and Callbacks for leaving various contexts
	//===----------------------------------------------------------------------===//

	/// EnterSourceFile - Add a source file to the top of the include stack and
	/// start lexing tokens from it instead of the current buffer.
	void Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir,
	SourceLocation Loc) {
	assert(CurTokenLexer == 0 && "Cannot #include a file inside a macro!");
	++NumEnteredSourceFiles;

	if (MaxIncludeStackDepth < IncludeMacroStack.size())
	MaxIncludeStackDepth = IncludeMacroStack.size();

	if (PTH) {
	if (PTHLexer *PL = PTH->CreateLexer(FID)) {
	EnterSourceFileWithPTH(PL, CurDir);
	return;
	}
	}

	// Get the MemoryBuffer for this FID, if it fails, we fail.
	bool Invalid = false;
	const llvm::MemoryBuffer *InputFile =
	getSourceManager().getBuffer(FID, Loc, &Invalid);
	if (Invalid) {
	SourceLocation FileStart = SourceMgr.getLocForStartOfFile(FID);
	Diag(Loc, diag::err_pp_error_opening_file)
	<< std::string(SourceMgr.getBufferName(FileStart)) << "";
	return;
	}

	if (isCodeCompletionEnabled() &&
	SourceMgr.getFileEntryForID(FID) == CodeCompletionFile) {
	CodeCompletionFileLoc = SourceMgr.getLocForStartOfFile(FID);
	CodeCompletionLoc =
	CodeCompletionFileLoc.getLocWithOffset(CodeCompletionOffset);
	}

	EnterSourceFileWithLexer(new Lexer(FID, InputFile, *this), CurDir);
	return;
	}

	/// EnterSourceFileWithLexer - Add a source file to the top of the include stack
	/// and start lexing tokens from it instead of the current buffer.
	void Preprocessor::EnterSourceFileWithLexer(Lexer *TheLexer,
	const DirectoryLookup *CurDir) {

	// Add the current lexer to the include stack.
	if (CurPPLexer \|\| CurTokenLexer)
	PushIncludeMacroStack();

	CurLexer.reset(TheLexer);
	CurPPLexer = TheLexer;
	CurDirLookup = CurDir;
	if (CurLexerKind != CLK_LexAfterModuleImport)
	CurLexerKind = CLK_Lexer;

	// Notify the client, if desired, that we are in a new source file.
	if (Callbacks && !CurLexer->Is_PragmaLexer) {
	SrcMgr::CharacteristicKind FileType =
	SourceMgr.getFileCharacteristic(CurLexer->getFileLoc());

	Callbacks->FileChanged(CurLexer->getFileLoc(),
	PPCallbacks::EnterFile, FileType);
	}
	}

	/// EnterSourceFileWithPTH - Add a source file to the top of the include stack
	/// and start getting tokens from it using the PTH cache.
	void Preprocessor::EnterSourceFileWithPTH(PTHLexer *PL,
	const DirectoryLookup *CurDir) {

	if (CurPPLexer \|\| CurTokenLexer)
	PushIncludeMacroStack();

	CurDirLookup = CurDir;
	CurPTHLexer.reset(PL);
	CurPPLexer = CurPTHLexer.get();
	if (CurLexerKind != CLK_LexAfterModuleImport)
	CurLexerKind = CLK_PTHLexer;

	// Notify the client, if desired, that we are in a new source file.
	if (Callbacks) {
	FileID FID = CurPPLexer->getFileID();
	SourceLocation EnterLoc = SourceMgr.getLocForStartOfFile(FID);
	SrcMgr::CharacteristicKind FileType =
	SourceMgr.getFileCharacteristic(EnterLoc);
	Callbacks->FileChanged(EnterLoc, PPCallbacks::EnterFile, FileType);
	}
	}

	/// EnterMacro - Add a Macro to the top of the include stack and start lexing
	/// tokens from it instead of the current buffer.
	void Preprocessor::EnterMacro(Token &Tok, SourceLocation ILEnd,
	MacroArgs *Args) {
	PushIncludeMacroStack();
	CurDirLookup = 0;

	if (NumCachedTokenLexers == 0) {
	CurTokenLexer.reset(new TokenLexer(Tok, ILEnd, Args, *this));
	} else {
	CurTokenLexer.reset(TokenLexerCache[--NumCachedTokenLexers]);
	CurTokenLexer->Init(Tok, ILEnd, Args);
	}
	if (CurLexerKind != CLK_LexAfterModuleImport)
	CurLexerKind = CLK_TokenLexer;
	}

	/// EnterTokenStream - Add a "macro" context to the top of the include stack,
	/// which will cause the lexer to start returning the specified tokens.
	///
	/// If DisableMacroExpansion is true, tokens lexed from the token stream will
	/// not be subject to further macro expansion. Otherwise, these tokens will
	/// be re-macro-expanded when/if expansion is enabled.
	///
	/// If OwnsTokens is false, this method assumes that the specified stream of
	/// tokens has a permanent owner somewhere, so they do not need to be copied.
	/// If it is true, it assumes the array of tokens is allocated with new[] and
	/// must be freed.
	///
	void Preprocessor::EnterTokenStream(const Token *Toks, unsigned NumToks,
	bool DisableMacroExpansion,
	bool OwnsTokens) {
	// Save our current state.
	PushIncludeMacroStack();
	CurDirLookup = 0;

	// Create a macro expander to expand from the specified token stream.
	if (NumCachedTokenLexers == 0) {
	CurTokenLexer.reset(new TokenLexer(Toks, NumToks, DisableMacroExpansion,
	OwnsTokens, *this));
	} else {
	CurTokenLexer.reset(TokenLexerCache[--NumCachedTokenLexers]);
	CurTokenLexer->Init(Toks, NumToks, DisableMacroExpansion, OwnsTokens);
	}
	if (CurLexerKind != CLK_LexAfterModuleImport)
	CurLexerKind = CLK_TokenLexer;
	}

	/// \brief Compute the relative path that names the given file relative to
	/// the given directory.
	static void computeRelativePath(FileManager &FM, const DirectoryEntry *Dir,
	const FileEntry *File,
	SmallString<128> &Result) {
	Result.clear();

	StringRef FilePath = File->getDir()->getName();
	StringRef Path = FilePath;
	while (!Path.empty()) {
	if (const DirectoryEntry *CurDir = FM.getDirectory(Path)) {
	if (CurDir == Dir) {
	Result = FilePath.substr(Path.size());
	llvm::sys::path::append(Result,
	llvm::sys::path::filename(File->getName()));
	return;
	}
	}

	Path = llvm::sys::path::parent_path(Path);
	}

	Result = File->getName();
	}

	/// HandleEndOfFile - This callback is invoked when the lexer hits the end of
	/// the current file. This either returns the EOF token or pops a level off
	/// the include stack and keeps going.
	bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
	assert(!CurTokenLexer &&
	"Ending a file when currently in a macro!");

	// See if this file had a controlling macro.
	if (CurPPLexer) { // Not ending a macro, ignore it.
	if (const IdentifierInfo *ControllingMacro =
	CurPPLexer->MIOpt.GetControllingMacroAtEndOfFile()) {
	// Okay, this has a controlling macro, remember in HeaderFileInfo.
	if (const FileEntry *FE =
	SourceMgr.getFileEntryForID(CurPPLexer->getFileID()))
	HeaderInfo.SetFileControllingMacro(FE, ControllingMacro);
	}
	}

	// Complain about reaching a true EOF within arc_cf_code_audited.
	// We don't want to complain about reaching the end of a macro
	// instantiation or a _Pragma.
	if (PragmaARCCFCodeAuditedLoc.isValid() &&
	!isEndOfMacro && !(CurLexer && CurLexer->Is_PragmaLexer)) {
	Diag(PragmaARCCFCodeAuditedLoc, diag::err_pp_eof_in_arc_cf_code_audited);

	// Recover by leaving immediately.
	PragmaARCCFCodeAuditedLoc = SourceLocation();
	}

	// If this is a #include'd file, pop it off the include stack and continue
	// lexing the #includer file.
	if (!IncludeMacroStack.empty()) {

	// If we lexed the code-completion file, act as if we reached EOF.
	if (isCodeCompletionEnabled() && CurPPLexer &&
	SourceMgr.getLocForStartOfFile(CurPPLexer->getFileID()) ==
	CodeCompletionFileLoc) {
	if (CurLexer) {
	Result.startToken();
	CurLexer->FormTokenWithChars(Result, CurLexer->BufferEnd, tok::eof);
	CurLexer.reset();
	} else {
	assert(CurPTHLexer && "Got EOF but no current lexer set!");
	CurPTHLexer->getEOF(Result);
	CurPTHLexer.reset();
	}

	CurPPLexer = 0;
	return true;
	}

	if (!isEndOfMacro && CurPPLexer &&
	SourceMgr.getIncludeLoc(CurPPLexer->getFileID()).isValid()) {
	// Notify SourceManager to record the number of FileIDs that were created
	// during lexing of the #include'd file.
	unsigned NumFIDs =
	SourceMgr.local_sloc_entry_size() -
	CurPPLexer->getInitialNumSLocEntries() + 1/#include'd file/;
	SourceMgr.setNumCreatedFIDsForFileID(CurPPLexer->getFileID(), NumFIDs);
	}

	FileID ExitedFID;
	if (Callbacks && !isEndOfMacro && CurPPLexer)
	ExitedFID = CurPPLexer->getFileID();

	// We're done with the #included file.
	RemoveTopOfLexerStack();

	// Notify the client, if desired, that we are in a new source file.
	if (Callbacks && !isEndOfMacro && CurPPLexer) {
	SrcMgr::CharacteristicKind FileType =
	SourceMgr.getFileCharacteristic(CurPPLexer->getSourceLocation());
	Callbacks->FileChanged(CurPPLexer->getSourceLocation(),
	PPCallbacks::ExitFile, FileType, ExitedFID);
	}

	// Client should lex another token.
	return false;
	}

	// If the file ends with a newline, form the EOF token on the newline itself,
	// rather than "on the line following it", which doesn't exist. This makes
	// diagnostics relating to the end of file include the last file that the user
	// actually typed, which is goodness.
	if (CurLexer) {
	const char *EndPos = CurLexer->BufferEnd;
	if (EndPos != CurLexer->BufferStart &&
	(EndPos[-1] == '\n' \|\| EndPos[-1] == '\r')) {
	--EndPos;

	// Handle \n\r and \r\n:
	if (EndPos != CurLexer->BufferStart &&
	(EndPos[-1] == '\n' \|\| EndPos[-1] == '\r') &&
	EndPos[-1] != EndPos[0])
	--EndPos;
	}

	Result.startToken();
	CurLexer->BufferPtr = EndPos;
	CurLexer->FormTokenWithChars(Result, EndPos, tok::eof);

	if (!isIncrementalProcessingEnabled())
	// We're done with lexing.
	CurLexer.reset();
	} else {
	assert(CurPTHLexer && "Got EOF but no current lexer set!");
	CurPTHLexer->getEOF(Result);
	CurPTHLexer.reset();
	}

	if (!isIncrementalProcessingEnabled())
	CurPPLexer = 0;

	// This is the end of the top-level file. 'WarnUnusedMacroLocs' has collected
	// all macro locations that we need to warn because they are not used.
	for (WarnUnusedMacroLocsTy::iterator
	I=WarnUnusedMacroLocs.begin(), E=WarnUnusedMacroLocs.end(); I!=E; ++I)
	Diag(*I, diag::pp_macro_not_used);

	// If we are building a module that has an umbrella header, make sure that
	// each of the headers within the directory covered by the umbrella header
	// was actually included by the umbrella header.
	if (Module *Mod = getCurrentModule()) {
	if (Mod->getUmbrellaHeader()) {
	SourceLocation StartLoc
	= SourceMgr.getLocForStartOfFile(SourceMgr.getMainFileID());

	if (getDiagnostics().getDiagnosticLevel(
	diag::warn_uncovered_module_header,
	StartLoc) != DiagnosticsEngine::Ignored) {
	ModuleMap &ModMap = getHeaderSearchInfo().getModuleMap();
	typedef llvm::sys::fs::recursive_directory_iterator
	recursive_directory_iterator;
	const DirectoryEntry *Dir = Mod->getUmbrellaDir();
	llvm::error_code EC;
	for (recursive_directory_iterator Entry(Dir->getName(), EC), End;
	Entry != End && !EC; Entry.increment(EC)) {
	using llvm::StringSwitch;

	// Check whether this entry has an extension typically associated with
	// headers.
	if (!StringSwitch<bool>(llvm::sys::path::extension(Entry->path()))
	.Cases(".h", ".H", ".hh", ".hpp", true)
	.Default(false))
	continue;

	if (const FileEntry *Header = getFileManager().getFile(Entry->path()))
	if (!getSourceManager().hasFileInfo(Header)) {
	if (!ModMap.isHeaderInUnavailableModule(Header)) {
	// Find the relative path that would access this header.
	SmallString<128> RelativePath;
	computeRelativePath(FileMgr, Dir, Header, RelativePath);
	Diag(StartLoc, diag::warn_uncovered_module_header)
	<< RelativePath;
	}
	}
	}
	}
	}
	}

	return true;
	}

	/// HandleEndOfTokenLexer - This callback is invoked when the current TokenLexer
	/// hits the end of its token stream.
	bool Preprocessor::HandleEndOfTokenLexer(Token &Result) {
	assert(CurTokenLexer && !CurPPLexer &&
	"Ending a macro when currently in a #include file!");

	if (!MacroExpandingLexersStack.empty() &&
	MacroExpandingLexersStack.back().first == CurTokenLexer.get())
	removeCachedMacroExpandedTokensOfLastLexer();

	// Delete or cache the now-dead macro expander.
	if (NumCachedTokenLexers == TokenLexerCacheSize)
	CurTokenLexer.reset();
	else
	TokenLexerCache[NumCachedTokenLexers++] = CurTokenLexer.take();

	// Handle this like a #include file being popped off the stack.
	return HandleEndOfFile(Result, true);
	}

	/// RemoveTopOfLexerStack - Pop the current lexer/macro exp off the top of the
	/// lexer stack. This should only be used in situations where the current
	/// state of the top-of-stack lexer is unknown.
	void Preprocessor::RemoveTopOfLexerStack() {
	assert(!IncludeMacroStack.empty() && "Ran out of stack entries to load");

	if (CurTokenLexer) {
	// Delete or cache the now-dead macro expander.
	if (NumCachedTokenLexers == TokenLexerCacheSize)
	CurTokenLexer.reset();
	else
	TokenLexerCache[NumCachedTokenLexers++] = CurTokenLexer.take();
	}

	PopIncludeMacroStack();
	}

	/// HandleMicrosoftCommentPaste - When the macro expander pastes together a
	/// comment (/##/) in microsoft mode, this method handles updating the current
	/// state, returning the token on the next source line.
	void Preprocessor::HandleMicrosoftCommentPaste(Token &Tok) {
	assert(CurTokenLexer && !CurPPLexer &&
	"Pasted comment can only be formed from macro");

	// We handle this by scanning for the closest real lexer, switching it to
	// raw mode and preprocessor mode. This will cause it to return \n as an
	// explicit EOD token.
	PreprocessorLexer *FoundLexer = 0;
	bool LexerWasInPPMode = false;
	for (unsigned i = 0, e = IncludeMacroStack.size(); i != e; ++i) {
	IncludeStackInfo &ISI = *(IncludeMacroStack.end()-i-1);
	if (ISI.ThePPLexer == 0) continue; // Scan for a real lexer.

	// Once we find a real lexer, mark it as raw mode (disabling macro
	// expansions) and preprocessor mode (return EOD). We know that the lexer
	// was not in raw mode before, because the macro that the comment came
	// from was expanded. However, it could have already been in preprocessor
	// mode (#if COMMENT) in which case we have to return it to that mode and
	// return EOD.
	FoundLexer = ISI.ThePPLexer;
	FoundLexer->LexingRawMode = true;
	LexerWasInPPMode = FoundLexer->ParsingPreprocessorDirective;
	FoundLexer->ParsingPreprocessorDirective = true;
	break;
	}

	// Okay, we either found and switched over the lexer, or we didn't find a
	// lexer. In either case, finish off the macro the comment came from, getting
	// the next token.
	if (!HandleEndOfTokenLexer(Tok)) Lex(Tok);

	// Discarding comments as long as we don't have EOF or EOD. This 'comments
	// out' the rest of the line, including any tokens that came from other macros
	// that were active, as in:
	// #define submacro a COMMENT b
	// submacro c
	// which should lex to 'a' only: 'b' and 'c' should be removed.
	while (Tok.isNot(tok::eod) && Tok.isNot(tok::eof))
	Lex(Tok);

	// If we got an eod token, then we successfully found the end of the line.
	if (Tok.is(tok::eod)) {
	assert(FoundLexer && "Can't get end of line without an active lexer");
	// Restore the lexer back to normal mode instead of raw mode.
	FoundLexer->LexingRawMode = false;

	// If the lexer was already in preprocessor mode, just return the EOD token
	// to finish the preprocessor line.
	if (LexerWasInPPMode) return;

	// Otherwise, switch out of PP mode and return the next lexed token.
	FoundLexer->ParsingPreprocessorDirective = false;
	return Lex(Tok);
	}

	// If we got an EOF token, then we reached the end of the token stream but
	// didn't find an explicit \n. This can only happen if there was no lexer
	// active (an active lexer would return EOD at EOF if there was no \n in
	// preprocessor directive mode), so just return EOF as our token.
	assert(!FoundLexer && "Lexer should return EOD before EOF in PP mode");
	}