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      1 //===--- HeaderIncludes.cpp - Generate Header Includes --------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #include "clang/Frontend/Utils.h"
     11 #include "clang/Basic/SourceManager.h"
     12 #include "clang/Frontend/FrontendDiagnostic.h"
     13 #include "clang/Lex/Preprocessor.h"
     14 #include "llvm/ADT/SmallString.h"
     15 #include "llvm/Support/raw_ostream.h"
     16 using namespace clang;
     17 
     18 namespace {
     19 class HeaderIncludesCallback : public PPCallbacks {
     20   SourceManager &SM;
     21   raw_ostream *OutputFile;
     22   unsigned CurrentIncludeDepth;
     23   bool HasProcessedPredefines;
     24   bool OwnsOutputFile;
     25   bool ShowAllHeaders;
     26   bool ShowDepth;
     27 
     28 public:
     29   HeaderIncludesCallback(const Preprocessor *PP, bool ShowAllHeaders_,
     30                          raw_ostream *OutputFile_, bool OwnsOutputFile_,
     31                          bool ShowDepth_)
     32     : SM(PP->getSourceManager()), OutputFile(OutputFile_),
     33       CurrentIncludeDepth(0), HasProcessedPredefines(false),
     34       OwnsOutputFile(OwnsOutputFile_), ShowAllHeaders(ShowAllHeaders_),
     35       ShowDepth(ShowDepth_) {}
     36 
     37   ~HeaderIncludesCallback() {
     38     if (OwnsOutputFile)
     39       delete OutputFile;
     40   }
     41 
     42   virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
     43                            SrcMgr::CharacteristicKind FileType,
     44                            FileID PrevFID);
     45 };
     46 }
     47 
     48 void clang::AttachHeaderIncludeGen(Preprocessor &PP, bool ShowAllHeaders,
     49                                    StringRef OutputPath, bool ShowDepth) {
     50   raw_ostream *OutputFile = &llvm::errs();
     51   bool OwnsOutputFile = false;
     52 
     53   // Open the output file, if used.
     54   if (!OutputPath.empty()) {
     55     std::string Error;
     56     llvm::raw_fd_ostream *OS = new llvm::raw_fd_ostream(
     57       OutputPath.str().c_str(), Error, llvm::raw_fd_ostream::F_Append);
     58     if (!Error.empty()) {
     59       PP.getDiagnostics().Report(
     60         clang::diag::warn_fe_cc_print_header_failure) << Error;
     61       delete OS;
     62     } else {
     63       OS->SetUnbuffered();
     64       OS->SetUseAtomicWrites(true);
     65       OutputFile = OS;
     66       OwnsOutputFile = true;
     67     }
     68   }
     69 
     70   PP.addPPCallbacks(new HeaderIncludesCallback(&PP, ShowAllHeaders,
     71                                                OutputFile, OwnsOutputFile,
     72                                                ShowDepth));
     73 }
     74 
     75 void HeaderIncludesCallback::FileChanged(SourceLocation Loc,
     76                                          FileChangeReason Reason,
     77                                        SrcMgr::CharacteristicKind NewFileType,
     78                                        FileID PrevFID) {
     79   // Unless we are exiting a #include, make sure to skip ahead to the line the
     80   // #include directive was at.
     81   PresumedLoc UserLoc = SM.getPresumedLoc(Loc);
     82   if (UserLoc.isInvalid())
     83     return;
     84 
     85   // Adjust the current include depth.
     86   if (Reason == PPCallbacks::EnterFile) {
     87     ++CurrentIncludeDepth;
     88   } else if (Reason == PPCallbacks::ExitFile) {
     89     if (CurrentIncludeDepth)
     90       --CurrentIncludeDepth;
     91 
     92     // We track when we are done with the predefines by watching for the first
     93     // place where we drop back to a nesting depth of 1.
     94     if (CurrentIncludeDepth == 1 && !HasProcessedPredefines)
     95       HasProcessedPredefines = true;
     96 
     97     return;
     98   } else
     99     return;
    100 
    101   // Show the header if we are (a) past the predefines, or (b) showing all
    102   // headers and in the predefines at a depth past the initial file and command
    103   // line buffers.
    104   bool ShowHeader = (HasProcessedPredefines ||
    105                      (ShowAllHeaders && CurrentIncludeDepth > 2));
    106 
    107   // Dump the header include information we are past the predefines buffer or
    108   // are showing all headers.
    109   if (ShowHeader && Reason == PPCallbacks::EnterFile) {
    110     // Write to a temporary string to avoid unnecessary flushing on errs().
    111     SmallString<512> Filename(UserLoc.getFilename());
    112     Lexer::Stringify(Filename);
    113 
    114     SmallString<256> Msg;
    115     if (ShowDepth) {
    116       // The main source file is at depth 1, so skip one dot.
    117       for (unsigned i = 1; i != CurrentIncludeDepth; ++i)
    118         Msg += '.';
    119       Msg += ' ';
    120     }
    121     Msg += Filename;
    122     Msg += '\n';
    123 
    124     OutputFile->write(Msg.data(), Msg.size());
    125   }
    126 }
    127