//===--- DependencyGraph.cpp - Generate dependency file -------------------===//

//

// 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 code generates a header dependency graph in DOT format, for use

// with, e.g., GraphViz.

//

//===----------------------------------------------------------------------===//

#include "clang/Frontend/Utils.h"

#include "clang/Basic/FileManager.h"

#include "clang/Basic/SourceManager.h"

#include "clang/Frontend/FrontendDiagnostic.h"

#include "clang/Lex/PPCallbacks.h"

#include "clang/Lex/Preprocessor.h"

#include "llvm/ADT/SetVector.h"

#include "llvm/Support/GraphWriter.h"

#include "llvm/Support/raw_ostream.h"

using namespace clang;

namespace DOT = llvm::DOT;

namespace {

class DependencyGraphCallback : public PPCallbacks {

  const Preprocessor *PP;

  std::string OutputFile;

  std::string SysRoot;

  llvm::SetVector<FileEntryRef> AllFiles;

  using DependencyMap =

      llvm::DenseMap<FileEntryRef, SmallVector<FileEntryRef, 2>>;

  DependencyMap Dependencies;

private:

  raw_ostream &writeNodeReference(raw_ostream &OS,

                                  const FileEntry *Node);

  void OutputGraphFile();

public:

  DependencyGraphCallback(const Preprocessor *_PP, StringRef OutputFile,

                          StringRef SysRoot)

    : PP(_PP), OutputFile(OutputFile.str()), SysRoot(SysRoot.str()) { }

  void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,

                          StringRef FileName, bool IsAngled,

                          CharSourceRange FilenameRange,

                          OptionalFileEntryRef File, StringRef SearchPath,

                          StringRef RelativePath, const Module *Imported,

                          SrcMgr::CharacteristicKind FileType) override;

  void EndOfMainFile() override {

    OutputGraphFile();

  }

};

}

void clang::AttachDependencyGraphGen(Preprocessor &PP, StringRef OutputFile,

                                     StringRef SysRoot) {

  PP.addPPCallbacks(std::make_unique<DependencyGraphCallback>(&PP, OutputFile,

                                                               SysRoot));

}

void DependencyGraphCallback::InclusionDirective(

    SourceLocation HashLoc, const Token &IncludeTok, StringRef FileName,

    bool IsAngled, CharSourceRange FilenameRange, OptionalFileEntryRef File,

    StringRef SearchPath, StringRef RelativePath, const Module *Imported,

    SrcMgr::CharacteristicKind FileType) {

  if (!File)

    return;

  SourceManager &SM = PP->getSourceManager();

  OptionalFileEntryRef FromFile =

      SM.getFileEntryRefForID(SM.getFileID(SM.getExpansionLoc(HashLoc)));

  if (!FromFile)

    return;

  Dependencies[*FromFile].push_back(*File);

  AllFiles.insert(*File);

  AllFiles.insert(*FromFile);

}

raw_ostream &

DependencyGraphCallback::writeNodeReference(raw_ostream &OS,

                                            const FileEntry *Node) {

  OS << "header_" << Node->getUID();

  return OS;

}

void DependencyGraphCallback::OutputGraphFile() {

  std::error_code EC;

  llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::OF_TextWithCRLF);

  if (EC) {

    PP->getDiagnostics().Report(diag::err_fe_error_opening) << OutputFile

                                                            << EC.message();

    return;

  }

  OS << "digraph \"dependencies\" {\n";

  // Write the nodes

  for (unsigned I = 0, N = AllFiles.size(); I != N; ++I) {

    // Write the node itself.

    OS.indent(2);

    writeNodeReference(OS, AllFiles[I]);

    OS << " [ shape=\"box\", label=\"";

    StringRef FileName = AllFiles[I].getName();

    FileName.consume_front(SysRoot);

    OS << DOT::EscapeString(std::string(FileName)) << "\"];\n";

  }

  // Write the edges

  for (DependencyMap::iterator F = Dependencies.begin(),

                            FEnd = Dependencies.end();

       F != FEnd; ++F) {

    for (unsigned I = 0, N = F->second.size(); I != N; ++I) {

      OS.indent(2);

      writeNodeReference(OS, F->first);

      OS << " -> ";

      writeNodeReference(OS, F->second[I]);

      OS << ";\n";

    }

  }

  OS << "}\n";

}