//===--- ASTUnit.cpp - ASTUnit utility ------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// ASTUnit Implementation.
//
//===----------------------------------------------------------------------===//

#include "clang/Frontend/ASTUnit.h"
#include "clang/Frontend/PCHReader.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclVisitor.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Basic/Diagnostic.h"
#include "llvm/Support/Compiler.h"

using namespace clang;

ASTUnit::ASTUnit(Diagnostic &_Diags) : Diags(_Diags) { }
ASTUnit::~ASTUnit() { }

namespace {

/// \brief Gathers information from PCHReader that will be used to initialize
/// a Preprocessor.
class VISIBILITY_HIDDEN PCHInfoCollector : public PCHReaderListener {
  LangOptions &LangOpt;
  HeaderSearch &HSI;
  std::string &TargetTriple;
  std::string &Predefines;
  unsigned &Counter;

  unsigned NumHeaderInfos;

public:
  PCHInfoCollector(LangOptions &LangOpt, HeaderSearch &HSI,
                   std::string &TargetTriple, std::string &Predefines,
                   unsigned &Counter)
    : LangOpt(LangOpt), HSI(HSI), TargetTriple(TargetTriple),
      Predefines(Predefines), Counter(Counter), NumHeaderInfos(0) {}

  virtual bool ReadLanguageOptions(const LangOptions &LangOpts) {
    LangOpt = LangOpts;
    return false;
  }

  virtual bool ReadTargetTriple(const std::string &Triple) {
    TargetTriple = Triple;
    return false;
  }

  virtual bool ReadPredefinesBuffer(const char *PCHPredef,
                                    unsigned PCHPredefLen,
                                    FileID PCHBufferID,
                                    std::string &SuggestedPredefines) {
    Predefines = PCHPredef;
    return false;
  }

  virtual void ReadHeaderFileInfo(const HeaderFileInfo &HFI) {
    HSI.setHeaderFileInfoForUID(HFI, NumHeaderInfos++);
  }

  virtual void ReadCounter(unsigned Value) {
    Counter = Value;
  }
};

} // anonymous namespace

const std::string &ASTUnit::getOriginalSourceFileName() {
  return dyn_cast<PCHReader>(Ctx->getExternalSource())->getOriginalSourceFile();
}

FileManager &ASTUnit::getFileManager() {
  return HeaderInfo->getFileMgr();
}

ASTUnit *ASTUnit::LoadFromPCHFile(const std::string &Filename,
                                  Diagnostic &Diags,
                                  FileManager &FileMgr,
                                  std::string *ErrMsg) {
  llvm::OwningPtr<ASTUnit> AST(new ASTUnit(Diags));

  AST->HeaderInfo.reset(new HeaderSearch(FileMgr));

  // Gather Info for preprocessor construction later on.

  LangOptions LangInfo;
  HeaderSearch &HeaderInfo = *AST->HeaderInfo.get();
  std::string TargetTriple;
  std::string Predefines;
  unsigned Counter;

  llvm::OwningPtr<PCHReader> Reader;
  llvm::OwningPtr<ExternalASTSource> Source;

  Reader.reset(new PCHReader(AST->getSourceManager(), FileMgr, AST->Diags));
  Reader->setListener(new PCHInfoCollector(LangInfo, HeaderInfo, TargetTriple,
                                           Predefines, Counter));

  switch (Reader->ReadPCH(Filename)) {
  case PCHReader::Success:
    break;

  case PCHReader::Failure:
  case PCHReader::IgnorePCH:
    if (ErrMsg)
      *ErrMsg = "Could not load PCH file";
    return NULL;
  }

  // PCH loaded successfully. Now create the preprocessor.

  // Get information about the target being compiled for.
  AST->Target.reset(TargetInfo::CreateTargetInfo(TargetTriple));
  AST->PP.reset(new Preprocessor(AST->Diags, LangInfo, *AST->Target.get(),
                                 AST->getSourceManager(), HeaderInfo));
  Preprocessor &PP = *AST->PP.get();

  PP.setPredefines(Reader->getSuggestedPredefines());
  PP.setCounterValue(Counter);
  Reader->setPreprocessor(PP);

  // Create and initialize the ASTContext.

  AST->Ctx.reset(new ASTContext(LangInfo,
                                AST->getSourceManager(),
                                *AST->Target.get(),
                                PP.getIdentifierTable(),
                                PP.getSelectorTable(),
                                PP.getBuiltinInfo(),
                                /* FreeMemory = */ true,
                                /* size_reserve = */0));
  ASTContext &Context = *AST->Ctx.get();

  Reader->InitializeContext(Context);

  // Attach the PCH reader to the AST context as an external AST
  // source, so that declarations will be deserialized from the
  // PCH file as needed.
  Source.reset(Reader.take());
  Context.setExternalSource(Source);

  return AST.take();
}