// Copyright 2017-2018 ccls Authors
// SPDX-License-Identifier: Apache-2.0

#include "indexer.h"

#include "clang_tu.h"
#include "log.hh"
#include "platform.h"
#include "serializer.h"
using ccls::Intern;

#include <clang/AST/AST.h>
#include <clang/Frontend/FrontendAction.h>
#include <clang/Index/IndexDataConsumer.h>
#include <clang/Index/IndexingAction.h>
#include <clang/Index/USRGeneration.h>
#include <clang/Lex/PreprocessorOptions.h>
#include <llvm/ADT/DenseSet.h>
#include <llvm/Support/CrashRecoveryContext.h>
#include <llvm/Support/Path.h>
#include <llvm/Support/Timer.h>
using namespace clang;
using llvm::Timer;

#include <algorithm>
#include <inttypes.h>
#include <limits.h>
#include <map>
#include <unordered_set>

namespace {

constexpr int kInitializerMaxLines = 3;

struct IndexParam {
  std::unordered_map<llvm::sys::fs::UniqueID, std::string> SeenUniqueID;
  std::unordered_map<std::string, FileContents> file_contents;
  std::unordered_map<std::string, int64_t> file2write_time;
  struct DeclInfo {
    Usr usr;
    std::string short_name;
    std::string qualified;
  };
  std::unordered_map<const Decl *, DeclInfo> Decl2Info;

  ASTContext *Ctx;
  FileConsumer *file_consumer = nullptr;

  IndexParam(FileConsumer *file_consumer) : file_consumer(file_consumer) {}

  void SeenFile(const FileEntry &File) {
    // If this is the first time we have seen the file (ignoring if we are
    // generating an index for it):
    auto [it, inserted] = SeenUniqueID.try_emplace(File.getUniqueID());
    if (inserted) {
      std::string file_name = FileName(File);
      it->second = file_name;

      // Set modification time.
      std::optional<int64_t> write_time = LastWriteTime(file_name);
      LOG_IF_S(ERROR, !write_time)
          << "failed to fetch write time for " << file_name;
      if (write_time)
        file2write_time[file_name] = *write_time;
    }
  }

  IndexFile *ConsumeFile(const FileEntry &File) {
    SeenFile(File);
    return file_consumer->TryConsumeFile(File, &file_contents);
  }
};

StringRef GetSourceInRange(const SourceManager &SM, const LangOptions &LangOpts,
                           SourceRange R) {
  SourceLocation BLoc = R.getBegin(), ELoc = R.getEnd();
  std::pair<FileID, unsigned> BInfo = SM.getDecomposedLoc(BLoc),
                              EInfo = SM.getDecomposedLoc(ELoc);
  bool invalid = false;
  StringRef Buf = SM.getBufferData(BInfo.first, &invalid);
  if (invalid)
    return "";
  return Buf.substr(BInfo.second,
                    EInfo.second +
                        Lexer::MeasureTokenLength(ELoc, SM, LangOpts) -
                        BInfo.second);
}

SymbolKind GetSymbolKind(const Decl *D) {
  switch (D->getKind()) {
  case Decl::TranslationUnit:
    return SymbolKind::File;
  case Decl::ObjCMethod:
  case Decl::FunctionTemplate:
  case Decl::Function:
  case Decl::CXXMethod:
  case Decl::CXXConstructor:
  case Decl::CXXConversion:
  case Decl::CXXDestructor:
    return SymbolKind::Func;
  case Decl::Namespace:
  case Decl::NamespaceAlias:
  case Decl::ObjCCategory:
  case Decl::ObjCInterface:
  case Decl::ObjCProtocol:
  case Decl::ClassTemplate:
  case Decl::TypeAliasTemplate:
  case Decl::TemplateTemplateParm:
  case Decl::Enum:
  case Decl::Record:
  case Decl::CXXRecord:
  case Decl::ClassTemplateSpecialization:
  case Decl::ClassTemplatePartialSpecialization:
  case Decl::TypeAlias:
  case Decl::Typedef:
  case Decl::UnresolvedUsingTypename:
    return SymbolKind::Type;
  case Decl::ObjCProperty:
  case Decl::VarTemplate:
  case Decl::Binding:
  case Decl::Field:
  case Decl::ObjCIvar:
  case Decl::Var:
  case Decl::ParmVar:
  case Decl::ImplicitParam:
  case Decl::Decomposition:
  case Decl::VarTemplateSpecialization:
  case Decl::VarTemplatePartialSpecialization:
  case Decl::EnumConstant:
  case Decl::UnresolvedUsingValue:
    return SymbolKind::Var;
  default:
    return SymbolKind::Invalid;
  }
}

LanguageId GetDeclLanguage(const Decl *D) {
  switch (D->getKind()) {
  default:
    return LanguageId::C;
  case Decl::ImplicitParam:
  case Decl::ObjCAtDefsField:
  case Decl::ObjCCategory:
  case Decl::ObjCCategoryImpl:
  case Decl::ObjCCompatibleAlias:
  case Decl::ObjCImplementation:
  case Decl::ObjCInterface:
  case Decl::ObjCIvar:
  case Decl::ObjCMethod:
  case Decl::ObjCProperty:
  case Decl::ObjCPropertyImpl:
  case Decl::ObjCProtocol:
  case Decl::ObjCTypeParam:
    return LanguageId::ObjC;
  case Decl::CXXConstructor:
  case Decl::CXXConversion:
  case Decl::CXXDestructor:
  case Decl::CXXMethod:
  case Decl::CXXRecord:
  case Decl::ClassTemplate:
  case Decl::ClassTemplatePartialSpecialization:
  case Decl::ClassTemplateSpecialization:
  case Decl::Friend:
  case Decl::FriendTemplate:
  case Decl::FunctionTemplate:
  case Decl::LinkageSpec:
  case Decl::Namespace:
  case Decl::NamespaceAlias:
  case Decl::NonTypeTemplateParm:
  case Decl::StaticAssert:
  case Decl::TemplateTemplateParm:
  case Decl::TemplateTypeParm:
  case Decl::UnresolvedUsingTypename:
  case Decl::UnresolvedUsingValue:
  case Decl::Using:
  case Decl::UsingDirective:
  case Decl::UsingShadow:
    return LanguageId::Cpp;
  }
}

// clang/lib/AST/DeclPrinter.cpp
QualType GetBaseType(QualType T, bool deduce_auto) {
  QualType BaseType = T;
  while (!BaseType.isNull() && !BaseType->isSpecifierType()) {
    if (const PointerType *PTy = BaseType->getAs<PointerType>())
      BaseType = PTy->getPointeeType();
    else if (const BlockPointerType *BPy = BaseType->getAs<BlockPointerType>())
      BaseType = BPy->getPointeeType();
    else if (const ArrayType *ATy = dyn_cast<ArrayType>(BaseType))
      BaseType = ATy->getElementType();
    else if (const VectorType *VTy = BaseType->getAs<VectorType>())
      BaseType = VTy->getElementType();
    else if (const ReferenceType *RTy = BaseType->getAs<ReferenceType>())
      BaseType = RTy->getPointeeType();
    else if (const ParenType *PTy = BaseType->getAs<ParenType>())
      BaseType = PTy->desugar();
    else if (deduce_auto) {
      if (const AutoType *ATy = BaseType->getAs<AutoType>())
        BaseType = ATy->getDeducedType();
      else
        break;
    } else
      break;
  }
  return BaseType;
}

const Decl *GetTypeDecl(QualType T, bool *specialization = nullptr) {
  Decl *D = nullptr;
  T = GetBaseType(T.getUnqualifiedType(), true);
  const Type *TP = T.getTypePtrOrNull();
  if (!TP)
    return nullptr;

try_again:
  switch (TP->getTypeClass()) {
  case Type::Typedef:
    D = cast<TypedefType>(TP)->getDecl();
    break;
  case Type::ObjCObject:
    D = cast<ObjCObjectType>(TP)->getInterface();
    break;
  case Type::ObjCInterface:
    D = cast<ObjCInterfaceType>(TP)->getDecl();
    break;
  case Type::Record:
  case Type::Enum:
    D = cast<TagType>(TP)->getDecl();
    break;
  case Type::TemplateTypeParm:
    D = cast<TemplateTypeParmType>(TP)->getDecl();
    break;
  case Type::TemplateSpecialization:
    if (specialization)
      *specialization = true;
    if (const RecordType *Record = TP->getAs<RecordType>())
      D = Record->getDecl();
    else
      D = cast<TemplateSpecializationType>(TP)
              ->getTemplateName()
              .getAsTemplateDecl();
    break;

  case Type::Auto:
  case Type::DeducedTemplateSpecialization:
    TP = cast<DeducedType>(TP)->getDeducedType().getTypePtrOrNull();
    if (TP)
      goto try_again;
    break;

  case Type::InjectedClassName:
    D = cast<InjectedClassNameType>(TP)->getDecl();
    break;

    // FIXME: Template type parameters!

  case Type::Elaborated:
    TP = cast<ElaboratedType>(TP)->getNamedType().getTypePtrOrNull();
    goto try_again;

  default:
    break;
  }
  return D;
}

const Decl *GetSpecialized(const Decl *D) {
  if (!D)
    return D;
  Decl *Template = nullptr;
  if (const CXXRecordDecl *CXXRecord = dyn_cast<CXXRecordDecl>(D)) {
    if (const ClassTemplatePartialSpecializationDecl *PartialSpec =
            dyn_cast<ClassTemplatePartialSpecializationDecl>(CXXRecord))
      Template = PartialSpec->getSpecializedTemplate();
    else if (const ClassTemplateSpecializationDecl *ClassSpec =
                 dyn_cast<ClassTemplateSpecializationDecl>(CXXRecord)) {
      llvm::PointerUnion<ClassTemplateDecl *,
                         ClassTemplatePartialSpecializationDecl *>
          Result = ClassSpec->getSpecializedTemplateOrPartial();
      if (Result.is<ClassTemplateDecl *>())
        Template = Result.get<ClassTemplateDecl *>();
      else
        Template = Result.get<ClassTemplatePartialSpecializationDecl *>();

    } else
      Template = CXXRecord->getInstantiatedFromMemberClass();
  } else if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
    Template = Function->getPrimaryTemplate();
    if (!Template)
      Template = Function->getInstantiatedFromMemberFunction();
  } else if (const VarDecl *Var = dyn_cast<VarDecl>(D)) {
    if (Var->isStaticDataMember())
      Template = Var->getInstantiatedFromStaticDataMember();
  } else if (const RedeclarableTemplateDecl *Tmpl =
                 dyn_cast<RedeclarableTemplateDecl>(D))
    Template = Tmpl->getInstantiatedFromMemberTemplate();
  else
    return nullptr;
  return Template;
}

bool ValidateRecord(const RecordDecl *RD) {
  for (const auto *I : RD->fields()) {
    QualType FQT = I->getType();
    if (FQT->isIncompleteType() || FQT->isDependentType())
      return false;
    if (const RecordType *ChildType = I->getType()->getAs<RecordType>())
      if (const RecordDecl *Child = ChildType->getDecl())
        if (!ValidateRecord(Child))
          return false;
  }
  return true;
}

class IndexDataConsumer : public index::IndexDataConsumer {
public:
  ASTContext *Ctx;
  IndexParam &param;

  std::string GetComment(const Decl *D) {
    SourceManager &SM = Ctx->getSourceManager();
    const RawComment *RC = Ctx->getRawCommentForAnyRedecl(D);
    if (!RC)
      return "";
    StringRef Raw = RC->getRawText(Ctx->getSourceManager());
    SourceRange R = RC->getSourceRange();
    std::pair<FileID, unsigned> BInfo = SM.getDecomposedLoc(R.getBegin());
    unsigned start_column = SM.getLineNumber(BInfo.first, BInfo.second);
    std::string ret;
    int pad = -1;
    for (const char *p = Raw.data(), *E = Raw.end(); p < E;) {
      // The first line starts with a comment marker, but the rest needs
      // un-indenting.
      unsigned skip = start_column - 1;
      for (; skip > 0 && p < E && (*p == ' ' || *p == '\t'); p++)
        skip--;
      const char *q = p;
      while (q < E && *q != '\n')
        q++;
      if (q < E)
        q++;
      // A minimalist approach to skip Doxygen comment markers.
      // See https://www.stack.nl/~dimitri/doxygen/manual/docblocks.html
      if (pad < 0) {
        // First line, detect the length of comment marker and put into |pad|
        const char *begin = p;
        while (p < E && (*p == '/' || *p == '*' || *p == '-' || *p == '='))
          p++;
        if (p < E && (*p == '<' || *p == '!'))
          p++;
        if (p < E && *p == ' ')
          p++;
        if (p + 1 == q)
          p++;
        else
          pad = int(p - begin);
      } else {
        // Other lines, skip |pad| bytes
        int prefix = pad;
        while (prefix > 0 && p < E &&
               (*p == ' ' || *p == '/' || *p == '*' || *p == '<' || *p == '!'))
          prefix--, p++;
      }
      ret.insert(ret.end(), p, q);
      p = q;
    }
    while (ret.size() && isspace(ret.back()))
      ret.pop_back();
    if (StringRef(ret).endswith("*/") || StringRef(ret).endswith("\n/"))
      ret.resize(ret.size() - 2);
    while (ret.size() && isspace(ret.back()))
      ret.pop_back();
    return ret;
  }

  Usr GetUsr(const Decl *D, IndexParam::DeclInfo **info = nullptr) const {
    D = D->getCanonicalDecl();
    auto [it, inserted] = param.Decl2Info.try_emplace(D);
    if (inserted) {
      SmallString<256> USR;
      index::generateUSRForDecl(D, USR);
      auto &info = it->second;
      info.usr = HashUsr(USR);
      if (auto *ND = dyn_cast<NamedDecl>(D)) {
        info.short_name = ND->getNameAsString();
        info.qualified = ND->getQualifiedNameAsString();
        SimplifyAnonymous(info.qualified);
      }
    }
    if (info)
      *info = &it->second;
    return it->second.usr;
  }

  Use GetUse(IndexFile *db, int lid, Range range, const DeclContext *DC,
             Role role) const {
    if (!DC)
      return {{range, 0, SymbolKind::File, role}, lid};
    const Decl *D = cast<Decl>(DC);
    switch (GetSymbolKind(D)) {
    case SymbolKind::Func:
      return {{range, db->ToFunc(GetUsr(D)).usr, SymbolKind::Func, role}, lid};
    case SymbolKind::Type:
      return {{range, db->ToType(GetUsr(D)).usr, SymbolKind::Type, role}, lid};
    case SymbolKind::Var:
      return {{range, db->ToVar(GetUsr(D)).usr, SymbolKind::Var, role}, lid};
    default:
      return {{range, 0, SymbolKind::File, role}, lid};
    }
  }

  PrintingPolicy GetDefaultPolicy() const {
    PrintingPolicy PP(Ctx->getLangOpts());
    PP.AnonymousTagLocations = false;
    PP.TerseOutput = true;
    PP.PolishForDeclaration = true;
    PP.ConstantsAsWritten = true;
    PP.SuppressTagKeyword = true;
    PP.SuppressInitializers = true;
    PP.FullyQualifiedName = false;
    return PP;
  }

  static void SimplifyAnonymous(std::string &name) {
    for (std::string::size_type i = 0;;) {
      if ((i = name.find("(anonymous ", i)) == std::string::npos)
        break;
      i++;
      if (name.size() - i > 19 && name.compare(i + 10, 9, "namespace") == 0)
        name.replace(i, 19, "anon ns");
      else
        name.replace(i, 9, "anon");
    }
  }

  template <typename Def>
  void SetName(const Decl *D, std::string_view short_name,
               std::string_view qualified, Def &def) {
    SmallString<256> Str;
    llvm::raw_svector_ostream OS(Str);
    D->print(OS, GetDefaultPolicy());

    std::string name = OS.str();
    SimplifyAnonymous(name);
    // Remove \n in DeclPrinter.cpp "{\n" + if(!TerseOutput)something + "}"
    for (std::string::size_type i = 0;;) {
      if ((i = name.find("{\n}", i)) == std::string::npos)
        break;
      name.replace(i, 3, "{}");
    }
    auto i = name.find(short_name);
    if (short_name.size())
      while (i != std::string::npos && ((i && isalnum(name[i - 1])) ||
                                        isalnum(name[i + short_name.size()])))
        i = name.find(short_name, i + short_name.size());
    if (i == std::string::npos) {
      // e.g. operator type-parameter-1
      i = 0;
      def.short_name_offset = 0;
    } else if (short_name.size() && (!i || name[i - 1] != ':')) {
      name.replace(i, short_name.size(), qualified);
      def.short_name_offset = i + qualified.size() - short_name.size();
    } else {
      def.short_name_offset = i;
    }
    def.short_name_size = short_name.size();
    for (int paren = 0; i; i--) {
      // Skip parentheses in "(anon struct)::name"
      if (name[i - 1] == ')')
        paren++;
      else if (name[i - 1] == '(')
        paren--;
      else if (!(paren > 0 || isalnum(name[i - 1]) || name[i - 1] == '_' ||
                 name[i - 1] == ':'))
        break;
    }
    def.qual_name_offset = i;
    def.detailed_name = Intern(name);
  }

  void SetVarName(const Decl *D, std::string_view short_name,
                  std::string_view qualified, IndexVar::Def &def) {
    QualType T;
    const Expr *init = nullptr;
    bool binding = false;
    if (auto *VD = dyn_cast<VarDecl>(D)) {
      T = VD->getType();
      init = VD->getAnyInitializer();
      def.storage = VD->getStorageClass();
    } else if (auto *FD = dyn_cast<FieldDecl>(D)) {
      T = FD->getType();
      init = FD->getInClassInitializer();
    } else if (auto *BD = dyn_cast<BindingDecl>(D)) {
      T = BD->getType();
      binding = true;
    }
    auto BT = GetBaseType(T, false);
    if (!BT.isNull() && (binding || BT->getAs<AutoType>())) {
      SmallString<256> Str;
      llvm::raw_svector_ostream OS(Str);
      PrintingPolicy PP = GetDefaultPolicy();
      T.print(OS, PP);
      if (Str.size() &&
          (Str.back() != ' ' && Str.back() != '*' && Str.back() != '&'))
        Str += ' ';
      def.qual_name_offset = Str.size();
      def.short_name_offset = Str.size() + qualified.size() - short_name.size();
      def.short_name_size = short_name.size();
      Str += StringRef(qualified.data(), qualified.size());
      def.detailed_name = Intern(Str.str());
    } else {
      SetName(D, short_name, qualified, def);
    }
    if (init) {
      SourceManager &SM = Ctx->getSourceManager();
      const LangOptions &Lang = Ctx->getLangOpts();
      SourceRange R = SM.getExpansionRange(init->getSourceRange())
#if LLVM_VERSION_MAJOR >= 7
                          .getAsRange()
#endif
          ;
      SourceLocation L = D->getLocation();
      if (L.isMacroID() || !SM.isBeforeInTranslationUnit(L, R.getBegin()))
        return;
      StringRef Buf = GetSourceInRange(SM, Lang, R);
      Twine Init = Buf.count('\n') <= kInitializerMaxLines - 1
                       ? Buf.size() && Buf[0] == ':' ? Twine(" ", Buf)
                                                     : Twine(" = ", Buf)
                       : Twine();
      Twine T = def.detailed_name + Init;
      def.hover =
          def.storage == SC_Static && strncmp(def.detailed_name, "static ", 7)
              ? Intern(("static " + T).str())
              : Intern(T.str());
    }
  }

  static int GetFileLID(IndexFile *db, SourceManager &SM, const FileEntry &FE) {
    auto [it, inserted] = db->uid2lid_and_path.try_emplace(FE.getUniqueID());
    if (inserted) {
      it->second.first = db->uid2lid_and_path.size() - 1;
      SmallString<256> Path = FE.tryGetRealPathName();
      if (Path.empty())
        Path = FE.getName();
      if (!llvm::sys::path::is_absolute(Path) &&
          !SM.getFileManager().makeAbsolutePath(Path))
        return -1;
      it->second.second = Path.str();
    }
    return it->second.first;
  }

  void AddMacroUse(IndexFile *db, SourceManager &SM, Usr usr, SymbolKind kind,
                   SourceLocation Spell) const {
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(Spell));
    if (!FE)
      return;
    int lid = GetFileLID(db, SM, *FE);
    if (lid < 0)
      return;
    Range spell =
        FromTokenRange(SM, Ctx->getLangOpts(), SourceRange(Spell, Spell));
    Use use{{spell, 0, SymbolKind::File, Role::Dynamic}, lid};
    switch (kind) {
    case SymbolKind::Func:
      db->ToFunc(usr).uses.push_back(use);
      break;
    case SymbolKind::Type:
      db->ToType(usr).uses.push_back(use);
      break;
    case SymbolKind::Var:
      db->ToVar(usr).uses.push_back(use);
      break;
    default:
      llvm_unreachable("");
    }
  }

public:
  IndexDataConsumer(IndexParam &param) : param(param) {}
  void initialize(ASTContext &Ctx) override { this->Ctx = param.Ctx = &Ctx; }
  bool handleDeclOccurence(const Decl *D, index::SymbolRoleSet Roles,
                           ArrayRef<index::SymbolRelation> Relations,
#if LLVM_VERSION_MAJOR >= 7
                           SourceLocation Loc,
#else
                           FileID LocFID, unsigned LocOffset,
#endif
                           ASTNodeInfo ASTNode) override {
    SourceManager &SM = Ctx->getSourceManager();
    const LangOptions &Lang = Ctx->getLangOpts();
#if LLVM_VERSION_MAJOR < 7
    SourceLocation Loc;
    {
      const SrcMgr::SLocEntry &Entry = SM.getSLocEntry(LocFID);
      unsigned off = Entry.getOffset() + LocOffset;
      if (!Entry.isFile())
        off |= 1u << 31;
      Loc = SourceLocation::getFromRawEncoding(off);
    }
#else
    FileID LocFID;
#endif
    SourceLocation Spell = SM.getSpellingLoc(Loc);
    const FileEntry *FE;
    Range loc;
#if LLVM_VERSION_MAJOR < 7
    CharSourceRange R;
    if (SM.isMacroArgExpansion(Loc))
      R = CharSourceRange::getTokenRange(Spell);
    else {
      auto P = SM.getExpansionRange(Loc);
      R = CharSourceRange::getTokenRange(P.first, P.second);
    }
#else
    auto R = SM.isMacroArgExpansion(Loc) ? CharSourceRange::getTokenRange(Spell)
                                         : SM.getExpansionRange(Loc);
#endif
    loc = FromCharSourceRange(SM, Lang, R);
    LocFID = SM.getFileID(R.getBegin());
    FE = SM.getFileEntryForID(LocFID);
    if (!FE)
      return true;
    int lid = -1;
    IndexFile *db;
    if (g_config->index.multiVersion) {
      db = param.ConsumeFile(*SM.getFileEntryForID(SM.getMainFileID()));
      if (!db)
        return true;
      param.SeenFile(*FE);
      if (!SM.isInMainFile(R.getBegin()))
        lid = GetFileLID(db, SM, *FE);
    } else {
      db = param.ConsumeFile(*FE);
      if (!db)
        return true;
    }

    const Decl *OrigD = ASTNode.OrigD;
    const DeclContext *SemDC = OrigD->getDeclContext();
    const DeclContext *LexDC = ASTNode.ContainerDC;
    Role role = static_cast<Role>(Roles);
    db->language = LanguageId((int)db->language | (int)GetDeclLanguage(OrigD));

    bool is_decl = Roles & uint32_t(index::SymbolRole::Declaration);
    bool is_def = Roles & uint32_t(index::SymbolRole::Definition);
    if (is_decl && D->getKind() == Decl::Binding)
      is_def = true;
    IndexFunc *func = nullptr;
    IndexType *type = nullptr;
    IndexVar *var = nullptr;
    SymbolKind kind = GetSymbolKind(D);
    IndexParam::DeclInfo *info;
    Usr usr = GetUsr(D, &info);

    auto do_def_decl = [&](auto *entity) {
      if (is_def) {
        entity->def.spell = GetUse(db, lid, loc, SemDC, role);
        SourceRange R = OrigD->getSourceRange();
        entity->def.extent =
            GetUse(db, lid,
                   R.getBegin().isFileID()
                       ? FromTokenRange(SM, Lang, OrigD->getSourceRange())
                       : loc,
                   LexDC, Role::None);
      } else if (is_decl) {
        entity->declarations.push_back(GetUse(db, lid, loc, LexDC, role));
      } else {
        entity->uses.push_back(GetUse(db, lid, loc, LexDC, role));
        return;
      }
      if (entity->def.comments[0] == '\0' && g_config->index.comments)
        entity->def.comments = Intern(GetComment(OrigD));
    };
    switch (kind) {
    case SymbolKind::Invalid:
      LOG_S(INFO) << "Unhandled " << int(D->getKind()) << " " << info->qualified
                  << " in " << db->path << ":" << loc.start.line + 1;
      return true;
    case SymbolKind::File:
      return true;
    case SymbolKind::Func:
      func = &db->ToFunc(usr);
      // Span one more column to the left/right if D is CXXConstructor.
      if (!is_def && !is_decl && D->getKind() == Decl::CXXConstructor)
        role = Role(role | Role::Implicit);
      do_def_decl(func);
      if (Spell != Loc)
        AddMacroUse(db, SM, usr, SymbolKind::Func, Spell);
      if (func->def.detailed_name[0] == '\0')
        SetName(OrigD, info->short_name, info->qualified, func->def);
      if (is_def || is_decl) {
        const Decl *DC = cast<Decl>(SemDC);
        if (GetSymbolKind(DC) == SymbolKind::Type)
          db->ToType(GetUsr(DC)).def.funcs.push_back(usr);
      } else {
        const Decl *DC = cast<Decl>(LexDC);
        if (GetSymbolKind(DC) == SymbolKind::Func)
          db->ToFunc(GetUsr(DC))
              .def.callees.push_back({{loc, usr, SymbolKind::Func, role}});
      }
      break;
    case SymbolKind::Type:
      type = &db->ToType(usr);
      do_def_decl(type);
      if (Spell != Loc)
        AddMacroUse(db, SM, usr, SymbolKind::Type, Spell);
      if (type->def.detailed_name[0] == '\0')
        SetName(OrigD, info->short_name, info->qualified, type->def);
      if (is_def || is_decl) {
        const Decl *DC = cast<Decl>(SemDC);
        if (GetSymbolKind(DC) == SymbolKind::Type)
          db->ToType(GetUsr(DC)).def.types.push_back(usr);
      }
      break;
    case SymbolKind::Var:
      var = &db->ToVar(usr);
      do_def_decl(var);
      if (Spell != Loc)
        AddMacroUse(db, SM, usr, SymbolKind::Var, Spell);
      if (var->def.detailed_name[0] == '\0')
        SetVarName(OrigD, info->short_name, info->qualified, var->def);
      QualType T;
      if (auto *VD = dyn_cast<VarDecl>(D))
        T = VD->getType();
      else if (auto *FD = dyn_cast<FieldDecl>(D))
        T = FD->getType();
      if (is_def || is_decl) {
        const Decl *DC = cast<Decl>(SemDC);
        if (GetSymbolKind(DC) == SymbolKind::Func)
          db->ToFunc(GetUsr(DC)).def.vars.push_back(usr);
        else if (auto *ND = dyn_cast<NamespaceDecl>(SemDC))
          db->ToType(GetUsr(ND)).def.vars.emplace_back(usr, -1);
        if (!T.isNull()) {
          if (auto *BT = T->getAs<BuiltinType>()) {
            Usr usr1 = static_cast<Usr>(BT->getKind());
            var->def.type = usr1;
            db->ToType(usr1).instances.push_back(usr);
          } else {
            for (const Decl *D1 = GetTypeDecl(T); D1; D1 = GetSpecialized(D1)) {
              IndexParam::DeclInfo *info1;
              Usr usr1 = GetUsr(D1, &info1);
              auto it = db->usr2type.find(usr1);
              if (it != db->usr2type.end()) {
                var->def.type = usr1;
                it->second.instances.push_back(usr);
                break;
              }
              // e.g. TemplateTypeParmDecl is not handled by
              // handleDeclOccurence.
              SourceRange R1 = D1->getSourceRange();
              if (SM.getFileID(R1.getBegin()) == LocFID) {
                IndexType &type1 = db->ToType(usr1);
                SourceLocation L1 = D1->getLocation();
                type1.def.spell =
                    GetUse(db, lid, FromTokenRange(SM, Lang, {L1, L1}), SemDC,
                           Role::Definition);
                type1.def.extent = GetUse(db, lid, FromTokenRange(SM, Lang, R1),
                                          LexDC, Role::None);
                type1.def.detailed_name = Intern(info1->short_name);
                type1.def.short_name_size = int16_t(info1->short_name.size());
                type1.def.kind = lsSymbolKind::TypeParameter;
                var->def.type = usr1;
                type1.instances.push_back(usr);
                break;
              }
            }
          }
        }
      } else if (!var->def.spell && var->declarations.empty()) {
        // e.g. lambda parameter
        SourceLocation L = OrigD->getLocation();
        if (SM.getFileID(L) == LocFID) {
          var->def.spell = GetUse(db, lid, FromTokenRange(SM, Lang, {L, L}),
                                  SemDC, Role::Definition);
          var->def.extent =
              GetUse(db, lid, FromTokenRange(SM, Lang, OrigD->getSourceRange()),
                     LexDC, Role::None);
        }
      }
      break;
    }

    switch (D->getKind()) {
    case Decl::Namespace:
      type->def.kind = lsSymbolKind::Namespace;
      if (OrigD->isFirstDecl()) {
        auto *ND = cast<NamespaceDecl>(OrigD);
        auto *ND1 = cast<Decl>(ND->getParent());
        if (isa<NamespaceDecl>(ND1)) {
          Usr usr1 = GetUsr(ND1);
          type->def.bases.push_back(usr1);
          db->ToType(usr1).derived.push_back(usr);
        }
      }
      break;
    case Decl::NamespaceAlias: {
      type->def.kind = lsSymbolKind::TypeAlias;
      auto *NAD = cast<NamespaceAliasDecl>(D);
      if (const NamespaceDecl *ND = NAD->getNamespace()) {
        Usr usr1 = GetUsr(ND);
        type->def.alias_of = usr1;
        (void)db->ToType(usr1);
      }
      break;
    }
    case Decl::ObjCCategory:
    case Decl::ObjCImplementation:
    case Decl::ObjCInterface:
    case Decl::ObjCProtocol:
      type->def.kind = lsSymbolKind::Interface;
      break;
    case Decl::ObjCMethod:
      func->def.kind = lsSymbolKind::Method;
      break;
    case Decl::ObjCProperty:
      var->def.kind = lsSymbolKind::Property;
      break;
    case Decl::ClassTemplate:
      type->def.kind = lsSymbolKind::Class;
      break;
    case Decl::FunctionTemplate:
      func->def.kind = lsSymbolKind::Function;
      break;
    case Decl::TypeAliasTemplate:
      type->def.kind = lsSymbolKind::TypeAlias;
      break;
    case Decl::VarTemplate:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::TemplateTemplateParm:
      type->def.kind = lsSymbolKind::TypeParameter;
      break;
    case Decl::Enum:
      type->def.kind = lsSymbolKind::Enum;
      break;
    case Decl::CXXRecord:
      if (is_def) {
        auto *RD = dyn_cast<CXXRecordDecl>(OrigD);
        if (RD && RD->hasDefinition()) {
          for (const CXXBaseSpecifier &Base : RD->bases()) {
            QualType T = Base.getType();
            const NamedDecl *BaseD = nullptr;
            if (auto *TDT = T->getAs<TypedefType>()) {
              BaseD = TDT->getDecl();
            } else if (auto *TST = T->getAs<TemplateSpecializationType>()) {
              BaseD = TST->getTemplateName().getAsTemplateDecl();
            } else if (auto *RT = T->getAs<RecordType>()) {
              BaseD = RT->getDecl();
            }
            if (BaseD) {
              Usr usr1 = GetUsr(BaseD);
              type->def.bases.push_back(usr1);
              db->ToType(usr1).derived.push_back(usr);
            }
          }
        }
      }
      [[fallthrough]];
    case Decl::Record:
      if (auto *RD = dyn_cast<RecordDecl>(OrigD)) {
        // spec has no Union, use Class
        type->def.kind = RD->getTagKind() == TTK_Struct ? lsSymbolKind::Struct
                                                        : lsSymbolKind::Class;
        if (is_def) {
          SmallVector<std::pair<const RecordDecl *, int>, 2> Stack{{RD, 0}};
          llvm::DenseSet<const RecordDecl *> Seen;
          Seen.insert(RD);
          while (Stack.size()) {
            int offset;
            std::tie(RD, offset) = Stack.back();
            Stack.pop_back();
            if (!RD->isCompleteDefinition() || RD->isDependentType() ||
                RD->isInvalidDecl() || !ValidateRecord(RD))
              offset = -1;
            for (FieldDecl *FD : RD->fields()) {
              int offset1 = offset < 0 ? -1 : offset + Ctx->getFieldOffset(FD);
              if (FD->getIdentifier())
                type->def.vars.emplace_back(GetUsr(FD), offset1);
              else if (const auto *RT1 = FD->getType()->getAs<RecordType>()) {
                if (const RecordDecl *RD1 = RT1->getDecl())
                  if (Seen.insert(RD1).second)
                    Stack.push_back({RD1, offset1});
              }
            }
          }
        }
      }
      break;
    case Decl::ClassTemplateSpecialization:
    case Decl::ClassTemplatePartialSpecialization:
      type->def.kind = lsSymbolKind::Class;
      if (is_def || is_decl) {
        if (auto *RD = dyn_cast<CXXRecordDecl>(D)) {
          Decl *D1 = nullptr;
          if (auto *SD = dyn_cast<ClassTemplatePartialSpecializationDecl>(RD))
            D1 = SD->getSpecializedTemplate();
          else if (auto *SD = dyn_cast<ClassTemplateSpecializationDecl>(RD)) {
            llvm::PointerUnion<ClassTemplateDecl *,
                               ClassTemplatePartialSpecializationDecl *>
                Result = SD->getSpecializedTemplateOrPartial();
            if (Result.is<ClassTemplateDecl *>())
              D1 = Result.get<ClassTemplateDecl *>();
            else
              D1 = Result.get<ClassTemplatePartialSpecializationDecl *>();

          } else
            D1 = RD->getInstantiatedFromMemberClass();
          if (D1) {
            Usr usr1 = GetUsr(D1);
            type->def.bases.push_back(usr1);
            db->ToType(usr1).derived.push_back(usr);
          }
        }
      }
      break;
    case Decl::TypeAlias:
    case Decl::Typedef:
    case Decl::UnresolvedUsingTypename:
      type->def.kind = lsSymbolKind::TypeAlias;
      if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
        bool specialization = false;
        QualType T = TD->getUnderlyingType();
        if (const Decl *D1 = GetTypeDecl(T, &specialization)) {
          Usr usr1 = GetUsr(D1);
          IndexType &type1 = db->ToType(usr1);
          type->def.alias_of = usr1;
          // Not visited template<class T> struct B {typedef A<T> t;};
          if (specialization) {
            const TypeSourceInfo *TSI = TD->getTypeSourceInfo();
            SourceLocation L1 = TSI->getTypeLoc().getBeginLoc();
            if (SM.getFileID(L1) == LocFID) {
              Range loc1 = FromTokenRange(SM, Lang, {L1, L1});
              type1.uses.push_back(
                  GetUse(db, lid, loc1, LexDC, Role::Reference));
            }
          }
        }
      }
      break;
    case Decl::Binding:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::Field:
    case Decl::ObjCIvar:
      var->def.kind = lsSymbolKind::Field;
      break;
    case Decl::Function:
      func->def.kind = lsSymbolKind::Function;
      break;
    case Decl::CXXMethod: {
      const auto *MD = cast<CXXMethodDecl>(D);
      func->def.kind =
          MD->isStatic() ? lsSymbolKind::StaticMethod : lsSymbolKind::Method;
      if (is_def || is_decl) {
        if (auto *ND = dyn_cast<NamedDecl>(D)) {
          SmallVector<const NamedDecl *, 8> OverDecls;
          Ctx->getOverriddenMethods(ND, OverDecls);
          for (const auto *ND1 : OverDecls) {
            Usr usr1 = GetUsr(ND1);
            func->def.bases.push_back(usr1);
            db->ToFunc(usr1).derived.push_back(usr);
          }
        }
      }
      break;
    }
    case Decl::CXXConstructor:
    case Decl::CXXConversion:
      func->def.kind = lsSymbolKind::Constructor;
      break;
    case Decl::CXXDestructor:
      func->def.kind = lsSymbolKind::Method;
      break;
    case Decl::Var:
    case Decl::Decomposition:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::ImplicitParam:
    case Decl::ParmVar:
      // ccls extension
      var->def.kind = lsSymbolKind::Parameter;
      break;
    case Decl::VarTemplateSpecialization:
    case Decl::VarTemplatePartialSpecialization:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::EnumConstant:
      var->def.kind = lsSymbolKind::EnumMember;
      // TODO Pretty printer may print =
      if (is_def && strchr(var->def.detailed_name, '=') == nullptr) {
        auto *ECD = cast<EnumConstantDecl>(D);
        const auto &Val = ECD->getInitVal();
        std::string init =
            " = " + (Val.isSigned() ? std::to_string(Val.getSExtValue())
                                    : std::to_string(Val.getZExtValue()));
        var->def.hover = Intern(var->def.detailed_name + init);
      }
      break;
    case Decl::UnresolvedUsingValue:
      var->def.kind = lsSymbolKind::Variable;
      break;
    default:
      LOG_S(INFO) << "Unhandled " << int(D->getKind());
      break;
    }
    return true;
  }
};

class IndexPPCallbacks : public PPCallbacks {
  SourceManager &SM;
  IndexParam &param;

  std::pair<StringRef, Usr> GetMacro(const Token &Tok) const {
    StringRef Name = Tok.getIdentifierInfo()->getName();
    SmallString<256> USR("@macro@");
    USR += Name;
    return {Name, HashUsr(USR)};
  }

public:
  IndexPPCallbacks(SourceManager &SM, IndexParam &param)
      : SM(SM), param(param) {}
  void InclusionDirective(SourceLocation HashLoc, const Token &Tok,
                          StringRef Included, bool IsAngled,
                          CharSourceRange FilenameRange, const FileEntry *File,
                          StringRef SearchPath, StringRef RelativePath,
                          const Module *Imported
#if LLVM_VERSION_MAJOR >= 7
                          ,
                          SrcMgr::CharacteristicKind FileType
#endif
                          ) override {
    if (!File)
      return;
    llvm::sys::fs::UniqueID UniqueID;
    auto spell = FromCharSourceRange(SM, param.Ctx->getLangOpts(),
                                     FilenameRange, &UniqueID);
    const FileEntry *FE =
        SM.getFileEntryForID(SM.getFileID(FilenameRange.getBegin()));
    if (!FE)
      return;
    if (IndexFile *db = param.ConsumeFile(*FE)) {
      std::string file_name = FileName(*File);
      if (file_name.size())
        db->includes.push_back({spell.start.line, std::move(file_name)});
    }
  }
  void MacroDefined(const Token &Tok, const MacroDirective *MD) override {
    llvm::sys::fs::UniqueID UniqueID;
    const LangOptions &Lang = param.Ctx->getLangOpts();
    SourceLocation L = MD->getLocation();
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(L));
    if (!FE)
      return;
    if (IndexFile *db = param.ConsumeFile(*FE)) {
      auto [Name, usr] = GetMacro(Tok);
      IndexVar &var = db->ToVar(usr);
      auto range = FromTokenRange(SM, Lang, {L, L}, &UniqueID);
      var.def.kind = lsSymbolKind::Macro;
      if (var.def.spell)
        var.declarations.push_back(*var.def.spell);
      var.def.spell = Use{{range, 0, SymbolKind::File, Role::Definition}};
      const MacroInfo *MI = MD->getMacroInfo();
      SourceRange R(MI->getDefinitionLoc(), MI->getDefinitionEndLoc());
      range = FromTokenRange(SM, param.Ctx->getLangOpts(), R);
      var.def.extent = Use{{range, 0, SymbolKind::File, Role::None}};
      if (var.def.detailed_name[0] == '\0') {
        var.def.detailed_name = Intern(Name);
        var.def.short_name_size = Name.size();
        StringRef Buf = GetSourceInRange(SM, Lang, R);
        var.def.hover =
            Intern(Buf.count('\n') <= kInitializerMaxLines - 1
                       ? Twine("#define ", GetSourceInRange(SM, Lang, R)).str()
                       : Twine("#define ", Name).str());
      }
    }
  }
  void MacroExpands(const Token &Tok, const MacroDefinition &MD, SourceRange R,
                    const MacroArgs *Args) override {
    llvm::sys::fs::UniqueID UniqueID;
    SourceLocation L = SM.getSpellingLoc(R.getBegin());
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(L));
    if (!FE)
      return;
    if (IndexFile *db = param.ConsumeFile(*FE)) {
      IndexVar &var = db->ToVar(GetMacro(Tok).second);
      var.uses.push_back(
          {{FromTokenRange(SM, param.Ctx->getLangOpts(), {L, L}, &UniqueID), 0,
            SymbolKind::File, Role::Dynamic}});
    }
  }
  void MacroUndefined(const Token &Tok, const MacroDefinition &MD,
                      const MacroDirective *UD) override {
    if (UD) {
      SourceLocation L = UD->getLocation();
      MacroExpands(Tok, MD, {L, L}, nullptr);
    }
  }
  void SourceRangeSkipped(SourceRange Range, SourceLocation EndifLoc) override {
    llvm::sys::fs::UniqueID UniqueID;
    auto range = FromCharRange(SM, param.Ctx->getLangOpts(), Range, &UniqueID);
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(Range.getBegin()));
    if (IndexFile *db = param.ConsumeFile(*FE))
      db->skipped_ranges.push_back(range);
  }
};

class IndexFrontendAction : public ASTFrontendAction {
  IndexParam &param;

public:
  IndexFrontendAction(IndexParam &param) : param(param) {}
  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
                                                 StringRef InFile) override {
    Preprocessor &PP = CI.getPreprocessor();
    PP.addPPCallbacks(
        std::make_unique<IndexPPCallbacks>(PP.getSourceManager(), param));
    return std::make_unique<ASTConsumer>();
  }
};
} // namespace

const int IndexFile::kMajorVersion = 17;
const int IndexFile::kMinorVersion = 1;

IndexFile::IndexFile(llvm::sys::fs::UniqueID UniqueID, const std::string &path,
                     const std::string &contents)
    : UniqueID(UniqueID), path(path), file_contents(contents) {}

IndexFunc &IndexFile::ToFunc(Usr usr) {
  auto [it, inserted] = usr2func.try_emplace(usr);
  if (inserted)
    it->second.usr = usr;
  return it->second;
}

IndexType &IndexFile::ToType(Usr usr) {
  auto [it, inserted] = usr2type.try_emplace(usr);
  if (inserted)
    it->second.usr = usr;
  return it->second;
}

IndexVar &IndexFile::ToVar(Usr usr) {
  auto [it, inserted] = usr2var.try_emplace(usr);
  if (inserted)
    it->second.usr = usr;
  return it->second;
}

std::string IndexFile::ToString() {
  return ccls::Serialize(SerializeFormat::Json, *this);
}

template <typename T> void Uniquify(std::vector<T> &a) {
  std::unordered_set<T> seen;
  size_t n = 0;
  for (size_t i = 0; i < a.size(); i++)
    if (seen.insert(a[i]).second)
      a[n++] = a[i];
  a.resize(n);
}

namespace ccls::idx {
std::vector<std::unique_ptr<IndexFile>>
Index(VFS *vfs, const std::string &opt_wdir, const std::string &file,
      const std::vector<std::string> &args,
      const std::vector<FileContents> &file_contents) {
  if (!g_config->index.enabled)
    return {};

  auto PCH = std::make_shared<PCHContainerOperations>();
  llvm::IntrusiveRefCntPtr<vfs::FileSystem> FS = vfs::getRealFileSystem();
  std::shared_ptr<CompilerInvocation> CI = BuildCompilerInvocation(args, FS);
  if (!CI)
    return {};
  // -fparse-all-comments enables documentation in the indexer and in
  // code completion.
  CI->getLangOpts()->CommentOpts.ParseAllComments =
      g_config->index.comments > 1;
  CI->getLangOpts()->RetainCommentsFromSystemHeaders = true;
  CI->getLangOpts()->SpellChecking = false;

  DiagnosticConsumer DC;
  auto Clang = std::make_unique<CompilerInstance>(PCH);
  Clang->setInvocation(std::move(CI));
  Clang->setVirtualFileSystem(FS);
  Clang->createDiagnostics(&DC, false);
  Clang->setTarget(TargetInfo::CreateTargetInfo(
      Clang->getDiagnostics(), Clang->getInvocation().TargetOpts));
  if (!Clang->hasTarget())
    return {};

  FileConsumer file_consumer(vfs, file);
  IndexParam param(&file_consumer);
  auto DataConsumer = std::make_shared<IndexDataConsumer>(param);

  index::IndexingOptions IndexOpts;
  IndexOpts.SystemSymbolFilter =
      index::IndexingOptions::SystemSymbolFilterKind::All;
  IndexOpts.IndexFunctionLocals = true;
#if LLVM_VERSION_MAJOR >= 7
  IndexOpts.IndexImplicitInstantiation = true;
#endif

  std::unique_ptr<FrontendAction> Action = createIndexingAction(
      DataConsumer, IndexOpts, std::make_unique<IndexFrontendAction>(param));

  bool ok = false;
  {
    llvm::CrashRecoveryContext CRC;
    auto parse = [&]() {
                   if (!Action->BeginSourceFile(*Clang, Clang->getFrontendOpts().Inputs[0]))
                     return;
                   if (!Action->Execute())
                     return;
                   Action->EndSourceFile();
                   ok = true;
                 };
    if (!CRC.RunSafely(parse)) {
      LOG_S(ERROR) << "clang crashed for " << file;
      return {};
    }
  }
  if (!ok) {
    LOG_S(ERROR) << "failed to index " << file;
    return {};
  }

  auto result = param.file_consumer->TakeLocalState();
  for (std::unique_ptr<IndexFile> &entry : result) {
    entry->import_file = file;
    entry->args = args;
    for (auto &[_, it] : entry->uid2lid_and_path)
      entry->lid2path.emplace_back(it.first, std::move(it.second));
    entry->uid2lid_and_path.clear();
    for (auto &it : entry->usr2func) {
      // e.g. declaration + out-of-line definition
      Uniquify(it.second.derived);
      Uniquify(it.second.uses);
    }
    for (auto &it : entry->usr2type) {
      Uniquify(it.second.derived);
      Uniquify(it.second.uses);
      // e.g. declaration + out-of-line definition
      Uniquify(it.second.def.bases);
      Uniquify(it.second.def.funcs);
    }
    for (auto &it : entry->usr2var)
      Uniquify(it.second.uses);

    // Update file contents and modification time.
    entry->last_write_time = param.file2write_time[entry->path];

    // Update dependencies for the file. Do not include the file in its own
    // dependency set.
    for (auto &[_, path] : param.SeenUniqueID)
      if (path != entry->path && path != entry->import_file)
        entry->dependencies[path] = param.file2write_time[path];
  }

  return result;
}
} // namespace ccls::idx

// |SymbolRef| is serialized this way.
// |Use| also uses this though it has an extra field |file|,
// which is not used by Index* so it does not need to be serialized.
void Reflect(Reader &vis, Reference &v) {
  if (vis.Format() == SerializeFormat::Json) {
    std::string t = vis.GetString();
    char *s = const_cast<char *>(t.c_str());
    v.range = Range::FromString(s);
    s = strchr(s, '|');
    v.usr = strtoull(s + 1, &s, 10);
    v.kind = static_cast<SymbolKind>(strtol(s + 1, &s, 10));
    v.role = static_cast<Role>(strtol(s + 1, &s, 10));
  } else {
    Reflect(vis, v.range);
    Reflect(vis, v.usr);
    Reflect(vis, v.kind);
    Reflect(vis, v.role);
  }
}
void Reflect(Writer &vis, Reference &v) {
  if (vis.Format() == SerializeFormat::Json) {
    char buf[99];
    snprintf(buf, sizeof buf, "%s|%" PRIu64 "|%d|%d",
             v.range.ToString().c_str(), v.usr, int(v.kind), int(v.role));
    std::string s(buf);
    Reflect(vis, s);
  } else {
    Reflect(vis, v.range);
    Reflect(vis, v.usr);
    Reflect(vis, v.kind);
    Reflect(vis, v.role);
  }
}

void Reflect(Reader &vis, Use &v) {
  if (vis.Format() == SerializeFormat::Json) {
    std::string t = vis.GetString();
    char *s = const_cast<char *>(t.c_str());
    v.range = Range::FromString(s);
    s = strchr(s, '|');
    v.usr = strtoull(s + 1, &s, 10);
    v.kind = static_cast<SymbolKind>(strtol(s + 1, &s, 10));
    v.role = static_cast<Role>(strtol(s + 1, &s, 10));
    if (*s == '|')
      v.file_id = static_cast<int>(strtol(s + 1, &s, 10));
  } else {
    Reflect(vis, static_cast<Reference &>(v));
    Reflect(vis, v.file_id);
  }
}
void Reflect(Writer &vis, Use &v) {
  if (vis.Format() == SerializeFormat::Json) {
    char buf[99];
    if (v.file_id == -1)
      snprintf(buf, sizeof buf, "%s|%" PRIu64 "|%d|%d",
               v.range.ToString().c_str(), v.usr, int(v.kind), int(v.role));
    else
      snprintf(buf, sizeof buf, "%s|%" PRIu64 "|%d|%d|%d",
               v.range.ToString().c_str(), v.usr, int(v.kind), int(v.role),
               v.file_id);
    std::string s(buf);
    Reflect(vis, s);
  } else {
    Reflect(vis, static_cast<Reference &>(v));
    Reflect(vis, v.file_id);
  }
}