C++ StringRef::drop_back方法代码示例

/// Skip a type suffix that can be dropped.
static Optional<StringRef> skipTypeSuffix(StringRef typeName) {
  if (typeName.empty()) return None;

  auto lastWord = camel_case::getLastWord(typeName);

  // "Type" suffix.
  if (lastWord == "Type" && typeName.size() > 4) {
    return typeName.drop_back(4);
  }

  // "Ref" suffix.
  if (lastWord == "Ref" && typeName.size() > 3) {
    return typeName.drop_back(3);
  }

  // \d+D for dimensionality.
  if (typeName.back() == 'D' && typeName.size() > 1) {
    unsigned firstDigit = typeName.size() - 1;
    while (firstDigit > 0) {
      if (!isdigit(typeName[firstDigit-1])) break;
      --firstDigit;
    }

    if (firstDigit < typeName.size()-1) {
      return typeName.substr(0, firstDigit);
    }
  }

  // _t.
  if (typeName.size() > 2 && typeName.endswith("_t")) {
    return typeName.drop_back(2);
  }
  return None;
}

static bool matchCrtObjName(StringRef objName, StringRef objPath) {
  if (!objPath.endswith(".o"))
    return false;

  // check *<objName> case
  objPath = objPath.drop_back(2);
  if (objPath.endswith(objName))
    return true;

  // check *<objName>? case
  return !objPath.empty() && objPath.drop_back(1).endswith(objName);
}

 /// \brief Tries to find the node under this \c FileMatchTrieNode that best
 /// matches 'FileName'.
 ///
 /// If multiple paths fit 'FileName' equally well, \c IsAmbiguous is set to
 /// \c true and an empty string is returned. If no path fits 'FileName', an
 /// empty string is returned. \c ConsumedLength denotes the number of
 /// \c Filename's trailing characters already consumed during recursion.
 ///
 /// To find the best matching node for a given path 'p', the
 /// \c findEquivalent() function is called recursively for each path segment
 /// (back to fron) of 'p' until a node 'n' is reached that does not ..
 /// - .. have children. In this case it is checked
 ///   whether the stored path is equivalent to 'p'. If yes, the best match is
 ///   found. Otherwise continue with the parent node as if this node did not
 ///   exist.
 /// - .. a child matching the next path segment. In this case, all children of
 ///   'n' are an equally good match for 'p'. All children are of 'n' are found
 ///   recursively and their equivalence to 'p' is determined. If none are
 ///   equivalent, continue with the parent node as if 'n' didn't exist. If one
 ///   is equivalent, the best match is found. Otherwise, report and ambigiuity
 ///   error.
 StringRef findEquivalent(const PathComparator& Comparator,
                          StringRef FileName,
                          bool &IsAmbiguous,
                          unsigned ConsumedLength = 0) const {
   if (Children.empty()) {
     if (Comparator.equivalent(StringRef(Path), FileName))
       return StringRef(Path);
     return StringRef();
   }
   StringRef Element(llvm::sys::path::filename(FileName.drop_back(
       ConsumedLength)));
   llvm::StringMap<FileMatchTrieNode>::const_iterator MatchingChild =
       Children.find(Element);
   if (MatchingChild != Children.end()) {
     StringRef Result = MatchingChild->getValue().findEquivalent(
         Comparator, FileName, IsAmbiguous,
         ConsumedLength + Element.size() + 1);
     if (!Result.empty() || IsAmbiguous)
       return Result;
   }
   std::vector<StringRef> AllChildren;
   getAll(AllChildren, MatchingChild);
   StringRef Result;
   for (unsigned i = 0; i < AllChildren.size(); i++) {
     if (Comparator.equivalent(AllChildren[i], FileName)) {
       if (Result.empty()) {
         Result = AllChildren[i];
       } else {
         IsAmbiguous = true;
         return StringRef();
       }
     }
   }
   return Result;
 }

static bool matchesStyle(StringRef Name,
                         IdentifierNamingCheck::NamingStyle Style) {
  static llvm::Regex Matchers[] = {
      llvm::Regex("^.*$"),
      llvm::Regex("^[a-z][a-z0-9_]*$"),
      llvm::Regex("^[a-z][a-zA-Z0-9]*$"),
      llvm::Regex("^[A-Z][A-Z0-9_]*$"),
      llvm::Regex("^[A-Z][a-zA-Z0-9]*$"),
      llvm::Regex("^[A-Z]([a-z0-9]*(_[A-Z])?)*"),
      llvm::Regex("^[a-z]([a-z0-9]*(_[A-Z])?)*"),
  };

  bool Matches = true;
  if (Name.startswith(Style.Prefix))
    Name = Name.drop_front(Style.Prefix.size());
  else
    Matches = false;

  if (Name.endswith(Style.Suffix))
    Name = Name.drop_back(Style.Suffix.size());
  else
    Matches = false;

  // Ensure the name doesn't have any extra underscores beyond those specified
  // in the prefix and suffix.
  if (Name.startswith("_") || Name.endswith("_"))
    Matches = false;

  if (Style.Case && !Matchers[static_cast<size_t>(*Style.Case)].match(Name))
    Matches = false;

  return Matches;
}

static bool matchesStyle(StringRef Name,
                         IdentifierNamingCheck::NamingStyle Style) {
  static llvm::Regex Matchers[] = {
      llvm::Regex("^.*$"),
      llvm::Regex("^[a-z][a-z0-9_]*$"),
      llvm::Regex("^[a-z][a-zA-Z0-9]*$"),
      llvm::Regex("^[A-Z][A-Z0-9_]*$"),
      llvm::Regex("^[A-Z][a-zA-Z0-9]*$"),
      llvm::Regex("^[A-Z]([a-z0-9]*(_[A-Z])?)*"),
      llvm::Regex("^[a-z]([a-z0-9]*(_[A-Z])?)*"),
  };

  bool Matches = true;
  if (Name.startswith(Style.Prefix))
    Name = Name.drop_front(Style.Prefix.size());
  else
    Matches = false;

  if (Name.endswith(Style.Suffix))
    Name = Name.drop_back(Style.Suffix.size());
  else
    Matches = false;

  if (!Matchers[static_cast<size_t>(Style.Case)].match(Name))
    Matches = false;

  return Matches;
}

static void WriteOutputFile(const Module *M) {
  // Infer the output filename if needed.
  if (OutputFilename.empty()) {
    if (InputFilename == "-") {
      OutputFilename = "-";
    } else {
      StringRef IFN = InputFilename;
      OutputFilename = (IFN.endswith(".ll") ? IFN.drop_back(3) : IFN).str();
      OutputFilename += ".bc";
    }
  }

  std::error_code EC;
  std::unique_ptr<ToolOutputFile> Out(
      new ToolOutputFile(OutputFilename, EC, sys::fs::F_None));
  if (EC) {
    errs() << EC.message() << '\n';
    exit(1);
  }

  if (Force || !CheckBitcodeOutputToConsole(Out->os(), true))
    WriteBitcodeToFile(*M, Out->os(), PreserveBitcodeUseListOrder, nullptr,
                       EmitModuleHash);

  // Declare success.
  Out->keep();
}

int main(int argc, char **argv) {
  // Print a stack trace if we signal out.
  sys::PrintStackTraceOnErrorSignal(argv[0]);
  PrettyStackTraceProgram X(argc, argv);

  LLVMContext Context;
  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.

  Context.setDiagnosticHandler(diagnosticHandler, argv[0]);

  cl::ParseCommandLineOptions(argc, argv, "llvm .bc -> .ll disassembler\n");

  Expected<std::unique_ptr<Module>> MOrErr = openInputFile(Context);
  if (!MOrErr) {
    handleAllErrors(MOrErr.takeError(), [&](ErrorInfoBase &EIB) {
      errs() << argv[0] << ": ";
      EIB.log(errs());
      errs() << '\n';
    });
    return 1;
  }
  std::unique_ptr<Module> M = std::move(*MOrErr);

  // Just use stdout.  We won't actually print anything on it.
  if (DontPrint)
    OutputFilename = "-";

  if (OutputFilename.empty()) { // Unspecified output, infer it.
    if (InputFilename == "-") {
      OutputFilename = "-";
    } else {
      StringRef IFN = InputFilename;
      OutputFilename = (IFN.endswith(".bc") ? IFN.drop_back(3) : IFN).str();
      OutputFilename += ".ll";
    }
  }

  std::error_code EC;
  std::unique_ptr<tool_output_file> Out(
      new tool_output_file(OutputFilename, EC, sys::fs::F_None));
  if (EC) {
    errs() << EC.message() << '\n';
    return 1;
  }

  std::unique_ptr<AssemblyAnnotationWriter> Annotator;
  if (ShowAnnotations)
    Annotator.reset(new CommentWriter());

  // All that llvm-dis does is write the assembly to a file.
  if (!DontPrint)
    M->print(Out->os(), Annotator.get(), PreserveAssemblyUseListOrder);

  // Declare success.
  Out->keep();

  return 0;
}

/// Returns the common word-prefix of two strings, allowing the second string
/// to be a common English plural form of the first.
///
/// For example, given "NSProperty" and "NSProperties", the full "NSProperty"
/// is returned. Given "NSMagicArmor" and "NSMagicArmory", only
/// "NSMagic" is returned.
///
/// The "-s", "-es", and "-ies" patterns cover every plural NS_OPTIONS name
/// in Cocoa and Cocoa Touch.
///
/// \see getCommonWordPrefix
StringRef importer::getCommonPluralPrefix(StringRef singular,
                                          StringRef plural) {
  assert(!plural.empty());

  if (singular.empty())
    return singular;

  bool ignored;
  StringRef commonPrefix = getCommonWordPrefix(singular, plural, ignored);
  if (commonPrefix.size() == singular.size() || plural.back() != 's')
    return commonPrefix;

  StringRef leftover = singular.substr(commonPrefix.size());
  StringRef firstLeftoverWord = camel_case::getFirstWord(leftover);
  StringRef commonPrefixPlusWord =
      singular.substr(0, commonPrefix.size() + firstLeftoverWord.size());

  // Is the plural string just "[singular]s"?
  plural = plural.drop_back();
  if (plural.endswith(firstLeftoverWord))
    return commonPrefixPlusWord;

  if (plural.empty() || plural.back() != 'e')
    return commonPrefix;

  // Is the plural string "[singular]es"?
  plural = plural.drop_back();
  if (plural.endswith(firstLeftoverWord))
    return commonPrefixPlusWord;

  if (plural.empty() || !(plural.back() == 'i' && singular.back() == 'y'))
    return commonPrefix;

  // Is the plural string "[prefix]ies" and the singular "[prefix]y"?
  plural = plural.drop_back();
  firstLeftoverWord = firstLeftoverWord.drop_back();
  if (plural.endswith(firstLeftoverWord))
    return commonPrefixPlusWord;

  return commonPrefix;
}

bool HasNameMatcher::matchesNodeFull(const NamedDecl &Node) const {
  llvm::SmallString<128> NodeName = StringRef("::");
  llvm::raw_svector_ostream OS(NodeName);
  Node.printQualifiedName(OS);
  const StringRef FullName = OS.str();
  const StringRef Pattern = Name;

  if (Pattern.startswith("::"))
    return FullName == Pattern;

  return FullName.endswith(Pattern) &&
         FullName.drop_back(Pattern.size()).endswith("::");
}

// Makes a given pathname an absolute path first, and then remove
// beginning /. For example, "../foo.o" is converted to "home/john/foo.o",
// assuming that the current directory is "/home/john/bar".
// Returned string is a forward slash separated path even on Windows to avoid
// a mess with backslash-as-escape and backslash-as-path-separator.
std::string lld::relativeToRoot(StringRef Path) {
  SmallString<128> Abs = Path;
  if (fs::make_absolute(Abs))
    return Path;
  path::remove_dots(Abs, /*remove_dot_dot=*/true);

  // This is Windows specific. root_name() returns a drive letter
  // (e.g. "c:") or a UNC name (//net). We want to keep it as part
  // of the result.
  SmallString<128> Res;
  StringRef Root = path::root_name(Abs);
  if (Root.endswith(":"))
    Res = Root.drop_back();
  else if (Root.startswith("//"))
    Res = Root.substr(2);

  path::append(Res, path::relative_path(Abs));
  return path::convert_to_slash(Res);
}

static void WriteOutputFile(const Module *M, const ModuleSummaryIndex *Index) {
  // Infer the output filename if needed.
  if (OutputFilename.empty()) {
    if (InputFilename == "-") {
      OutputFilename = "-";
    } else {
      StringRef IFN = InputFilename;
      OutputFilename = (IFN.endswith(".ll") ? IFN.drop_back(3) : IFN).str();
      OutputFilename += ".bc";
    }
  }

  std::error_code EC;
  std::unique_ptr<ToolOutputFile> Out(
      new ToolOutputFile(OutputFilename, EC, sys::fs::F_None));
  if (EC) {
    errs() << EC.message() << '\n';
    exit(1);
  }

  if (Force || !CheckBitcodeOutputToConsole(Out->os(), true)) {
    const ModuleSummaryIndex *IndexToWrite = nullptr;
    // Don't attempt to write a summary index unless it contains any entries.
    // Otherwise we get an empty summary section.
    if (Index && Index->begin() != Index->end())
      IndexToWrite = Index;
    if (!IndexToWrite || (M && (!M->empty() || !M->global_empty())))
      // If we have a non-empty Module, then we write the Module plus
      // any non-null Index along with it as a per-module Index.
      // If both are empty, this will give an empty module block, which is
      // the expected behavior.
      WriteBitcodeToFile(*M, Out->os(), PreserveBitcodeUseListOrder,
                         IndexToWrite, EmitModuleHash);
    else
      // Otherwise, with an empty Module but non-empty Index, we write a
      // combined index.
      WriteIndexToFile(*IndexToWrite, Out->os());
  }

  // Declare success.
  Out->keep();
}

bool MSP430AsmParser::ParseInstruction(ParseInstructionInfo &Info,
                                       StringRef Name, SMLoc NameLoc,
                                       OperandVector &Operands) {
  // Drop .w suffix
  if (Name.endswith_lower(".w"))
    Name = Name.drop_back(2);

  if (!parseJccInstruction(Info, Name, NameLoc, Operands))
    return false;

  // First operand is instruction mnemonic
  Operands.push_back(MSP430Operand::CreateToken(Name, NameLoc));

  // If there are no more operands, then finish
  if (getLexer().is(AsmToken::EndOfStatement))
    return false;

  // Parse first operand
  if (ParseOperand(Operands))
    return true;

  // Parse second operand if any
  if (getLexer().is(AsmToken::Comma)) {
    getLexer().Lex(); // Eat ','
    if (ParseOperand(Operands))
      return true;
  }

  if (getLexer().isNot(AsmToken::EndOfStatement)) {
    SMLoc Loc = getLexer().getLoc();
    getParser().eatToEndOfStatement();
    return Error(Loc, "unexpected token");
  }

  getParser().Lex(); // Consume the EndOfStatement.
  return false;
}

static bool MacroBodyEndsInBackslash(StringRef MacroBody) {
  while (!MacroBody.empty() && isWhitespace(MacroBody.back()))
    MacroBody = MacroBody.drop_back();
  return !MacroBody.empty() && MacroBody.back() == '\\';
}

IAMResult IAMInference::infer(const clang::NamedDecl *clangDecl) {
  if (clangDecl->getName().startswith("_")) {
    ++SkipLeadingUnderscore;
    return {};
  }

  // Try to infer a member variable
  if (auto varDecl = dyn_cast<clang::VarDecl>(clangDecl))
    return inferVar(varDecl);

  // Try to infer a member function
  auto funcDecl = dyn_cast<clang::FunctionDecl>(clangDecl);
  if (!funcDecl) {
    // TODO: Do we want to collects stats here? Should it be assert?
    return {};
  }

  auto fail = [funcDecl]() -> IAMResult {
    DEBUG(llvm::dbgs() << "failed to infer function: ");
    DEBUG(funcDecl->print(llvm::dbgs()));
    DEBUG(llvm::dbgs() << "\n");
    ++FailInferFunction;
    return {};
  };

  // Can't really import variadics well
  if (funcDecl->isVariadic())
    return fail();

  // FIXME: drop "Mutable"...

  StringRef workingName = funcDecl->getName();
  auto retTy = funcDecl->getReturnType();
  unsigned numParams = funcDecl->getNumParams();

  // 0) Special cases are specially handled
  //
  StringRef getTypeID = "GetTypeID";
  StringRef cfSpecials[] = {"Release", "Retain", "Autorelease"};
  // *GetTypeID
  if (numParams == 0 && workingName.endswith(getTypeID)) {
    NameBuffer remainingName;
    if (auto effectiveDC = findTypeAndMatch(
            workingName.drop_back(getTypeID.size()), remainingName)) {
      // We shouldn't have anything else left in our name for typeID
      if (remainingName.empty()) {

        return importAsTypeID(retTy, effectiveDC);
      }
    }
    // *Release/*Retain/*Autorelease
  } else if (numParams == 1 &&
             std::any_of(std::begin(cfSpecials), std::end(cfSpecials),
                         [workingName](StringRef suffix) {
                           return workingName.endswith(suffix);
                         })) {
    if (auto type =
            funcDecl->getParamDecl(0)->getType()->getAs<clang::TypedefType>()) {
      if (CFPointeeInfo::classifyTypedef(type->getDecl())) {
        ++SkipCFMemoryManagement;
        return {};
      }
    }
  }

  // 1) If we find an init specifier and our name matches the return type, we
  //    import as some kind of constructor
  //
  if (!retTy->isVoidType()) {
    NameBuffer remainingName;
    if (matchTypeName(workingName, retTy, remainingName))
      for (auto initSpec : InitSpecifiers)
        if (hasWord(remainingName, initSpec))
          if (auto effectiveDC = getEffectiveDC(retTy))
            return importAsConstructor(
                remainingName, initSpec,
                {funcDecl->param_begin(), funcDecl->param_end()}, effectiveDC);
  }

  // 2) If we find a likely self reference in the parameters, make an instance
  //    member (method or property)
  //
  SmallVector<const clang::ParmVarDecl *, 8> nonSelfParams;
  unsigned selfIdx = 0;
  for (auto paramI = funcDecl->param_begin(), paramE = funcDecl->param_end();
       paramI != paramE; ++paramI, ++selfIdx) {
    auto param = *paramI;
    NameBuffer remainingName;
    if (matchTypeName(workingName, param->getType(), remainingName)) {
      auto effectiveDC = getEffectiveDC(param->getType());
      if (!effectiveDC)
        continue;
      nonSelfParams.append(funcDecl->param_begin(), paramI);
      nonSelfParams.append(++paramI, paramE);
      // See if it's a property
      for (auto propSpec : PropertySpecifiers) {
        NameBuffer propName;
        if (match(remainingName, propSpec, propName)) {
          const clang::FunctionDecl *pairedAccessor;
          if (validToImportAsProperty(funcDecl, propSpec, selfIdx,
//.........这里部分代码省略.........

/// Return the name to import a CF typedef as.
static StringRef getImportedCFTypeName(StringRef name) {
  // If the name ends in the CF typedef suffix ("Ref"), drop that.
  if (name.endswith(SWIFT_CFTYPE_SUFFIX))
    return name.drop_back(strlen(SWIFT_CFTYPE_SUFFIX));
  return name;
}