xref: /llvm-project-15.0.7/clang/lib/Format/Format.cpp (revision 4eb8393c)

//===--- Format.cpp - Format C++ code -------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief This file implements functions declared in Format.h. This will be
/// split into separate files as we go.
///
//===----------------------------------------------------------------------===//

#include "clang/Format/Format.h"
#include "AffectedRangeManager.h"
#include "ContinuationIndenter.h"
#include "TokenAnnotator.h"
#include "UnwrappedLineFormatter.h"
#include "UnwrappedLineParser.h"
#include "WhitespaceManager.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/DiagnosticOptions.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/VirtualFileSystem.h"
#include "clang/Lex/Lexer.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Regex.h"
#include "llvm/Support/YAMLTraits.h"
#include <memory>
#include <queue>
#include <string>

#define DEBUG_TYPE "format-formatter"

using clang::format::FormatStyle;

LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(std::string)
LLVM_YAML_IS_SEQUENCE_VECTOR(clang::format::FormatStyle::IncludeCategory)

namespace llvm {
namespace yaml {
template <> struct ScalarEnumerationTraits<FormatStyle::LanguageKind> {
  static void enumeration(IO &IO, FormatStyle::LanguageKind &Value) {
    IO.enumCase(Value, "Cpp", FormatStyle::LK_Cpp);
    IO.enumCase(Value, "Java", FormatStyle::LK_Java);
    IO.enumCase(Value, "JavaScript", FormatStyle::LK_JavaScript);
    IO.enumCase(Value, "Proto", FormatStyle::LK_Proto);
    IO.enumCase(Value, "TableGen", FormatStyle::LK_TableGen);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::LanguageStandard> {
  static void enumeration(IO &IO, FormatStyle::LanguageStandard &Value) {
    IO.enumCase(Value, "Cpp03", FormatStyle::LS_Cpp03);
    IO.enumCase(Value, "C++03", FormatStyle::LS_Cpp03);
    IO.enumCase(Value, "Cpp11", FormatStyle::LS_Cpp11);
    IO.enumCase(Value, "C++11", FormatStyle::LS_Cpp11);
    IO.enumCase(Value, "Auto", FormatStyle::LS_Auto);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::UseTabStyle> {
  static void enumeration(IO &IO, FormatStyle::UseTabStyle &Value) {
    IO.enumCase(Value, "Never", FormatStyle::UT_Never);
    IO.enumCase(Value, "false", FormatStyle::UT_Never);
    IO.enumCase(Value, "Always", FormatStyle::UT_Always);
    IO.enumCase(Value, "true", FormatStyle::UT_Always);
    IO.enumCase(Value, "ForIndentation", FormatStyle::UT_ForIndentation);
    IO.enumCase(Value, "ForContinuationAndIndentation",
                FormatStyle::UT_ForContinuationAndIndentation);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::JavaScriptQuoteStyle> {
  static void enumeration(IO &IO, FormatStyle::JavaScriptQuoteStyle &Value) {
    IO.enumCase(Value, "Leave", FormatStyle::JSQS_Leave);
    IO.enumCase(Value, "Single", FormatStyle::JSQS_Single);
    IO.enumCase(Value, "Double", FormatStyle::JSQS_Double);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::ShortFunctionStyle> {
  static void enumeration(IO &IO, FormatStyle::ShortFunctionStyle &Value) {
    IO.enumCase(Value, "None", FormatStyle::SFS_None);
    IO.enumCase(Value, "false", FormatStyle::SFS_None);
    IO.enumCase(Value, "All", FormatStyle::SFS_All);
    IO.enumCase(Value, "true", FormatStyle::SFS_All);
    IO.enumCase(Value, "Inline", FormatStyle::SFS_Inline);
    IO.enumCase(Value, "Empty", FormatStyle::SFS_Empty);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::BinaryOperatorStyle> {
  static void enumeration(IO &IO, FormatStyle::BinaryOperatorStyle &Value) {
    IO.enumCase(Value, "All", FormatStyle::BOS_All);
    IO.enumCase(Value, "true", FormatStyle::BOS_All);
    IO.enumCase(Value, "None", FormatStyle::BOS_None);
    IO.enumCase(Value, "false", FormatStyle::BOS_None);
    IO.enumCase(Value, "NonAssignment", FormatStyle::BOS_NonAssignment);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::BraceBreakingStyle> {
  static void enumeration(IO &IO, FormatStyle::BraceBreakingStyle &Value) {
    IO.enumCase(Value, "Attach", FormatStyle::BS_Attach);
    IO.enumCase(Value, "Linux", FormatStyle::BS_Linux);
    IO.enumCase(Value, "Mozilla", FormatStyle::BS_Mozilla);
    IO.enumCase(Value, "Stroustrup", FormatStyle::BS_Stroustrup);
    IO.enumCase(Value, "Allman", FormatStyle::BS_Allman);
    IO.enumCase(Value, "GNU", FormatStyle::BS_GNU);
    IO.enumCase(Value, "WebKit", FormatStyle::BS_WebKit);
    IO.enumCase(Value, "Custom", FormatStyle::BS_Custom);
  }
};

template <>
struct ScalarEnumerationTraits<FormatStyle::ReturnTypeBreakingStyle> {
  static void enumeration(IO &IO, FormatStyle::ReturnTypeBreakingStyle &Value) {
    IO.enumCase(Value, "None", FormatStyle::RTBS_None);
    IO.enumCase(Value, "All", FormatStyle::RTBS_All);
    IO.enumCase(Value, "TopLevel", FormatStyle::RTBS_TopLevel);
    IO.enumCase(Value, "TopLevelDefinitions",
                FormatStyle::RTBS_TopLevelDefinitions);
    IO.enumCase(Value, "AllDefinitions", FormatStyle::RTBS_AllDefinitions);
  }
};

template <>
struct ScalarEnumerationTraits<FormatStyle::DefinitionReturnTypeBreakingStyle> {
  static void
  enumeration(IO &IO, FormatStyle::DefinitionReturnTypeBreakingStyle &Value) {
    IO.enumCase(Value, "None", FormatStyle::DRTBS_None);
    IO.enumCase(Value, "All", FormatStyle::DRTBS_All);
    IO.enumCase(Value, "TopLevel", FormatStyle::DRTBS_TopLevel);

    // For backward compatibility.
    IO.enumCase(Value, "false", FormatStyle::DRTBS_None);
    IO.enumCase(Value, "true", FormatStyle::DRTBS_All);
  }
};

template <>
struct ScalarEnumerationTraits<FormatStyle::NamespaceIndentationKind> {
  static void enumeration(IO &IO,
                          FormatStyle::NamespaceIndentationKind &Value) {
    IO.enumCase(Value, "None", FormatStyle::NI_None);
    IO.enumCase(Value, "Inner", FormatStyle::NI_Inner);
    IO.enumCase(Value, "All", FormatStyle::NI_All);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::BracketAlignmentStyle> {
  static void enumeration(IO &IO, FormatStyle::BracketAlignmentStyle &Value) {
    IO.enumCase(Value, "Align", FormatStyle::BAS_Align);
    IO.enumCase(Value, "DontAlign", FormatStyle::BAS_DontAlign);
    IO.enumCase(Value, "AlwaysBreak", FormatStyle::BAS_AlwaysBreak);

    // For backward compatibility.
    IO.enumCase(Value, "true", FormatStyle::BAS_Align);
    IO.enumCase(Value, "false", FormatStyle::BAS_DontAlign);
  }
};

template <> struct ScalarEnumerationTraits<FormatStyle::PointerAlignmentStyle> {
  static void enumeration(IO &IO, FormatStyle::PointerAlignmentStyle &Value) {
    IO.enumCase(Value, "Middle", FormatStyle::PAS_Middle);
    IO.enumCase(Value, "Left", FormatStyle::PAS_Left);
    IO.enumCase(Value, "Right", FormatStyle::PAS_Right);

    // For backward compatibility.
    IO.enumCase(Value, "true", FormatStyle::PAS_Left);
    IO.enumCase(Value, "false", FormatStyle::PAS_Right);
  }
};

template <>
struct ScalarEnumerationTraits<FormatStyle::SpaceBeforeParensOptions> {
  static void enumeration(IO &IO,
                          FormatStyle::SpaceBeforeParensOptions &Value) {
    IO.enumCase(Value, "Never", FormatStyle::SBPO_Never);
    IO.enumCase(Value, "ControlStatements",
                FormatStyle::SBPO_ControlStatements);
    IO.enumCase(Value, "Always", FormatStyle::SBPO_Always);

    // For backward compatibility.
    IO.enumCase(Value, "false", FormatStyle::SBPO_Never);
    IO.enumCase(Value, "true", FormatStyle::SBPO_ControlStatements);
  }
};

template <> struct MappingTraits<FormatStyle> {
  static void mapping(IO &IO, FormatStyle &Style) {
    // When reading, read the language first, we need it for getPredefinedStyle.
    IO.mapOptional("Language", Style.Language);

    if (IO.outputting()) {
      StringRef StylesArray[] = {"LLVM",    "Google", "Chromium",
                                 "Mozilla", "WebKit", "GNU"};
      ArrayRef<StringRef> Styles(StylesArray);
      for (size_t i = 0, e = Styles.size(); i < e; ++i) {
        StringRef StyleName(Styles[i]);
        FormatStyle PredefinedStyle;
        if (getPredefinedStyle(StyleName, Style.Language, &PredefinedStyle) &&
            Style == PredefinedStyle) {
          IO.mapOptional("# BasedOnStyle", StyleName);
          break;
        }
      }
    } else {
      StringRef BasedOnStyle;
      IO.mapOptional("BasedOnStyle", BasedOnStyle);
      if (!BasedOnStyle.empty()) {
        FormatStyle::LanguageKind OldLanguage = Style.Language;
        FormatStyle::LanguageKind Language =
            ((FormatStyle *)IO.getContext())->Language;
        if (!getPredefinedStyle(BasedOnStyle, Language, &Style)) {
          IO.setError(Twine("Unknown value for BasedOnStyle: ", BasedOnStyle));
          return;
        }
        Style.Language = OldLanguage;
      }
    }

    // For backward compatibility.
    if (!IO.outputting()) {
      IO.mapOptional("DerivePointerBinding", Style.DerivePointerAlignment);
      IO.mapOptional("IndentFunctionDeclarationAfterType",
                     Style.IndentWrappedFunctionNames);
      IO.mapOptional("PointerBindsToType", Style.PointerAlignment);
      IO.mapOptional("SpaceAfterControlStatementKeyword",
                     Style.SpaceBeforeParens);
    }

    IO.mapOptional("AccessModifierOffset", Style.AccessModifierOffset);
    IO.mapOptional("AlignAfterOpenBracket", Style.AlignAfterOpenBracket);
    IO.mapOptional("AlignConsecutiveAssignments",
                   Style.AlignConsecutiveAssignments);
    IO.mapOptional("AlignConsecutiveDeclarations",
                   Style.AlignConsecutiveDeclarations);
    IO.mapOptional("AlignEscapedNewlinesLeft", Style.AlignEscapedNewlinesLeft);
    IO.mapOptional("AlignOperands", Style.AlignOperands);
    IO.mapOptional("AlignTrailingComments", Style.AlignTrailingComments);
    IO.mapOptional("AllowAllParametersOfDeclarationOnNextLine",
                   Style.AllowAllParametersOfDeclarationOnNextLine);
    IO.mapOptional("AllowShortBlocksOnASingleLine",
                   Style.AllowShortBlocksOnASingleLine);
    IO.mapOptional("AllowShortCaseLabelsOnASingleLine",
                   Style.AllowShortCaseLabelsOnASingleLine);
    IO.mapOptional("AllowShortFunctionsOnASingleLine",
                   Style.AllowShortFunctionsOnASingleLine);
    IO.mapOptional("AllowShortIfStatementsOnASingleLine",
                   Style.AllowShortIfStatementsOnASingleLine);
    IO.mapOptional("AllowShortLoopsOnASingleLine",
                   Style.AllowShortLoopsOnASingleLine);
    IO.mapOptional("AlwaysBreakAfterDefinitionReturnType",
                   Style.AlwaysBreakAfterDefinitionReturnType);
    IO.mapOptional("AlwaysBreakAfterReturnType",
                   Style.AlwaysBreakAfterReturnType);
    // If AlwaysBreakAfterDefinitionReturnType was specified but
    // AlwaysBreakAfterReturnType was not, initialize the latter from the
    // former for backwards compatibility.
    if (Style.AlwaysBreakAfterDefinitionReturnType != FormatStyle::DRTBS_None &&
        Style.AlwaysBreakAfterReturnType == FormatStyle::RTBS_None) {
      if (Style.AlwaysBreakAfterDefinitionReturnType == FormatStyle::DRTBS_All)
        Style.AlwaysBreakAfterReturnType = FormatStyle::RTBS_AllDefinitions;
      else if (Style.AlwaysBreakAfterDefinitionReturnType ==
               FormatStyle::DRTBS_TopLevel)
        Style.AlwaysBreakAfterReturnType =
            FormatStyle::RTBS_TopLevelDefinitions;
    }

    IO.mapOptional("AlwaysBreakBeforeMultilineStrings",
                   Style.AlwaysBreakBeforeMultilineStrings);
    IO.mapOptional("AlwaysBreakTemplateDeclarations",
                   Style.AlwaysBreakTemplateDeclarations);
    IO.mapOptional("BinPackArguments", Style.BinPackArguments);
    IO.mapOptional("BinPackParameters", Style.BinPackParameters);
    IO.mapOptional("BraceWrapping", Style.BraceWrapping);
    IO.mapOptional("BreakBeforeBinaryOperators",
                   Style.BreakBeforeBinaryOperators);
    IO.mapOptional("BreakBeforeBraces", Style.BreakBeforeBraces);
    IO.mapOptional("BreakBeforeTernaryOperators",
                   Style.BreakBeforeTernaryOperators);
    IO.mapOptional("BreakConstructorInitializersBeforeComma",
                   Style.BreakConstructorInitializersBeforeComma);
    IO.mapOptional("BreakAfterJavaFieldAnnotations",
                   Style.BreakAfterJavaFieldAnnotations);
    IO.mapOptional("BreakStringLiterals", Style.BreakStringLiterals);
    IO.mapOptional("ColumnLimit", Style.ColumnLimit);
    IO.mapOptional("CommentPragmas", Style.CommentPragmas);
    IO.mapOptional("ConstructorInitializerAllOnOneLineOrOnePerLine",
                   Style.ConstructorInitializerAllOnOneLineOrOnePerLine);
    IO.mapOptional("ConstructorInitializerIndentWidth",
                   Style.ConstructorInitializerIndentWidth);
    IO.mapOptional("ContinuationIndentWidth", Style.ContinuationIndentWidth);
    IO.mapOptional("Cpp11BracedListStyle", Style.Cpp11BracedListStyle);
    IO.mapOptional("DerivePointerAlignment", Style.DerivePointerAlignment);
    IO.mapOptional("DisableFormat", Style.DisableFormat);
    IO.mapOptional("ExperimentalAutoDetectBinPacking",
                   Style.ExperimentalAutoDetectBinPacking);
    IO.mapOptional("ForEachMacros", Style.ForEachMacros);
    IO.mapOptional("IncludeCategories", Style.IncludeCategories);
    IO.mapOptional("IncludeIsMainRegex", Style.IncludeIsMainRegex);
    IO.mapOptional("IndentCaseLabels", Style.IndentCaseLabels);
    IO.mapOptional("IndentWidth", Style.IndentWidth);
    IO.mapOptional("IndentWrappedFunctionNames",
                   Style.IndentWrappedFunctionNames);
    IO.mapOptional("KeepEmptyLinesAtTheStartOfBlocks",
                   Style.KeepEmptyLinesAtTheStartOfBlocks);
    IO.mapOptional("MacroBlockBegin", Style.MacroBlockBegin);
    IO.mapOptional("MacroBlockEnd", Style.MacroBlockEnd);
    IO.mapOptional("MaxEmptyLinesToKeep", Style.MaxEmptyLinesToKeep);
    IO.mapOptional("NamespaceIndentation", Style.NamespaceIndentation);
    IO.mapOptional("ObjCBlockIndentWidth", Style.ObjCBlockIndentWidth);
    IO.mapOptional("ObjCSpaceAfterProperty", Style.ObjCSpaceAfterProperty);
    IO.mapOptional("ObjCSpaceBeforeProtocolList",
                   Style.ObjCSpaceBeforeProtocolList);
    IO.mapOptional("PenaltyBreakBeforeFirstCallParameter",
                   Style.PenaltyBreakBeforeFirstCallParameter);
    IO.mapOptional("PenaltyBreakComment", Style.PenaltyBreakComment);
    IO.mapOptional("PenaltyBreakFirstLessLess",
                   Style.PenaltyBreakFirstLessLess);
    IO.mapOptional("PenaltyBreakString", Style.PenaltyBreakString);
    IO.mapOptional("PenaltyExcessCharacter", Style.PenaltyExcessCharacter);
    IO.mapOptional("PenaltyReturnTypeOnItsOwnLine",
                   Style.PenaltyReturnTypeOnItsOwnLine);
    IO.mapOptional("PointerAlignment", Style.PointerAlignment);
    IO.mapOptional("ReflowComments", Style.ReflowComments);
    IO.mapOptional("SortIncludes", Style.SortIncludes);
    IO.mapOptional("SpaceAfterCStyleCast", Style.SpaceAfterCStyleCast);
    IO.mapOptional("SpaceBeforeAssignmentOperators",
                   Style.SpaceBeforeAssignmentOperators);
    IO.mapOptional("SpaceBeforeParens", Style.SpaceBeforeParens);
    IO.mapOptional("SpaceInEmptyParentheses", Style.SpaceInEmptyParentheses);
    IO.mapOptional("SpacesBeforeTrailingComments",
                   Style.SpacesBeforeTrailingComments);
    IO.mapOptional("SpacesInAngles", Style.SpacesInAngles);
    IO.mapOptional("SpacesInContainerLiterals",
                   Style.SpacesInContainerLiterals);
    IO.mapOptional("SpacesInCStyleCastParentheses",
                   Style.SpacesInCStyleCastParentheses);
    IO.mapOptional("SpacesInParentheses", Style.SpacesInParentheses);
    IO.mapOptional("SpacesInSquareBrackets", Style.SpacesInSquareBrackets);
    IO.mapOptional("Standard", Style.Standard);
    IO.mapOptional("TabWidth", Style.TabWidth);
    IO.mapOptional("UseTab", Style.UseTab);
    IO.mapOptional("JavaScriptQuotes", Style.JavaScriptQuotes);
  }
};

template <> struct MappingTraits<FormatStyle::BraceWrappingFlags> {
  static void mapping(IO &IO, FormatStyle::BraceWrappingFlags &Wrapping) {
    IO.mapOptional("AfterClass", Wrapping.AfterClass);
    IO.mapOptional("AfterControlStatement", Wrapping.AfterControlStatement);
    IO.mapOptional("AfterEnum", Wrapping.AfterEnum);
    IO.mapOptional("AfterFunction", Wrapping.AfterFunction);
    IO.mapOptional("AfterNamespace", Wrapping.AfterNamespace);
    IO.mapOptional("AfterObjCDeclaration", Wrapping.AfterObjCDeclaration);
    IO.mapOptional("AfterStruct", Wrapping.AfterStruct);
    IO.mapOptional("AfterUnion", Wrapping.AfterUnion);
    IO.mapOptional("BeforeCatch", Wrapping.BeforeCatch);
    IO.mapOptional("BeforeElse", Wrapping.BeforeElse);
    IO.mapOptional("IndentBraces", Wrapping.IndentBraces);
  }
};

template <> struct MappingTraits<FormatStyle::IncludeCategory> {
  static void mapping(IO &IO, FormatStyle::IncludeCategory &Category) {
    IO.mapOptional("Regex", Category.Regex);
    IO.mapOptional("Priority", Category.Priority);
  }
};

// Allows to read vector<FormatStyle> while keeping default values.
// IO.getContext() should contain a pointer to the FormatStyle structure, that
// will be used to get default values for missing keys.
// If the first element has no Language specified, it will be treated as the
// default one for the following elements.
template <> struct DocumentListTraits<std::vector<FormatStyle>> {
  static size_t size(IO &IO, std::vector<FormatStyle> &Seq) {
    return Seq.size();
  }
  static FormatStyle &element(IO &IO, std::vector<FormatStyle> &Seq,
                              size_t Index) {
    if (Index >= Seq.size()) {
      assert(Index == Seq.size());
      FormatStyle Template;
      if (Seq.size() > 0 && Seq[0].Language == FormatStyle::LK_None) {
        Template = Seq[0];
      } else {
        Template = *((const FormatStyle *)IO.getContext());
        Template.Language = FormatStyle::LK_None;
      }
      Seq.resize(Index + 1, Template);
    }
    return Seq[Index];
  }
};
} // namespace yaml
} // namespace llvm

namespace clang {
namespace format {

const std::error_category &getParseCategory() {
  static ParseErrorCategory C;
  return C;
}
std::error_code make_error_code(ParseError e) {
  return std::error_code(static_cast<int>(e), getParseCategory());
}

const char *ParseErrorCategory::name() const LLVM_NOEXCEPT {
  return "clang-format.parse_error";
}

std::string ParseErrorCategory::message(int EV) const {
  switch (static_cast<ParseError>(EV)) {
  case ParseError::Success:
    return "Success";
  case ParseError::Error:
    return "Invalid argument";
  case ParseError::Unsuitable:
    return "Unsuitable";
  }
  llvm_unreachable("unexpected parse error");
}

static FormatStyle expandPresets(const FormatStyle &Style) {
  if (Style.BreakBeforeBraces == FormatStyle::BS_Custom)
    return Style;
  FormatStyle Expanded = Style;
  Expanded.BraceWrapping = {false, false, false, false, false, false,
                            false, false, false, false, false};
  switch (Style.BreakBeforeBraces) {
  case FormatStyle::BS_Linux:
    Expanded.BraceWrapping.AfterClass = true;
    Expanded.BraceWrapping.AfterFunction = true;
    Expanded.BraceWrapping.AfterNamespace = true;
    break;
  case FormatStyle::BS_Mozilla:
    Expanded.BraceWrapping.AfterClass = true;
    Expanded.BraceWrapping.AfterEnum = true;
    Expanded.BraceWrapping.AfterFunction = true;
    Expanded.BraceWrapping.AfterStruct = true;
    Expanded.BraceWrapping.AfterUnion = true;
    break;
  case FormatStyle::BS_Stroustrup:
    Expanded.BraceWrapping.AfterFunction = true;
    Expanded.BraceWrapping.BeforeCatch = true;
    Expanded.BraceWrapping.BeforeElse = true;
    break;
  case FormatStyle::BS_Allman:
    Expanded.BraceWrapping.AfterClass = true;
    Expanded.BraceWrapping.AfterControlStatement = true;
    Expanded.BraceWrapping.AfterEnum = true;
    Expanded.BraceWrapping.AfterFunction = true;
    Expanded.BraceWrapping.AfterNamespace = true;
    Expanded.BraceWrapping.AfterObjCDeclaration = true;
    Expanded.BraceWrapping.AfterStruct = true;
    Expanded.BraceWrapping.BeforeCatch = true;
    Expanded.BraceWrapping.BeforeElse = true;
    break;
  case FormatStyle::BS_GNU:
    Expanded.BraceWrapping = {true, true, true, true, true, true,
                              true, true, true, true, true};
    break;
  case FormatStyle::BS_WebKit:
    Expanded.BraceWrapping.AfterFunction = true;
    break;
  default:
    break;
  }
  return Expanded;
}

FormatStyle getLLVMStyle() {
  FormatStyle LLVMStyle;
  LLVMStyle.Language = FormatStyle::LK_Cpp;
  LLVMStyle.AccessModifierOffset = -2;
  LLVMStyle.AlignEscapedNewlinesLeft = false;
  LLVMStyle.AlignAfterOpenBracket = FormatStyle::BAS_Align;
  LLVMStyle.AlignOperands = true;
  LLVMStyle.AlignTrailingComments = true;
  LLVMStyle.AlignConsecutiveAssignments = false;
  LLVMStyle.AlignConsecutiveDeclarations = false;
  LLVMStyle.AllowAllParametersOfDeclarationOnNextLine = true;
  LLVMStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_All;
  LLVMStyle.AllowShortBlocksOnASingleLine = false;
  LLVMStyle.AllowShortCaseLabelsOnASingleLine = false;
  LLVMStyle.AllowShortIfStatementsOnASingleLine = false;
  LLVMStyle.AllowShortLoopsOnASingleLine = false;
  LLVMStyle.AlwaysBreakAfterReturnType = FormatStyle::RTBS_None;
  LLVMStyle.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
  LLVMStyle.AlwaysBreakBeforeMultilineStrings = false;
  LLVMStyle.AlwaysBreakTemplateDeclarations = false;
  LLVMStyle.BinPackParameters = true;
  LLVMStyle.BinPackArguments = true;
  LLVMStyle.BreakBeforeBinaryOperators = FormatStyle::BOS_None;
  LLVMStyle.BreakBeforeTernaryOperators = true;
  LLVMStyle.BreakBeforeBraces = FormatStyle::BS_Attach;
  LLVMStyle.BraceWrapping = {false, false, false, false, false, false,
                             false, false, false, false, false};
  LLVMStyle.BreakAfterJavaFieldAnnotations = false;
  LLVMStyle.BreakConstructorInitializersBeforeComma = false;
  LLVMStyle.BreakStringLiterals = true;
  LLVMStyle.ColumnLimit = 80;
  LLVMStyle.CommentPragmas = "^ IWYU pragma:";
  LLVMStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = false;
  LLVMStyle.ConstructorInitializerIndentWidth = 4;
  LLVMStyle.ContinuationIndentWidth = 4;
  LLVMStyle.Cpp11BracedListStyle = true;
  LLVMStyle.DerivePointerAlignment = false;
  LLVMStyle.ExperimentalAutoDetectBinPacking = false;
  LLVMStyle.ForEachMacros.push_back("foreach");
  LLVMStyle.ForEachMacros.push_back("Q_FOREACH");
  LLVMStyle.ForEachMacros.push_back("BOOST_FOREACH");
  LLVMStyle.IncludeCategories = {{"^\"(llvm|llvm-c|clang|clang-c)/", 2},
                                 {"^(<|\"(gtest|isl|json)/)", 3},
                                 {".*", 1}};
  LLVMStyle.IncludeIsMainRegex = "$";
  LLVMStyle.IndentCaseLabels = false;
  LLVMStyle.IndentWrappedFunctionNames = false;
  LLVMStyle.IndentWidth = 2;
  LLVMStyle.TabWidth = 8;
  LLVMStyle.MaxEmptyLinesToKeep = 1;
  LLVMStyle.KeepEmptyLinesAtTheStartOfBlocks = true;
  LLVMStyle.NamespaceIndentation = FormatStyle::NI_None;
  LLVMStyle.ObjCBlockIndentWidth = 2;
  LLVMStyle.ObjCSpaceAfterProperty = false;
  LLVMStyle.ObjCSpaceBeforeProtocolList = true;
  LLVMStyle.PointerAlignment = FormatStyle::PAS_Right;
  LLVMStyle.SpacesBeforeTrailingComments = 1;
  LLVMStyle.Standard = FormatStyle::LS_Cpp11;
  LLVMStyle.UseTab = FormatStyle::UT_Never;
  LLVMStyle.JavaScriptQuotes = FormatStyle::JSQS_Leave;
  LLVMStyle.ReflowComments = true;
  LLVMStyle.SpacesInParentheses = false;
  LLVMStyle.SpacesInSquareBrackets = false;
  LLVMStyle.SpaceInEmptyParentheses = false;
  LLVMStyle.SpacesInContainerLiterals = true;
  LLVMStyle.SpacesInCStyleCastParentheses = false;
  LLVMStyle.SpaceAfterCStyleCast = false;
  LLVMStyle.SpaceBeforeParens = FormatStyle::SBPO_ControlStatements;
  LLVMStyle.SpaceBeforeAssignmentOperators = true;
  LLVMStyle.SpacesInAngles = false;

  LLVMStyle.PenaltyBreakComment = 300;
  LLVMStyle.PenaltyBreakFirstLessLess = 120;
  LLVMStyle.PenaltyBreakString = 1000;
  LLVMStyle.PenaltyExcessCharacter = 1000000;
  LLVMStyle.PenaltyReturnTypeOnItsOwnLine = 60;
  LLVMStyle.PenaltyBreakBeforeFirstCallParameter = 19;

  LLVMStyle.DisableFormat = false;
  LLVMStyle.SortIncludes = true;

  return LLVMStyle;
}

FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
  FormatStyle GoogleStyle = getLLVMStyle();
  GoogleStyle.Language = Language;

  GoogleStyle.AccessModifierOffset = -1;
  GoogleStyle.AlignEscapedNewlinesLeft = true;
  GoogleStyle.AllowShortIfStatementsOnASingleLine = true;
  GoogleStyle.AllowShortLoopsOnASingleLine = true;
  GoogleStyle.AlwaysBreakBeforeMultilineStrings = true;
  GoogleStyle.AlwaysBreakTemplateDeclarations = true;
  GoogleStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = true;
  GoogleStyle.DerivePointerAlignment = true;
  GoogleStyle.IncludeCategories = {{"^<.*\\.h>", 1}, {"^<.*", 2}, {".*", 3}};
  GoogleStyle.IncludeIsMainRegex = "([-_](test|unittest))?$";
  GoogleStyle.IndentCaseLabels = true;
  GoogleStyle.KeepEmptyLinesAtTheStartOfBlocks = false;
  GoogleStyle.ObjCSpaceAfterProperty = false;
  GoogleStyle.ObjCSpaceBeforeProtocolList = false;
  GoogleStyle.PointerAlignment = FormatStyle::PAS_Left;
  GoogleStyle.SpacesBeforeTrailingComments = 2;
  GoogleStyle.Standard = FormatStyle::LS_Auto;

  GoogleStyle.PenaltyReturnTypeOnItsOwnLine = 200;
  GoogleStyle.PenaltyBreakBeforeFirstCallParameter = 1;

  if (Language == FormatStyle::LK_Java) {
    GoogleStyle.AlignAfterOpenBracket = FormatStyle::BAS_DontAlign;
    GoogleStyle.AlignOperands = false;
    GoogleStyle.AlignTrailingComments = false;
    GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Empty;
    GoogleStyle.AllowShortIfStatementsOnASingleLine = false;
    GoogleStyle.AlwaysBreakBeforeMultilineStrings = false;
    GoogleStyle.BreakBeforeBinaryOperators = FormatStyle::BOS_NonAssignment;
    GoogleStyle.ColumnLimit = 100;
    GoogleStyle.SpaceAfterCStyleCast = true;
    GoogleStyle.SpacesBeforeTrailingComments = 1;
  } else if (Language == FormatStyle::LK_JavaScript) {
    GoogleStyle.AlignAfterOpenBracket = FormatStyle::BAS_AlwaysBreak;
    GoogleStyle.AlignOperands = false;
    GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
    GoogleStyle.AlwaysBreakBeforeMultilineStrings = false;
    GoogleStyle.BreakBeforeTernaryOperators = false;
    GoogleStyle.CommentPragmas = "@(export|return|see|visibility) ";
    GoogleStyle.MaxEmptyLinesToKeep = 3;
    GoogleStyle.SpacesInContainerLiterals = false;
    GoogleStyle.JavaScriptQuotes = FormatStyle::JSQS_Single;
  } else if (Language == FormatStyle::LK_Proto) {
    GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_None;
    GoogleStyle.SpacesInContainerLiterals = false;
  }

  return GoogleStyle;
}

FormatStyle getChromiumStyle(FormatStyle::LanguageKind Language) {
  FormatStyle ChromiumStyle = getGoogleStyle(Language);
  if (Language == FormatStyle::LK_Java) {
    ChromiumStyle.AllowShortIfStatementsOnASingleLine = true;
    ChromiumStyle.BreakAfterJavaFieldAnnotations = true;
    ChromiumStyle.ContinuationIndentWidth = 8;
    ChromiumStyle.IndentWidth = 4;
  } else {
    ChromiumStyle.AllowAllParametersOfDeclarationOnNextLine = false;
    ChromiumStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
    ChromiumStyle.AllowShortIfStatementsOnASingleLine = false;
    ChromiumStyle.AllowShortLoopsOnASingleLine = false;
    ChromiumStyle.BinPackParameters = false;
    ChromiumStyle.DerivePointerAlignment = false;
  }
  ChromiumStyle.SortIncludes = false;
  return ChromiumStyle;
}

FormatStyle getMozillaStyle() {
  FormatStyle MozillaStyle = getLLVMStyle();
  MozillaStyle.AllowAllParametersOfDeclarationOnNextLine = false;
  MozillaStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
  MozillaStyle.AlwaysBreakAfterReturnType =
      FormatStyle::RTBS_TopLevelDefinitions;
  MozillaStyle.AlwaysBreakAfterDefinitionReturnType =
      FormatStyle::DRTBS_TopLevel;
  MozillaStyle.AlwaysBreakTemplateDeclarations = true;
  MozillaStyle.BreakBeforeBraces = FormatStyle::BS_Mozilla;
  MozillaStyle.BreakConstructorInitializersBeforeComma = true;
  MozillaStyle.ConstructorInitializerIndentWidth = 2;
  MozillaStyle.ContinuationIndentWidth = 2;
  MozillaStyle.Cpp11BracedListStyle = false;
  MozillaStyle.IndentCaseLabels = true;
  MozillaStyle.ObjCSpaceAfterProperty = true;
  MozillaStyle.ObjCSpaceBeforeProtocolList = false;
  MozillaStyle.PenaltyReturnTypeOnItsOwnLine = 200;
  MozillaStyle.PointerAlignment = FormatStyle::PAS_Left;
  return MozillaStyle;
}

FormatStyle getWebKitStyle() {
  FormatStyle Style = getLLVMStyle();
  Style.AccessModifierOffset = -4;
  Style.AlignAfterOpenBracket = FormatStyle::BAS_DontAlign;
  Style.AlignOperands = false;
  Style.AlignTrailingComments = false;
  Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
  Style.BreakBeforeBraces = FormatStyle::BS_WebKit;
  Style.BreakConstructorInitializersBeforeComma = true;
  Style.Cpp11BracedListStyle = false;
  Style.ColumnLimit = 0;
  Style.IndentWidth = 4;
  Style.NamespaceIndentation = FormatStyle::NI_Inner;
  Style.ObjCBlockIndentWidth = 4;
  Style.ObjCSpaceAfterProperty = true;
  Style.PointerAlignment = FormatStyle::PAS_Left;
  Style.Standard = FormatStyle::LS_Cpp03;
  return Style;
}

FormatStyle getGNUStyle() {
  FormatStyle Style = getLLVMStyle();
  Style.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_All;
  Style.AlwaysBreakAfterReturnType = FormatStyle::RTBS_AllDefinitions;
  Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
  Style.BreakBeforeBraces = FormatStyle::BS_GNU;
  Style.BreakBeforeTernaryOperators = true;
  Style.Cpp11BracedListStyle = false;
  Style.ColumnLimit = 79;
  Style.SpaceBeforeParens = FormatStyle::SBPO_Always;
  Style.Standard = FormatStyle::LS_Cpp03;
  return Style;
}

FormatStyle getNoStyle() {
  FormatStyle NoStyle = getLLVMStyle();
  NoStyle.DisableFormat = true;
  NoStyle.SortIncludes = false;
  return NoStyle;
}

bool getPredefinedStyle(StringRef Name, FormatStyle::LanguageKind Language,
                        FormatStyle *Style) {
  if (Name.equals_lower("llvm")) {
    *Style = getLLVMStyle();
  } else if (Name.equals_lower("chromium")) {
    *Style = getChromiumStyle(Language);
  } else if (Name.equals_lower("mozilla")) {
    *Style = getMozillaStyle();
  } else if (Name.equals_lower("google")) {
    *Style = getGoogleStyle(Language);
  } else if (Name.equals_lower("webkit")) {
    *Style = getWebKitStyle();
  } else if (Name.equals_lower("gnu")) {
    *Style = getGNUStyle();
  } else if (Name.equals_lower("none")) {
    *Style = getNoStyle();
  } else {
    return false;
  }

  Style->Language = Language;
  return true;
}

std::error_code parseConfiguration(StringRef Text, FormatStyle *Style) {
  assert(Style);
  FormatStyle::LanguageKind Language = Style->Language;
  assert(Language != FormatStyle::LK_None);
  if (Text.trim().empty())
    return make_error_code(ParseError::Error);

  std::vector<FormatStyle> Styles;
  llvm::yaml::Input Input(Text);
  // DocumentListTraits<vector<FormatStyle>> uses the context to get default
  // values for the fields, keys for which are missing from the configuration.
  // Mapping also uses the context to get the language to find the correct
  // base style.
  Input.setContext(Style);
  Input >> Styles;
  if (Input.error())
    return Input.error();

  for (unsigned i = 0; i < Styles.size(); ++i) {
    // Ensures that only the first configuration can skip the Language option.
    if (Styles[i].Language == FormatStyle::LK_None && i != 0)
      return make_error_code(ParseError::Error);
    // Ensure that each language is configured at most once.
    for (unsigned j = 0; j < i; ++j) {
      if (Styles[i].Language == Styles[j].Language) {
        DEBUG(llvm::dbgs()
              << "Duplicate languages in the config file on positions " << j
              << " and " << i << "\n");
        return make_error_code(ParseError::Error);
      }
    }
  }
  // Look for a suitable configuration starting from the end, so we can
  // find the configuration for the specific language first, and the default
  // configuration (which can only be at slot 0) after it.
  for (int i = Styles.size() - 1; i >= 0; --i) {
    if (Styles[i].Language == Language ||
        Styles[i].Language == FormatStyle::LK_None) {
      *Style = Styles[i];
      Style->Language = Language;
      return make_error_code(ParseError::Success);
    }
  }
  return make_error_code(ParseError::Unsuitable);
}

std::string configurationAsText(const FormatStyle &Style) {
  std::string Text;
  llvm::raw_string_ostream Stream(Text);
  llvm::yaml::Output Output(Stream);
  // We use the same mapping method for input and output, so we need a non-const
  // reference here.
  FormatStyle NonConstStyle = expandPresets(Style);
  Output << NonConstStyle;
  return Stream.str();
}

namespace {

class FormatTokenLexer {
public:
  FormatTokenLexer(SourceManager &SourceMgr, FileID ID,
                   const FormatStyle &Style, encoding::Encoding Encoding)
      : FormatTok(nullptr), IsFirstToken(true), GreaterStashed(false),
        LessStashed(false), Column(0), TrailingWhitespace(0),
        SourceMgr(SourceMgr), ID(ID), Style(Style),
        IdentTable(getFormattingLangOpts(Style)), Keywords(IdentTable),
        Encoding(Encoding), FirstInLineIndex(0), FormattingDisabled(false),
        MacroBlockBeginRegex(Style.MacroBlockBegin),
        MacroBlockEndRegex(Style.MacroBlockEnd) {
    Lex.reset(new Lexer(ID, SourceMgr.getBuffer(ID), SourceMgr,
                        getFormattingLangOpts(Style)));
    Lex->SetKeepWhitespaceMode(true);

    for (const std::string &ForEachMacro : Style.ForEachMacros)
      ForEachMacros.push_back(&IdentTable.get(ForEachMacro));
    std::sort(ForEachMacros.begin(), ForEachMacros.end());
  }

  ArrayRef<FormatToken *> lex() {
    assert(Tokens.empty());
    assert(FirstInLineIndex == 0);
    do {
      Tokens.push_back(getNextToken());
      if (Style.Language == FormatStyle::LK_JavaScript)
        tryParseJSRegexLiteral();
      tryMergePreviousTokens();
      if (Tokens.back()->NewlinesBefore > 0 || Tokens.back()->IsMultiline)
        FirstInLineIndex = Tokens.size() - 1;
    } while (Tokens.back()->Tok.isNot(tok::eof));
    return Tokens;
  }

  const AdditionalKeywords &getKeywords() { return Keywords; }

private:
  void tryMergePreviousTokens() {
    if (tryMerge_TMacro())
      return;
    if (tryMergeConflictMarkers())
      return;
    if (tryMergeLessLess())
      return;

    if (Style.Language == FormatStyle::LK_JavaScript) {
      if (tryMergeTemplateString())
        return;

      static const tok::TokenKind JSIdentity[] = {tok::equalequal, tok::equal};
      static const tok::TokenKind JSNotIdentity[] = {tok::exclaimequal,
                                                     tok::equal};
      static const tok::TokenKind JSShiftEqual[] = {tok::greater, tok::greater,
                                                    tok::greaterequal};
      static const tok::TokenKind JSRightArrow[] = {tok::equal, tok::greater};
      // FIXME: Investigate what token type gives the correct operator priority.
      if (tryMergeTokens(JSIdentity, TT_BinaryOperator))
        return;
      if (tryMergeTokens(JSNotIdentity, TT_BinaryOperator))
        return;
      if (tryMergeTokens(JSShiftEqual, TT_BinaryOperator))
        return;
      if (tryMergeTokens(JSRightArrow, TT_JsFatArrow))
        return;
    }
  }

  bool tryMergeLessLess() {
    // Merge X,less,less,Y into X,lessless,Y unless X or Y is less.
    if (Tokens.size() < 3)
      return false;

    bool FourthTokenIsLess = false;
    if (Tokens.size() > 3)
      FourthTokenIsLess = (Tokens.end() - 4)[0]->is(tok::less);

    auto First = Tokens.end() - 3;
    if (First[2]->is(tok::less) || First[1]->isNot(tok::less) ||
        First[0]->isNot(tok::less) || FourthTokenIsLess)
      return false;

    // Only merge if there currently is no whitespace between the two "<".
    if (First[1]->WhitespaceRange.getBegin() !=
        First[1]->WhitespaceRange.getEnd())
      return false;

    First[0]->Tok.setKind(tok::lessless);
    First[0]->TokenText = "<<";
    First[0]->ColumnWidth += 1;
    Tokens.erase(Tokens.end() - 2);
    return true;
  }

  bool tryMergeTokens(ArrayRef<tok::TokenKind> Kinds, TokenType NewType) {
    if (Tokens.size() < Kinds.size())
      return false;

    SmallVectorImpl<FormatToken *>::const_iterator First =
        Tokens.end() - Kinds.size();
    if (!First[0]->is(Kinds[0]))
      return false;
    unsigned AddLength = 0;
    for (unsigned i = 1; i < Kinds.size(); ++i) {
      if (!First[i]->is(Kinds[i]) ||
          First[i]->WhitespaceRange.getBegin() !=
              First[i]->WhitespaceRange.getEnd())
        return false;
      AddLength += First[i]->TokenText.size();
    }
    Tokens.resize(Tokens.size() - Kinds.size() + 1);
    First[0]->TokenText = StringRef(First[0]->TokenText.data(),
                                    First[0]->TokenText.size() + AddLength);
    First[0]->ColumnWidth += AddLength;
    First[0]->Type = NewType;
    return true;
  }

  // Returns \c true if \p Tok can only be followed by an operand in JavaScript.
  bool precedesOperand(FormatToken *Tok) {
    // NB: This is not entirely correct, as an r_paren can introduce an operand
    // location in e.g. `if (foo) /bar/.exec(...);`. That is a rare enough
    // corner case to not matter in practice, though.
    return Tok->isOneOf(tok::period, tok::l_paren, tok::comma, tok::l_brace,
                        tok::r_brace, tok::l_square, tok::semi, tok::exclaim,
                        tok::colon, tok::question, tok::tilde) ||
           Tok->isOneOf(tok::kw_return, tok::kw_do, tok::kw_case, tok::kw_throw,
                        tok::kw_else, tok::kw_new, tok::kw_delete, tok::kw_void,
                        tok::kw_typeof, Keywords.kw_instanceof,
                        Keywords.kw_in) ||
           Tok->isBinaryOperator();
  }

  bool canPrecedeRegexLiteral(FormatToken *Prev) {
    if (!Prev)
      return true;

    // Regex literals can only follow after prefix unary operators, not after
    // postfix unary operators. If the '++' is followed by a non-operand
    // introducing token, the slash here is the operand and not the start of a
    // regex.
    if (Prev->isOneOf(tok::plusplus, tok::minusminus))
      return (Tokens.size() < 3 || precedesOperand(Tokens[Tokens.size() - 3]));

    // The previous token must introduce an operand location where regex
    // literals can occur.
    if (!precedesOperand(Prev))
      return false;

    return true;
  }

  // Tries to parse a JavaScript Regex literal starting at the current token,
  // if that begins with a slash and is in a location where JavaScript allows
  // regex literals. Changes the current token to a regex literal and updates
  // its text if successful.
  void tryParseJSRegexLiteral() {
    FormatToken *RegexToken = Tokens.back();
    if (!RegexToken->isOneOf(tok::slash, tok::slashequal))
      return;

    FormatToken *Prev = nullptr;
    for (auto I = Tokens.rbegin() + 1, E = Tokens.rend(); I != E; ++I) {
      // NB: Because previous pointers are not initialized yet, this cannot use
      // Token.getPreviousNonComment.
      if ((*I)->isNot(tok::comment)) {
        Prev = *I;
        break;
      }
    }

    if (!canPrecedeRegexLiteral(Prev))
      return;

    // 'Manually' lex ahead in the current file buffer.
    const char *Offset = Lex->getBufferLocation();
    const char *RegexBegin = Offset - RegexToken->TokenText.size();
    StringRef Buffer = Lex->getBuffer();
    bool InCharacterClass = false;
    bool HaveClosingSlash = false;
    for (; !HaveClosingSlash && Offset != Buffer.end(); ++Offset) {
      // Regular expressions are terminated with a '/', which can only be
      // escaped using '\' or a character class between '[' and ']'.
      // See http://www.ecma-international.org/ecma-262/5.1/#sec-7.8.5.
      switch (*Offset) {
      case '\\':
        // Skip the escaped character.
        ++Offset;
        break;
      case '[':
        InCharacterClass = true;
        break;
      case ']':
        InCharacterClass = false;
        break;
      case '/':
        if (!InCharacterClass)
          HaveClosingSlash = true;
        break;
      }
    }

    RegexToken->Type = TT_RegexLiteral;
    // Treat regex literals like other string_literals.
    RegexToken->Tok.setKind(tok::string_literal);
    RegexToken->TokenText = StringRef(RegexBegin, Offset - RegexBegin);
    RegexToken->ColumnWidth = RegexToken->TokenText.size();

    resetLexer(SourceMgr.getFileOffset(Lex->getSourceLocation(Offset)));
  }

  bool tryMergeTemplateString() {
    if (Tokens.size() < 2)
      return false;

    FormatToken *EndBacktick = Tokens.back();
    // Backticks get lexed as tok::unknown tokens. If a template string contains
    // a comment start, it gets lexed as a tok::comment, or tok::unknown if
    // unterminated.
    if (!EndBacktick->isOneOf(tok::comment, tok::string_literal,
                              tok::char_constant, tok::unknown))
      return false;
    size_t CommentBacktickPos = EndBacktick->TokenText.find('`');
    // Unknown token that's not actually a backtick, or a comment that doesn't
    // contain a backtick.
    if (CommentBacktickPos == StringRef::npos)
      return false;

    unsigned TokenCount = 0;
    bool IsMultiline = false;
    unsigned EndColumnInFirstLine =
        EndBacktick->OriginalColumn + EndBacktick->ColumnWidth;
    for (auto I = Tokens.rbegin() + 1, E = Tokens.rend(); I != E; I++) {
      ++TokenCount;
      if (I[0]->IsMultiline)
        IsMultiline = true;

      // If there was a preceding template string, this must be the start of a
      // template string, not the end.
      if (I[0]->is(TT_TemplateString))
        return false;

      if (I[0]->isNot(tok::unknown) || I[0]->TokenText != "`") {
        // Keep track of the rhs offset of the last token to wrap across lines -
        // its the rhs offset of the first line of the template string, used to
        // determine its width.
        if (I[0]->IsMultiline)
          EndColumnInFirstLine = I[0]->OriginalColumn + I[0]->ColumnWidth;
        // If the token has newlines, the token before it (if it exists) is the
        // rhs end of the previous line.
        if (I[0]->NewlinesBefore > 0 && (I + 1 != E)) {
          EndColumnInFirstLine = I[1]->OriginalColumn + I[1]->ColumnWidth;
          IsMultiline = true;
        }
        continue;
      }

      Tokens.resize(Tokens.size() - TokenCount);
      Tokens.back()->Type = TT_TemplateString;
      const char *EndOffset =
          EndBacktick->TokenText.data() + 1 + CommentBacktickPos;
      if (CommentBacktickPos != 0) {
        // If the backtick was not the first character (e.g. in a comment),
        // re-lex after the backtick position.
        SourceLocation Loc = EndBacktick->Tok.getLocation();
        resetLexer(SourceMgr.getFileOffset(Loc) + CommentBacktickPos + 1);
      }
      Tokens.back()->TokenText =
          StringRef(Tokens.back()->TokenText.data(),
                    EndOffset - Tokens.back()->TokenText.data());

      unsigned EndOriginalColumn = EndBacktick->OriginalColumn;
      if (EndOriginalColumn == 0) {
        SourceLocation Loc = EndBacktick->Tok.getLocation();
        EndOriginalColumn = SourceMgr.getSpellingColumnNumber(Loc);
      }
      // If the ` is further down within the token (e.g. in a comment).
      EndOriginalColumn += CommentBacktickPos;

      if (IsMultiline) {
        // ColumnWidth is from backtick to last token in line.
        // LastLineColumnWidth is 0 to backtick.
        // x = `some content
        //     until here`;
        Tokens.back()->ColumnWidth =
            EndColumnInFirstLine - Tokens.back()->OriginalColumn;
        // +1 for the ` itself.
        Tokens.back()->LastLineColumnWidth = EndOriginalColumn + 1;
        Tokens.back()->IsMultiline = true;
      } else {
        // Token simply spans from start to end, +1 for the ` itself.
        Tokens.back()->ColumnWidth =
            EndOriginalColumn - Tokens.back()->OriginalColumn + 1;
      }
      return true;
    }
    return false;
  }

  bool tryMerge_TMacro() {
    if (Tokens.size() < 4)
      return false;
    FormatToken *Last = Tokens.back();
    if (!Last->is(tok::r_paren))
      return false;

    FormatToken *String = Tokens[Tokens.size() - 2];
    if (!String->is(tok::string_literal) || String->IsMultiline)
      return false;

    if (!Tokens[Tokens.size() - 3]->is(tok::l_paren))
      return false;

    FormatToken *Macro = Tokens[Tokens.size() - 4];
    if (Macro->TokenText != "_T")
      return false;

    const char *Start = Macro->TokenText.data();
    const char *End = Last->TokenText.data() + Last->TokenText.size();
    String->TokenText = StringRef(Start, End - Start);
    String->IsFirst = Macro->IsFirst;
    String->LastNewlineOffset = Macro->LastNewlineOffset;
    String->WhitespaceRange = Macro->WhitespaceRange;
    String->OriginalColumn = Macro->OriginalColumn;
    String->ColumnWidth = encoding::columnWidthWithTabs(
        String->TokenText, String->OriginalColumn, Style.TabWidth, Encoding);
    String->NewlinesBefore = Macro->NewlinesBefore;
    String->HasUnescapedNewline = Macro->HasUnescapedNewline;

    Tokens.pop_back();
    Tokens.pop_back();
    Tokens.pop_back();
    Tokens.back() = String;
    return true;
  }

  bool tryMergeConflictMarkers() {
    if (Tokens.back()->NewlinesBefore == 0 && Tokens.back()->isNot(tok::eof))
      return false;

    // Conflict lines look like:
    // <marker> <text from the vcs>
    // For example:
    // >>>>>>> /file/in/file/system at revision 1234
    //
    // We merge all tokens in a line that starts with a conflict marker
    // into a single token with a special token type that the unwrapped line
    // parser will use to correctly rebuild the underlying code.

    FileID ID;
    // Get the position of the first token in the line.
    unsigned FirstInLineOffset;
    std::tie(ID, FirstInLineOffset) = SourceMgr.getDecomposedLoc(
        Tokens[FirstInLineIndex]->getStartOfNonWhitespace());
    StringRef Buffer = SourceMgr.getBuffer(ID)->getBuffer();
    // Calculate the offset of the start of the current line.
    auto LineOffset = Buffer.rfind('\n', FirstInLineOffset);
    if (LineOffset == StringRef::npos) {
      LineOffset = 0;
    } else {
      ++LineOffset;
    }

    auto FirstSpace = Buffer.find_first_of(" \n", LineOffset);
    StringRef LineStart;
    if (FirstSpace == StringRef::npos) {
      LineStart = Buffer.substr(LineOffset);
    } else {
      LineStart = Buffer.substr(LineOffset, FirstSpace - LineOffset);
    }

    TokenType Type = TT_Unknown;
    if (LineStart == "<<<<<<<" || LineStart == ">>>>") {
      Type = TT_ConflictStart;
    } else if (LineStart == "|||||||" || LineStart == "=======" ||
               LineStart == "====") {
      Type = TT_ConflictAlternative;
    } else if (LineStart == ">>>>>>>" || LineStart == "<<<<") {
      Type = TT_ConflictEnd;
    }

    if (Type != TT_Unknown) {
      FormatToken *Next = Tokens.back();

      Tokens.resize(FirstInLineIndex + 1);
      // We do not need to build a complete token here, as we will skip it
      // during parsing anyway (as we must not touch whitespace around conflict
      // markers).
      Tokens.back()->Type = Type;
      Tokens.back()->Tok.setKind(tok::kw___unknown_anytype);

      Tokens.push_back(Next);
      return true;
    }

    return false;
  }

  FormatToken *getStashedToken() {
    // Create a synthesized second '>' or '<' token.
    Token Tok = FormatTok->Tok;
    StringRef TokenText = FormatTok->TokenText;

    unsigned OriginalColumn = FormatTok->OriginalColumn;
    FormatTok = new (Allocator.Allocate()) FormatToken;
    FormatTok->Tok = Tok;
    SourceLocation TokLocation =
        FormatTok->Tok.getLocation().getLocWithOffset(Tok.getLength() - 1);
    FormatTok->Tok.setLocation(TokLocation);
    FormatTok->WhitespaceRange = SourceRange(TokLocation, TokLocation);
    FormatTok->TokenText = TokenText;
    FormatTok->ColumnWidth = 1;
    FormatTok->OriginalColumn = OriginalColumn + 1;

    return FormatTok;
  }

  FormatToken *getNextToken() {
    if (GreaterStashed) {
      GreaterStashed = false;
      return getStashedToken();
    }
    if (LessStashed) {
      LessStashed = false;
      return getStashedToken();
    }

    FormatTok = new (Allocator.Allocate()) FormatToken;
    readRawToken(*FormatTok);
    SourceLocation WhitespaceStart =
        FormatTok->Tok.getLocation().getLocWithOffset(-TrailingWhitespace);
    FormatTok->IsFirst = IsFirstToken;
    IsFirstToken = false;

    // Consume and record whitespace until we find a significant token.
    unsigned WhitespaceLength = TrailingWhitespace;
    while (FormatTok->Tok.is(tok::unknown)) {
      StringRef Text = FormatTok->TokenText;
      auto EscapesNewline = [&](int pos) {
        // A '\r' here is just part of '\r\n'. Skip it.
        if (pos >= 0 && Text[pos] == '\r')
          --pos;
        // See whether there is an odd number of '\' before this.
        unsigned count = 0;
        for (; pos >= 0; --pos, ++count)
          if (Text[pos] != '\\')
            break;
        return count & 1;
      };
      // FIXME: This miscounts tok:unknown tokens that are not just
      // whitespace, e.g. a '`' character.
      for (int i = 0, e = Text.size(); i != e; ++i) {
        switch (Text[i]) {
        case '\n':
          ++FormatTok->NewlinesBefore;
          FormatTok->HasUnescapedNewline = !EscapesNewline(i - 1);
          FormatTok->LastNewlineOffset = WhitespaceLength + i + 1;
          Column = 0;
          break;
        case '\r':
          FormatTok->LastNewlineOffset = WhitespaceLength + i + 1;
          Column = 0;
          break;
        case '\f':
        case '\v':
          Column = 0;
          break;
        case ' ':
          ++Column;
          break;
        case '\t':
          Column += Style.TabWidth - Column % Style.TabWidth;
          break;
        case '\\':
          if (i + 1 == e || (Text[i + 1] != '\r' && Text[i + 1] != '\n'))
            FormatTok->Type = TT_ImplicitStringLiteral;
          break;
        default:
          FormatTok->Type = TT_ImplicitStringLiteral;
          break;
        }
        if (FormatTok->Type == TT_ImplicitStringLiteral)
          break;
      }

      if (FormatTok->is(TT_ImplicitStringLiteral))
        break;
      WhitespaceLength += FormatTok->Tok.getLength();

      readRawToken(*FormatTok);
    }

    // In case the token starts with escaped newlines, we want to
    // take them into account as whitespace - this pattern is quite frequent
    // in macro definitions.
    // FIXME: Add a more explicit test.
    while (FormatTok->TokenText.size() > 1 && FormatTok->TokenText[0] == '\\' &&
           FormatTok->TokenText[1] == '\n') {
      ++FormatTok->NewlinesBefore;
      WhitespaceLength += 2;
      FormatTok->LastNewlineOffset = 2;
      Column = 0;
      FormatTok->TokenText = FormatTok->TokenText.substr(2);
    }

    FormatTok->WhitespaceRange = SourceRange(
        WhitespaceStart, WhitespaceStart.getLocWithOffset(WhitespaceLength));

    FormatTok->OriginalColumn = Column;

    TrailingWhitespace = 0;
    if (FormatTok->Tok.is(tok::comment)) {
      // FIXME: Add the trimmed whitespace to Column.
      StringRef UntrimmedText = FormatTok->TokenText;
      FormatTok->TokenText = FormatTok->TokenText.rtrim(" \t\v\f");
      TrailingWhitespace = UntrimmedText.size() - FormatTok->TokenText.size();
    } else if (FormatTok->Tok.is(tok::raw_identifier)) {
      IdentifierInfo &Info = IdentTable.get(FormatTok->TokenText);
      FormatTok->Tok.setIdentifierInfo(&Info);
      FormatTok->Tok.setKind(Info.getTokenID());
      if (Style.Language == FormatStyle::LK_Java &&
          FormatTok->isOneOf(tok::kw_struct, tok::kw_union, tok::kw_delete,
                             tok::kw_operator)) {
        FormatTok->Tok.setKind(tok::identifier);
        FormatTok->Tok.setIdentifierInfo(nullptr);
      } else if (Style.Language == FormatStyle::LK_JavaScript &&
                 FormatTok->isOneOf(tok::kw_struct, tok::kw_union,
                                    tok::kw_operator)) {
        FormatTok->Tok.setKind(tok::identifier);
        FormatTok->Tok.setIdentifierInfo(nullptr);
      }
    } else if (FormatTok->Tok.is(tok::greatergreater)) {
      FormatTok->Tok.setKind(tok::greater);
      FormatTok->TokenText = FormatTok->TokenText.substr(0, 1);
      GreaterStashed = true;
    } else if (FormatTok->Tok.is(tok::lessless)) {
      FormatTok->Tok.setKind(tok::less);
      FormatTok->TokenText = FormatTok->TokenText.substr(0, 1);
      LessStashed = true;
    }

    // Now FormatTok is the next non-whitespace token.

    StringRef Text = FormatTok->TokenText;
    size_t FirstNewlinePos = Text.find('\n');
    if (FirstNewlinePos == StringRef::npos) {
      // FIXME: ColumnWidth actually depends on the start column, we need to
      // take this into account when the token is moved.
      FormatTok->ColumnWidth =
          encoding::columnWidthWithTabs(Text, Column, Style.TabWidth, Encoding);
      Column += FormatTok->ColumnWidth;
    } else {
      FormatTok->IsMultiline = true;
      // FIXME: ColumnWidth actually depends on the start column, we need to
      // take this into account when the token is moved.
      FormatTok->ColumnWidth = encoding::columnWidthWithTabs(
          Text.substr(0, FirstNewlinePos), Column, Style.TabWidth, Encoding);

      // The last line of the token always starts in column 0.
      // Thus, the length can be precomputed even in the presence of tabs.
      FormatTok->LastLineColumnWidth = encoding::columnWidthWithTabs(
          Text.substr(Text.find_last_of('\n') + 1), 0, Style.TabWidth,
          Encoding);
      Column = FormatTok->LastLineColumnWidth;
    }

    if (Style.Language == FormatStyle::LK_Cpp) {
      if (!(Tokens.size() > 0 && Tokens.back()->Tok.getIdentifierInfo() &&
            Tokens.back()->Tok.getIdentifierInfo()->getPPKeywordID() ==
                tok::pp_define) &&
          std::find(ForEachMacros.begin(), ForEachMacros.end(),
                    FormatTok->Tok.getIdentifierInfo()) !=
              ForEachMacros.end()) {
        FormatTok->Type = TT_ForEachMacro;
      } else if (FormatTok->is(tok::identifier)) {
        if (MacroBlockBeginRegex.match(Text)) {
          FormatTok->Type = TT_MacroBlockBegin;
        } else if (MacroBlockEndRegex.match(Text)) {
          FormatTok->Type = TT_MacroBlockEnd;
        }
      }
    }

    return FormatTok;
  }

  FormatToken *FormatTok;
  bool IsFirstToken;
  bool GreaterStashed, LessStashed;
  unsigned Column;
  unsigned TrailingWhitespace;
  std::unique_ptr<Lexer> Lex;
  SourceManager &SourceMgr;
  FileID ID;
  const FormatStyle &Style;
  IdentifierTable IdentTable;
  AdditionalKeywords Keywords;
  encoding::Encoding Encoding;
  llvm::SpecificBumpPtrAllocator<FormatToken> Allocator;
  // Index (in 'Tokens') of the last token that starts a new line.
  unsigned FirstInLineIndex;
  SmallVector<FormatToken *, 16> Tokens;
  SmallVector<IdentifierInfo *, 8> ForEachMacros;

  bool FormattingDisabled;

  llvm::Regex MacroBlockBeginRegex;
  llvm::Regex MacroBlockEndRegex;

  void readRawToken(FormatToken &Tok) {
    Lex->LexFromRawLexer(Tok.Tok);
    Tok.TokenText = StringRef(SourceMgr.getCharacterData(Tok.Tok.getLocation()),
                              Tok.Tok.getLength());
    // For formatting, treat unterminated string literals like normal string
    // literals.
    if (Tok.is(tok::unknown)) {
      if (!Tok.TokenText.empty() && Tok.TokenText[0] == '"') {
        Tok.Tok.setKind(tok::string_literal);
        Tok.IsUnterminatedLiteral = true;
      } else if (Style.Language == FormatStyle::LK_JavaScript &&
                 Tok.TokenText == "''") {
        Tok.Tok.setKind(tok::string_literal);
      }
    }

    if (Style.Language == FormatStyle::LK_JavaScript &&
        Tok.is(tok::char_constant)) {
      Tok.Tok.setKind(tok::string_literal);
    }

    if (Tok.is(tok::comment) && (Tok.TokenText == "// clang-format on" ||
                                 Tok.TokenText == "/* clang-format on */")) {
      FormattingDisabled = false;
    }

    Tok.Finalized = FormattingDisabled;

    if (Tok.is(tok::comment) && (Tok.TokenText == "// clang-format off" ||
                                 Tok.TokenText == "/* clang-format off */")) {
      FormattingDisabled = true;
    }
  }

  void resetLexer(unsigned Offset) {
    StringRef Buffer = SourceMgr.getBufferData(ID);
    Lex.reset(new Lexer(SourceMgr.getLocForStartOfFile(ID),
                        getFormattingLangOpts(Style), Buffer.begin(),
                        Buffer.begin() + Offset, Buffer.end()));
    Lex->SetKeepWhitespaceMode(true);
    TrailingWhitespace = 0;
  }
};

static StringRef getLanguageName(FormatStyle::LanguageKind Language) {
  switch (Language) {
  case FormatStyle::LK_Cpp:
    return "C++";
  case FormatStyle::LK_Java:
    return "Java";
  case FormatStyle::LK_JavaScript:
    return "JavaScript";
  case FormatStyle::LK_Proto:
    return "Proto";
  default:
    return "Unknown";
  }
}

class Environment {
public:
  Environment(const FormatStyle &Style, SourceManager &SM, FileID ID,
              ArrayRef<CharSourceRange> Ranges)
      : Style(Style), ID(ID), CharRanges(Ranges.begin(), Ranges.end()), SM(SM) {
  }

  Environment(const FormatStyle &Style, FileID ID,
              std::unique_ptr<FileManager> FileMgr,
              std::unique_ptr<SourceManager> VirtualSM,
              std::unique_ptr<DiagnosticsEngine> Diagnostics,
              std::vector<CharSourceRange> CharRanges)
      : Style(Style), ID(ID), CharRanges(CharRanges.begin(), CharRanges.end()),
        SM(*VirtualSM), FileMgr(std::move(FileMgr)),
        VirtualSM(std::move(VirtualSM)), Diagnostics(std::move(Diagnostics)) {}

  // This sets up an virtual file system with file \p FileName containing \p
  // Code.
  static std::unique_ptr<Environment>
  CreateVirtualEnvironment(const FormatStyle &Style, StringRef Code,
                           StringRef FileName,
                           ArrayRef<tooling::Range> Ranges) {
    // This is referenced by `FileMgr` and will be released by `FileMgr` when it
    // is deleted.
    IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
        new vfs::InMemoryFileSystem);
    // This is passed to `SM` as reference, so the pointer has to be referenced
    // in `Environment` so that `FileMgr` can out-live this function scope.
    std::unique_ptr<FileManager> FileMgr(
        new FileManager(FileSystemOptions(), InMemoryFileSystem));
    // This is passed to `SM` as reference, so the pointer has to be referenced
    // by `Environment` due to the same reason above.
    std::unique_ptr<DiagnosticsEngine> Diagnostics(new DiagnosticsEngine(
        IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs),
        new DiagnosticOptions));
    // This will be stored as reference, so the pointer has to be stored in
    // due to the same reason above.
    std::unique_ptr<SourceManager> VirtualSM(
        new SourceManager(*Diagnostics, *FileMgr));
    InMemoryFileSystem->addFile(
        FileName, 0, llvm::MemoryBuffer::getMemBuffer(
                         Code, FileName, /*RequiresNullTerminator=*/false));
    FileID ID = VirtualSM->createFileID(
        FileMgr->getFile(FileName), SourceLocation(), clang::SrcMgr::C_User);
    assert(ID.isValid());
    SourceLocation StartOfFile = VirtualSM->getLocForStartOfFile(ID);
    std::vector<CharSourceRange> CharRanges;
    for (const tooling::Range &Range : Ranges) {
      SourceLocation Start = StartOfFile.getLocWithOffset(Range.getOffset());
      SourceLocation End = Start.getLocWithOffset(Range.getLength());
      CharRanges.push_back(CharSourceRange::getCharRange(Start, End));
    }
    return llvm::make_unique<Environment>(Style, ID, std::move(FileMgr),
                                          std::move(VirtualSM),
                                          std::move(Diagnostics), CharRanges);
  }

  FormatStyle &getFormatStyle() { return Style; }

  const FormatStyle &getFormatStyle() const { return Style; }

  FileID getFileID() const { return ID; }

  StringRef getFileName() const { return FileName; }

  ArrayRef<CharSourceRange> getCharRanges() const { return CharRanges; }

  SourceManager &getSourceManager() { return SM; }

private:
  FormatStyle Style;
  FileID ID;
  StringRef FileName;
  SmallVector<CharSourceRange, 8> CharRanges;
  SourceManager &SM;

  // The order of these fields are important - they should be in the same order
  // as they are created in `CreateVirtualEnvironment` so that they can be
  // deleted in the reverse order as they are created.
  std::unique_ptr<FileManager> FileMgr;
  std::unique_ptr<SourceManager> VirtualSM;
  std::unique_ptr<DiagnosticsEngine> Diagnostics;
};

class TokenAnalyzer : public UnwrappedLineConsumer {
public:
  TokenAnalyzer(Environment &Env)
      : Env(Env), AffectedRangeMgr(Env.getSourceManager(), Env.getCharRanges()),
        UnwrappedLines(1),
        Encoding(encoding::detectEncoding(
            Env.getSourceManager().getBufferData(Env.getFileID()))) {
    DEBUG(llvm::dbgs() << "File encoding: "
                       << (Encoding == encoding::Encoding_UTF8 ? "UTF8"
                                                               : "unknown")
                       << "\n");
    DEBUG(llvm::dbgs() << "Language: "
                       << getLanguageName(Env.getFormatStyle().Language)
                       << "\n");
  }

  tooling::Replacements process() {
    tooling::Replacements Result;
    FormatTokenLexer Tokens(Env.getSourceManager(), Env.getFileID(),
                            Env.getFormatStyle(), Encoding);

    UnwrappedLineParser Parser(Env.getFormatStyle(), Tokens.getKeywords(),
                               Tokens.lex(), *this);
    Parser.parse();
    assert(UnwrappedLines.rbegin()->empty());
    for (unsigned Run = 0, RunE = UnwrappedLines.size(); Run + 1 != RunE;
         ++Run) {
      DEBUG(llvm::dbgs() << "Run " << Run << "...\n");
      SmallVector<AnnotatedLine *, 16> AnnotatedLines;

      TokenAnnotator Annotator(Env.getFormatStyle(), Tokens.getKeywords());
      for (unsigned i = 0, e = UnwrappedLines[Run].size(); i != e; ++i) {
        AnnotatedLines.push_back(new AnnotatedLine(UnwrappedLines[Run][i]));
        Annotator.annotate(*AnnotatedLines.back());
      }

      tooling::Replacements RunResult =
          analyze(Annotator, AnnotatedLines, Tokens, Result);

      DEBUG({
        llvm::dbgs() << "Replacements for run " << Run << ":\n";
        for (tooling::Replacements::iterator I = RunResult.begin(),
                                             E = RunResult.end();
             I != E; ++I) {
          llvm::dbgs() << I->toString() << "\n";
        }
      });
      for (unsigned i = 0, e = AnnotatedLines.size(); i != e; ++i) {
        delete AnnotatedLines[i];
      }
      Result.insert(RunResult.begin(), RunResult.end());
    }
    return Result;
  }

protected:
  virtual tooling::Replacements
  analyze(TokenAnnotator &Annotator,
          SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
          FormatTokenLexer &Tokens, tooling::Replacements &Result) = 0;

  void consumeUnwrappedLine(const UnwrappedLine &TheLine) override {
    assert(!UnwrappedLines.empty());
    UnwrappedLines.back().push_back(TheLine);
  }

  void finishRun() override {
    UnwrappedLines.push_back(SmallVector<UnwrappedLine, 16>());
  }

  // Stores Style, FileID and SourceManager etc.
  Environment &Env;
  // AffectedRangeMgr stores ranges to be fixed.
  AffectedRangeManager AffectedRangeMgr;
  SmallVector<SmallVector<UnwrappedLine, 16>, 2> UnwrappedLines;
  encoding::Encoding Encoding;
};

class Formatter : public TokenAnalyzer {
public:
  Formatter(Environment &Env, bool *IncompleteFormat)
      : TokenAnalyzer(Env), IncompleteFormat(IncompleteFormat) {}

  tooling::Replacements
  analyze(TokenAnnotator &Annotator,
          SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
          FormatTokenLexer &Tokens, tooling::Replacements &Result) override {
    deriveLocalStyle(AnnotatedLines);
    AffectedRangeMgr.computeAffectedLines(AnnotatedLines.begin(),
                                          AnnotatedLines.end());

    if (Env.getFormatStyle().Language == FormatStyle::LK_JavaScript &&
        Env.getFormatStyle().JavaScriptQuotes != FormatStyle::JSQS_Leave)
      requoteJSStringLiteral(AnnotatedLines, Result);

    for (unsigned i = 0, e = AnnotatedLines.size(); i != e; ++i) {
      Annotator.calculateFormattingInformation(*AnnotatedLines[i]);
    }

    Annotator.setCommentLineLevels(AnnotatedLines);

    WhitespaceManager Whitespaces(
        Env.getSourceManager(), Env.getFormatStyle(),
        inputUsesCRLF(Env.getSourceManager().getBufferData(Env.getFileID())));
    ContinuationIndenter Indenter(Env.getFormatStyle(), Tokens.getKeywords(),
                                  Env.getSourceManager(), Whitespaces, Encoding,
                                  BinPackInconclusiveFunctions);
    UnwrappedLineFormatter(&Indenter, &Whitespaces, Env.getFormatStyle(),
                           Tokens.getKeywords(), IncompleteFormat)
        .format(AnnotatedLines);
    return Whitespaces.generateReplacements();
  }

private:
  // If the last token is a double/single-quoted string literal, generates a
  // replacement with a single/double quoted string literal, re-escaping the
  // contents in the process.
  void requoteJSStringLiteral(SmallVectorImpl<AnnotatedLine *> &Lines,
                              tooling::Replacements &Result) {
    for (AnnotatedLine *Line : Lines) {
      requoteJSStringLiteral(Line->Children, Result);
      if (!Line->Affected)
        continue;
      for (FormatToken *FormatTok = Line->First; FormatTok;
           FormatTok = FormatTok->Next) {
        StringRef Input = FormatTok->TokenText;
        if (!FormatTok->isStringLiteral() ||
            // NB: testing for not starting with a double quote to avoid
            // breaking
            // `template strings`.
            (Env.getFormatStyle().JavaScriptQuotes ==
                 FormatStyle::JSQS_Single &&
             !Input.startswith("\"")) ||
            (Env.getFormatStyle().JavaScriptQuotes ==
                 FormatStyle::JSQS_Double &&
             !Input.startswith("\'")))
          continue;

        // Change start and end quote.
        bool IsSingle =
            Env.getFormatStyle().JavaScriptQuotes == FormatStyle::JSQS_Single;
        SourceLocation Start = FormatTok->Tok.getLocation();
        auto Replace = [&](SourceLocation Start, unsigned Length,
                           StringRef ReplacementText) {
          Result.insert(tooling::Replacement(Env.getSourceManager(), Start,
                                             Length, ReplacementText));
        };
        Replace(Start, 1, IsSingle ? "'" : "\"");
        Replace(FormatTok->Tok.getEndLoc().getLocWithOffset(-1), 1,
                IsSingle ? "'" : "\"");

        // Escape internal quotes.
        size_t ColumnWidth = FormatTok->TokenText.size();
        bool Escaped = false;
        for (size_t i = 1; i < Input.size() - 1; i++) {
          switch (Input[i]) {
          case '\\':
            if (!Escaped && i + 1 < Input.size() &&
                ((IsSingle && Input[i + 1] == '"') ||
                 (!IsSingle && Input[i + 1] == '\''))) {
              // Remove this \, it's escaping a " or ' that no longer needs
              // escaping
              ColumnWidth--;
              Replace(Start.getLocWithOffset(i), 1, "");
              continue;
            }
            Escaped = !Escaped;
            break;
          case '\"':
          case '\'':
            if (!Escaped && IsSingle == (Input[i] == '\'')) {
              // Escape the quote.
              Replace(Start.getLocWithOffset(i), 0, "\\");
              ColumnWidth++;
            }
            Escaped = false;
            break;
          default:
            Escaped = false;
            break;
          }
        }

        // For formatting, count the number of non-escaped single quotes in them
        // and adjust ColumnWidth to take the added escapes into account.
        // FIXME(martinprobst): this might conflict with code breaking a long
        // string literal (which clang-format doesn't do, yet). For that to
        // work, this code would have to modify TokenText directly.
        FormatTok->ColumnWidth = ColumnWidth;
      }
    }
  }

  static bool inputUsesCRLF(StringRef Text) {
    return Text.count('\r') * 2 > Text.count('\n');
  }

  bool
  hasCpp03IncompatibleFormat(const SmallVectorImpl<AnnotatedLine *> &Lines) {
    for (const AnnotatedLine *Line : Lines) {
      if (hasCpp03IncompatibleFormat(Line->Children))
        return true;
      for (FormatToken *Tok = Line->First->Next; Tok; Tok = Tok->Next) {
        if (Tok->WhitespaceRange.getBegin() == Tok->WhitespaceRange.getEnd()) {
          if (Tok->is(tok::coloncolon) && Tok->Previous->is(TT_TemplateOpener))
            return true;
          if (Tok->is(TT_TemplateCloser) &&
              Tok->Previous->is(TT_TemplateCloser))
            return true;
        }
      }
    }
    return false;
  }

  int countVariableAlignments(const SmallVectorImpl<AnnotatedLine *> &Lines) {
    int AlignmentDiff = 0;
    for (const AnnotatedLine *Line : Lines) {
      AlignmentDiff += countVariableAlignments(Line->Children);
      for (FormatToken *Tok = Line->First; Tok && Tok->Next; Tok = Tok->Next) {
        if (!Tok->is(TT_PointerOrReference))
          continue;
        bool SpaceBefore =
            Tok->WhitespaceRange.getBegin() != Tok->WhitespaceRange.getEnd();
        bool SpaceAfter = Tok->Next->WhitespaceRange.getBegin() !=
                          Tok->Next->WhitespaceRange.getEnd();
        if (SpaceBefore && !SpaceAfter)
          ++AlignmentDiff;
        if (!SpaceBefore && SpaceAfter)
          --AlignmentDiff;
      }
    }
    return AlignmentDiff;
  }

  void
  deriveLocalStyle(const SmallVectorImpl<AnnotatedLine *> &AnnotatedLines) {
    bool HasBinPackedFunction = false;
    bool HasOnePerLineFunction = false;
    for (unsigned i = 0, e = AnnotatedLines.size(); i != e; ++i) {
      if (!AnnotatedLines[i]->First->Next)
        continue;
      FormatToken *Tok = AnnotatedLines[i]->First->Next;
      while (Tok->Next) {
        if (Tok->PackingKind == PPK_BinPacked)
          HasBinPackedFunction = true;
        if (Tok->PackingKind == PPK_OnePerLine)
          HasOnePerLineFunction = true;

        Tok = Tok->Next;
      }
    }
    if (Env.getFormatStyle().DerivePointerAlignment)
      Env.getFormatStyle().PointerAlignment =
          countVariableAlignments(AnnotatedLines) <= 0 ? FormatStyle::PAS_Left
                                                       : FormatStyle::PAS_Right;
    if (Env.getFormatStyle().Standard == FormatStyle::LS_Auto)
      Env.getFormatStyle().Standard = hasCpp03IncompatibleFormat(AnnotatedLines)
                                          ? FormatStyle::LS_Cpp11
                                          : FormatStyle::LS_Cpp03;
    BinPackInconclusiveFunctions =
        HasBinPackedFunction || !HasOnePerLineFunction;
  }

  bool BinPackInconclusiveFunctions;
  bool *IncompleteFormat;
};

// This class clean up the erroneous/redundant code around the given ranges in
// file.
class Cleaner : public TokenAnalyzer {
public:
  Cleaner(Environment &Env)
      : TokenAnalyzer(Env),
        DeletedTokens(FormatTokenLess(Env.getSourceManager())) {}

  // FIXME: eliminate unused parameters.
  tooling::Replacements
  analyze(TokenAnnotator &Annotator,
          SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
          FormatTokenLexer &Tokens, tooling::Replacements &Result) override {
    // FIXME: in the current implementation the granularity of affected range
    // is an annotated line. However, this is not sufficient. Furthermore,
    // redundant code introduced by replacements does not necessarily
    // intercept with ranges of replacements that result in the redundancy.
    // To determine if some redundant code is actually introduced by
    // replacements(e.g. deletions), we need to come up with a more
    // sophisticated way of computing affected ranges.
    AffectedRangeMgr.computeAffectedLines(AnnotatedLines.begin(),
                                          AnnotatedLines.end());

    checkEmptyNamespace(AnnotatedLines);

    return generateFixes();
  }

private:
  bool containsOnlyComments(const AnnotatedLine &Line) {
    for (FormatToken *Tok = Line.First; Tok != nullptr; Tok = Tok->Next) {
      if (Tok->isNot(tok::comment))
        return false;
    }
    return true;
  }

  // Iterate through all lines and remove any empty (nested) namespaces.
  void checkEmptyNamespace(SmallVectorImpl<AnnotatedLine *> &AnnotatedLines) {
    for (unsigned i = 0, e = AnnotatedLines.size(); i != e; ++i) {
      auto &Line = *AnnotatedLines[i];
      if (Line.startsWith(tok::kw_namespace) ||
          Line.startsWith(tok::kw_inline, tok::kw_namespace)) {
        checkEmptyNamespace(AnnotatedLines, i, i);
      }
    }

    for (auto Line : DeletedLines) {
      FormatToken *Tok = AnnotatedLines[Line]->First;
      while (Tok) {
        deleteToken(Tok);
        Tok = Tok->Next;
      }
    }
  }

  // The function checks if the namespace, which starts from \p CurrentLine, and
  // its nested namespaces are empty and delete them if they are empty. It also
  // sets \p NewLine to the last line checked.
  // Returns true if the current namespace is empty.
  bool checkEmptyNamespace(SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
                           unsigned CurrentLine, unsigned &NewLine) {
    unsigned InitLine = CurrentLine, End = AnnotatedLines.size();
    if (Env.getFormatStyle().BraceWrapping.AfterNamespace) {
      // If the left brace is in a new line, we should consume it first so that
      // it does not make the namespace non-empty.
      // FIXME: error handling if there is no left brace.
      if (!AnnotatedLines[++CurrentLine]->startsWith(tok::l_brace)) {
        NewLine = CurrentLine;
        return false;
      }
    } else if (!AnnotatedLines[CurrentLine]->endsWith(tok::l_brace)) {
      return false;
    }
    while (++CurrentLine < End) {
      if (AnnotatedLines[CurrentLine]->startsWith(tok::r_brace))
        break;

      if (AnnotatedLines[CurrentLine]->startsWith(tok::kw_namespace) ||
          AnnotatedLines[CurrentLine]->startsWith(tok::kw_inline,
                                                  tok::kw_namespace)) {
        if (!checkEmptyNamespace(AnnotatedLines, CurrentLine, NewLine))
          return false;
        CurrentLine = NewLine;
        continue;
      }

      if (containsOnlyComments(*AnnotatedLines[CurrentLine]))
        continue;

      // If there is anything other than comments or nested namespaces in the
      // current namespace, the namespace cannot be empty.
      NewLine = CurrentLine;
      return false;
    }

    NewLine = CurrentLine;
    if (CurrentLine >= End)
      return false;

    // Check if the empty namespace is actually affected by changed ranges.
    if (!AffectedRangeMgr.affectsCharSourceRange(CharSourceRange::getCharRange(
            AnnotatedLines[InitLine]->First->Tok.getLocation(),
            AnnotatedLines[CurrentLine]->Last->Tok.getEndLoc())))
      return false;

    for (unsigned i = InitLine; i <= CurrentLine; ++i) {
      DeletedLines.insert(i);
    }

    return true;
  }

  // Delete the given token.
  inline void deleteToken(FormatToken *Tok) {
    if (Tok)
      DeletedTokens.insert(Tok);
  }

  tooling::Replacements generateFixes() {
    tooling::Replacements Fixes;
    std::vector<FormatToken *> Tokens;
    std::copy(DeletedTokens.begin(), DeletedTokens.end(),
              std::back_inserter(Tokens));

    // Merge multiple continuous token deletions into one big deletion so that
    // the number of replacements can be reduced. This makes computing affected
    // ranges more efficient when we run reformat on the changed code.
    unsigned Idx = 0;
    while (Idx < Tokens.size()) {
      unsigned St = Idx, End = Idx;
      while ((End + 1) < Tokens.size() &&
             Tokens[End]->Next == Tokens[End + 1]) {
        End++;
      }
      auto SR = CharSourceRange::getCharRange(Tokens[St]->Tok.getLocation(),
                                              Tokens[End]->Tok.getEndLoc());
      Fixes.insert(tooling::Replacement(Env.getSourceManager(), SR, ""));
      Idx = End + 1;
    }

    return Fixes;
  }

  // Class for less-than inequality comparason for the set `RedundantTokens`.
  // We store tokens in the order they appear in the translation unit so that
  // we do not need to sort them in `generateFixes()`.
  struct FormatTokenLess {
    FormatTokenLess(SourceManager &SM) : SM(SM) {}

    bool operator()(const FormatToken *LHS, const FormatToken *RHS) {
      return SM.isBeforeInTranslationUnit(LHS->Tok.getLocation(),
                                          RHS->Tok.getLocation());
    }
    SourceManager &SM;
  };

  // Tokens to be deleted.
  std::set<FormatToken *, FormatTokenLess> DeletedTokens;
  // The line numbers of lines to be deleted.
  std::set<unsigned> DeletedLines;
};

struct IncludeDirective {
  StringRef Filename;
  StringRef Text;
  unsigned Offset;
  int Category;
};

} // end anonymous namespace

// Determines whether 'Ranges' intersects with ('Start', 'End').
static bool affectsRange(ArrayRef<tooling::Range> Ranges, unsigned Start,
                         unsigned End) {
  for (auto Range : Ranges) {
    if (Range.getOffset() < End &&
        Range.getOffset() + Range.getLength() > Start)
      return true;
  }
  return false;
}

// Sorts a block of includes given by 'Includes' alphabetically adding the
// necessary replacement to 'Replaces'. 'Includes' must be in strict source
// order.
static void sortIncludes(const FormatStyle &Style,
                         const SmallVectorImpl<IncludeDirective> &Includes,
                         ArrayRef<tooling::Range> Ranges, StringRef FileName,
                         tooling::Replacements &Replaces, unsigned *Cursor) {
  if (!affectsRange(Ranges, Includes.front().Offset,
                    Includes.back().Offset + Includes.back().Text.size()))
    return;
  SmallVector<unsigned, 16> Indices;
  for (unsigned i = 0, e = Includes.size(); i != e; ++i)
    Indices.push_back(i);
  std::stable_sort(
      Indices.begin(), Indices.end(), [&](unsigned LHSI, unsigned RHSI) {
        return std::tie(Includes[LHSI].Category, Includes[LHSI].Filename) <
               std::tie(Includes[RHSI].Category, Includes[RHSI].Filename);
      });

  // If the #includes are out of order, we generate a single replacement fixing
  // the entire block. Otherwise, no replacement is generated.
  bool OutOfOrder = false;
  for (unsigned i = 1, e = Indices.size(); i != e; ++i) {
    if (Indices[i] != i) {
      OutOfOrder = true;
      break;
    }
  }
  if (!OutOfOrder)
    return;

  std::string result;
  bool CursorMoved = false;
  for (unsigned Index : Indices) {
    if (!result.empty())
      result += "\n";
    result += Includes[Index].Text;

    if (Cursor && !CursorMoved) {
      unsigned Start = Includes[Index].Offset;
      unsigned End = Start + Includes[Index].Text.size();
      if (*Cursor >= Start && *Cursor < End) {
        *Cursor = Includes.front().Offset + result.size() + *Cursor - End;
        CursorMoved = true;
      }
    }
  }

  // Sorting #includes shouldn't change their total number of characters.
  // This would otherwise mess up 'Ranges'.
  assert(result.size() ==
         Includes.back().Offset + Includes.back().Text.size() -
             Includes.front().Offset);

  Replaces.insert(tooling::Replacement(FileName, Includes.front().Offset,
                                       result.size(), result));
}

tooling::Replacements sortIncludes(const FormatStyle &Style, StringRef Code,
                                   ArrayRef<tooling::Range> Ranges,
                                   StringRef FileName, unsigned *Cursor) {
  tooling::Replacements Replaces;
  if (!Style.SortIncludes)
    return Replaces;

  unsigned Prev = 0;
  unsigned SearchFrom = 0;
  llvm::Regex IncludeRegex(
      R"(^[\t\ ]*#[\t\ ]*(import|include)[^"<]*(["<][^">]*[">]))");
  SmallVector<StringRef, 4> Matches;
  SmallVector<IncludeDirective, 16> IncludesInBlock;

  // In compiled files, consider the first #include to be the main #include of
  // the file if it is not a system #include. This ensures that the header
  // doesn't have hidden dependencies
  // (http://llvm.org/docs/CodingStandards.html#include-style).
  //
  // FIXME: Do some sanity checking, e.g. edit distance of the base name, to fix
  // cases where the first #include is unlikely to be the main header.
  bool IsSource = FileName.endswith(".c") || FileName.endswith(".cc") ||
                  FileName.endswith(".cpp") || FileName.endswith(".c++") ||
                  FileName.endswith(".cxx") || FileName.endswith(".m") ||
                  FileName.endswith(".mm");
  StringRef FileStem = llvm::sys::path::stem(FileName);
  bool FirstIncludeBlock = true;
  bool MainIncludeFound = false;

  // Create pre-compiled regular expressions for the #include categories.
  SmallVector<llvm::Regex, 4> CategoryRegexs;
  for (const auto &Category : Style.IncludeCategories)
    CategoryRegexs.emplace_back(Category.Regex);

  bool FormattingOff = false;

  for (;;) {
    auto Pos = Code.find('\n', SearchFrom);
    StringRef Line =
        Code.substr(Prev, (Pos != StringRef::npos ? Pos : Code.size()) - Prev);

    StringRef Trimmed = Line.trim();
    if (Trimmed == "// clang-format off")
      FormattingOff = true;
    else if (Trimmed == "// clang-format on")
      FormattingOff = false;

    if (!FormattingOff && !Line.endswith("\\")) {
      if (IncludeRegex.match(Line, &Matches)) {
        StringRef IncludeName = Matches[2];
        int Category = INT_MAX;
        for (unsigned i = 0, e = CategoryRegexs.size(); i != e; ++i) {
          if (CategoryRegexs[i].match(IncludeName)) {
            Category = Style.IncludeCategories[i].Priority;
            break;
          }
        }
        if (IsSource && !MainIncludeFound && Category > 0 &&
            FirstIncludeBlock && IncludeName.startswith("\"")) {
          StringRef HeaderStem =
              llvm::sys::path::stem(IncludeName.drop_front(1).drop_back(1));
          if (FileStem.startswith(HeaderStem)) {
            llvm::Regex MainIncludeRegex(
                (HeaderStem + Style.IncludeIsMainRegex).str());
            if (MainIncludeRegex.match(FileStem)) {
              Category = 0;
              MainIncludeFound = true;
            }
          }
        }
        IncludesInBlock.push_back({IncludeName, Line, Prev, Category});
      } else if (!IncludesInBlock.empty()) {
        sortIncludes(Style, IncludesInBlock, Ranges, FileName, Replaces,
                     Cursor);
        IncludesInBlock.clear();
        FirstIncludeBlock = false;
      }
      Prev = Pos + 1;
    }
    if (Pos == StringRef::npos || Pos + 1 == Code.size())
      break;
    SearchFrom = Pos + 1;
  }
  if (!IncludesInBlock.empty())
    sortIncludes(Style, IncludesInBlock, Ranges, FileName, Replaces, Cursor);
  return Replaces;
}

template <typename T>
static tooling::Replacements
processReplacements(T ProcessFunc, StringRef Code,
                    const tooling::Replacements &Replaces,
                    const FormatStyle &Style) {
  if (Replaces.empty())
    return tooling::Replacements();

  std::string NewCode = applyAllReplacements(Code, Replaces);
  std::vector<tooling::Range> ChangedRanges =
      tooling::calculateChangedRanges(Replaces);
  StringRef FileName = Replaces.begin()->getFilePath();

  tooling::Replacements FormatReplaces =
      ProcessFunc(Style, NewCode, ChangedRanges, FileName);

  return mergeReplacements(Replaces, FormatReplaces);
}

tooling::Replacements formatReplacements(StringRef Code,
                                         const tooling::Replacements &Replaces,
                                         const FormatStyle &Style) {
  // We need to use lambda function here since there are two versions of
  // `reformat`.
  auto Reformat = [](const FormatStyle &Style, StringRef Code,
                     std::vector<tooling::Range> Ranges,
                     StringRef FileName) -> tooling::Replacements {
    return reformat(Style, Code, Ranges, FileName);
  };
  return processReplacements(Reformat, Code, Replaces, Style);
}

tooling::Replacements
cleanupAroundReplacements(StringRef Code, const tooling::Replacements &Replaces,
                          const FormatStyle &Style) {
  // We need to use lambda function here since there are two versions of
  // `cleanup`.
  auto Cleanup = [](const FormatStyle &Style, StringRef Code,
                    std::vector<tooling::Range> Ranges,
                    StringRef FileName) -> tooling::Replacements {
    return cleanup(Style, Code, Ranges, FileName);
  };
  return processReplacements(Cleanup, Code, Replaces, Style);
}

tooling::Replacements reformat(const FormatStyle &Style, SourceManager &SM,
                               FileID ID, ArrayRef<CharSourceRange> Ranges,
                               bool *IncompleteFormat) {
  FormatStyle Expanded = expandPresets(Style);
  if (Expanded.DisableFormat)
    return tooling::Replacements();

  Environment Env(Expanded, SM, ID, Ranges);
  Formatter Format(Env, IncompleteFormat);
  return Format.process();
}

tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
                               ArrayRef<tooling::Range> Ranges,
                               StringRef FileName, bool *IncompleteFormat) {
  FormatStyle Expanded = expandPresets(Style);
  if (Expanded.DisableFormat)
    return tooling::Replacements();

  std::unique_ptr<Environment> Env =
      Environment::CreateVirtualEnvironment(Expanded, Code, FileName, Ranges);
  Formatter Format(*Env, IncompleteFormat);
  return Format.process();
}

tooling::Replacements cleanup(const FormatStyle &Style, SourceManager &SM,
                              FileID ID, ArrayRef<CharSourceRange> Ranges) {
  Environment Env(Style, SM, ID, Ranges);
  Cleaner Clean(Env);
  return Clean.process();
}

tooling::Replacements cleanup(const FormatStyle &Style, StringRef Code,
                              ArrayRef<tooling::Range> Ranges,
                              StringRef FileName) {
  std::unique_ptr<Environment> Env =
      Environment::CreateVirtualEnvironment(Style, Code, FileName, Ranges);
  Cleaner Clean(*Env);
  return Clean.process();
}

LangOptions getFormattingLangOpts(const FormatStyle &Style) {
  LangOptions LangOpts;
  LangOpts.CPlusPlus = 1;
  LangOpts.CPlusPlus11 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
  LangOpts.CPlusPlus14 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
  LangOpts.LineComment = 1;
  bool AlternativeOperators = Style.Language == FormatStyle::LK_Cpp;
  LangOpts.CXXOperatorNames = AlternativeOperators ? 1 : 0;
  LangOpts.Bool = 1;
  LangOpts.ObjC1 = 1;
  LangOpts.ObjC2 = 1;
  LangOpts.MicrosoftExt = 1;    // To get kw___try, kw___finally.
  LangOpts.DeclSpecKeyword = 1; // To get __declspec.
  return LangOpts;
}

const char *StyleOptionHelpDescription =
    "Coding style, currently supports:\n"
    "  LLVM, Google, Chromium, Mozilla, WebKit.\n"
    "Use -style=file to load style configuration from\n"
    ".clang-format file located in one of the parent\n"
    "directories of the source file (or current\n"
    "directory for stdin).\n"
    "Use -style=\"{key: value, ...}\" to set specific\n"
    "parameters, e.g.:\n"
    "  -style=\"{BasedOnStyle: llvm, IndentWidth: 8}\"";

static FormatStyle::LanguageKind getLanguageByFileName(StringRef FileName) {
  if (FileName.endswith(".java"))
    return FormatStyle::LK_Java;
  if (FileName.endswith_lower(".js") || FileName.endswith_lower(".ts"))
    return FormatStyle::LK_JavaScript; // JavaScript or TypeScript.
  if (FileName.endswith_lower(".proto") ||
      FileName.endswith_lower(".protodevel"))
    return FormatStyle::LK_Proto;
  if (FileName.endswith_lower(".td"))
    return FormatStyle::LK_TableGen;
  return FormatStyle::LK_Cpp;
}

FormatStyle getStyle(StringRef StyleName, StringRef FileName,
                     StringRef FallbackStyle, vfs::FileSystem *FS) {
  if (!FS) {
    FS = vfs::getRealFileSystem().get();
  }
  FormatStyle Style = getLLVMStyle();
  Style.Language = getLanguageByFileName(FileName);
  if (!getPredefinedStyle(FallbackStyle, Style.Language, &Style)) {
    llvm::errs() << "Invalid fallback style \"" << FallbackStyle
                 << "\" using LLVM style\n";
    return Style;
  }

  if (StyleName.startswith("{")) {
    // Parse YAML/JSON style from the command line.
    if (std::error_code ec = parseConfiguration(StyleName, &Style)) {
      llvm::errs() << "Error parsing -style: " << ec.message() << ", using "
                   << FallbackStyle << " style\n";
    }
    return Style;
  }

  if (!StyleName.equals_lower("file")) {
    if (!getPredefinedStyle(StyleName, Style.Language, &Style))
      llvm::errs() << "Invalid value for -style, using " << FallbackStyle
                   << " style\n";
    return Style;
  }

  // Look for .clang-format/_clang-format file in the file's parent directories.
  SmallString<128> UnsuitableConfigFiles;
  SmallString<128> Path(FileName);
  llvm::sys::fs::make_absolute(Path);
  for (StringRef Directory = Path; !Directory.empty();
       Directory = llvm::sys::path::parent_path(Directory)) {

    auto Status = FS->status(Directory);
    if (!Status ||
        Status->getType() != llvm::sys::fs::file_type::directory_file) {
      continue;
    }

    SmallString<128> ConfigFile(Directory);

    llvm::sys::path::append(ConfigFile, ".clang-format");
    DEBUG(llvm::dbgs() << "Trying " << ConfigFile << "...\n");

    Status = FS->status(ConfigFile.str());
    bool IsFile =
        Status && (Status->getType() == llvm::sys::fs::file_type::regular_file);
    if (!IsFile) {
      // Try _clang-format too, since dotfiles are not commonly used on Windows.
      ConfigFile = Directory;
      llvm::sys::path::append(ConfigFile, "_clang-format");
      DEBUG(llvm::dbgs() << "Trying " << ConfigFile << "...\n");
      Status = FS->status(ConfigFile.str());
      IsFile = Status &&
               (Status->getType() == llvm::sys::fs::file_type::regular_file);
    }

    if (IsFile) {
      llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
          FS->getBufferForFile(ConfigFile.str());
      if (std::error_code EC = Text.getError()) {
        llvm::errs() << EC.message() << "\n";
        break;
      }
      if (std::error_code ec =
              parseConfiguration(Text.get()->getBuffer(), &Style)) {
        if (ec == ParseError::Unsuitable) {
          if (!UnsuitableConfigFiles.empty())
            UnsuitableConfigFiles.append(", ");
          UnsuitableConfigFiles.append(ConfigFile);
          continue;
        }
        llvm::errs() << "Error reading " << ConfigFile << ": " << ec.message()
                     << "\n";
        break;
      }
      DEBUG(llvm::dbgs() << "Using configuration file " << ConfigFile << "\n");
      return Style;
    }
  }
  if (!UnsuitableConfigFiles.empty()) {
    llvm::errs() << "Configuration file(s) do(es) not support "
                 << getLanguageName(Style.Language) << ": "
                 << UnsuitableConfigFiles << "\n";
  }
  return Style;
}

} // namespace format
} // namespace clang