contrib/llvm/tools/clang/lib/Format/ContinuationIndenter.cpp

   1 //===--- ContinuationIndenter.cpp - Format C++ code -----------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 ///
  10 /// \file
  11 /// \brief This file implements the continuation indenter.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #define DEBUG_TYPE "format-formatter"
  16
  17 #include "BreakableToken.h"
  18 #include "ContinuationIndenter.h"
  19 #include "WhitespaceManager.h"
  20 #include "clang/Basic/OperatorPrecedence.h"
  21 #include "clang/Basic/SourceManager.h"
  22 #include "clang/Format/Format.h"
  23 #include "llvm/Support/Debug.h"
  24 #include <string>
  25
  26 namespace clang {
  27 namespace format {
  28
  29 // Returns the length of everything up to the first possible line break after
  30 // the ), ], } or > matching \c Tok.
  31 static unsigned getLengthToMatchingParen(const FormatToken &Tok) {
  32   if (Tok.MatchingParen == NULL)
  33     return 0;
  34   FormatToken *End = Tok.MatchingParen;
  35   while (End->Next && !End->Next->CanBreakBefore) {
  36     End = End->Next;
  37   }
  38   return End->TotalLength - Tok.TotalLength + 1;
  39 }
  40
  41 // Returns \c true if \c Tok is the "." or "->" of a call and starts the next
  42 // segment of a builder type call.
  43 static bool startsSegmentOfBuilderTypeCall(const FormatToken &Tok) {
  44   return Tok.isMemberAccess() && Tok.Previous && Tok.Previous->closesScope();
  45 }
  46
  47 // Returns \c true if \c Current starts a new parameter.
  48 static bool startsNextParameter(const FormatToken &Current,
  49                                 const FormatStyle &Style) {
  50   const FormatToken &Previous = *Current.Previous;
  51   if (Current.Type == TT_CtorInitializerComma &&
  52       Style.BreakConstructorInitializersBeforeComma)
  53     return true;
  54   return Previous.is(tok::comma) && !Current.isTrailingComment() &&
  55          (Previous.Type != TT_CtorInitializerComma ||
  56           !Style.BreakConstructorInitializersBeforeComma);
  57 }
  58
  59 ContinuationIndenter::ContinuationIndenter(const FormatStyle &Style,
  60                                            SourceManager &SourceMgr,
  61                                            WhitespaceManager &Whitespaces,
  62                                            encoding::Encoding Encoding,
  63                                            bool BinPackInconclusiveFunctions)
  64     : Style(Style), SourceMgr(SourceMgr), Whitespaces(Whitespaces),
  65       Encoding(Encoding),
  66       BinPackInconclusiveFunctions(BinPackInconclusiveFunctions) {}
  67
  68 LineState ContinuationIndenter::getInitialState(unsigned FirstIndent,
  69                                                 const AnnotatedLine *Line,
  70                                                 bool DryRun) {
  71   LineState State;
  72   State.FirstIndent = FirstIndent;
  73   State.Column = FirstIndent;
  74   State.Line = Line;
  75   State.NextToken = Line->First;
  76   State.Stack.push_back(ParenState(FirstIndent, Line->Level, FirstIndent,
  77                                    /*AvoidBinPacking=*/false,
  78                                    /*NoLineBreak=*/false));
  79   State.LineContainsContinuedForLoopSection = false;
  80   State.ParenLevel = 0;
  81   State.StartOfStringLiteral = 0;
  82   State.StartOfLineLevel = State.ParenLevel;
  83   State.LowestLevelOnLine = State.ParenLevel;
  84   State.IgnoreStackForComparison = false;
  85
  86   // The first token has already been indented and thus consumed.
  87   moveStateToNextToken(State, DryRun, /*Newline=*/false);
  88   return State;
  89 }
  90
  91 bool ContinuationIndenter::canBreak(const LineState &State) {
  92   const FormatToken &Current = *State.NextToken;
  93   const FormatToken &Previous = *Current.Previous;
  94   assert(&Previous == Current.Previous);
  95   if (!Current.CanBreakBefore && !(State.Stack.back().BreakBeforeClosingBrace &&
  96                                    Current.closesBlockTypeList(Style)))
  97     return false;
  98   // The opening "{" of a braced list has to be on the same line as the first
  99   // element if it is nested in another braced init list or function call.
 100   if (!Current.MustBreakBefore && Previous.is(tok::l_brace) &&
 101       Previous.Type != TT_DictLiteral &&
 102       Previous.BlockKind == BK_BracedInit && Previous.Previous &&
 103       Previous.Previous->isOneOf(tok::l_brace, tok::l_paren, tok::comma))
 104     return false;
 105   // This prevents breaks like:
 106   //   ...
 107   //   SomeParameter, OtherParameter).DoSomething(
 108   //   ...
 109   // As they hide "DoSomething" and are generally bad for readability.
 110   if (Previous.opensScope() && State.LowestLevelOnLine < State.StartOfLineLevel)
 111     return false;
 112   if (Current.isMemberAccess() && State.Stack.back().ContainsUnwrappedBuilder)
 113     return false;
 114   return !State.Stack.back().NoLineBreak;
 115 }
 116
 117 bool ContinuationIndenter::mustBreak(const LineState &State) {
 118   const FormatToken &Current = *State.NextToken;
 119   const FormatToken &Previous = *Current.Previous;
 120   if (Current.MustBreakBefore || Current.Type == TT_InlineASMColon)
 121     return true;
 122   if (State.Stack.back().BreakBeforeClosingBrace &&
 123       Current.closesBlockTypeList(Style))
 124     return true;
 125   if (Previous.is(tok::semi) && State.LineContainsContinuedForLoopSection)
 126     return true;
 127   if ((startsNextParameter(Current, Style) || Previous.is(tok::semi) ||
 128        (Style.BreakBeforeTernaryOperators &&
 129         (Current.is(tok::question) || (Current.Type == TT_ConditionalExpr &&
 130                                        Previous.isNot(tok::question)))) ||
 131        (!Style.BreakBeforeTernaryOperators &&
 132         (Previous.is(tok::question) || Previous.Type == TT_ConditionalExpr))) &&
 133       State.Stack.back().BreakBeforeParameter && !Current.isTrailingComment() &&
 134       !Current.isOneOf(tok::r_paren, tok::r_brace))
 135     return true;
 136   if (Style.AlwaysBreakBeforeMultilineStrings &&
 137       State.Column > State.Stack.back().Indent && // Breaking saves columns.
 138       !Previous.isOneOf(tok::kw_return, tok::lessless, tok::at) &&
 139       Previous.Type != TT_InlineASMColon && NextIsMultilineString(State))
 140     return true;
 141   if (((Previous.Type == TT_DictLiteral && Previous.is(tok::l_brace)) ||
 142        Previous.Type == TT_ArrayInitializerLSquare) &&
 143       getLengthToMatchingParen(Previous) + State.Column > getColumnLimit(State))
 144     return true;
 145
 146   if (!Style.BreakBeforeBinaryOperators) {
 147     // If we need to break somewhere inside the LHS of a binary expression, we
 148     // should also break after the operator. Otherwise, the formatting would
 149     // hide the operator precedence, e.g. in:
 150     //   if (aaaaaaaaaaaaaa ==
 151     //           bbbbbbbbbbbbbb && c) {..
 152     // For comparisons, we only apply this rule, if the LHS is a binary
 153     // expression itself as otherwise, the line breaks seem superfluous.
 154     // We need special cases for ">>" which we have split into two ">" while
 155     // lexing in order to make template parsing easier.
 156     //
 157     // FIXME: We'll need something similar for styles that break before binary
 158     // operators.
 159     bool IsComparison = (Previous.getPrecedence() == prec::Relational ||
 160                          Previous.getPrecedence() == prec::Equality) &&
 161                         Previous.Previous &&
 162                         Previous.Previous->Type != TT_BinaryOperator; // For >>.
 163     bool LHSIsBinaryExpr =
 164         Previous.Previous && Previous.Previous->EndsBinaryExpression;
 165     if (Previous.Type == TT_BinaryOperator &&
 166         (!IsComparison || LHSIsBinaryExpr) &&
 167         Current.Type != TT_BinaryOperator && // For >>.
 168         !Current.isTrailingComment() &&
 169         !Previous.isOneOf(tok::lessless, tok::question) &&
 170         Previous.getPrecedence() != prec::Assignment &&
 171         State.Stack.back().BreakBeforeParameter)
 172       return true;
 173   }
 174
 175   // Same as above, but for the first "<<" operator.
 176   if (Current.is(tok::lessless) && State.Stack.back().BreakBeforeParameter &&
 177       State.Stack.back().FirstLessLess == 0)
 178     return true;
 179
 180   // FIXME: Comparing LongestObjCSelectorName to 0 is a hacky way of finding
 181   // out whether it is the first parameter. Clean this up.
 182   if (Current.Type == TT_ObjCSelectorName &&
 183       Current.LongestObjCSelectorName == 0 &&
 184       State.Stack.back().BreakBeforeParameter)
 185     return true;
 186   if ((Current.Type == TT_CtorInitializerColon ||
 187        (Previous.ClosesTemplateDeclaration && State.ParenLevel == 0 &&
 188         !Current.isTrailingComment())))
 189     return true;
 190
 191   if ((Current.Type == TT_StartOfName || Current.is(tok::kw_operator)) &&
 192       State.Line->MightBeFunctionDecl &&
 193       State.Stack.back().BreakBeforeParameter && State.ParenLevel == 0)
 194     return true;
 195   if (startsSegmentOfBuilderTypeCall(Current) &&
 196       (State.Stack.back().CallContinuation != 0 ||
 197        (State.Stack.back().BreakBeforeParameter &&
 198         State.Stack.back().ContainsUnwrappedBuilder)))
 199     return true;
 200   return false;
 201 }
 202
 203 unsigned ContinuationIndenter::addTokenToState(LineState &State, bool Newline,
 204                                                bool DryRun,
 205                                                unsigned ExtraSpaces) {
 206   const FormatToken &Current = *State.NextToken;
 207
 208   if (State.Stack.size() == 0 ||
 209       (Current.Type == TT_ImplicitStringLiteral &&
 210        (Current.Previous->Tok.getIdentifierInfo() == NULL ||
 211         Current.Previous->Tok.getIdentifierInfo()->getPPKeywordID() ==
 212             tok::pp_not_keyword))) {
 213     // FIXME: Is this correct?
 214     int WhitespaceLength = SourceMgr.getSpellingColumnNumber(
 215                                State.NextToken->WhitespaceRange.getEnd()) -
 216                            SourceMgr.getSpellingColumnNumber(
 217                                State.NextToken->WhitespaceRange.getBegin());
 218     State.Column += WhitespaceLength + State.NextToken->ColumnWidth;
 219     State.NextToken = State.NextToken->Next;
 220     return 0;
 221   }
 222
 223   unsigned Penalty = 0;
 224   if (Newline)
 225     Penalty = addTokenOnNewLine(State, DryRun);
 226   else
 227     addTokenOnCurrentLine(State, DryRun, ExtraSpaces);
 228
 229   return moveStateToNextToken(State, DryRun, Newline) + Penalty;
 230 }
 231
 232 void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
 233                                                  unsigned ExtraSpaces) {
 234   FormatToken &Current = *State.NextToken;
 235   const FormatToken &Previous = *State.NextToken->Previous;
 236   if (Current.is(tok::equal) &&
 237       (State.Line->First->is(tok::kw_for) || State.ParenLevel == 0) &&
 238       State.Stack.back().VariablePos == 0) {
 239     State.Stack.back().VariablePos = State.Column;
 240     // Move over * and & if they are bound to the variable name.
 241     const FormatToken *Tok = &Previous;
 242     while (Tok && State.Stack.back().VariablePos >= Tok->ColumnWidth) {
 243       State.Stack.back().VariablePos -= Tok->ColumnWidth;
 244       if (Tok->SpacesRequiredBefore != 0)
 245         break;
 246       Tok = Tok->Previous;
 247     }
 248     if (Previous.PartOfMultiVariableDeclStmt)
 249       State.Stack.back().LastSpace = State.Stack.back().VariablePos;
 250   }
 251
 252   unsigned Spaces = Current.SpacesRequiredBefore + ExtraSpaces;
 253
 254   if (!DryRun)
 255     Whitespaces.replaceWhitespace(Current, /*Newlines=*/0, /*IndentLevel=*/0,
 256                                   Spaces, State.Column + Spaces);
 257
 258   if (Current.Type == TT_ObjCSelectorName && State.Stack.back().ColonPos == 0) {
 259     if (State.Stack.back().Indent + Current.LongestObjCSelectorName >
 260         State.Column + Spaces + Current.ColumnWidth)
 261       State.Stack.back().ColonPos =
 262           State.Stack.back().Indent + Current.LongestObjCSelectorName;
 263     else
 264       State.Stack.back().ColonPos = State.Column + Spaces + Current.ColumnWidth;
 265   }
 266
 267   if (Previous.opensScope() && Previous.Type != TT_ObjCMethodExpr &&
 268       Current.Type != TT_LineComment)
 269     State.Stack.back().Indent = State.Column + Spaces;
 270   if (State.Stack.back().AvoidBinPacking && startsNextParameter(Current, Style))
 271     State.Stack.back().NoLineBreak = true;
 272   if (startsSegmentOfBuilderTypeCall(Current))
 273     State.Stack.back().ContainsUnwrappedBuilder = true;
 274
 275   State.Column += Spaces;
 276   if (Current.is(tok::l_paren) && Previous.isOneOf(tok::kw_if, tok::kw_for))
 277     // Treat the condition inside an if as if it was a second function
 278     // parameter, i.e. let nested calls have a continuation indent.
 279     State.Stack.back().LastSpace = State.Column + 1; // 1 is length of "(".
 280   else if (Previous.is(tok::comma) || Previous.Type == TT_ObjCMethodExpr)
 281     State.Stack.back().LastSpace = State.Column;
 282   else if ((Previous.Type == TT_BinaryOperator ||
 283             Previous.Type == TT_ConditionalExpr ||
 284             Previous.Type == TT_UnaryOperator ||
 285             Previous.Type == TT_CtorInitializerColon) &&
 286            (Previous.getPrecedence() != prec::Assignment ||
 287             Current.StartsBinaryExpression))
 288     // Always indent relative to the RHS of the expression unless this is a
 289     // simple assignment without binary expression on the RHS. Also indent
 290     // relative to unary operators and the colons of constructor initializers.
 291     State.Stack.back().LastSpace = State.Column;
 292   else if (Previous.Type == TT_InheritanceColon) {
 293     State.Stack.back().Indent = State.Column;
 294     State.Stack.back().LastSpace = State.Column;
 295   } else if (Previous.opensScope()) {
 296     // If a function has a trailing call, indent all parameters from the
 297     // opening parenthesis. This avoids confusing indents like:
 298     //   OuterFunction(InnerFunctionCall( // break
 299     //       ParameterToInnerFunction))   // break
 300     //       .SecondInnerFunctionCall();
 301     bool HasTrailingCall = false;
 302     if (Previous.MatchingParen) {
 303       const FormatToken *Next = Previous.MatchingParen->getNextNonComment();
 304       HasTrailingCall = Next && Next->isMemberAccess();
 305     }
 306     if (HasTrailingCall &&
 307         State.Stack[State.Stack.size() - 2].CallContinuation == 0)
 308       State.Stack.back().LastSpace = State.Column;
 309   }
 310 }
 311
 312 unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
 313                                                  bool DryRun) {
 314   FormatToken &Current = *State.NextToken;
 315   const FormatToken &Previous = *State.NextToken->Previous;
 316   // If we are continuing an expression, we want to use the continuation indent.
 317   unsigned ContinuationIndent =
 318       std::max(State.Stack.back().LastSpace, State.Stack.back().Indent) +
 319       Style.ContinuationIndentWidth;
 320   // Extra penalty that needs to be added because of the way certain line
 321   // breaks are chosen.
 322   unsigned Penalty = 0;
 323
 324   const FormatToken *PreviousNonComment =
 325       State.NextToken->getPreviousNonComment();
 326   // The first line break on any ParenLevel causes an extra penalty in order
 327   // prefer similar line breaks.
 328   if (!State.Stack.back().ContainsLineBreak)
 329     Penalty += 15;
 330   State.Stack.back().ContainsLineBreak = true;
 331
 332   Penalty += State.NextToken->SplitPenalty;
 333
 334   // Breaking before the first "<<" is generally not desirable if the LHS is
 335   // short.
 336   if (Current.is(tok::lessless) && State.Stack.back().FirstLessLess == 0 &&
 337       State.Column <= Style.ColumnLimit / 2)
 338     Penalty += Style.PenaltyBreakFirstLessLess;
 339
 340   if (Current.is(tok::l_brace) && Current.BlockKind == BK_Block) {
 341     State.Column = State.FirstIndent;
 342   } else if (Current.isOneOf(tok::r_brace, tok::r_square)) {
 343     if (Current.closesBlockTypeList(Style) ||
 344         (Current.MatchingParen &&
 345          Current.MatchingParen->BlockKind == BK_BracedInit))
 346       State.Column = State.Stack[State.Stack.size() - 2].LastSpace;
 347     else
 348       State.Column = State.FirstIndent;
 349   } else if (Current.is(tok::string_literal) &&
 350              State.StartOfStringLiteral != 0) {
 351     State.Column = State.StartOfStringLiteral;
 352     State.Stack.back().BreakBeforeParameter = true;
 353   } else if (Current.is(tok::lessless) &&
 354              State.Stack.back().FirstLessLess != 0) {
 355     State.Column = State.Stack.back().FirstLessLess;
 356   } else if (Current.isMemberAccess()) {
 357     if (State.Stack.back().CallContinuation == 0) {
 358       State.Column = ContinuationIndent;
 359       State.Stack.back().CallContinuation = State.Column;
 360     } else {
 361       State.Column = State.Stack.back().CallContinuation;
 362     }
 363   } else if (State.Stack.back().QuestionColumn != 0 &&
 364              (Current.Type == TT_ConditionalExpr ||
 365               Previous.Type == TT_ConditionalExpr)) {
 366     State.Column = State.Stack.back().QuestionColumn;
 367   } else if (Previous.is(tok::comma) && State.Stack.back().VariablePos != 0) {
 368     State.Column = State.Stack.back().VariablePos;
 369   } else if ((PreviousNonComment &&
 370               PreviousNonComment->ClosesTemplateDeclaration) ||
 371              ((Current.Type == TT_StartOfName ||
 372                Current.is(tok::kw_operator)) &&
 373               State.ParenLevel == 0 &&
 374               (!Style.IndentFunctionDeclarationAfterType ||
 375                State.Line->StartsDefinition))) {
 376     State.Column = State.Stack.back().Indent;
 377   } else if (Current.Type == TT_ObjCSelectorName) {
 378     if (State.Stack.back().ColonPos == 0) {
 379       State.Stack.back().ColonPos =
 380           State.Stack.back().Indent + Current.LongestObjCSelectorName;
 381       State.Column = State.Stack.back().ColonPos - Current.ColumnWidth;
 382     } else if (State.Stack.back().ColonPos > Current.ColumnWidth) {
 383       State.Column = State.Stack.back().ColonPos - Current.ColumnWidth;
 384     } else {
 385       State.Column = State.Stack.back().Indent;
 386       State.Stack.back().ColonPos = State.Column + Current.ColumnWidth;
 387     }
 388   } else if (Current.Type == TT_ArraySubscriptLSquare) {
 389     if (State.Stack.back().StartOfArraySubscripts != 0)
 390       State.Column = State.Stack.back().StartOfArraySubscripts;
 391     else
 392       State.Column = ContinuationIndent;
 393   } else if (Current.Type == TT_StartOfName ||
 394              Previous.isOneOf(tok::coloncolon, tok::equal) ||
 395              Previous.Type == TT_ObjCMethodExpr) {
 396     State.Column = ContinuationIndent;
 397   } else if (Current.Type == TT_CtorInitializerColon) {
 398     State.Column = State.FirstIndent + Style.ConstructorInitializerIndentWidth;
 399   } else if (Current.Type == TT_CtorInitializerComma) {
 400     State.Column = State.Stack.back().Indent;
 401   } else {
 402     State.Column = State.Stack.back().Indent;
 403     // Ensure that we fall back to the continuation indent width instead of just
 404     // flushing continuations left.
 405     if (State.Column == State.FirstIndent &&
 406         PreviousNonComment->isNot(tok::r_brace))
 407       State.Column += Style.ContinuationIndentWidth;
 408   }
 409
 410   if ((Previous.isOneOf(tok::comma, tok::semi) &&
 411        !State.Stack.back().AvoidBinPacking) ||
 412       Previous.Type == TT_BinaryOperator)
 413     State.Stack.back().BreakBeforeParameter = false;
 414   if (Previous.Type == TT_TemplateCloser && State.ParenLevel == 0)
 415     State.Stack.back().BreakBeforeParameter = false;
 416   if (Current.is(tok::question) ||
 417       (PreviousNonComment && PreviousNonComment->is(tok::question)))
 418     State.Stack.back().BreakBeforeParameter = true;
 419
 420   if (!DryRun) {
 421     unsigned Newlines = 1;
 422     if (Current.is(tok::comment))
 423       Newlines = std::max(Newlines, std::min(Current.NewlinesBefore,
 424                                              Style.MaxEmptyLinesToKeep + 1));
 425     Whitespaces.replaceWhitespace(Current, Newlines,
 426                                   State.Stack.back().IndentLevel, State.Column,
 427                                   State.Column, State.Line->InPPDirective);
 428   }
 429
 430   if (!Current.isTrailingComment())
 431     State.Stack.back().LastSpace = State.Column;
 432   if (Current.isMemberAccess())
 433     State.Stack.back().LastSpace += Current.ColumnWidth;
 434   State.StartOfLineLevel = State.ParenLevel;
 435   State.LowestLevelOnLine = State.ParenLevel;
 436
 437   // Any break on this level means that the parent level has been broken
 438   // and we need to avoid bin packing there.
 439   for (unsigned i = 0, e = State.Stack.size() - 1; i != e; ++i) {
 440     State.Stack[i].BreakBeforeParameter = true;
 441   }
 442   if (PreviousNonComment &&
 443       !PreviousNonComment->isOneOf(tok::comma, tok::semi) &&
 444       PreviousNonComment->Type != TT_TemplateCloser &&
 445       PreviousNonComment->Type != TT_BinaryOperator &&
 446       Current.Type != TT_BinaryOperator &&
 447       !PreviousNonComment->opensScope())
 448     State.Stack.back().BreakBeforeParameter = true;
 449
 450   // If we break after { or the [ of an array initializer, we should also break
 451   // before the corresponding } or ].
 452   if (Previous.is(tok::l_brace) || Previous.Type == TT_ArrayInitializerLSquare)
 453     State.Stack.back().BreakBeforeClosingBrace = true;
 454
 455   if (State.Stack.back().AvoidBinPacking) {
 456     // If we are breaking after '(', '{', '<', this is not bin packing
 457     // unless AllowAllParametersOfDeclarationOnNextLine is false.
 458     if (!(Previous.isOneOf(tok::l_paren, tok::l_brace) ||
 459           Previous.Type == TT_BinaryOperator) ||
 460         (!Style.AllowAllParametersOfDeclarationOnNextLine &&
 461          State.Line->MustBeDeclaration))
 462       State.Stack.back().BreakBeforeParameter = true;
 463   }
 464
 465   return Penalty;
 466 }
 467
 468 unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
 469                                                     bool DryRun, bool Newline) {
 470   const FormatToken &Current = *State.NextToken;
 471   assert(State.Stack.size());
 472
 473   if (Current.Type == TT_InheritanceColon)
 474     State.Stack.back().AvoidBinPacking = true;
 475   if (Current.is(tok::lessless) && State.Stack.back().FirstLessLess == 0)
 476     State.Stack.back().FirstLessLess = State.Column;
 477   if (Current.Type == TT_ArraySubscriptLSquare &&
 478       State.Stack.back().StartOfArraySubscripts == 0)
 479     State.Stack.back().StartOfArraySubscripts = State.Column;
 480   if ((Current.is(tok::question) && Style.BreakBeforeTernaryOperators) ||
 481       (Current.getPreviousNonComment() && Current.isNot(tok::colon) &&
 482        Current.getPreviousNonComment()->is(tok::question) &&
 483        !Style.BreakBeforeTernaryOperators))
 484     State.Stack.back().QuestionColumn = State.Column;
 485   if (!Current.opensScope() && !Current.closesScope())
 486     State.LowestLevelOnLine =
 487         std::min(State.LowestLevelOnLine, State.ParenLevel);
 488   if (Current.isMemberAccess())
 489     State.Stack.back().StartOfFunctionCall =
 490         Current.LastInChainOfCalls ? 0 : State.Column + Current.ColumnWidth;
 491   if (Current.Type == TT_CtorInitializerColon) {
 492     // Indent 2 from the column, so:
 493     // SomeClass::SomeClass()
 494     //     : First(...), ...
 495     //       Next(...)
 496     //       ^ line up here.
 497     State.Stack.back().Indent =
 498         State.Column + (Style.BreakConstructorInitializersBeforeComma ? 0 : 2);
 499     if (Style.ConstructorInitializerAllOnOneLineOrOnePerLine)
 500       State.Stack.back().AvoidBinPacking = true;
 501     State.Stack.back().BreakBeforeParameter = false;
 502   }
 503
 504   // In ObjC method declaration we align on the ":" of parameters, but we need
 505   // to ensure that we indent parameters on subsequent lines by at least our
 506   // continuation indent width.
 507   if (Current.Type == TT_ObjCMethodSpecifier)
 508     State.Stack.back().Indent += Style.ContinuationIndentWidth;
 509
 510   // Insert scopes created by fake parenthesis.
 511   const FormatToken *Previous = Current.getPreviousNonComment();
 512   // Don't add extra indentation for the first fake parenthesis after
 513   // 'return', assignements or opening <({[. The indentation for these cases
 514   // is special cased.
 515   bool SkipFirstExtraIndent =
 516       (Previous && (Previous->opensScope() || Previous->is(tok::kw_return) ||
 517                     Previous->getPrecedence() == prec::Assignment ||
 518                     Previous->Type == TT_ObjCMethodExpr));
 519   for (SmallVectorImpl<prec::Level>::const_reverse_iterator
 520            I = Current.FakeLParens.rbegin(),
 521            E = Current.FakeLParens.rend();
 522        I != E; ++I) {
 523     ParenState NewParenState = State.Stack.back();
 524     NewParenState.ContainsLineBreak = false;
 525
 526     // Indent from 'LastSpace' unless this the fake parentheses encapsulating a
 527     // builder type call after 'return'. If such a call is line-wrapped, we
 528     // commonly just want to indent from the start of the line.
 529     if (!Previous || Previous->isNot(tok::kw_return) || *I > 0)
 530       NewParenState.Indent =
 531           std::max(std::max(State.Column, NewParenState.Indent),
 532                    State.Stack.back().LastSpace);
 533
 534     // Do not indent relative to the fake parentheses inserted for "." or "->".
 535     // This is a special case to make the following to statements consistent:
 536     //   OuterFunction(InnerFunctionCall( // break
 537     //       ParameterToInnerFunction));
 538     //   OuterFunction(SomeObject.InnerFunctionCall( // break
 539     //       ParameterToInnerFunction));
 540     if (*I > prec::Unknown)
 541       NewParenState.LastSpace = std::max(NewParenState.LastSpace, State.Column);
 542
 543     // Always indent conditional expressions. Never indent expression where
 544     // the 'operator' is ',', ';' or an assignment (i.e. *I <=
 545     // prec::Assignment) as those have different indentation rules. Indent
 546     // other expression, unless the indentation needs to be skipped.
 547     if (*I == prec::Conditional ||
 548         (!SkipFirstExtraIndent && *I > prec::Assignment &&
 549          !Style.BreakBeforeBinaryOperators))
 550       NewParenState.Indent += Style.ContinuationIndentWidth;
 551     if ((Previous && !Previous->opensScope()) || *I > prec::Comma)
 552       NewParenState.BreakBeforeParameter = false;
 553     State.Stack.push_back(NewParenState);
 554     SkipFirstExtraIndent = false;
 555   }
 556
 557   // If we encounter an opening (, [, { or <, we add a level to our stacks to
 558   // prepare for the following tokens.
 559   if (Current.opensScope()) {
 560     unsigned NewIndent;
 561     unsigned NewIndentLevel = State.Stack.back().IndentLevel;
 562     bool AvoidBinPacking;
 563     bool BreakBeforeParameter = false;
 564     if (Current.is(tok::l_brace) ||
 565         Current.Type == TT_ArrayInitializerLSquare) {
 566       if (Current.MatchingParen && Current.BlockKind == BK_Block) {
 567         // If this is an l_brace starting a nested block, we pretend (wrt. to
 568         // indentation) that we already consumed the corresponding r_brace.
 569         // Thus, we remove all ParenStates caused bake fake parentheses that end
 570         // at the r_brace. The net effect of this is that we don't indent
 571         // relative to the l_brace, if the nested block is the last parameter of
 572         // a function. For example, this formats:
 573         //
 574         //   SomeFunction(a, [] {
 575         //     f();  // break
 576         //   });
 577         //
 578         // instead of:
 579         //   SomeFunction(a, [] {
 580         //                        f();  // break
 581         //                      });
 582         for (unsigned i = 0; i != Current.MatchingParen->FakeRParens; ++i)
 583           State.Stack.pop_back();
 584         NewIndent = State.Stack.back().LastSpace + Style.IndentWidth;
 585         ++NewIndentLevel;
 586         BreakBeforeParameter = true;
 587       } else {
 588         NewIndent = State.Stack.back().LastSpace;
 589         if (Current.opensBlockTypeList(Style)) {
 590           NewIndent += Style.IndentWidth;
 591           ++NewIndentLevel;
 592         } else {
 593           NewIndent += Style.ContinuationIndentWidth;
 594         }
 595       }
 596       const FormatToken *NextNoComment = Current.getNextNonComment();
 597       AvoidBinPacking = Current.BlockKind == BK_Block ||
 598                         Current.Type == TT_ArrayInitializerLSquare ||
 599                         Current.Type == TT_DictLiteral ||
 600                         (NextNoComment &&
 601                          NextNoComment->Type == TT_DesignatedInitializerPeriod);
 602     } else {
 603       NewIndent = Style.ContinuationIndentWidth +
 604                   std::max(State.Stack.back().LastSpace,
 605                            State.Stack.back().StartOfFunctionCall);
 606       AvoidBinPacking = !Style.BinPackParameters ||
 607                         (Style.ExperimentalAutoDetectBinPacking &&
 608                          (Current.PackingKind == PPK_OnePerLine ||
 609                           (!BinPackInconclusiveFunctions &&
 610                            Current.PackingKind == PPK_Inconclusive)));
 611       // If this '[' opens an ObjC call, determine whether all parameters fit
 612       // into one line and put one per line if they don't.
 613       if (Current.Type == TT_ObjCMethodExpr &&
 614           getLengthToMatchingParen(Current) + State.Column >
 615               getColumnLimit(State))
 616         BreakBeforeParameter = true;
 617     }
 618
 619     bool NoLineBreak = State.Stack.back().NoLineBreak ||
 620                        (Current.Type == TT_TemplateOpener &&
 621                         State.Stack.back().ContainsUnwrappedBuilder);
 622     State.Stack.push_back(ParenState(NewIndent, NewIndentLevel,
 623                                      State.Stack.back().LastSpace,
 624                                      AvoidBinPacking, NoLineBreak));
 625     State.Stack.back().BreakBeforeParameter = BreakBeforeParameter;
 626     ++State.ParenLevel;
 627   }
 628
 629   // If we encounter a closing ), ], } or >, we can remove a level from our
 630   // stacks.
 631   if (State.Stack.size() > 1 &&
 632       (Current.isOneOf(tok::r_paren, tok::r_square) ||
 633        (Current.is(tok::r_brace) && State.NextToken != State.Line->First) ||
 634        State.NextToken->Type == TT_TemplateCloser)) {
 635     State.Stack.pop_back();
 636     --State.ParenLevel;
 637   }
 638   if (Current.is(tok::r_square)) {
 639     // If this ends the array subscript expr, reset the corresponding value.
 640     const FormatToken *NextNonComment = Current.getNextNonComment();
 641     if (NextNonComment && NextNonComment->isNot(tok::l_square))
 642       State.Stack.back().StartOfArraySubscripts = 0;
 643   }
 644
 645   // Remove scopes created by fake parenthesis.
 646   if (Current.isNot(tok::r_brace) ||
 647       (Current.MatchingParen && Current.MatchingParen->BlockKind != BK_Block)) {
 648     // Don't remove FakeRParens attached to r_braces that surround nested blocks
 649     // as they will have been removed early (see above).
 650     for (unsigned i = 0, e = Current.FakeRParens; i != e; ++i) {
 651       unsigned VariablePos = State.Stack.back().VariablePos;
 652       State.Stack.pop_back();
 653       State.Stack.back().VariablePos = VariablePos;
 654     }
 655   }
 656
 657   if (Current.is(tok::string_literal) && State.StartOfStringLiteral == 0) {
 658     State.StartOfStringLiteral = State.Column;
 659   } else if (!Current.isOneOf(tok::comment, tok::identifier, tok::hash,
 660                               tok::string_literal)) {
 661     State.StartOfStringLiteral = 0;
 662   }
 663
 664   State.Column += Current.ColumnWidth;
 665   State.NextToken = State.NextToken->Next;
 666   unsigned Penalty = breakProtrudingToken(Current, State, DryRun);
 667   if (State.Column > getColumnLimit(State)) {
 668     unsigned ExcessCharacters = State.Column - getColumnLimit(State);
 669     Penalty += Style.PenaltyExcessCharacter * ExcessCharacters;
 670   }
 671
 672   // If the previous has a special role, let it consume tokens as appropriate.
 673   // It is necessary to start at the previous token for the only implemented
 674   // role (comma separated list). That way, the decision whether or not to break
 675   // after the "{" is already done and both options are tried and evaluated.
 676   // FIXME: This is ugly, find a better way.
 677   if (Previous && Previous->Role)
 678     Penalty += Previous->Role->format(State, this, DryRun);
 679
 680   return Penalty;
 681 }
 682
 683 unsigned ContinuationIndenter::addMultilineToken(const FormatToken &Current,
 684                                                  LineState &State) {
 685   // Break before further function parameters on all levels.
 686   for (unsigned i = 0, e = State.Stack.size(); i != e; ++i)
 687     State.Stack[i].BreakBeforeParameter = true;
 688
 689   unsigned ColumnsUsed = State.Column;
 690   // We can only affect layout of the first and the last line, so the penalty
 691   // for all other lines is constant, and we ignore it.
 692   State.Column = Current.LastLineColumnWidth;
 693
 694   if (ColumnsUsed > getColumnLimit(State))
 695     return Style.PenaltyExcessCharacter * (ColumnsUsed - getColumnLimit(State));
 696   return 0;
 697 }
 698
 699 static bool getRawStringLiteralPrefixPostfix(StringRef Text,
 700                                              StringRef &Prefix,
 701                                              StringRef &Postfix) {
 702   if (Text.startswith(Prefix = "R\"") || Text.startswith(Prefix = "uR\"") ||
 703       Text.startswith(Prefix = "UR\"") || Text.startswith(Prefix = "u8R\"") ||
 704       Text.startswith(Prefix = "LR\"")) {
 705     size_t ParenPos = Text.find('(');
 706     if (ParenPos != StringRef::npos) {
 707       StringRef Delimiter =
 708           Text.substr(Prefix.size(), ParenPos - Prefix.size());
 709       Prefix = Text.substr(0, ParenPos + 1);
 710       Postfix = Text.substr(Text.size() - 2 - Delimiter.size());
 711       return Postfix.front() == ')' && Postfix.back() == '"' &&
 712              Postfix.substr(1).startswith(Delimiter);
 713     }
 714   }
 715   return false;
 716 }
 717
 718 unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
 719                                                     LineState &State,
 720                                                     bool DryRun) {
 721   // Don't break multi-line tokens other than block comments. Instead, just
 722   // update the state.
 723   if (Current.Type != TT_BlockComment && Current.IsMultiline)
 724     return addMultilineToken(Current, State);
 725
 726   // Don't break implicit string literals.
 727   if (Current.Type == TT_ImplicitStringLiteral)
 728     return 0;
 729
 730   if (!Current.isOneOf(tok::string_literal, tok::wide_string_literal,
 731                        tok::utf8_string_literal, tok::utf16_string_literal,
 732                        tok::utf32_string_literal, tok::comment))
 733     return 0;
 734
 735   llvm::OwningPtr<BreakableToken> Token;
 736   unsigned StartColumn = State.Column - Current.ColumnWidth;
 737   unsigned ColumnLimit = getColumnLimit(State);
 738
 739   if (Current.isOneOf(tok::string_literal, tok::wide_string_literal,
 740                       tok::utf8_string_literal, tok::utf16_string_literal,
 741                       tok::utf32_string_literal) &&
 742       Current.Type != TT_ImplicitStringLiteral) {
 743     // Don't break string literals inside preprocessor directives (except for
 744     // #define directives, as their contents are stored in separate lines and
 745     // are not affected by this check).
 746     // This way we avoid breaking code with line directives and unknown
 747     // preprocessor directives that contain long string literals.
 748     if (State.Line->Type == LT_PreprocessorDirective)
 749       return 0;
 750     // Exempts unterminated string literals from line breaking. The user will
 751     // likely want to terminate the string before any line breaking is done.
 752     if (Current.IsUnterminatedLiteral)
 753       return 0;
 754
 755     StringRef Text = Current.TokenText;
 756     StringRef Prefix;
 757     StringRef Postfix;
 758     // FIXME: Handle whitespace between '_T', '(', '"..."', and ')'.
 759     // FIXME: Store Prefix and Suffix (or PrefixLength and SuffixLength to
 760     // reduce the overhead) for each FormatToken, which is a string, so that we
 761     // don't run multiple checks here on the hot path.
 762     if ((Text.endswith(Postfix = "\"") &&
 763          (Text.startswith(Prefix = "\"") || Text.startswith(Prefix = "u\"") ||
 764           Text.startswith(Prefix = "U\"") || Text.startswith(Prefix = "u8\"") ||
 765           Text.startswith(Prefix = "L\""))) ||
 766         (Text.startswith(Prefix = "_T(\"") && Text.endswith(Postfix = "\")")) ||
 767         getRawStringLiteralPrefixPostfix(Text, Prefix, Postfix)) {
 768       Token.reset(new BreakableStringLiteral(
 769           Current, State.Line->Level, StartColumn, Prefix, Postfix,
 770           State.Line->InPPDirective, Encoding, Style));
 771     } else {
 772       return 0;
 773     }
 774   } else if (Current.Type == TT_BlockComment && Current.isTrailingComment()) {
 775     Token.reset(new BreakableBlockComment(
 776         Current, State.Line->Level, StartColumn, Current.OriginalColumn,
 777         !Current.Previous, State.Line->InPPDirective, Encoding, Style));
 778   } else if (Current.Type == TT_LineComment &&
 779              (Current.Previous == NULL ||
 780               Current.Previous->Type != TT_ImplicitStringLiteral)) {
 781     Token.reset(new BreakableLineComment(Current, State.Line->Level,
 782                                          StartColumn, /*InPPDirective=*/false,
 783                                          Encoding, Style));
 784     // We don't insert backslashes when breaking line comments.
 785     ColumnLimit = Style.ColumnLimit;
 786   } else {
 787     return 0;
 788   }
 789   if (Current.UnbreakableTailLength >= ColumnLimit)
 790     return 0;
 791
 792   unsigned RemainingSpace = ColumnLimit - Current.UnbreakableTailLength;
 793   bool BreakInserted = false;
 794   unsigned Penalty = 0;
 795   unsigned RemainingTokenColumns = 0;
 796   for (unsigned LineIndex = 0, EndIndex = Token->getLineCount();
 797        LineIndex != EndIndex; ++LineIndex) {
 798     if (!DryRun)
 799       Token->replaceWhitespaceBefore(LineIndex, Whitespaces);
 800     unsigned TailOffset = 0;
 801     RemainingTokenColumns =
 802         Token->getLineLengthAfterSplit(LineIndex, TailOffset, StringRef::npos);
 803     while (RemainingTokenColumns > RemainingSpace) {
 804       BreakableToken::Split Split =
 805           Token->getSplit(LineIndex, TailOffset, ColumnLimit);
 806       if (Split.first == StringRef::npos) {
 807         // The last line's penalty is handled in addNextStateToQueue().
 808         if (LineIndex < EndIndex - 1)
 809           Penalty += Style.PenaltyExcessCharacter *
 810                      (RemainingTokenColumns - RemainingSpace);
 811         break;
 812       }
 813       assert(Split.first != 0);
 814       unsigned NewRemainingTokenColumns = Token->getLineLengthAfterSplit(
 815           LineIndex, TailOffset + Split.first + Split.second, StringRef::npos);
 816
 817       // We can remove extra whitespace instead of breaking the line.
 818       if (RemainingTokenColumns + 1 - Split.second <= RemainingSpace) {
 819         RemainingTokenColumns = 0;
 820         if (!DryRun)
 821           Token->replaceWhitespace(LineIndex, TailOffset, Split, Whitespaces);
 822         break;
 823       }
 824
 825       assert(NewRemainingTokenColumns < RemainingTokenColumns);
 826       if (!DryRun)
 827         Token->insertBreak(LineIndex, TailOffset, Split, Whitespaces);
 828       Penalty += Current.SplitPenalty;
 829       unsigned ColumnsUsed =
 830           Token->getLineLengthAfterSplit(LineIndex, TailOffset, Split.first);
 831       if (ColumnsUsed > ColumnLimit) {
 832         Penalty += Style.PenaltyExcessCharacter * (ColumnsUsed - ColumnLimit);
 833       }
 834       TailOffset += Split.first + Split.second;
 835       RemainingTokenColumns = NewRemainingTokenColumns;
 836       BreakInserted = true;
 837     }
 838   }
 839
 840   State.Column = RemainingTokenColumns;
 841
 842   if (BreakInserted) {
 843     // If we break the token inside a parameter list, we need to break before
 844     // the next parameter on all levels, so that the next parameter is clearly
 845     // visible. Line comments already introduce a break.
 846     if (Current.Type != TT_LineComment) {
 847       for (unsigned i = 0, e = State.Stack.size(); i != e; ++i)
 848         State.Stack[i].BreakBeforeParameter = true;
 849     }
 850
 851     Penalty += Current.is(tok::string_literal) ? Style.PenaltyBreakString
 852                                                : Style.PenaltyBreakComment;
 853
 854     State.Stack.back().LastSpace = StartColumn;
 855   }
 856   return Penalty;
 857 }
 858
 859 unsigned ContinuationIndenter::getColumnLimit(const LineState &State) const {
 860   // In preprocessor directives reserve two chars for trailing " \"
 861   return Style.ColumnLimit - (State.Line->InPPDirective ? 2 : 0);
 862 }
 863
 864 bool ContinuationIndenter::NextIsMultilineString(const LineState &State) {
 865   const FormatToken &Current = *State.NextToken;
 866   if (!Current.is(tok::string_literal))
 867     return false;
 868   // We never consider raw string literals "multiline" for the purpose of
 869   // AlwaysBreakBeforeMultilineStrings implementation.
 870   if (Current.TokenText.startswith("R\""))
 871     return false;
 872   if (Current.IsMultiline)
 873     return true;
 874   if (Current.getNextNonComment() &&
 875       Current.getNextNonComment()->is(tok::string_literal))
 876     return true; // Implicit concatenation.
 877   if (State.Column + Current.ColumnWidth + Current.UnbreakableTailLength >
 878       Style.ColumnLimit)
 879     return true; // String will be split.
 880   return false;
 881 }
 882
 883 } // namespace format
 884 } // namespace clang