1 files changed, 592 insertions, 349 deletions
diff --git a/lib/Format/UnwrappedLineFormatter.cpp b/lib/Format/UnwrappedLineFormatter.cpp
index ca66e73..cbf8c6c 100644
--- a/lib/Format/UnwrappedLineFormatter.cpp
+++ b/lib/Format/UnwrappedLineFormatter.cpp
@@ -25,19 +25,152 @@ bool startsExternCBlock(const AnnotatedLine &Line) {
          NextNext && NextNext->is(tok::l_brace);
 }
 
+/// \brief Tracks the indent level of \c AnnotatedLines across levels.
+///
+/// \c nextLine must be called for each \c AnnotatedLine, after which \c
+/// getIndent() will return the indent for the last line \c nextLine was called
+/// with.
+/// If the line is not formatted (and thus the indent does not change), calling
+/// \c adjustToUnmodifiedLine after the call to \c nextLine will cause
+/// subsequent lines on the same level to be indented at the same level as the
+/// given line.
+class LevelIndentTracker {
+public:
+  LevelIndentTracker(const FormatStyle &Style,
+                     const AdditionalKeywords &Keywords, unsigned StartLevel,
+                     int AdditionalIndent)
+      : Style(Style), Keywords(Keywords), AdditionalIndent(AdditionalIndent) {
+    for (unsigned i = 0; i != StartLevel; ++i)
+      IndentForLevel.push_back(Style.IndentWidth * i + AdditionalIndent);
+  }
+
+  /// \brief Returns the indent for the current line.
+  unsigned getIndent() const { return Indent; }
+
+  /// \brief Update the indent state given that \p Line is going to be formatted
+  /// next.
+  void nextLine(const AnnotatedLine &Line) {
+    Offset = getIndentOffset(*Line.First);
+    if (Line.InPPDirective) {
+      Indent = Line.Level * Style.IndentWidth + AdditionalIndent;
+    } else {
+      while (IndentForLevel.size() <= Line.Level)
+        IndentForLevel.push_back(-1);
+      IndentForLevel.resize(Line.Level + 1);
+      Indent = getIndent(IndentForLevel, Line.Level);
+    }
+    if (static_cast<int>(Indent) + Offset >= 0)
+      Indent += Offset;
+  }
+
+  /// \brief Update the level indent to adapt to the given \p Line.
+  ///
+  /// When a line is not formatted, we move the subsequent lines on the same
+  /// level to the same indent.
+  /// Note that \c nextLine must have been called before this method.
+  void adjustToUnmodifiedLine(const AnnotatedLine &Line) {
+    unsigned LevelIndent = Line.First->OriginalColumn;
+    if (static_cast<int>(LevelIndent) - Offset >= 0)
+      LevelIndent -= Offset;
+    if ((Line.First->isNot(tok::comment) || IndentForLevel[Line.Level] == -1) &&
+        !Line.InPPDirective)
+      IndentForLevel[Line.Level] = LevelIndent;
+  }
+
+private:
+  /// \brief Get the offset of the line relatively to the level.
+  ///
+  /// For example, 'public:' labels in classes are offset by 1 or 2
+  /// characters to the left from their level.
+  int getIndentOffset(const FormatToken &RootToken) {
+    if (Style.Language == FormatStyle::LK_Java ||
+        Style.Language == FormatStyle::LK_JavaScript)
+      return 0;
+    if (RootToken.isAccessSpecifier(false) ||
+        RootToken.isObjCAccessSpecifier() ||
+        (RootToken.is(Keywords.kw_signals) && RootToken.Next &&
+         RootToken.Next->is(tok::colon)))
+      return Style.AccessModifierOffset;
+    return 0;
+  }
+
+  /// \brief Get the indent of \p Level from \p IndentForLevel.
+  ///
+  /// \p IndentForLevel must contain the indent for the level \c l
+  /// at \p IndentForLevel[l], or a value < 0 if the indent for
+  /// that level is unknown.
+  unsigned getIndent(ArrayRef<int> IndentForLevel, unsigned Level) {
+    if (IndentForLevel[Level] != -1)
+      return IndentForLevel[Level];
+    if (Level == 0)
+      return 0;
+    return getIndent(IndentForLevel, Level - 1) + Style.IndentWidth;
+  }
+
+  const FormatStyle &Style;
+  const AdditionalKeywords &Keywords;
+  const unsigned AdditionalIndent;
+
+  /// \brief The indent in characters for each level.
+  std::vector<int> IndentForLevel;
+
+  /// \brief Offset of the current line relative to the indent level.
+  ///
+  /// For example, the 'public' keywords is often indented with a negative
+  /// offset.
+  int Offset = 0;
+
+  /// \brief The current line's indent.
+  unsigned Indent = 0;
+};
+
 class LineJoiner {
 public:
-  LineJoiner(const FormatStyle &Style) : Style(Style) {}
+  LineJoiner(const FormatStyle &Style, const AdditionalKeywords &Keywords,
+             const SmallVectorImpl<AnnotatedLine *> &Lines)
+      : Style(Style), Keywords(Keywords), End(Lines.end()),
+        Next(Lines.begin()) {}
+
+  /// \brief Returns the next line, merging multiple lines into one if possible.
+  const AnnotatedLine *getNextMergedLine(bool DryRun,
+                                         LevelIndentTracker &IndentTracker) {
+    if (Next == End)
+      return nullptr;
+    const AnnotatedLine *Current = *Next;
+    IndentTracker.nextLine(*Current);
+    unsigned MergedLines =
+        tryFitMultipleLinesInOne(IndentTracker.getIndent(), Next, End);
+    if (MergedLines > 0 && Style.ColumnLimit == 0)
+      // Disallow line merging if there is a break at the start of one of the
+      // input lines.
+      for (unsigned i = 0; i < MergedLines; ++i)
+        if (Next[i + 1]->First->NewlinesBefore > 0)
+          MergedLines = 0;
+    if (!DryRun)
+      for (unsigned i = 0; i < MergedLines; ++i)
+        join(*Next[i], *Next[i + 1]);
+    Next = Next + MergedLines + 1;
+    return Current;
+  }
 
+private:
   /// \brief Calculates how many lines can be merged into 1 starting at \p I.
   unsigned
   tryFitMultipleLinesInOne(unsigned Indent,
                            SmallVectorImpl<AnnotatedLine *>::const_iterator I,
                            SmallVectorImpl<AnnotatedLine *>::const_iterator E) {
+    // Can't join the last line with anything.
+    if (I + 1 == E)
+      return 0;
     // We can never merge stuff if there are trailing line comments.
     const AnnotatedLine *TheLine = *I;
     if (TheLine->Last->is(TT_LineComment))
       return 0;
+    if (I[1]->Type == LT_Invalid || I[1]->First->MustBreakBefore)
+      return 0;
+    if (TheLine->InPPDirective &&
+        (!I[1]->InPPDirective || I[1]->First->HasUnescapedNewline))
+      return 0;
 
     if (Style.ColumnLimit > 0 && Indent > Style.ColumnLimit)
       return 0;
@@ -50,9 +183,6 @@ public:
                 ? 0
                 : Limit - TheLine->Last->TotalLength;
 
-    if (I + 1 == E || I[1]->Type == LT_Invalid || I[1]->First->MustBreakBefore)
-      return 0;
-
     // FIXME: TheLine->Level != 0 might or might not be the right check to do.
     // If necessary, change to something smarter.
     bool MergeShortFunctions =
@@ -113,15 +243,12 @@ public:
     return 0;
   }
 
-private:
   unsigned
   tryMergeSimplePPDirective(SmallVectorImpl<AnnotatedLine *>::const_iterator I,
                             SmallVectorImpl<AnnotatedLine *>::const_iterator E,
                             unsigned Limit) {
     if (Limit == 0)
       return 0;
-    if (!I[1]->InPPDirective || I[1]->First->HasUnescapedNewline)
-      return 0;
     if (I + 2 != E && I[2]->InPPDirective && !I[2]->First->HasUnescapedNewline)
       return 0;
     if (1 + I[1]->Last->TotalLength > Limit)
@@ -147,8 +274,8 @@ private:
       return 0;
     if (1 + I[1]->Last->TotalLength > Limit)
       return 0;
-    if (I[1]->First->isOneOf(tok::semi, tok::kw_if, tok::kw_for,
-                             tok::kw_while, TT_LineComment))
+    if (I[1]->First->isOneOf(tok::semi, tok::kw_if, tok::kw_for, tok::kw_while,
+                             TT_LineComment))
       return 0;
     // Only inline simple if's (no nested if or else).
     if (I + 2 != E && Line.First->is(tok::kw_if) &&
@@ -157,9 +284,10 @@ private:
     return 1;
   }
 
-  unsigned tryMergeShortCaseLabels(
-      SmallVectorImpl<AnnotatedLine *>::const_iterator I,
-      SmallVectorImpl<AnnotatedLine *>::const_iterator E, unsigned Limit) {
+  unsigned
+  tryMergeShortCaseLabels(SmallVectorImpl<AnnotatedLine *>::const_iterator I,
+                          SmallVectorImpl<AnnotatedLine *>::const_iterator E,
+                          unsigned Limit) {
     if (Limit == 0 || I + 1 == E ||
         I[1]->First->isOneOf(tok::kw_case, tok::kw_default))
       return 0;
@@ -191,16 +319,21 @@ private:
     AnnotatedLine &Line = **I;
 
     // Don't merge ObjC @ keywords and methods.
+    // FIXME: If an option to allow short exception handling clauses on a single
+    // line is added, change this to not return for @try and friends.
     if (Style.Language != FormatStyle::LK_Java &&
         Line.First->isOneOf(tok::at, tok::minus, tok::plus))
       return 0;
 
     // Check that the current line allows merging. This depends on whether we
     // are in a control flow statements as well as several style flags.
-    if (Line.First->isOneOf(tok::kw_else, tok::kw_case))
+    if (Line.First->isOneOf(tok::kw_else, tok::kw_case) ||
+        (Line.First->Next && Line.First->Next->is(tok::kw_else)))
       return 0;
     if (Line.First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_do, tok::kw_try,
-                            tok::kw_catch, tok::kw_for, tok::r_brace)) {
+                            tok::kw___try, tok::kw_catch, tok::kw___finally,
+                            tok::kw_for, tok::r_brace) ||
+        Line.First->is(Keywords.kw___except)) {
       if (!Style.AllowShortBlocksOnASingleLine)
         return 0;
       if (!Style.AllowShortIfStatementsOnASingleLine &&
@@ -211,7 +344,11 @@ private:
         return 0;
       // FIXME: Consider an option to allow short exception handling clauses on
       // a single line.
-      if (Line.First->isOneOf(tok::kw_try, tok::kw_catch))
+      // FIXME: This isn't covered by tests.
+      // FIXME: For catch, __except, __finally the first token on the line
+      // is '}', so this isn't correct here.
+      if (Line.First->isOneOf(tok::kw_try, tok::kw___try, tok::kw_catch,
+                              Keywords.kw___except, tok::kw___finally))
         return 0;
     }
 
@@ -226,7 +363,8 @@ private:
     } else if (Limit != 0 && Line.First->isNot(tok::kw_namespace) &&
                !startsExternCBlock(Line)) {
       // We don't merge short records.
-      if (Line.First->isOneOf(tok::kw_class, tok::kw_union, tok::kw_struct))
+      if (Line.First->isOneOf(tok::kw_class, tok::kw_union, tok::kw_struct,
+                              Keywords.kw_interface))
         return 0;
 
       // Check that we still have three lines and they fit into the limit.
@@ -252,6 +390,10 @@ private:
       if (Tok->isNot(tok::r_brace))
         return 0;
 
+      // Don't merge "if (a) { .. } else {".
+      if (Tok->Next && Tok->Next->is(tok::kw_else))
+        return 0;
+
       return 2;
     }
     return 0;
@@ -285,28 +427,367 @@ private:
     return false;
   }
 
+  void join(AnnotatedLine &A, const AnnotatedLine &B) {
+    assert(!A.Last->Next);
+    assert(!B.First->Previous);
+    if (B.Affected)
+      A.Affected = true;
+    A.Last->Next = B.First;
+    B.First->Previous = A.Last;
+    B.First->CanBreakBefore = true;
+    unsigned LengthA = A.Last->TotalLength + B.First->SpacesRequiredBefore;
+    for (FormatToken *Tok = B.First; Tok; Tok = Tok->Next) {
+      Tok->TotalLength += LengthA;
+      A.Last = Tok;
+    }
+  }
+
   const FormatStyle &Style;
+  const AdditionalKeywords &Keywords;
+  const SmallVectorImpl<AnnotatedLine*>::const_iterator End;
+
+  SmallVectorImpl<AnnotatedLine*>::const_iterator Next;
 };
 
-class NoColumnLimitFormatter {
+static void markFinalized(FormatToken *Tok) {
+  for (; Tok; Tok = Tok->Next) {
+    Tok->Finalized = true;
+    for (AnnotatedLine *Child : Tok->Children)
+      markFinalized(Child->First);
+  }
+}
+
+#ifndef NDEBUG
+static void printLineState(const LineState &State) {
+  llvm::dbgs() << "State: ";
+  for (const ParenState &P : State.Stack) {
+    llvm::dbgs() << P.Indent << "|" << P.LastSpace << "|" << P.NestedBlockIndent
+                 << " ";
+  }
+  llvm::dbgs() << State.NextToken->TokenText << "\n";
+}
+#endif
+
+/// \brief Base class for classes that format one \c AnnotatedLine.
+class LineFormatter {
 public:
-  NoColumnLimitFormatter(ContinuationIndenter *Indenter) : Indenter(Indenter) {}
+  LineFormatter(ContinuationIndenter *Indenter, WhitespaceManager *Whitespaces,
+                const FormatStyle &Style,
+                UnwrappedLineFormatter *BlockFormatter)
+      : Indenter(Indenter), Whitespaces(Whitespaces), Style(Style),
+        BlockFormatter(BlockFormatter) {}
+  virtual ~LineFormatter() {}
+
+  /// \brief Formats an \c AnnotatedLine and returns the penalty.
+  ///
+  /// If \p DryRun is \c false, directly applies the changes.
+  virtual unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
+                              bool DryRun) = 0;
+
+protected:
+  /// \brief If the \p State's next token is an r_brace closing a nested block,
+  /// format the nested block before it.
+  ///
+  /// Returns \c true if all children could be placed successfully and adapts
+  /// \p Penalty as well as \p State. If \p DryRun is false, also directly
+  /// creates changes using \c Whitespaces.
+  ///
+  /// The crucial idea here is that children always get formatted upon
+  /// encountering the closing brace right after the nested block. Now, if we
+  /// are currently trying to keep the "}" on the same line (i.e. \p NewLine is
+  /// \c false), the entire block has to be kept on the same line (which is only
+  /// possible if it fits on the line, only contains a single statement, etc.
+  ///
+  /// If \p NewLine is true, we format the nested block on separate lines, i.e.
+  /// break after the "{", format all lines with correct indentation and the put
+  /// the closing "}" on yet another new line.
+  ///
+  /// This enables us to keep the simple structure of the
+  /// \c UnwrappedLineFormatter, where we only have two options for each token:
+  /// break or don't break.
+  bool formatChildren(LineState &State, bool NewLine, bool DryRun,
+                      unsigned &Penalty) {
+    const FormatToken *LBrace = State.NextToken->getPreviousNonComment();
+    FormatToken &Previous = *State.NextToken->Previous;
+    if (!LBrace || LBrace->isNot(tok::l_brace) ||
+        LBrace->BlockKind != BK_Block || Previous.Children.size() == 0)
+      // The previous token does not open a block. Nothing to do. We don't
+      // assert so that we can simply call this function for all tokens.
+      return true;
+
+    if (NewLine) {
+      int AdditionalIndent = State.Stack.back().Indent -
+                             Previous.Children[0]->Level * Style.IndentWidth;
+
+      Penalty +=
+          BlockFormatter->format(Previous.Children, DryRun, AdditionalIndent,
+                                 /*FixBadIndentation=*/true);
+      return true;
+    }
+
+    if (Previous.Children[0]->First->MustBreakBefore)
+      return false;
+
+    // Cannot merge multiple statements into a single line.
+    if (Previous.Children.size() > 1)
+      return false;
+
+    // Cannot merge into one line if this line ends on a comment.
+    if (Previous.is(tok::comment))
+      return false;
+
+    // We can't put the closing "}" on a line with a trailing comment.
+    if (Previous.Children[0]->Last->isTrailingComment())
+      return false;
+
+    // If the child line exceeds the column limit, we wouldn't want to merge it.
+    // We add +2 for the trailing " }".
+    if (Style.ColumnLimit > 0 &&
+        Previous.Children[0]->Last->TotalLength + State.Column + 2 >
+            Style.ColumnLimit)
+      return false;
+
+    if (!DryRun) {
+      Whitespaces->replaceWhitespace(
+          *Previous.Children[0]->First,
+          /*Newlines=*/0, /*IndentLevel=*/0, /*Spaces=*/1,
+          /*StartOfTokenColumn=*/State.Column, State.Line->InPPDirective);
+    }
+    Penalty += formatLine(*Previous.Children[0], State.Column + 1, DryRun);
+
+    State.Column += 1 + Previous.Children[0]->Last->TotalLength;
+    return true;
+  }
+
+  ContinuationIndenter *Indenter;
+
+private:
+  WhitespaceManager *Whitespaces;
+  const FormatStyle &Style;
+  UnwrappedLineFormatter *BlockFormatter;
+};
 
-  /// \brief Formats the line starting at \p State, simply keeping all of the
-  /// input's line breaking decisions.
-  void format(unsigned FirstIndent, const AnnotatedLine *Line) {
+/// \brief Formatter that keeps the existing line breaks.
+class NoColumnLimitLineFormatter : public LineFormatter {
+public:
+  NoColumnLimitLineFormatter(ContinuationIndenter *Indenter,
+                             WhitespaceManager *Whitespaces,
+                             const FormatStyle &Style,
+                             UnwrappedLineFormatter *BlockFormatter)
+      : LineFormatter(Indenter, Whitespaces, Style, BlockFormatter) {}
+
+  /// \brief Formats the line, simply keeping all of the input's line breaking
+  /// decisions.
+  unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
+                      bool DryRun) override {
+    assert(!DryRun);
     LineState State =
-        Indenter->getInitialState(FirstIndent, Line, /*DryRun=*/false);
+        Indenter->getInitialState(FirstIndent, &Line, /*DryRun=*/false);
     while (State.NextToken) {
       bool Newline =
           Indenter->mustBreak(State) ||
           (Indenter->canBreak(State) && State.NextToken->NewlinesBefore > 0);
+      unsigned Penalty = 0;
+      formatChildren(State, Newline, /*DryRun=*/false, Penalty);
       Indenter->addTokenToState(State, Newline, /*DryRun=*/false);
     }
+    return 0;
+  }
+};
+
+/// \brief Formatter that puts all tokens into a single line without breaks.
+class NoLineBreakFormatter : public LineFormatter {
+public:
+  NoLineBreakFormatter(ContinuationIndenter *Indenter,
+                       WhitespaceManager *Whitespaces, const FormatStyle &Style,
+                       UnwrappedLineFormatter *BlockFormatter)
+      : LineFormatter(Indenter, Whitespaces, Style, BlockFormatter) {}
+
+  /// \brief Puts all tokens into a single line.
+  unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
+                      bool DryRun) {
+    unsigned Penalty = 0;
+    LineState State = Indenter->getInitialState(FirstIndent, &Line, DryRun);
+    while (State.NextToken) {
+      formatChildren(State, /*Newline=*/false, DryRun, Penalty);
+      Indenter->addTokenToState(State, /*Newline=*/false, DryRun);
+    }
+    return Penalty;
+  }
+};
+
+/// \brief Finds the best way to break lines.
+class OptimizingLineFormatter : public LineFormatter {
+public:
+  OptimizingLineFormatter(ContinuationIndenter *Indenter,
+                          WhitespaceManager *Whitespaces,
+                          const FormatStyle &Style,
+                          UnwrappedLineFormatter *BlockFormatter)
+      : LineFormatter(Indenter, Whitespaces, Style, BlockFormatter) {}
+
+  /// \brief Formats the line by finding the best line breaks with line lengths
+  /// below the column limit.
+  unsigned formatLine(const AnnotatedLine &Line, unsigned FirstIndent,
+                      bool DryRun) {
+    LineState State = Indenter->getInitialState(FirstIndent, &Line, DryRun);
+
+    // If the ObjC method declaration does not fit on a line, we should format
+    // it with one arg per line.
+    if (State.Line->Type == LT_ObjCMethodDecl)
+      State.Stack.back().BreakBeforeParameter = true;
+
+    // Find best solution in solution space.
+    return analyzeSolutionSpace(State, DryRun);
   }
 
 private:
-  ContinuationIndenter *Indenter;
+  struct CompareLineStatePointers {
+    bool operator()(LineState *obj1, LineState *obj2) const {
+      return *obj1 < *obj2;
+    }
+  };
+
+  /// \brief A pair of <penalty, count> that is used to prioritize the BFS on.
+  ///
+  /// In case of equal penalties, we want to prefer states that were inserted
+  /// first. During state generation we make sure that we insert states first
+  /// that break the line as late as possible.
+  typedef std::pair<unsigned, unsigned> OrderedPenalty;
+
+  /// \brief An edge in the solution space from \c Previous->State to \c State,
+  /// inserting a newline dependent on the \c NewLine.
+  struct StateNode {
+    StateNode(const LineState &State, bool NewLine, StateNode *Previous)
+        : State(State), NewLine(NewLine), Previous(Previous) {}
+    LineState State;
+    bool NewLine;
+    StateNode *Previous;
+  };
+
+  /// \brief An item in the prioritized BFS search queue. The \c StateNode's
+  /// \c State has the given \c OrderedPenalty.
+  typedef std::pair<OrderedPenalty, StateNode *> QueueItem;
+
+  /// \brief The BFS queue type.
+  typedef std::priority_queue<QueueItem, std::vector<QueueItem>,
+                              std::greater<QueueItem>> QueueType;
+
+  /// \brief Analyze the entire solution space starting from \p InitialState.
+  ///
+  /// This implements a variant of Dijkstra's algorithm on the graph that spans
+  /// the solution space (\c LineStates are the nodes). The algorithm tries to
+  /// find the shortest path (the one with lowest penalty) from \p InitialState
+  /// to a state where all tokens are placed. Returns the penalty.
+  ///
+  /// If \p DryRun is \c false, directly applies the changes.
+  unsigned analyzeSolutionSpace(LineState &InitialState, bool DryRun) {
+    std::set<LineState *, CompareLineStatePointers> Seen;
+
+    // Increasing count of \c StateNode items we have created. This is used to
+    // create a deterministic order independent of the container.
+    unsigned Count = 0;
+    QueueType Queue;
+
+    // Insert start element into queue.
+    StateNode *Node =
+        new (Allocator.Allocate()) StateNode(InitialState, false, nullptr);
+    Queue.push(QueueItem(OrderedPenalty(0, Count), Node));
+    ++Count;
+
+    unsigned Penalty = 0;
+
+    // While not empty, take first element and follow edges.
+    while (!Queue.empty()) {
+      Penalty = Queue.top().first.first;
+      StateNode *Node = Queue.top().second;
+      if (!Node->State.NextToken) {
+        DEBUG(llvm::dbgs() << "\n---\nPenalty for line: " << Penalty << "\n");
+        break;
+      }
+      Queue.pop();
+
+      // Cut off the analysis of certain solutions if the analysis gets too
+      // complex. See description of IgnoreStackForComparison.
+      if (Count > 10000)
+        Node->State.IgnoreStackForComparison = true;
+
+      if (!Seen.insert(&Node->State).second)
+        // State already examined with lower penalty.
+        continue;
+
+      FormatDecision LastFormat = Node->State.NextToken->Decision;
+      if (LastFormat == FD_Unformatted || LastFormat == FD_Continue)
+        addNextStateToQueue(Penalty, Node, /*NewLine=*/false, &Count, &Queue);
+      if (LastFormat == FD_Unformatted || LastFormat == FD_Break)
+        addNextStateToQueue(Penalty, Node, /*NewLine=*/true, &Count, &Queue);
+    }
+
+    if (Queue.empty()) {
+      // We were unable to find a solution, do nothing.
+      // FIXME: Add diagnostic?
+      DEBUG(llvm::dbgs() << "Could not find a solution.\n");
+      return 0;
+    }
+
+    // Reconstruct the solution.
+    if (!DryRun)
+      reconstructPath(InitialState, Queue.top().second);
+
+    DEBUG(llvm::dbgs() << "Total number of analyzed states: " << Count << "\n");
+    DEBUG(llvm::dbgs() << "---\n");
+
+    return Penalty;
+  }
+
+  /// \brief Add the following state to the analysis queue \c Queue.
+  ///
+  /// Assume the current state is \p PreviousNode and has been reached with a
+  /// penalty of \p Penalty. Insert a line break if \p NewLine is \c true.
+  void addNextStateToQueue(unsigned Penalty, StateNode *PreviousNode,
+                           bool NewLine, unsigned *Count, QueueType *Queue) {
+    if (NewLine && !Indenter->canBreak(PreviousNode->State))
+      return;
+    if (!NewLine && Indenter->mustBreak(PreviousNode->State))
+      return;
+
+    StateNode *Node = new (Allocator.Allocate())
+        StateNode(PreviousNode->State, NewLine, PreviousNode);
+    if (!formatChildren(Node->State, NewLine, /*DryRun=*/true, Penalty))
+      return;
+
+    Penalty += Indenter->addTokenToState(Node->State, NewLine, true);
+
+    Queue->push(QueueItem(OrderedPenalty(Penalty, *Count), Node));
+    ++(*Count);
+  }
+
+  /// \brief Applies the best formatting by reconstructing the path in the
+  /// solution space that leads to \c Best.
+  void reconstructPath(LineState &State, StateNode *Best) {
+    std::deque<StateNode *> Path;
+    // We do not need a break before the initial token.
+    while (Best->Previous) {
+      Path.push_front(Best);
+      Best = Best->Previous;
+    }
+    for (std::deque<StateNode *>::iterator I = Path.begin(), E = Path.end();
+         I != E; ++I) {
+      unsigned Penalty = 0;
+      formatChildren(State, (*I)->NewLine, /*DryRun=*/false, Penalty);
+      Penalty += Indenter->addTokenToState(State, (*I)->NewLine, false);
+
+      DEBUG({
+        printLineState((*I)->Previous->State);
+        if ((*I)->NewLine) {
+          llvm::dbgs() << "Penalty for placing "
+                       << (*I)->Previous->State.NextToken->Tok.getName() << ": "
+                       << Penalty << "\n";
+        }
+      });
+    }
+  }
+
+  llvm::SpecificBumpPtrAllocator<StateNode> Allocator;
 };
 
 } // namespace
@@ -315,7 +796,7 @@ unsigned
 UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
                                bool DryRun, int AdditionalIndent,
                                bool FixBadIndentation) {
-  LineJoiner Joiner(Style);
+  LineJoiner Joiner(Style, Keywords, Lines);
 
   // Try to look up already computed penalty in DryRun-mode.
   std::pair<const SmallVectorImpl<AnnotatedLine *> *, unsigned> CacheKey(
@@ -326,151 +807,93 @@ UnwrappedLineFormatter::format(const SmallVectorImpl<AnnotatedLine *> &Lines,
 
   assert(!Lines.empty());
   unsigned Penalty = 0;
-  std::vector<int> IndentForLevel;
-  for (unsigned i = 0, e = Lines[0]->Level; i != e; ++i)
-    IndentForLevel.push_back(Style.IndentWidth * i + AdditionalIndent);
+  LevelIndentTracker IndentTracker(Style, Keywords, Lines[0]->Level,
+                                   AdditionalIndent);
   const AnnotatedLine *PreviousLine = nullptr;
-  for (SmallVectorImpl<AnnotatedLine *>::const_iterator I = Lines.begin(),
-                                                        E = Lines.end();
-       I != E; ++I) {
-    const AnnotatedLine &TheLine = **I;
-    const FormatToken *FirstTok = TheLine.First;
-    int Offset = getIndentOffset(*FirstTok);
-
-    // Determine indent and try to merge multiple unwrapped lines.
-    unsigned Indent;
-    if (TheLine.InPPDirective) {
-      Indent = TheLine.Level * Style.IndentWidth;
-    } else {
-      while (IndentForLevel.size() <= TheLine.Level)
-        IndentForLevel.push_back(-1);
-      IndentForLevel.resize(TheLine.Level + 1);
-      Indent = getIndent(IndentForLevel, TheLine.Level);
-    }
-    unsigned LevelIndent = Indent;
-    if (static_cast<int>(Indent) + Offset >= 0)
-      Indent += Offset;
-
-    // Merge multiple lines if possible.
-    unsigned MergedLines = Joiner.tryFitMultipleLinesInOne(Indent, I, E);
-    if (MergedLines > 0 && Style.ColumnLimit == 0) {
-      // Disallow line merging if there is a break at the start of one of the
-      // input lines.
-      for (unsigned i = 0; i < MergedLines; ++i) {
-        if (I[i + 1]->First->NewlinesBefore > 0)
-          MergedLines = 0;
-      }
-    }
-    if (!DryRun) {
-      for (unsigned i = 0; i < MergedLines; ++i) {
-        join(*I[i], *I[i + 1]);
-      }
-    }
-    I += MergedLines;
-
+  const AnnotatedLine *NextLine = nullptr;
+  for (const AnnotatedLine *Line =
+           Joiner.getNextMergedLine(DryRun, IndentTracker);
+       Line; Line = NextLine) {
+    const AnnotatedLine &TheLine = *Line;
+    unsigned Indent = IndentTracker.getIndent();
     bool FixIndentation =
-        FixBadIndentation && (LevelIndent != FirstTok->OriginalColumn);
-    if (TheLine.First->is(tok::eof)) {
-      if (PreviousLine && PreviousLine->Affected && !DryRun) {
-        // Remove the file's trailing whitespace.
-        unsigned Newlines = std::min(FirstTok->NewlinesBefore, 1u);
-        Whitespaces->replaceWhitespace(*TheLine.First, Newlines,
-                                       /*IndentLevel=*/0, /*Spaces=*/0,
-                                       /*TargetColumn=*/0);
-      }
-    } else if (TheLine.Type != LT_Invalid &&
-               (TheLine.Affected || FixIndentation)) {
-      if (FirstTok->WhitespaceRange.isValid()) {
-        if (!DryRun)
-          formatFirstToken(*TheLine.First, PreviousLine, TheLine.Level, Indent,
+        FixBadIndentation && (Indent != TheLine.First->OriginalColumn);
+    bool ShouldFormat = TheLine.Affected || FixIndentation;
+    // We cannot format this line; if the reason is that the line had a
+    // parsing error, remember that.
+    if (ShouldFormat && TheLine.Type == LT_Invalid && IncompleteFormat)
+      *IncompleteFormat = true;
+
+    if (ShouldFormat && TheLine.Type != LT_Invalid) {
+      if (!DryRun)
+        formatFirstToken(*TheLine.First, PreviousLine, TheLine.Level, Indent,
+                         TheLine.InPPDirective);
+
+      NextLine = Joiner.getNextMergedLine(DryRun, IndentTracker);
+      unsigned ColumnLimit = getColumnLimit(TheLine.InPPDirective, NextLine);
+      bool FitsIntoOneLine =
+          TheLine.Last->TotalLength + Indent <= ColumnLimit ||
+          TheLine.Type == LT_ImportStatement;
+
+      if (Style.ColumnLimit == 0)
+        NoColumnLimitLineFormatter(Indenter, Whitespaces, Style, this)
+            .formatLine(TheLine, Indent, DryRun);
+      else if (FitsIntoOneLine)
+        Penalty += NoLineBreakFormatter(Indenter, Whitespaces, Style, this)
+                       .formatLine(TheLine, Indent, DryRun);
+      else
+        Penalty += OptimizingLineFormatter(Indenter, Whitespaces, Style, this)
+                       .formatLine(TheLine, Indent, DryRun);
+    } else {
+      // If no token in the current line is affected, we still need to format
+      // affected children.
+      if (TheLine.ChildrenAffected)
+        format(TheLine.Children, DryRun);
+
+      // Adapt following lines on the current indent level to the same level
+      // unless the current \c AnnotatedLine is not at the beginning of a line.
+      bool StartsNewLine =
+          TheLine.First->NewlinesBefore > 0 || TheLine.First->IsFirst;
+      if (StartsNewLine)
+        IndentTracker.adjustToUnmodifiedLine(TheLine);
+      if (!DryRun) {
+        bool ReformatLeadingWhitespace =
+            StartsNewLine && ((PreviousLine && PreviousLine->Affected) ||
+                              TheLine.LeadingEmptyLinesAffected);
+        // Format the first token.
+        if (ReformatLeadingWhitespace)
+          formatFirstToken(*TheLine.First, PreviousLine, TheLine.Level,
+                           TheLine.First->OriginalColumn,
                            TheLine.InPPDirective);
-      } else {
-        Indent = LevelIndent = FirstTok->OriginalColumn;
-      }
-
-      // If everything fits on a single line, just put it there.
-      unsigned ColumnLimit = Style.ColumnLimit;
-      if (I + 1 != E) {
-        AnnotatedLine *NextLine = I[1];
-        if (NextLine->InPPDirective && !NextLine->First->HasUnescapedNewline)
-          ColumnLimit = getColumnLimit(TheLine.InPPDirective);
-      }
+        else
+          Whitespaces->addUntouchableToken(*TheLine.First,
+                                           TheLine.InPPDirective);
 
-      if (TheLine.Last->TotalLength + Indent <= ColumnLimit ||
-          TheLine.Type == LT_ImportStatement) {
-        LineState State = Indenter->getInitialState(Indent, &TheLine, DryRun);
-        while (State.NextToken) {
-          formatChildren(State, /*Newline=*/false, /*DryRun=*/false, Penalty);
-          Indenter->addTokenToState(State, /*Newline=*/false, DryRun);
-        }
-      } else if (Style.ColumnLimit == 0) {
-        // FIXME: Implement nested blocks for ColumnLimit = 0.
-        NoColumnLimitFormatter Formatter(Indenter);
-        if (!DryRun)
-          Formatter.format(Indent, &TheLine);
-      } else {
-        Penalty += format(TheLine, Indent, DryRun);
-      }
-
-      if (!TheLine.InPPDirective)
-        IndentForLevel[TheLine.Level] = LevelIndent;
-    } else if (TheLine.ChildrenAffected) {
-      format(TheLine.Children, DryRun);
-    } else {
-      // Format the first token if necessary, and notify the WhitespaceManager
-      // about the unchanged whitespace.
-      for (FormatToken *Tok = TheLine.First; Tok; Tok = Tok->Next) {
-        if (Tok == TheLine.First && (Tok->NewlinesBefore > 0 || Tok->IsFirst)) {
-          unsigned LevelIndent = Tok->OriginalColumn;
-          if (!DryRun) {
-            // Remove trailing whitespace of the previous line.
-            if ((PreviousLine && PreviousLine->Affected) ||
-                TheLine.LeadingEmptyLinesAffected) {
-              formatFirstToken(*Tok, PreviousLine, TheLine.Level, LevelIndent,
-                               TheLine.InPPDirective);
-            } else {
-              Whitespaces->addUntouchableToken(*Tok, TheLine.InPPDirective);
-            }
-          }
-
-          if (static_cast<int>(LevelIndent) - Offset >= 0)
-            LevelIndent -= Offset;
-          if (Tok->isNot(tok::comment) && !TheLine.InPPDirective)
-            IndentForLevel[TheLine.Level] = LevelIndent;
-        } else if (!DryRun) {
+        // Notify the WhitespaceManager about the unchanged whitespace.
+        for (FormatToken *Tok = TheLine.First->Next; Tok; Tok = Tok->Next)
           Whitespaces->addUntouchableToken(*Tok, TheLine.InPPDirective);
-        }
-      }
-    }
-    if (!DryRun) {
-      for (FormatToken *Tok = TheLine.First; Tok; Tok = Tok->Next) {
-        Tok->Finalized = true;
       }
+      NextLine = Joiner.getNextMergedLine(DryRun, IndentTracker);
     }
-    PreviousLine = *I;
+    if (!DryRun)
+      markFinalized(TheLine.First);
+    PreviousLine = &TheLine;
   }
   PenaltyCache[CacheKey] = Penalty;
   return Penalty;
 }
 
-unsigned UnwrappedLineFormatter::format(const AnnotatedLine &Line,
-                                        unsigned FirstIndent, bool DryRun) {
-  LineState State = Indenter->getInitialState(FirstIndent, &Line, DryRun);
-
-  // If the ObjC method declaration does not fit on a line, we should format
-  // it with one arg per line.
-  if (State.Line->Type == LT_ObjCMethodDecl)
-    State.Stack.back().BreakBeforeParameter = true;
-
-  // Find best solution in solution space.
-  return analyzeSolutionSpace(State, DryRun);
-}
-
 void UnwrappedLineFormatter::formatFirstToken(FormatToken &RootToken,
                                               const AnnotatedLine *PreviousLine,
                                               unsigned IndentLevel,
                                               unsigned Indent,
                                               bool InPPDirective) {
+  if (RootToken.is(tok::eof)) {
+    unsigned Newlines = std::min(RootToken.NewlinesBefore, 1u);
+    Whitespaces->replaceWhitespace(RootToken, Newlines, /*IndentLevel=*/0,
+                                   /*Spaces=*/0, /*TargetColumn=*/0);
+    return;
+  }
   unsigned Newlines =
       std::min(RootToken.NewlinesBefore, Style.MaxEmptyLinesToKeep + 1);
   // Remove empty lines before "}" where applicable.
@@ -496,7 +919,8 @@ void UnwrappedLineFormatter::formatFirstToken(FormatToken &RootToken,
     ++Newlines;
 
   // Remove empty lines after access specifiers.
-  if (PreviousLine && PreviousLine->First->isAccessSpecifier())
+  if (PreviousLine && PreviousLine->First->isAccessSpecifier() &&
+      (!PreviousLine->InPPDirective || !RootToken.HasUnescapedNewline))
     Newlines = std::min(1u, Newlines);
 
   Whitespaces->replaceWhitespace(RootToken, Newlines, IndentLevel, Indent,
@@ -504,202 +928,21 @@ void UnwrappedLineFormatter::formatFirstToken(FormatToken &RootToken,
                                              !RootToken.HasUnescapedNewline);
 }
 
-/// \brief Get the indent of \p Level from \p IndentForLevel.
-///
-/// \p IndentForLevel must contain the indent for the level \c l
-/// at \p IndentForLevel[l], or a value < 0 if the indent for
-/// that level is unknown.
-unsigned UnwrappedLineFormatter::getIndent(ArrayRef<int> IndentForLevel,
-                                           unsigned Level) {
-  if (IndentForLevel[Level] != -1)
-    return IndentForLevel[Level];
-  if (Level == 0)
-    return 0;
-  return getIndent(IndentForLevel, Level - 1) + Style.IndentWidth;
-}
-
-void UnwrappedLineFormatter::join(AnnotatedLine &A, const AnnotatedLine &B) {
-  assert(!A.Last->Next);
-  assert(!B.First->Previous);
-  if (B.Affected)
-    A.Affected = true;
-  A.Last->Next = B.First;
-  B.First->Previous = A.Last;
-  B.First->CanBreakBefore = true;
-  unsigned LengthA = A.Last->TotalLength + B.First->SpacesRequiredBefore;
-  for (FormatToken *Tok = B.First; Tok; Tok = Tok->Next) {
-    Tok->TotalLength += LengthA;
-    A.Last = Tok;
-  }
-}
-
-unsigned UnwrappedLineFormatter::analyzeSolutionSpace(LineState &InitialState,
-                                                      bool DryRun) {
-  std::set<LineState *, CompareLineStatePointers> Seen;
-
-  // Increasing count of \c StateNode items we have created. This is used to
-  // create a deterministic order independent of the container.
-  unsigned Count = 0;
-  QueueType Queue;
-
-  // Insert start element into queue.
-  StateNode *Node =
-      new (Allocator.Allocate()) StateNode(InitialState, false, nullptr);
-  Queue.push(QueueItem(OrderedPenalty(0, Count), Node));
-  ++Count;
-
-  unsigned Penalty = 0;
-
-  // While not empty, take first element and follow edges.
-  while (!Queue.empty()) {
-    Penalty = Queue.top().first.first;
-    StateNode *Node = Queue.top().second;
-    if (!Node->State.NextToken) {
-      DEBUG(llvm::dbgs() << "\n---\nPenalty for line: " << Penalty << "\n");
-      break;
-    }
-    Queue.pop();
-
-    // Cut off the analysis of certain solutions if the analysis gets too
-    // complex. See description of IgnoreStackForComparison.
-    if (Count > 10000)
-      Node->State.IgnoreStackForComparison = true;
-
-    if (!Seen.insert(&Node->State).second)
-      // State already examined with lower penalty.
-      continue;
-
-    FormatDecision LastFormat = Node->State.NextToken->Decision;
-    if (LastFormat == FD_Unformatted || LastFormat == FD_Continue)
-      addNextStateToQueue(Penalty, Node, /*NewLine=*/false, &Count, &Queue);
-    if (LastFormat == FD_Unformatted || LastFormat == FD_Break)
-      addNextStateToQueue(Penalty, Node, /*NewLine=*/true, &Count, &Queue);
-  }
-
-  if (Queue.empty()) {
-    // We were unable to find a solution, do nothing.
-    // FIXME: Add diagnostic?
-    DEBUG(llvm::dbgs() << "Could not find a solution.\n");
-    return 0;
-  }
-
-  // Reconstruct the solution.
-  if (!DryRun)
-    reconstructPath(InitialState, Queue.top().second);
-
-  DEBUG(llvm::dbgs() << "Total number of analyzed states: " << Count << "\n");
-  DEBUG(llvm::dbgs() << "---\n");
-
-  return Penalty;
-}
-
-#ifndef NDEBUG
-static void printLineState(const LineState &State) {
-  llvm::dbgs() << "State: ";
-  for (const ParenState &P : State.Stack) {
-    llvm::dbgs() << P.Indent << "|" << P.LastSpace << "|" << P.NestedBlockIndent
-                 << " ";
-  }
-  llvm::dbgs() << State.NextToken->TokenText << "\n";
-}
-#endif
-
-void UnwrappedLineFormatter::reconstructPath(LineState &State,
-                                             StateNode *Current) {
-  std::deque<StateNode *> Path;
-  // We do not need a break before the initial token.
-  while (Current->Previous) {
-    Path.push_front(Current);
-    Current = Current->Previous;
-  }
-  for (std::deque<StateNode *>::iterator I = Path.begin(), E = Path.end();
-       I != E; ++I) {
-    unsigned Penalty = 0;
-    formatChildren(State, (*I)->NewLine, /*DryRun=*/false, Penalty);
-    Penalty += Indenter->addTokenToState(State, (*I)->NewLine, false);
-
-    DEBUG({
-      printLineState((*I)->Previous->State);
-      if ((*I)->NewLine) {
-        llvm::dbgs() << "Penalty for placing "
-                     << (*I)->Previous->State.NextToken->Tok.getName() << ": "
-                     << Penalty << "\n";
-      }
-    });
-  }
-}
-
-void UnwrappedLineFormatter::addNextStateToQueue(unsigned Penalty,
-                                                 StateNode *PreviousNode,
-                                                 bool NewLine, unsigned *Count,
-                                                 QueueType *Queue) {
-  if (NewLine && !Indenter->canBreak(PreviousNode->State))
-    return;
-  if (!NewLine && Indenter->mustBreak(PreviousNode->State))
-    return;
-
-  StateNode *Node = new (Allocator.Allocate())
-      StateNode(PreviousNode->State, NewLine, PreviousNode);
-  if (!formatChildren(Node->State, NewLine, /*DryRun=*/true, Penalty))
-    return;
-
-  Penalty += Indenter->addTokenToState(Node->State, NewLine, true);
-
-  Queue->push(QueueItem(OrderedPenalty(Penalty, *Count), Node));
-  ++(*Count);
-}
-
-bool UnwrappedLineFormatter::formatChildren(LineState &State, bool NewLine,
-                                            bool DryRun, unsigned &Penalty) {
-  FormatToken &Previous = *State.NextToken->Previous;
-  const FormatToken *LBrace = State.NextToken->getPreviousNonComment();
-  if (!LBrace || LBrace->isNot(tok::l_brace) || LBrace->BlockKind != BK_Block ||
-      Previous.Children.size() == 0)
-    // The previous token does not open a block. Nothing to do. We don't
-    // assert so that we can simply call this function for all tokens.
-    return true;
-
-  if (NewLine) {
-    int AdditionalIndent = State.Stack.back().Indent -
-                           Previous.Children[0]->Level * Style.IndentWidth;
-
-    Penalty += format(Previous.Children, DryRun, AdditionalIndent,
-                      /*FixBadIndentation=*/true);
-    return true;
-  }
-
-  if (Previous.Children[0]->First->MustBreakBefore)
-    return false;
-
-  // Cannot merge multiple statements into a single line.
-  if (Previous.Children.size() > 1)
-    return false;
-
-  // Cannot merge into one line if this line ends on a comment.
-  if (Previous.is(tok::comment))
-    return false;
-
-  // We can't put the closing "}" on a line with a trailing comment.
-  if (Previous.Children[0]->Last->isTrailingComment())
-    return false;
-
-  // If the child line exceeds the column limit, we wouldn't want to merge it.
-  // We add +2 for the trailing " }".
-  if (Style.ColumnLimit > 0 &&
-      Previous.Children[0]->Last->TotalLength + State.Column + 2 >
-          Style.ColumnLimit)
-    return false;
-
-  if (!DryRun) {
-    Whitespaces->replaceWhitespace(
-        *Previous.Children[0]->First,
-        /*Newlines=*/0, /*IndentLevel=*/0, /*Spaces=*/1,
-        /*StartOfTokenColumn=*/State.Column, State.Line->InPPDirective);
-  }
-  Penalty += format(*Previous.Children[0], State.Column + 1, DryRun);
-
-  State.Column += 1 + Previous.Children[0]->Last->TotalLength;
-  return true;
+unsigned
+UnwrappedLineFormatter::getColumnLimit(bool InPPDirective,
+                                       const AnnotatedLine *NextLine) const {
+  // In preprocessor directives reserve two chars for trailing " \" if the
+  // next line continues the preprocessor directive.
+  bool ContinuesPPDirective =
+      InPPDirective &&
+      // If there is no next line, this is likely a child line and the parent
+      // continues the preprocessor directive.
+      (!NextLine ||
+       (NextLine->InPPDirective &&
+        // If there is an unescaped newline between this line and the next, the
+        // next line starts a new preprocessor directive.
+        !NextLine->First->HasUnescapedNewline));
+  return Style.ColumnLimit - (ContinuesPPDirective ? 2 : 0);
 }
 
 } // namespace format