--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/lib/Format/BreakableToken.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,977 @@
+//===--- BreakableToken.cpp - Format C++ code -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Contains implementation of BreakableToken class and classes derived
+/// from it.
+///
+//===----------------------------------------------------------------------===//
+
+#include "BreakableToken.h"
+#include "ContinuationIndenter.h"
+#include "clang/Basic/CharInfo.h"
+#include "clang/Format/Format.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Debug.h"
+#include <algorithm>
+
+#define DEBUG_TYPE "format-token-breaker"
+
+namespace clang {
+namespace format {
+
+static const char *const Blanks = " \t\v\f\r";
+static bool IsBlank(char C) {
+  switch (C) {
+  case ' ':
+  case '\t':
+  case '\v':
+  case '\f':
+  case '\r':
+    return true;
+  default:
+    return false;
+  }
+}
+
+static StringRef getLineCommentIndentPrefix(StringRef Comment,
+                                            const FormatStyle &Style) {
+  static const char *const KnownCStylePrefixes[] = {"///<", "//!<", "///", "//",
+                                                    "//!"};
+  static const char *const KnownTextProtoPrefixes[] = {"//", "#", "##", "###",
+                                                       "####"};
+  ArrayRef<const char *> KnownPrefixes(KnownCStylePrefixes);
+  if (Style.Language == FormatStyle::LK_TextProto)
+    KnownPrefixes = KnownTextProtoPrefixes;
+
+  StringRef LongestPrefix;
+  for (StringRef KnownPrefix : KnownPrefixes) {
+    if (Comment.startswith(KnownPrefix)) {
+      size_t PrefixLength = KnownPrefix.size();
+      while (PrefixLength < Comment.size() && Comment[PrefixLength] == ' ')
+        ++PrefixLength;
+      if (PrefixLength > LongestPrefix.size())
+        LongestPrefix = Comment.substr(0, PrefixLength);
+    }
+  }
+  return LongestPrefix;
+}
+
+static BreakableToken::Split
+getCommentSplit(StringRef Text, unsigned ContentStartColumn,
+                unsigned ColumnLimit, unsigned TabWidth,
+                encoding::Encoding Encoding, const FormatStyle &Style,
+                bool DecorationEndsWithStar = false) {
+  LLVM_DEBUG(llvm::dbgs() << "Comment split: \"" << Text
+                          << "\", Column limit: " << ColumnLimit
+                          << ", Content start: " << ContentStartColumn << "\n");
+  if (ColumnLimit <= ContentStartColumn + 1)
+    return BreakableToken::Split(StringRef::npos, 0);
+
+  unsigned MaxSplit = ColumnLimit - ContentStartColumn + 1;
+  unsigned MaxSplitBytes = 0;
+
+  for (unsigned NumChars = 0;
+       NumChars < MaxSplit && MaxSplitBytes < Text.size();) {
+    unsigned BytesInChar =
+        encoding::getCodePointNumBytes(Text[MaxSplitBytes], Encoding);
+    NumChars +=
+        encoding::columnWidthWithTabs(Text.substr(MaxSplitBytes, BytesInChar),
+                                      ContentStartColumn, TabWidth, Encoding);
+    MaxSplitBytes += BytesInChar;
+  }
+
+  StringRef::size_type SpaceOffset = Text.find_last_of(Blanks, MaxSplitBytes);
+
+  static const auto kNumberedListRegexp = llvm::Regex("^[1-9][0-9]?\\.");
+  while (SpaceOffset != StringRef::npos) {
+    // Do not split before a number followed by a dot: this would be interpreted
+    // as a numbered list, which would prevent re-flowing in subsequent passes.
+    if (kNumberedListRegexp.match(Text.substr(SpaceOffset).ltrim(Blanks)))
+      SpaceOffset = Text.find_last_of(Blanks, SpaceOffset);
+    // In JavaScript, some @tags can be followed by {, and machinery that parses
+    // these comments will fail to understand the comment if followed by a line
+    // break. So avoid ever breaking before a {.
+    else if (Style.Language == FormatStyle::LK_JavaScript &&
+             SpaceOffset + 1 < Text.size() && Text[SpaceOffset + 1] == '{')
+      SpaceOffset = Text.find_last_of(Blanks, SpaceOffset);
+    else
+      break;
+  }
+
+  if (SpaceOffset == StringRef::npos ||
+      // Don't break at leading whitespace.
+      Text.find_last_not_of(Blanks, SpaceOffset) == StringRef::npos) {
+    // Make sure that we don't break at leading whitespace that
+    // reaches past MaxSplit.
+    StringRef::size_type FirstNonWhitespace = Text.find_first_not_of(Blanks);
+    if (FirstNonWhitespace == StringRef::npos)
+      // If the comment is only whitespace, we cannot split.
+      return BreakableToken::Split(StringRef::npos, 0);
+    SpaceOffset = Text.find_first_of(
+        Blanks, std::max<unsigned>(MaxSplitBytes, FirstNonWhitespace));
+  }
+  if (SpaceOffset != StringRef::npos && SpaceOffset != 0) {
+    // adaptStartOfLine will break after lines starting with /** if the comment
+    // is broken anywhere. Avoid emitting this break twice here.
+    // Example: in /** longtextcomesherethatbreaks */ (with ColumnLimit 20) will
+    // insert a break after /**, so this code must not insert the same break.
+    if (SpaceOffset == 1 && Text[SpaceOffset - 1] == '*')
+      return BreakableToken::Split(StringRef::npos, 0);
+    StringRef BeforeCut = Text.substr(0, SpaceOffset).rtrim(Blanks);
+    StringRef AfterCut = Text.substr(SpaceOffset);
+    // Don't trim the leading blanks if it would create a */ after the break.
+    if (!DecorationEndsWithStar || AfterCut.size() <= 1 || AfterCut[1] != '/')
+      AfterCut = AfterCut.ltrim(Blanks);
+    return BreakableToken::Split(BeforeCut.size(),
+                                 AfterCut.begin() - BeforeCut.end());
+  }
+  return BreakableToken::Split(StringRef::npos, 0);
+}
+
+static BreakableToken::Split
+getStringSplit(StringRef Text, unsigned UsedColumns, unsigned ColumnLimit,
+               unsigned TabWidth, encoding::Encoding Encoding) {
+  // FIXME: Reduce unit test case.
+  if (Text.empty())
+    return BreakableToken::Split(StringRef::npos, 0);
+  if (ColumnLimit <= UsedColumns)
+    return BreakableToken::Split(StringRef::npos, 0);
+  unsigned MaxSplit = ColumnLimit - UsedColumns;
+  StringRef::size_type SpaceOffset = 0;
+  StringRef::size_type SlashOffset = 0;
+  StringRef::size_type WordStartOffset = 0;
+  StringRef::size_type SplitPoint = 0;
+  for (unsigned Chars = 0;;) {
+    unsigned Advance;
+    if (Text[0] == '\\') {
+      Advance = encoding::getEscapeSequenceLength(Text);
+      Chars += Advance;
+    } else {
+      Advance = encoding::getCodePointNumBytes(Text[0], Encoding);
+      Chars += encoding::columnWidthWithTabs(
+          Text.substr(0, Advance), UsedColumns + Chars, TabWidth, Encoding);
+    }
+
+    if (Chars > MaxSplit || Text.size() <= Advance)
+      break;
+
+    if (IsBlank(Text[0]))
+      SpaceOffset = SplitPoint;
+    if (Text[0] == '/')
+      SlashOffset = SplitPoint;
+    if (Advance == 1 && !isAlphanumeric(Text[0]))
+      WordStartOffset = SplitPoint;
+
+    SplitPoint += Advance;
+    Text = Text.substr(Advance);
+  }
+
+  if (SpaceOffset != 0)
+    return BreakableToken::Split(SpaceOffset + 1, 0);
+  if (SlashOffset != 0)
+    return BreakableToken::Split(SlashOffset + 1, 0);
+  if (WordStartOffset != 0)
+    return BreakableToken::Split(WordStartOffset + 1, 0);
+  if (SplitPoint != 0)
+    return BreakableToken::Split(SplitPoint, 0);
+  return BreakableToken::Split(StringRef::npos, 0);
+}
+
+bool switchesFormatting(const FormatToken &Token) {
+  assert((Token.is(TT_BlockComment) || Token.is(TT_LineComment)) &&
+         "formatting regions are switched by comment tokens");
+  StringRef Content = Token.TokenText.substr(2).ltrim();
+  return Content.startswith("clang-format on") ||
+         Content.startswith("clang-format off");
+}
+
+unsigned
+BreakableToken::getLengthAfterCompression(unsigned RemainingTokenColumns,
+                                          Split Split) const {
+  // Example: consider the content
+  // lala  lala
+  // - RemainingTokenColumns is the original number of columns, 10;
+  // - Split is (4, 2), denoting the two spaces between the two words;
+  //
+  // We compute the number of columns when the split is compressed into a single
+  // space, like:
+  // lala lala
+  //
+  // FIXME: Correctly measure the length of whitespace in Split.second so it
+  // works with tabs.
+  return RemainingTokenColumns + 1 - Split.second;
+}
+
+unsigned BreakableStringLiteral::getLineCount() const { return 1; }
+
+unsigned BreakableStringLiteral::getRangeLength(unsigned LineIndex,
+                                                unsigned Offset,
+                                                StringRef::size_type Length,
+                                                unsigned StartColumn) const {
+  llvm_unreachable("Getting the length of a part of the string literal "
+                   "indicates that the code tries to reflow it.");
+}
+
+unsigned
+BreakableStringLiteral::getRemainingLength(unsigned LineIndex, unsigned Offset,
+                                           unsigned StartColumn) const {
+  return UnbreakableTailLength + Postfix.size() +
+         encoding::columnWidthWithTabs(Line.substr(Offset, StringRef::npos),
+                                       StartColumn, Style.TabWidth, Encoding);
+}
+
+unsigned BreakableStringLiteral::getContentStartColumn(unsigned LineIndex,
+                                                       bool Break) const {
+  return StartColumn + Prefix.size();
+}
+
+BreakableStringLiteral::BreakableStringLiteral(
+    const FormatToken &Tok, unsigned StartColumn, StringRef Prefix,
+    StringRef Postfix, unsigned UnbreakableTailLength, bool InPPDirective,
+    encoding::Encoding Encoding, const FormatStyle &Style)
+    : BreakableToken(Tok, InPPDirective, Encoding, Style),
+      StartColumn(StartColumn), Prefix(Prefix), Postfix(Postfix),
+      UnbreakableTailLength(UnbreakableTailLength) {
+  assert(Tok.TokenText.startswith(Prefix) && Tok.TokenText.endswith(Postfix));
+  Line = Tok.TokenText.substr(
+      Prefix.size(), Tok.TokenText.size() - Prefix.size() - Postfix.size());
+}
+
+BreakableToken::Split BreakableStringLiteral::getSplit(
+    unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
+    unsigned ContentStartColumn, const llvm::Regex &CommentPragmasRegex) const {
+  return getStringSplit(Line.substr(TailOffset), ContentStartColumn,
+                        ColumnLimit - Postfix.size(), Style.TabWidth, Encoding);
+}
+
+void BreakableStringLiteral::insertBreak(unsigned LineIndex,
+                                         unsigned TailOffset, Split Split,
+                                         unsigned ContentIndent,
+                                         WhitespaceManager &Whitespaces) const {
+  Whitespaces.replaceWhitespaceInToken(
+      Tok, Prefix.size() + TailOffset + Split.first, Split.second, Postfix,
+      Prefix, InPPDirective, 1, StartColumn);
+}
+
+BreakableComment::BreakableComment(const FormatToken &Token,
+                                   unsigned StartColumn, bool InPPDirective,
+                                   encoding::Encoding Encoding,
+                                   const FormatStyle &Style)
+    : BreakableToken(Token, InPPDirective, Encoding, Style),
+      StartColumn(StartColumn) {}
+
+unsigned BreakableComment::getLineCount() const { return Lines.size(); }
+
+BreakableToken::Split
+BreakableComment::getSplit(unsigned LineIndex, unsigned TailOffset,
+                           unsigned ColumnLimit, unsigned ContentStartColumn,
+                           const llvm::Regex &CommentPragmasRegex) const {
+  // Don't break lines matching the comment pragmas regex.
+  if (CommentPragmasRegex.match(Content[LineIndex]))
+    return Split(StringRef::npos, 0);
+  return getCommentSplit(Content[LineIndex].substr(TailOffset),
+                         ContentStartColumn, ColumnLimit, Style.TabWidth,
+                         Encoding, Style);
+}
+
+void BreakableComment::compressWhitespace(
+    unsigned LineIndex, unsigned TailOffset, Split Split,
+    WhitespaceManager &Whitespaces) const {
+  StringRef Text = Content[LineIndex].substr(TailOffset);
+  // Text is relative to the content line, but Whitespaces operates relative to
+  // the start of the corresponding token, so compute the start of the Split
+  // that needs to be compressed into a single space relative to the start of
+  // its token.
+  unsigned BreakOffsetInToken =
+      Text.data() - tokenAt(LineIndex).TokenText.data() + Split.first;
+  unsigned CharsToRemove = Split.second;
+  Whitespaces.replaceWhitespaceInToken(
+      tokenAt(LineIndex), BreakOffsetInToken, CharsToRemove, "", "",
+      /*InPPDirective=*/false, /*Newlines=*/0, /*Spaces=*/1);
+}
+
+const FormatToken &BreakableComment::tokenAt(unsigned LineIndex) const {
+  return Tokens[LineIndex] ? *Tokens[LineIndex] : Tok;
+}
+
+static bool mayReflowContent(StringRef Content) {
+  Content = Content.trim(Blanks);
+  // Lines starting with '@' commonly have special meaning.
+  // Lines starting with '-', '-#', '+' or '*' are bulleted/numbered lists.
+  bool hasSpecialMeaningPrefix = false;
+  for (StringRef Prefix :
+       {"@", "TODO", "FIXME", "XXX", "-# ", "- ", "+ ", "* "}) {
+    if (Content.startswith(Prefix)) {
+      hasSpecialMeaningPrefix = true;
+      break;
+    }
+  }
+
+  // Numbered lists may also start with a number followed by '.'
+  // To avoid issues if a line starts with a number which is actually the end
+  // of a previous line, we only consider numbers with up to 2 digits.
+  static const auto kNumberedListRegexp = llvm::Regex("^[1-9][0-9]?\\. ");
+  hasSpecialMeaningPrefix =
+      hasSpecialMeaningPrefix || kNumberedListRegexp.match(Content);
+
+  // Simple heuristic for what to reflow: content should contain at least two
+  // characters and either the first or second character must be
+  // non-punctuation.
+  return Content.size() >= 2 && !hasSpecialMeaningPrefix &&
+         !Content.endswith("\\") &&
+         // Note that this is UTF-8 safe, since if isPunctuation(Content[0]) is
+         // true, then the first code point must be 1 byte long.
+         (!isPunctuation(Content[0]) || !isPunctuation(Content[1]));
+}
+
+BreakableBlockComment::BreakableBlockComment(
+    const FormatToken &Token, unsigned StartColumn,
+    unsigned OriginalStartColumn, bool FirstInLine, bool InPPDirective,
+    encoding::Encoding Encoding, const FormatStyle &Style, bool UseCRLF)
+    : BreakableComment(Token, StartColumn, InPPDirective, Encoding, Style),
+      DelimitersOnNewline(false),
+      UnbreakableTailLength(Token.UnbreakableTailLength) {
+  assert(Tok.is(TT_BlockComment) &&
+         "block comment section must start with a block comment");
+
+  StringRef TokenText(Tok.TokenText);
+  assert(TokenText.startswith("/*") && TokenText.endswith("*/"));
+  TokenText.substr(2, TokenText.size() - 4)
+      .split(Lines, UseCRLF ? "\r\n" : "\n");
+
+  int IndentDelta = StartColumn - OriginalStartColumn;
+  Content.resize(Lines.size());
+  Content[0] = Lines[0];
+  ContentColumn.resize(Lines.size());
+  // Account for the initial '/*'.
+  ContentColumn[0] = StartColumn + 2;
+  Tokens.resize(Lines.size());
+  for (size_t i = 1; i < Lines.size(); ++i)
+    adjustWhitespace(i, IndentDelta);
+
+  // Align decorations with the column of the star on the first line,
+  // that is one column after the start "/*".
+  DecorationColumn = StartColumn + 1;
+
+  // Account for comment decoration patterns like this:
+  //
+  // /*
+  // ** blah blah blah
+  // */
+  if (Lines.size() >= 2 && Content[1].startswith("**") &&
+      static_cast<unsigned>(ContentColumn[1]) == StartColumn) {
+    DecorationColumn = StartColumn;
+  }
+
+  Decoration = "* ";
+  if (Lines.size() == 1 && !FirstInLine) {
+    // Comments for which FirstInLine is false can start on arbitrary column,
+    // and available horizontal space can be too small to align consecutive
+    // lines with the first one.
+    // FIXME: We could, probably, align them to current indentation level, but
+    // now we just wrap them without stars.
+    Decoration = "";
+  }
+  for (size_t i = 1, e = Lines.size(); i < e && !Decoration.empty(); ++i) {
+    // If the last line is empty, the closing "*/" will have a star.
+    if (i + 1 == e && Content[i].empty())
+      break;
+    if (!Content[i].empty() && i + 1 != e && Decoration.startswith(Content[i]))
+      continue;
+    while (!Content[i].startswith(Decoration))
+      Decoration = Decoration.substr(0, Decoration.size() - 1);
+  }
+
+  LastLineNeedsDecoration = true;
+  IndentAtLineBreak = ContentColumn[0] + 1;
+  for (size_t i = 1, e = Lines.size(); i < e; ++i) {
+    if (Content[i].empty()) {
+      if (i + 1 == e) {
+        // Empty last line means that we already have a star as a part of the
+        // trailing */. We also need to preserve whitespace, so that */ is
+        // correctly indented.
+        LastLineNeedsDecoration = false;
+        // Align the star in the last '*/' with the stars on the previous lines.
+        if (e >= 2 && !Decoration.empty()) {
+          ContentColumn[i] = DecorationColumn;
+        }
+      } else if (Decoration.empty()) {
+        // For all other lines, set the start column to 0 if they're empty, so
+        // we do not insert trailing whitespace anywhere.
+        ContentColumn[i] = 0;
+      }
+      continue;
+    }
+
+    // The first line already excludes the star.
+    // The last line excludes the star if LastLineNeedsDecoration is false.
+    // For all other lines, adjust the line to exclude the star and
+    // (optionally) the first whitespace.
+    unsigned DecorationSize = Decoration.startswith(Content[i])
+                                  ? Content[i].size()
+                                  : Decoration.size();
+    if (DecorationSize) {
+      ContentColumn[i] = DecorationColumn + DecorationSize;
+    }
+    Content[i] = Content[i].substr(DecorationSize);
+    if (!Decoration.startswith(Content[i]))
+      IndentAtLineBreak =
+          std::min<int>(IndentAtLineBreak, std::max(0, ContentColumn[i]));
+  }
+  IndentAtLineBreak = std::max<unsigned>(IndentAtLineBreak, Decoration.size());
+
+  // Detect a multiline jsdoc comment and set DelimitersOnNewline in that case.
+  if (Style.Language == FormatStyle::LK_JavaScript ||
+      Style.Language == FormatStyle::LK_Java) {
+    if ((Lines[0] == "*" || Lines[0].startswith("* ")) && Lines.size() > 1) {
+      // This is a multiline jsdoc comment.
+      DelimitersOnNewline = true;
+    } else if (Lines[0].startswith("* ") && Lines.size() == 1) {
+      // Detect a long single-line comment, like:
+      // /** long long long */
+      // Below, '2' is the width of '*/'.
+      unsigned EndColumn =
+          ContentColumn[0] +
+          encoding::columnWidthWithTabs(Lines[0], ContentColumn[0],
+                                        Style.TabWidth, Encoding) +
+          2;
+      DelimitersOnNewline = EndColumn > Style.ColumnLimit;
+    }
+  }
+
+  LLVM_DEBUG({
+    llvm::dbgs() << "IndentAtLineBreak " << IndentAtLineBreak << "\n";
+    llvm::dbgs() << "DelimitersOnNewline " << DelimitersOnNewline << "\n";
+    for (size_t i = 0; i < Lines.size(); ++i) {
+      llvm::dbgs() << i << " |" << Content[i] << "| "
+                   << "CC=" << ContentColumn[i] << "| "
+                   << "IN=" << (Content[i].data() - Lines[i].data()) << "\n";
+    }
+  });
+}
+
+BreakableToken::Split BreakableBlockComment::getSplit(
+    unsigned LineIndex, unsigned TailOffset, unsigned ColumnLimit,
+    unsigned ContentStartColumn, const llvm::Regex &CommentPragmasRegex) const {
+  // Don't break lines matching the comment pragmas regex.
+  if (CommentPragmasRegex.match(Content[LineIndex]))
+    return Split(StringRef::npos, 0);
+  return getCommentSplit(Content[LineIndex].substr(TailOffset),
+                         ContentStartColumn, ColumnLimit, Style.TabWidth,
+                         Encoding, Style, Decoration.endswith("*"));
+}
+
+void BreakableBlockComment::adjustWhitespace(unsigned LineIndex,
+                                             int IndentDelta) {
+  // When in a preprocessor directive, the trailing backslash in a block comment
+  // is not needed, but can serve a purpose of uniformity with necessary escaped
+  // newlines outside the comment. In this case we remove it here before
+  // trimming the trailing whitespace. The backslash will be re-added later when
+  // inserting a line break.
+  size_t EndOfPreviousLine = Lines[LineIndex - 1].size();
+  if (InPPDirective && Lines[LineIndex - 1].endswith("\\"))
+    --EndOfPreviousLine;
+
+  // Calculate the end of the non-whitespace text in the previous line.
+  EndOfPreviousLine =
+      Lines[LineIndex - 1].find_last_not_of(Blanks, EndOfPreviousLine);
+  if (EndOfPreviousLine == StringRef::npos)
+    EndOfPreviousLine = 0;
+  else
+    ++EndOfPreviousLine;
+  // Calculate the start of the non-whitespace text in the current line.
+  size_t StartOfLine = Lines[LineIndex].find_first_not_of(Blanks);
+  if (StartOfLine == StringRef::npos)
+    StartOfLine = Lines[LineIndex].size();
+
+  StringRef Whitespace = Lines[LineIndex].substr(0, StartOfLine);
+  // Adjust Lines to only contain relevant text.
+  size_t PreviousContentOffset =
+      Content[LineIndex - 1].data() - Lines[LineIndex - 1].data();
+  Content[LineIndex - 1] = Lines[LineIndex - 1].substr(
+      PreviousContentOffset, EndOfPreviousLine - PreviousContentOffset);
+  Content[LineIndex] = Lines[LineIndex].substr(StartOfLine);
+
+  // Adjust the start column uniformly across all lines.
+  ContentColumn[LineIndex] =
+      encoding::columnWidthWithTabs(Whitespace, 0, Style.TabWidth, Encoding) +
+      IndentDelta;
+}
+
+unsigned BreakableBlockComment::getRangeLength(unsigned LineIndex,
+                                               unsigned Offset,
+                                               StringRef::size_type Length,
+                                               unsigned StartColumn) const {
+  unsigned LineLength =
+      encoding::columnWidthWithTabs(Content[LineIndex].substr(Offset, Length),
+                                    StartColumn, Style.TabWidth, Encoding);
+  // FIXME: This should go into getRemainingLength instead, but we currently
+  // break tests when putting it there. Investigate how to fix those tests.
+  // The last line gets a "*/" postfix.
+  if (LineIndex + 1 == Lines.size()) {
+    LineLength += 2;
+    // We never need a decoration when breaking just the trailing "*/" postfix.
+    // Note that checking that Length == 0 is not enough, since Length could
+    // also be StringRef::npos.
+    if (Content[LineIndex].substr(Offset, StringRef::npos).empty()) {
+      LineLength -= Decoration.size();
+    }
+  }
+  return LineLength;
+}
+
+unsigned BreakableBlockComment::getRemainingLength(unsigned LineIndex,
+                                                   unsigned Offset,
+                                                   unsigned StartColumn) const {
+  return UnbreakableTailLength +
+         getRangeLength(LineIndex, Offset, StringRef::npos, StartColumn);
+}
+
+unsigned BreakableBlockComment::getContentStartColumn(unsigned LineIndex,
+                                                      bool Break) const {
+  if (Break)
+    return IndentAtLineBreak;
+  return std::max(0, ContentColumn[LineIndex]);
+}
+
+const llvm::StringSet<>
+    BreakableBlockComment::ContentIndentingJavadocAnnotations = {
+        "@param", "@return",     "@returns", "@throws",  "@type", "@template",
+        "@see",   "@deprecated", "@define",  "@exports", "@mods", "@private",
+};
+
+unsigned BreakableBlockComment::getContentIndent(unsigned LineIndex) const {
+  if (Style.Language != FormatStyle::LK_Java &&
+      Style.Language != FormatStyle::LK_JavaScript)
+    return 0;
+  // The content at LineIndex 0 of a comment like:
+  // /** line 0 */
+  // is "* line 0", so we need to skip over the decoration in that case.
+  StringRef ContentWithNoDecoration = Content[LineIndex];
+  if (LineIndex == 0 && ContentWithNoDecoration.startswith("*")) {
+    ContentWithNoDecoration = ContentWithNoDecoration.substr(1).ltrim(Blanks);
+  }
+  StringRef FirstWord = ContentWithNoDecoration.substr(
+      0, ContentWithNoDecoration.find_first_of(Blanks));
+  if (ContentIndentingJavadocAnnotations.find(FirstWord) !=
+      ContentIndentingJavadocAnnotations.end())
+    return Style.ContinuationIndentWidth;
+  return 0;
+}
+
+void BreakableBlockComment::insertBreak(unsigned LineIndex, unsigned TailOffset,
+                                        Split Split, unsigned ContentIndent,
+                                        WhitespaceManager &Whitespaces) const {
+  StringRef Text = Content[LineIndex].substr(TailOffset);
+  StringRef Prefix = Decoration;
+  // We need this to account for the case when we have a decoration "* " for all
+  // the lines except for the last one, where the star in "*/" acts as a
+  // decoration.
+  unsigned LocalIndentAtLineBreak = IndentAtLineBreak;
+  if (LineIndex + 1 == Lines.size() &&
+      Text.size() == Split.first + Split.second) {
+    // For the last line we need to break before "*/", but not to add "* ".
+    Prefix = "";
+    if (LocalIndentAtLineBreak >= 2)
+      LocalIndentAtLineBreak -= 2;
+  }
+  // The split offset is from the beginning of the line. Convert it to an offset
+  // from the beginning of the token text.
+  unsigned BreakOffsetInToken =
+      Text.data() - tokenAt(LineIndex).TokenText.data() + Split.first;
+  unsigned CharsToRemove = Split.second;
+  assert(LocalIndentAtLineBreak >= Prefix.size());
+  std::string PrefixWithTrailingIndent = std::string(Prefix);
+  for (unsigned I = 0; I < ContentIndent; ++I)
+    PrefixWithTrailingIndent += " ";
+  Whitespaces.replaceWhitespaceInToken(
+      tokenAt(LineIndex), BreakOffsetInToken, CharsToRemove, "",
+      PrefixWithTrailingIndent, InPPDirective, /*Newlines=*/1,
+      /*Spaces=*/LocalIndentAtLineBreak + ContentIndent -
+          PrefixWithTrailingIndent.size());
+}
+
+BreakableToken::Split BreakableBlockComment::getReflowSplit(
+    unsigned LineIndex, const llvm::Regex &CommentPragmasRegex) const {
+  if (!mayReflow(LineIndex, CommentPragmasRegex))
+    return Split(StringRef::npos, 0);
+
+  // If we're reflowing into a line with content indent, only reflow the next
+  // line if its starting whitespace matches the content indent.
+  size_t Trimmed = Content[LineIndex].find_first_not_of(Blanks);
+  if (LineIndex) {
+    unsigned PreviousContentIndent = getContentIndent(LineIndex - 1);
+    if (PreviousContentIndent && Trimmed != StringRef::npos &&
+        Trimmed != PreviousContentIndent)
+      return Split(StringRef::npos, 0);
+  }
+
+  return Split(0, Trimmed != StringRef::npos ? Trimmed : 0);
+}
+
+bool BreakableBlockComment::introducesBreakBeforeToken() const {
+  // A break is introduced when we want delimiters on newline.
+  return DelimitersOnNewline &&
+         Lines[0].substr(1).find_first_not_of(Blanks) != StringRef::npos;
+}
+
+void BreakableBlockComment::reflow(unsigned LineIndex,
+                                   WhitespaceManager &Whitespaces) const {
+  StringRef TrimmedContent = Content[LineIndex].ltrim(Blanks);
+  // Here we need to reflow.
+  assert(Tokens[LineIndex - 1] == Tokens[LineIndex] &&
+         "Reflowing whitespace within a token");
+  // This is the offset of the end of the last line relative to the start of
+  // the token text in the token.
+  unsigned WhitespaceOffsetInToken = Content[LineIndex - 1].data() +
+                                     Content[LineIndex - 1].size() -
+                                     tokenAt(LineIndex).TokenText.data();
+  unsigned WhitespaceLength = TrimmedContent.data() -
+                              tokenAt(LineIndex).TokenText.data() -
+                              WhitespaceOffsetInToken;
+  Whitespaces.replaceWhitespaceInToken(
+      tokenAt(LineIndex), WhitespaceOffsetInToken,
+      /*ReplaceChars=*/WhitespaceLength, /*PreviousPostfix=*/"",
+      /*CurrentPrefix=*/ReflowPrefix, InPPDirective, /*Newlines=*/0,
+      /*Spaces=*/0);
+}
+
+void BreakableBlockComment::adaptStartOfLine(
+    unsigned LineIndex, WhitespaceManager &Whitespaces) const {
+  if (LineIndex == 0) {
+    if (DelimitersOnNewline) {
+      // Since we're breaking at index 1 below, the break position and the
+      // break length are the same.
+      // Note: this works because getCommentSplit is careful never to split at
+      // the beginning of a line.
+      size_t BreakLength = Lines[0].substr(1).find_first_not_of(Blanks);
+      if (BreakLength != StringRef::npos)
+        insertBreak(LineIndex, 0, Split(1, BreakLength), /*ContentIndent=*/0,
+                    Whitespaces);
+    }
+    return;
+  }
+  // Here no reflow with the previous line will happen.
+  // Fix the decoration of the line at LineIndex.
+  StringRef Prefix = Decoration;
+  if (Content[LineIndex].empty()) {
+    if (LineIndex + 1 == Lines.size()) {
+      if (!LastLineNeedsDecoration) {
+        // If the last line was empty, we don't need a prefix, as the */ will
+        // line up with the decoration (if it exists).
+        Prefix = "";
+      }
+    } else if (!Decoration.empty()) {
+      // For other empty lines, if we do have a decoration, adapt it to not
+      // contain a trailing whitespace.
+      Prefix = Prefix.substr(0, 1);
+    }
+  } else {
+    if (ContentColumn[LineIndex] == 1) {
+      // This line starts immediately after the decorating *.
+      Prefix = Prefix.substr(0, 1);
+    }
+  }
+  // This is the offset of the end of the last line relative to the start of the
+  // token text in the token.
+  unsigned WhitespaceOffsetInToken = Content[LineIndex - 1].data() +
+                                     Content[LineIndex - 1].size() -
+                                     tokenAt(LineIndex).TokenText.data();
+  unsigned WhitespaceLength = Content[LineIndex].data() -
+                              tokenAt(LineIndex).TokenText.data() -
+                              WhitespaceOffsetInToken;
+  Whitespaces.replaceWhitespaceInToken(
+      tokenAt(LineIndex), WhitespaceOffsetInToken, WhitespaceLength, "", Prefix,
+      InPPDirective, /*Newlines=*/1, ContentColumn[LineIndex] - Prefix.size());
+}
+
+BreakableToken::Split
+BreakableBlockComment::getSplitAfterLastLine(unsigned TailOffset) const {
+  if (DelimitersOnNewline) {
+    // Replace the trailing whitespace of the last line with a newline.
+    // In case the last line is empty, the ending '*/' is already on its own
+    // line.
+    StringRef Line = Content.back().substr(TailOffset);
+    StringRef TrimmedLine = Line.rtrim(Blanks);
+    if (!TrimmedLine.empty())
+      return Split(TrimmedLine.size(), Line.size() - TrimmedLine.size());
+  }
+  return Split(StringRef::npos, 0);
+}
+
+bool BreakableBlockComment::mayReflow(
+    unsigned LineIndex, const llvm::Regex &CommentPragmasRegex) const {
+  // Content[LineIndex] may exclude the indent after the '*' decoration. In that
+  // case, we compute the start of the comment pragma manually.
+  StringRef IndentContent = Content[LineIndex];
+  if (Lines[LineIndex].ltrim(Blanks).startswith("*")) {
+    IndentContent = Lines[LineIndex].ltrim(Blanks).substr(1);
+  }
+  return LineIndex > 0 && !CommentPragmasRegex.match(IndentContent) &&
+         mayReflowContent(Content[LineIndex]) && !Tok.Finalized &&
+         !switchesFormatting(tokenAt(LineIndex));
+}
+
+BreakableLineCommentSection::BreakableLineCommentSection(
+    const FormatToken &Token, unsigned StartColumn,
+    unsigned OriginalStartColumn, bool FirstInLine, bool InPPDirective,
+    encoding::Encoding Encoding, const FormatStyle &Style)
+    : BreakableComment(Token, StartColumn, InPPDirective, Encoding, Style) {
+  assert(Tok.is(TT_LineComment) &&
+         "line comment section must start with a line comment");
+  FormatToken *LineTok = nullptr;
+  for (const FormatToken *CurrentTok = &Tok;
+       CurrentTok && CurrentTok->is(TT_LineComment);
+       CurrentTok = CurrentTok->Next) {
+    LastLineTok = LineTok;
+    StringRef TokenText(CurrentTok->TokenText);
+    assert((TokenText.startswith("//") || TokenText.startswith("#")) &&
+           "unsupported line comment prefix, '//' and '#' are supported");
+    size_t FirstLineIndex = Lines.size();
+    TokenText.split(Lines, "\n");
+    Content.resize(Lines.size());
+    ContentColumn.resize(Lines.size());
+    OriginalContentColumn.resize(Lines.size());
+    Tokens.resize(Lines.size());
+    Prefix.resize(Lines.size());
+    OriginalPrefix.resize(Lines.size());
+    for (size_t i = FirstLineIndex, e = Lines.size(); i < e; ++i) {
+      Lines[i] = Lines[i].ltrim(Blanks);
+      // We need to trim the blanks in case this is not the first line in a
+      // multiline comment. Then the indent is included in Lines[i].
+      StringRef IndentPrefix =
+          getLineCommentIndentPrefix(Lines[i].ltrim(Blanks), Style);
+      assert((TokenText.startswith("//") || TokenText.startswith("#")) &&
+             "unsupported line comment prefix, '//' and '#' are supported");
+      OriginalPrefix[i] = Prefix[i] = IndentPrefix;
+      if (Lines[i].size() > Prefix[i].size() &&
+          isAlphanumeric(Lines[i][Prefix[i].size()])) {
+        if (Prefix[i] == "//")
+          Prefix[i] = "// ";
+        else if (Prefix[i] == "///")
+          Prefix[i] = "/// ";
+        else if (Prefix[i] == "//!")
+          Prefix[i] = "//! ";
+        else if (Prefix[i] == "///<")
+          Prefix[i] = "///< ";
+        else if (Prefix[i] == "//!<")
+          Prefix[i] = "//!< ";
+        else if (Prefix[i] == "#" &&
+                 Style.Language == FormatStyle::LK_TextProto)
+          Prefix[i] = "# ";
+      }
+
+      Tokens[i] = LineTok;
+      Content[i] = Lines[i].substr(IndentPrefix.size());
+      OriginalContentColumn[i] =
+          StartColumn + encoding::columnWidthWithTabs(OriginalPrefix[i],
+                                                      StartColumn,
+                                                      Style.TabWidth, Encoding);
+      ContentColumn[i] =
+          StartColumn + encoding::columnWidthWithTabs(Prefix[i], StartColumn,
+                                                      Style.TabWidth, Encoding);
+
+      // Calculate the end of the non-whitespace text in this line.
+      size_t EndOfLine = Content[i].find_last_not_of(Blanks);
+      if (EndOfLine == StringRef::npos)
+        EndOfLine = Content[i].size();
+      else
+        ++EndOfLine;
+      Content[i] = Content[i].substr(0, EndOfLine);
+    }
+    LineTok = CurrentTok->Next;
+    if (CurrentTok->Next && !CurrentTok->Next->ContinuesLineCommentSection) {
+      // A line comment section needs to broken by a line comment that is
+      // preceded by at least two newlines. Note that we put this break here
+      // instead of breaking at a previous stage during parsing, since that
+      // would split the contents of the enum into two unwrapped lines in this
+      // example, which is undesirable:
+      // enum A {
+      //   a, // comment about a
+      //
+      //   // comment about b
+      //   b
+      // };
+      //
+      // FIXME: Consider putting separate line comment sections as children to
+      // the unwrapped line instead.
+      break;
+    }
+  }
+}
+
+unsigned
+BreakableLineCommentSection::getRangeLength(unsigned LineIndex, unsigned Offset,
+                                            StringRef::size_type Length,
+                                            unsigned StartColumn) const {
+  return encoding::columnWidthWithTabs(
+      Content[LineIndex].substr(Offset, Length), StartColumn, Style.TabWidth,
+      Encoding);
+}
+
+unsigned BreakableLineCommentSection::getContentStartColumn(unsigned LineIndex,
+                                                            bool Break) const {
+  if (Break)
+    return OriginalContentColumn[LineIndex];
+  return ContentColumn[LineIndex];
+}
+
+void BreakableLineCommentSection::insertBreak(
+    unsigned LineIndex, unsigned TailOffset, Split Split,
+    unsigned ContentIndent, WhitespaceManager &Whitespaces) const {
+  StringRef Text = Content[LineIndex].substr(TailOffset);
+  // Compute the offset of the split relative to the beginning of the token
+  // text.
+  unsigned BreakOffsetInToken =
+      Text.data() - tokenAt(LineIndex).TokenText.data() + Split.first;
+  unsigned CharsToRemove = Split.second;
+  // Compute the size of the new indent, including the size of the new prefix of
+  // the newly broken line.
+  unsigned IndentAtLineBreak = OriginalContentColumn[LineIndex] +
+                               Prefix[LineIndex].size() -
+                               OriginalPrefix[LineIndex].size();
+  assert(IndentAtLineBreak >= Prefix[LineIndex].size());
+  Whitespaces.replaceWhitespaceInToken(
+      tokenAt(LineIndex), BreakOffsetInToken, CharsToRemove, "",
+      Prefix[LineIndex], InPPDirective, /*Newlines=*/1,
+      /*Spaces=*/IndentAtLineBreak - Prefix[LineIndex].size());
+}
+
+BreakableComment::Split BreakableLineCommentSection::getReflowSplit(
+    unsigned LineIndex, const llvm::Regex &CommentPragmasRegex) const {
+  if (!mayReflow(LineIndex, CommentPragmasRegex))
+    return Split(StringRef::npos, 0);
+
+  size_t Trimmed = Content[LineIndex].find_first_not_of(Blanks);
+
+  // In a line comment section each line is a separate token; thus, after a
+  // split we replace all whitespace before the current line comment token
+  // (which does not need to be included in the split), plus the start of the
+  // line up to where the content starts.
+  return Split(0, Trimmed != StringRef::npos ? Trimmed : 0);
+}
+
+void BreakableLineCommentSection::reflow(unsigned LineIndex,
+                                         WhitespaceManager &Whitespaces) const {
+  if (LineIndex > 0 && Tokens[LineIndex] != Tokens[LineIndex - 1]) {
+    // Reflow happens between tokens. Replace the whitespace between the
+    // tokens by the empty string.
+    Whitespaces.replaceWhitespace(
+        *Tokens[LineIndex], /*Newlines=*/0, /*Spaces=*/0,
+        /*StartOfTokenColumn=*/StartColumn, /*InPPDirective=*/false);
+  } else if (LineIndex > 0) {
+    // In case we're reflowing after the '\' in:
+    //
+    //   // line comment \
+    //   // line 2
+    //
+    // the reflow happens inside the single comment token (it is a single line
+    // comment with an unescaped newline).
+    // Replace the whitespace between the '\' and '//' with the empty string.
+    //
+    // Offset points to after the '\' relative to start of the token.
+    unsigned Offset = Lines[LineIndex - 1].data() +
+                      Lines[LineIndex - 1].size() -
+                      tokenAt(LineIndex - 1).TokenText.data();
+    // WhitespaceLength is the number of chars between the '\' and the '//' on
+    // the next line.
+    unsigned WhitespaceLength =
+        Lines[LineIndex].data() - tokenAt(LineIndex).TokenText.data() - Offset;
+    Whitespaces.replaceWhitespaceInToken(*Tokens[LineIndex], Offset,
+                                         /*ReplaceChars=*/WhitespaceLength,
+                                         /*PreviousPostfix=*/"",
+                                         /*CurrentPrefix=*/"",
+                                         /*InPPDirective=*/false,
+                                         /*Newlines=*/0,
+                                         /*Spaces=*/0);
+  }
+  // Replace the indent and prefix of the token with the reflow prefix.
+  unsigned Offset =
+      Lines[LineIndex].data() - tokenAt(LineIndex).TokenText.data();
+  unsigned WhitespaceLength =
+      Content[LineIndex].data() - Lines[LineIndex].data();
+  Whitespaces.replaceWhitespaceInToken(*Tokens[LineIndex], Offset,
+                                       /*ReplaceChars=*/WhitespaceLength,
+                                       /*PreviousPostfix=*/"",
+                                       /*CurrentPrefix=*/ReflowPrefix,
+                                       /*InPPDirective=*/false,
+                                       /*Newlines=*/0,
+                                       /*Spaces=*/0);
+}
+
+void BreakableLineCommentSection::adaptStartOfLine(
+    unsigned LineIndex, WhitespaceManager &Whitespaces) const {
+  // If this is the first line of a token, we need to inform Whitespace Manager
+  // about it: either adapt the whitespace range preceding it, or mark it as an
+  // untouchable token.
+  // This happens for instance here:
+  // // line 1 \
+  // // line 2
+  if (LineIndex > 0 && Tokens[LineIndex] != Tokens[LineIndex - 1]) {
+    // This is the first line for the current token, but no reflow with the
+    // previous token is necessary. However, we still may need to adjust the
+    // start column. Note that ContentColumn[LineIndex] is the expected
+    // content column after a possible update to the prefix, hence the prefix
+    // length change is included.
+    unsigned LineColumn =
+        ContentColumn[LineIndex] -
+        (Content[LineIndex].data() - Lines[LineIndex].data()) +
+        (OriginalPrefix[LineIndex].size() - Prefix[LineIndex].size());
+
+    // We always want to create a replacement instead of adding an untouchable
+    // token, even if LineColumn is the same as the original column of the
+    // token. This is because WhitespaceManager doesn't align trailing
+    // comments if they are untouchable.
+    Whitespaces.replaceWhitespace(*Tokens[LineIndex],
+                                  /*Newlines=*/1,
+                                  /*Spaces=*/LineColumn,
+                                  /*StartOfTokenColumn=*/LineColumn,
+                                  /*InPPDirective=*/false);
+  }
+  if (OriginalPrefix[LineIndex] != Prefix[LineIndex]) {
+    // Adjust the prefix if necessary.
+
+    // Take care of the space possibly introduced after a decoration.
+    assert(Prefix[LineIndex] == (OriginalPrefix[LineIndex] + " ").str() &&
+           "Expecting a line comment prefix to differ from original by at most "
+           "a space");
+    Whitespaces.replaceWhitespaceInToken(
+        tokenAt(LineIndex), OriginalPrefix[LineIndex].size(), 0, "", "",
+        /*InPPDirective=*/false, /*Newlines=*/0, /*Spaces=*/1);
+  }
+}
+
+void BreakableLineCommentSection::updateNextToken(LineState &State) const {
+  if (LastLineTok) {
+    State.NextToken = LastLineTok->Next;
+  }
+}
+
+bool BreakableLineCommentSection::mayReflow(
+    unsigned LineIndex, const llvm::Regex &CommentPragmasRegex) const {
+  // Line comments have the indent as part of the prefix, so we need to
+  // recompute the start of the line.
+  StringRef IndentContent = Content[LineIndex];
+  if (Lines[LineIndex].startswith("//")) {
+    IndentContent = Lines[LineIndex].substr(2);
+  }
+  // FIXME: Decide whether we want to reflow non-regular indents:
+  // Currently, we only reflow when the OriginalPrefix[LineIndex] matches the
+  // OriginalPrefix[LineIndex-1]. That means we don't reflow
+  // // text that protrudes
+  // //    into text with different indent
+  // We do reflow in that case in block comments.
+  return LineIndex > 0 && !CommentPragmasRegex.match(IndentContent) &&
+         mayReflowContent(Content[LineIndex]) && !Tok.Finalized &&
+         !switchesFormatting(tokenAt(LineIndex)) &&
+         OriginalPrefix[LineIndex] == OriginalPrefix[LineIndex - 1];
+}
+
+} // namespace format
+} // namespace clang