1 files changed, 867 insertions, 0 deletions
diff --git a/clang/lib/AST/CommentLexer.cpp b/clang/lib/AST/CommentLexer.cpp
new file mode 100644
index 000000000000..c1ea3eab075e
--- /dev/null
+++ b/clang/lib/AST/CommentLexer.cpp
@@ -0,0 +1,867 @@
+//===--- CommentLexer.cpp -------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/CommentLexer.h"
+#include "clang/AST/CommentCommandTraits.h"
+#include "clang/AST/CommentDiagnostic.h"
+#include "clang/Basic/CharInfo.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/ConvertUTF.h"
+#include "llvm/Support/ErrorHandling.h"
+
+namespace clang {
+namespace comments {
+
+void Token::dump(const Lexer &L, const SourceManager &SM) const {
+  llvm::errs() << "comments::Token Kind=" << Kind << " ";
+  Loc.print(llvm::errs(), SM);
+  llvm::errs() << " " << Length << " \"" << L.getSpelling(*this, SM) << "\"\n";
+}
+
+static inline bool isHTMLNamedCharacterReferenceCharacter(char C) {
+  return isLetter(C);
+}
+
+static inline bool isHTMLDecimalCharacterReferenceCharacter(char C) {
+  return isDigit(C);
+}
+
+static inline bool isHTMLHexCharacterReferenceCharacter(char C) {
+  return isHexDigit(C);
+}
+
+static inline StringRef convertCodePointToUTF8(
+                                      llvm::BumpPtrAllocator &Allocator,
+                                      unsigned CodePoint) {
+  char *Resolved = Allocator.Allocate<char>(UNI_MAX_UTF8_BYTES_PER_CODE_POINT);
+  char *ResolvedPtr = Resolved;
+  if (llvm::ConvertCodePointToUTF8(CodePoint, ResolvedPtr))
+    return StringRef(Resolved, ResolvedPtr - Resolved);
+  else
+    return StringRef();
+}
+
+namespace {
+
+#include "clang/AST/CommentHTMLTags.inc"
+#include "clang/AST/CommentHTMLNamedCharacterReferences.inc"
+
+} // end anonymous namespace
+
+StringRef Lexer::resolveHTMLNamedCharacterReference(StringRef Name) const {
+  // Fast path, first check a few most widely used named character references.
+  return llvm::StringSwitch<StringRef>(Name)
+      .Case("amp", "&")
+      .Case("lt", "<")
+      .Case("gt", ">")
+      .Case("quot", "\"")
+      .Case("apos", "\'")
+      // Slow path.
+      .Default(translateHTMLNamedCharacterReferenceToUTF8(Name));
+}
+
+StringRef Lexer::resolveHTMLDecimalCharacterReference(StringRef Name) const {
+  unsigned CodePoint = 0;
+  for (unsigned i = 0, e = Name.size(); i != e; ++i) {
+    assert(isHTMLDecimalCharacterReferenceCharacter(Name[i]));
+    CodePoint *= 10;
+    CodePoint += Name[i] - '0';
+  }
+  return convertCodePointToUTF8(Allocator, CodePoint);
+}
+
+StringRef Lexer::resolveHTMLHexCharacterReference(StringRef Name) const {
+  unsigned CodePoint = 0;
+  for (unsigned i = 0, e = Name.size(); i != e; ++i) {
+    CodePoint *= 16;
+    const char C = Name[i];
+    assert(isHTMLHexCharacterReferenceCharacter(C));
+    CodePoint += llvm::hexDigitValue(C);
+  }
+  return convertCodePointToUTF8(Allocator, CodePoint);
+}
+
+void Lexer::skipLineStartingDecorations() {
+  // This function should be called only for C comments
+  assert(CommentState == LCS_InsideCComment);
+
+  if (BufferPtr == CommentEnd)
+    return;
+
+  switch (*BufferPtr) {
+  case ' ':
+  case '\t':
+  case '\f':
+  case '\v': {
+    const char *NewBufferPtr = BufferPtr;
+    NewBufferPtr++;
+    if (NewBufferPtr == CommentEnd)
+      return;
+
+    char C = *NewBufferPtr;
+    while (isHorizontalWhitespace(C)) {
+      NewBufferPtr++;
+      if (NewBufferPtr == CommentEnd)
+        return;
+      C = *NewBufferPtr;
+    }
+    if (C == '*')
+      BufferPtr = NewBufferPtr + 1;
+    break;
+  }
+  case '*':
+    BufferPtr++;
+    break;
+  }
+}
+
+namespace {
+/// Returns pointer to the first newline character in the string.
+const char *findNewline(const char *BufferPtr, const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (isVerticalWhitespace(*BufferPtr))
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+const char *skipNewline(const char *BufferPtr, const char *BufferEnd) {
+  if (BufferPtr == BufferEnd)
+    return BufferPtr;
+
+  if (*BufferPtr == '\n')
+    BufferPtr++;
+  else {
+    assert(*BufferPtr == '\r');
+    BufferPtr++;
+    if (BufferPtr != BufferEnd && *BufferPtr == '\n')
+      BufferPtr++;
+  }
+  return BufferPtr;
+}
+
+const char *skipNamedCharacterReference(const char *BufferPtr,
+                                        const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (!isHTMLNamedCharacterReferenceCharacter(*BufferPtr))
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+const char *skipDecimalCharacterReference(const char *BufferPtr,
+                                          const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (!isHTMLDecimalCharacterReferenceCharacter(*BufferPtr))
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+const char *skipHexCharacterReference(const char *BufferPtr,
+                                      const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (!isHTMLHexCharacterReferenceCharacter(*BufferPtr))
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+bool isHTMLIdentifierStartingCharacter(char C) {
+  return isLetter(C);
+}
+
+bool isHTMLIdentifierCharacter(char C) {
+  return isAlphanumeric(C);
+}
+
+const char *skipHTMLIdentifier(const char *BufferPtr, const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (!isHTMLIdentifierCharacter(*BufferPtr))
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+/// Skip HTML string quoted in single or double quotes.  Escaping quotes inside
+/// string allowed.
+///
+/// Returns pointer to closing quote.
+const char *skipHTMLQuotedString(const char *BufferPtr, const char *BufferEnd)
+{
+  const char Quote = *BufferPtr;
+  assert(Quote == '\"' || Quote == '\'');
+
+  BufferPtr++;
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    const char C = *BufferPtr;
+    if (C == Quote && BufferPtr[-1] != '\\')
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+const char *skipWhitespace(const char *BufferPtr, const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (!isWhitespace(*BufferPtr))
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+bool isWhitespace(const char *BufferPtr, const char *BufferEnd) {
+  return skipWhitespace(BufferPtr, BufferEnd) == BufferEnd;
+}
+
+bool isCommandNameStartCharacter(char C) {
+  return isLetter(C);
+}
+
+bool isCommandNameCharacter(char C) {
+  return isAlphanumeric(C);
+}
+
+const char *skipCommandName(const char *BufferPtr, const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (!isCommandNameCharacter(*BufferPtr))
+      return BufferPtr;
+  }
+  return BufferEnd;
+}
+
+/// Return the one past end pointer for BCPL comments.
+/// Handles newlines escaped with backslash or trigraph for backslahs.
+const char *findBCPLCommentEnd(const char *BufferPtr, const char *BufferEnd) {
+  const char *CurPtr = BufferPtr;
+  while (CurPtr != BufferEnd) {
+    while (!isVerticalWhitespace(*CurPtr)) {
+      CurPtr++;
+      if (CurPtr == BufferEnd)
+        return BufferEnd;
+    }
+    // We found a newline, check if it is escaped.
+    const char *EscapePtr = CurPtr - 1;
+    while(isHorizontalWhitespace(*EscapePtr))
+      EscapePtr--;
+
+    if (*EscapePtr == '\\' ||
+        (EscapePtr - 2 >= BufferPtr && EscapePtr[0] == '/' &&
+         EscapePtr[-1] == '?' && EscapePtr[-2] == '?')) {
+      // We found an escaped newline.
+      CurPtr = skipNewline(CurPtr, BufferEnd);
+    } else
+      return CurPtr; // Not an escaped newline.
+  }
+  return BufferEnd;
+}
+
+/// Return the one past end pointer for C comments.
+/// Very dumb, does not handle escaped newlines or trigraphs.
+const char *findCCommentEnd(const char *BufferPtr, const char *BufferEnd) {
+  for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
+    if (*BufferPtr == '*') {
+      assert(BufferPtr + 1 != BufferEnd);
+      if (*(BufferPtr + 1) == '/')
+        return BufferPtr;
+    }
+  }
+  llvm_unreachable("buffer end hit before '*/' was seen");
+}
+
+} // end anonymous namespace
+
+void Lexer::formTokenWithChars(Token &Result, const char *TokEnd,
+                               tok::TokenKind Kind) {
+  const unsigned TokLen = TokEnd - BufferPtr;
+  Result.setLocation(getSourceLocation(BufferPtr));
+  Result.setKind(Kind);
+  Result.setLength(TokLen);
+#ifndef NDEBUG
+  Result.TextPtr = "<UNSET>";
+  Result.IntVal = 7;
+#endif
+  BufferPtr = TokEnd;
+}
+
+void Lexer::lexCommentText(Token &T) {
+  assert(CommentState == LCS_InsideBCPLComment ||
+         CommentState == LCS_InsideCComment);
+
+  // Handles lexing non-command text, i.e. text and newline.
+  auto HandleNonCommandToken = [&]() -> void {
+    assert(State == LS_Normal);
+
+    const char *TokenPtr = BufferPtr;
+    assert(TokenPtr < CommentEnd);
+    switch (*TokenPtr) {
+      case '\n':
+      case '\r':
+          TokenPtr = skipNewline(TokenPtr, CommentEnd);
+          formTokenWithChars(T, TokenPtr, tok::newline);
+
+          if (CommentState == LCS_InsideCComment)
+            skipLineStartingDecorations();
+          return;
+
+      default: {
+          StringRef TokStartSymbols = ParseCommands ? "\n\r\\@&<" : "\n\r";
+          size_t End = StringRef(TokenPtr, CommentEnd - TokenPtr)
+                           .find_first_of(TokStartSymbols);
+          if (End != StringRef::npos)
+            TokenPtr += End;
+          else
+            TokenPtr = CommentEnd;
+          formTextToken(T, TokenPtr);
+          return;
+      }
+    }
+  };
+
+  if (!ParseCommands)
+    return HandleNonCommandToken();
+
+  switch (State) {
+  case LS_Normal:
+    break;
+  case LS_VerbatimBlockFirstLine:
+    lexVerbatimBlockFirstLine(T);
+    return;
+  case LS_VerbatimBlockBody:
+    lexVerbatimBlockBody(T);
+    return;
+  case LS_VerbatimLineText:
+    lexVerbatimLineText(T);
+    return;
+  case LS_HTMLStartTag:
+    lexHTMLStartTag(T);
+    return;
+  case LS_HTMLEndTag:
+    lexHTMLEndTag(T);
+    return;
+  }
+
+  assert(State == LS_Normal);
+  const char *TokenPtr = BufferPtr;
+  assert(TokenPtr < CommentEnd);
+  switch(*TokenPtr) {
+    case '\\':
+    case '@': {
+      // Commands that start with a backslash and commands that start with
+      // 'at' have equivalent semantics.  But we keep information about the
+      // exact syntax in AST for comments.
+      tok::TokenKind CommandKind =
+          (*TokenPtr == '@') ? tok::at_command : tok::backslash_command;
+      TokenPtr++;
+      if (TokenPtr == CommentEnd) {
+        formTextToken(T, TokenPtr);
+        return;
+      }
+      char C = *TokenPtr;
+      switch (C) {
+      default:
+        break;
+
+      case '\\': case '@': case '&': case '$':
+      case '#':  case '<': case '>': case '%':
+      case '\"': case '.': case ':':
+        // This is one of \\ \@ \& \$ etc escape sequences.
+        TokenPtr++;
+        if (C == ':' && TokenPtr != CommentEnd && *TokenPtr == ':') {
+          // This is the \:: escape sequence.
+          TokenPtr++;
+        }
+        StringRef UnescapedText(BufferPtr + 1, TokenPtr - (BufferPtr + 1));
+        formTokenWithChars(T, TokenPtr, tok::text);
+        T.setText(UnescapedText);
+        return;
+      }
+
+      // Don't make zero-length commands.
+      if (!isCommandNameStartCharacter(*TokenPtr)) {
+        formTextToken(T, TokenPtr);
+        return;
+      }
+
+      TokenPtr = skipCommandName(TokenPtr, CommentEnd);
+      unsigned Length = TokenPtr - (BufferPtr + 1);
+
+      // Hardcoded support for lexing LaTeX formula commands
+      // \f$ \f[ \f] \f{ \f} as a single command.
+      if (Length == 1 && TokenPtr[-1] == 'f' && TokenPtr != CommentEnd) {
+        C = *TokenPtr;
+        if (C == '$' || C == '[' || C == ']' || C == '{' || C == '}') {
+          TokenPtr++;
+          Length++;
+        }
+      }
+
+      StringRef CommandName(BufferPtr + 1, Length);
+
+      const CommandInfo *Info = Traits.getCommandInfoOrNULL(CommandName);
+      if (!Info) {
+        if ((Info = Traits.getTypoCorrectCommandInfo(CommandName))) {
+          StringRef CorrectedName = Info->Name;
+          SourceLocation Loc = getSourceLocation(BufferPtr);
+          SourceLocation EndLoc = getSourceLocation(TokenPtr);
+          SourceRange FullRange = SourceRange(Loc, EndLoc);
+          SourceRange CommandRange(Loc.getLocWithOffset(1), EndLoc);
+          Diag(Loc, diag::warn_correct_comment_command_name)
+            << FullRange << CommandName << CorrectedName
+            << FixItHint::CreateReplacement(CommandRange, CorrectedName);
+        } else {
+          formTokenWithChars(T, TokenPtr, tok::unknown_command);
+          T.setUnknownCommandName(CommandName);
+          Diag(T.getLocation(), diag::warn_unknown_comment_command_name)
+              << SourceRange(T.getLocation(), T.getEndLocation());
+          return;
+        }
+      }
+      if (Info->IsVerbatimBlockCommand) {
+        setupAndLexVerbatimBlock(T, TokenPtr, *BufferPtr, Info);
+        return;
+      }
+      if (Info->IsVerbatimLineCommand) {
+        setupAndLexVerbatimLine(T, TokenPtr, Info);
+        return;
+      }
+      formTokenWithChars(T, TokenPtr, CommandKind);
+      T.setCommandID(Info->getID());
+      return;
+    }
+
+    case '&':
+      lexHTMLCharacterReference(T);
+      return;
+
+    case '<': {
+      TokenPtr++;
+      if (TokenPtr == CommentEnd) {
+        formTextToken(T, TokenPtr);
+        return;
+      }
+      const char C = *TokenPtr;
+      if (isHTMLIdentifierStartingCharacter(C))
+        setupAndLexHTMLStartTag(T);
+      else if (C == '/')
+        setupAndLexHTMLEndTag(T);
+      else
+        formTextToken(T, TokenPtr);
+      return;
+    }
+
+    default:
+      return HandleNonCommandToken();
+  }
+}
+
+void Lexer::setupAndLexVerbatimBlock(Token &T,
+                                     const char *TextBegin,
+                                     char Marker, const CommandInfo *Info) {
+  assert(Info->IsVerbatimBlockCommand);
+
+  VerbatimBlockEndCommandName.clear();
+  VerbatimBlockEndCommandName.append(Marker == '\\' ? "\\" : "@");
+  VerbatimBlockEndCommandName.append(Info->EndCommandName);
+
+  formTokenWithChars(T, TextBegin, tok::verbatim_block_begin);
+  T.setVerbatimBlockID(Info->getID());
+
+  // If there is a newline following the verbatim opening command, skip the
+  // newline so that we don't create an tok::verbatim_block_line with empty
+  // text content.
+  if (BufferPtr != CommentEnd &&
+      isVerticalWhitespace(*BufferPtr)) {
+    BufferPtr = skipNewline(BufferPtr, CommentEnd);
+    State = LS_VerbatimBlockBody;
+    return;
+  }
+
+  State = LS_VerbatimBlockFirstLine;
+}
+
+void Lexer::lexVerbatimBlockFirstLine(Token &T) {
+again:
+  assert(BufferPtr < CommentEnd);
+
+  // FIXME: It would be better to scan the text once, finding either the block
+  // end command or newline.
+  //
+  // Extract current line.
+  const char *Newline = findNewline(BufferPtr, CommentEnd);
+  StringRef Line(BufferPtr, Newline - BufferPtr);
+
+  // Look for end command in current line.
+  size_t Pos = Line.find(VerbatimBlockEndCommandName);
+  const char *TextEnd;
+  const char *NextLine;
+  if (Pos == StringRef::npos) {
+    // Current line is completely verbatim.
+    TextEnd = Newline;
+    NextLine = skipNewline(Newline, CommentEnd);
+  } else if (Pos == 0) {
+    // Current line contains just an end command.
+    const char *End = BufferPtr + VerbatimBlockEndCommandName.size();
+    StringRef Name(BufferPtr + 1, End - (BufferPtr + 1));
+    formTokenWithChars(T, End, tok::verbatim_block_end);
+    T.setVerbatimBlockID(Traits.getCommandInfo(Name)->getID());
+    State = LS_Normal;
+    return;
+  } else {
+    // There is some text, followed by end command.  Extract text first.
+    TextEnd = BufferPtr + Pos;
+    NextLine = TextEnd;
+    // If there is only whitespace before end command, skip whitespace.
+    if (isWhitespace(BufferPtr, TextEnd)) {
+      BufferPtr = TextEnd;
+      goto again;
+    }
+  }
+
+  StringRef Text(BufferPtr, TextEnd - BufferPtr);
+  formTokenWithChars(T, NextLine, tok::verbatim_block_line);
+  T.setVerbatimBlockText(Text);
+
+  State = LS_VerbatimBlockBody;
+}
+
+void Lexer::lexVerbatimBlockBody(Token &T) {
+  assert(State == LS_VerbatimBlockBody);
+
+  if (CommentState == LCS_InsideCComment)
+    skipLineStartingDecorations();
+
+  if (BufferPtr == CommentEnd) {
+    formTokenWithChars(T, BufferPtr, tok::verbatim_block_line);
+    T.setVerbatimBlockText("");
+    return;
+  }
+
+  lexVerbatimBlockFirstLine(T);
+}
+
+void Lexer::setupAndLexVerbatimLine(Token &T, const char *TextBegin,
+                                    const CommandInfo *Info) {
+  assert(Info->IsVerbatimLineCommand);
+  formTokenWithChars(T, TextBegin, tok::verbatim_line_name);
+  T.setVerbatimLineID(Info->getID());
+
+  State = LS_VerbatimLineText;
+}
+
+void Lexer::lexVerbatimLineText(Token &T) {
+  assert(State == LS_VerbatimLineText);
+
+  // Extract current line.
+  const char *Newline = findNewline(BufferPtr, CommentEnd);
+  StringRef Text(BufferPtr, Newline - BufferPtr);
+  formTokenWithChars(T, Newline, tok::verbatim_line_text);
+  T.setVerbatimLineText(Text);
+
+  State = LS_Normal;
+}
+
+void Lexer::lexHTMLCharacterReference(Token &T) {
+  const char *TokenPtr = BufferPtr;
+  assert(*TokenPtr == '&');
+  TokenPtr++;
+  if (TokenPtr == CommentEnd) {
+    formTextToken(T, TokenPtr);
+    return;
+  }
+  const char *NamePtr;
+  bool isNamed = false;
+  bool isDecimal = false;
+  char C = *TokenPtr;
+  if (isHTMLNamedCharacterReferenceCharacter(C)) {
+    NamePtr = TokenPtr;
+    TokenPtr = skipNamedCharacterReference(TokenPtr, CommentEnd);
+    isNamed = true;
+  } else if (C == '#') {
+    TokenPtr++;
+    if (TokenPtr == CommentEnd) {
+      formTextToken(T, TokenPtr);
+      return;
+    }
+    C = *TokenPtr;
+    if (isHTMLDecimalCharacterReferenceCharacter(C)) {
+      NamePtr = TokenPtr;
+      TokenPtr = skipDecimalCharacterReference(TokenPtr, CommentEnd);
+      isDecimal = true;
+    } else if (C == 'x' || C == 'X') {
+      TokenPtr++;
+      NamePtr = TokenPtr;
+      TokenPtr = skipHexCharacterReference(TokenPtr, CommentEnd);
+    } else {
+      formTextToken(T, TokenPtr);
+      return;
+    }
+  } else {
+    formTextToken(T, TokenPtr);
+    return;
+  }
+  if (NamePtr == TokenPtr || TokenPtr == CommentEnd ||
+      *TokenPtr != ';') {
+    formTextToken(T, TokenPtr);
+    return;
+  }
+  StringRef Name(NamePtr, TokenPtr - NamePtr);
+  TokenPtr++; // Skip semicolon.
+  StringRef Resolved;
+  if (isNamed)
+    Resolved = resolveHTMLNamedCharacterReference(Name);
+  else if (isDecimal)
+    Resolved = resolveHTMLDecimalCharacterReference(Name);
+  else
+    Resolved = resolveHTMLHexCharacterReference(Name);
+
+  if (Resolved.empty()) {
+    formTextToken(T, TokenPtr);
+    return;
+  }
+  formTokenWithChars(T, TokenPtr, tok::text);
+  T.setText(Resolved);
+}
+
+void Lexer::setupAndLexHTMLStartTag(Token &T) {
+  assert(BufferPtr[0] == '<' &&
+         isHTMLIdentifierStartingCharacter(BufferPtr[1]));
+  const char *TagNameEnd = skipHTMLIdentifier(BufferPtr + 2, CommentEnd);
+  StringRef Name(BufferPtr + 1, TagNameEnd - (BufferPtr + 1));
+  if (!isHTMLTagName(Name)) {
+    formTextToken(T, TagNameEnd);
+    return;
+  }
+
+  formTokenWithChars(T, TagNameEnd, tok::html_start_tag);
+  T.setHTMLTagStartName(Name);
+
+  BufferPtr = skipWhitespace(BufferPtr, CommentEnd);
+
+  const char C = *BufferPtr;
+  if (BufferPtr != CommentEnd &&
+      (C == '>' || C == '/' || isHTMLIdentifierStartingCharacter(C)))
+    State = LS_HTMLStartTag;
+}
+
+void Lexer::lexHTMLStartTag(Token &T) {
+  assert(State == LS_HTMLStartTag);
+
+  const char *TokenPtr = BufferPtr;
+  char C = *TokenPtr;
+  if (isHTMLIdentifierCharacter(C)) {
+    TokenPtr = skipHTMLIdentifier(TokenPtr, CommentEnd);
+    StringRef Ident(BufferPtr, TokenPtr - BufferPtr);
+    formTokenWithChars(T, TokenPtr, tok::html_ident);
+    T.setHTMLIdent(Ident);
+  } else {
+    switch (C) {
+    case '=':
+      TokenPtr++;
+      formTokenWithChars(T, TokenPtr, tok::html_equals);
+      break;
+    case '\"':
+    case '\'': {
+      const char *OpenQuote = TokenPtr;
+      TokenPtr = skipHTMLQuotedString(TokenPtr, CommentEnd);
+      const char *ClosingQuote = TokenPtr;
+      if (TokenPtr != CommentEnd) // Skip closing quote.
+        TokenPtr++;
+      formTokenWithChars(T, TokenPtr, tok::html_quoted_string);
+      T.setHTMLQuotedString(StringRef(OpenQuote + 1,
+                                      ClosingQuote - (OpenQuote + 1)));
+      break;
+    }
+    case '>':
+      TokenPtr++;
+      formTokenWithChars(T, TokenPtr, tok::html_greater);
+      State = LS_Normal;
+      return;
+    case '/':
+      TokenPtr++;
+      if (TokenPtr != CommentEnd && *TokenPtr == '>') {
+        TokenPtr++;
+        formTokenWithChars(T, TokenPtr, tok::html_slash_greater);
+      } else
+        formTextToken(T, TokenPtr);
+
+      State = LS_Normal;
+      return;
+    }
+  }
+
+  // Now look ahead and return to normal state if we don't see any HTML tokens
+  // ahead.
+  BufferPtr = skipWhitespace(BufferPtr, CommentEnd);
+  if (BufferPtr == CommentEnd) {
+    State = LS_Normal;
+    return;
+  }
+
+  C = *BufferPtr;
+  if (!isHTMLIdentifierStartingCharacter(C) &&
+      C != '=' && C != '\"' && C != '\'' && C != '>') {
+    State = LS_Normal;
+    return;
+  }
+}
+
+void Lexer::setupAndLexHTMLEndTag(Token &T) {
+  assert(BufferPtr[0] == '<' && BufferPtr[1] == '/');
+
+  const char *TagNameBegin = skipWhitespace(BufferPtr + 2, CommentEnd);
+  const char *TagNameEnd = skipHTMLIdentifier(TagNameBegin, CommentEnd);
+  StringRef Name(TagNameBegin, TagNameEnd - TagNameBegin);
+  if (!isHTMLTagName(Name)) {
+    formTextToken(T, TagNameEnd);
+    return;
+  }
+
+  const char *End = skipWhitespace(TagNameEnd, CommentEnd);
+
+  formTokenWithChars(T, End, tok::html_end_tag);
+  T.setHTMLTagEndName(Name);
+
+  if (BufferPtr != CommentEnd && *BufferPtr == '>')
+    State = LS_HTMLEndTag;
+}
+
+void Lexer::lexHTMLEndTag(Token &T) {
+  assert(BufferPtr != CommentEnd && *BufferPtr == '>');
+
+  formTokenWithChars(T, BufferPtr + 1, tok::html_greater);
+  State = LS_Normal;
+}
+
+Lexer::Lexer(llvm::BumpPtrAllocator &Allocator, DiagnosticsEngine &Diags,
+             const CommandTraits &Traits, SourceLocation FileLoc,
+             const char *BufferStart, const char *BufferEnd,
+             bool ParseCommands)
+    : Allocator(Allocator), Diags(Diags), Traits(Traits),
+      BufferStart(BufferStart), BufferEnd(BufferEnd), FileLoc(FileLoc),
+      BufferPtr(BufferStart), CommentState(LCS_BeforeComment), State(LS_Normal),
+      ParseCommands(ParseCommands) {}
+
+void Lexer::lex(Token &T) {
+again:
+  switch (CommentState) {
+  case LCS_BeforeComment:
+    if (BufferPtr == BufferEnd) {
+      formTokenWithChars(T, BufferPtr, tok::eof);
+      return;
+    }
+
+    assert(*BufferPtr == '/');
+    BufferPtr++; // Skip first slash.
+    switch(*BufferPtr) {
+    case '/': { // BCPL comment.
+      BufferPtr++; // Skip second slash.
+
+      if (BufferPtr != BufferEnd) {
+        // Skip Doxygen magic marker, if it is present.
+        // It might be missing because of a typo //< or /*<, or because we
+        // merged this non-Doxygen comment into a bunch of Doxygen comments
+        // around it: /** ... */ /* ... */ /** ... */
+        const char C = *BufferPtr;
+        if (C == '/' || C == '!')
+          BufferPtr++;
+      }
+
+      // Skip less-than symbol that marks trailing comments.
+      // Skip it even if the comment is not a Doxygen one, because //< and /*<
+      // are frequent typos.
+      if (BufferPtr != BufferEnd && *BufferPtr == '<')
+        BufferPtr++;
+
+      CommentState = LCS_InsideBCPLComment;
+      if (State != LS_VerbatimBlockBody && State != LS_VerbatimBlockFirstLine)
+        State = LS_Normal;
+      CommentEnd = findBCPLCommentEnd(BufferPtr, BufferEnd);
+      goto again;
+    }
+    case '*': { // C comment.
+      BufferPtr++; // Skip star.
+
+      // Skip Doxygen magic marker.
+      const char C = *BufferPtr;
+      if ((C == '*' && *(BufferPtr + 1) != '/') || C == '!')
+        BufferPtr++;
+
+      // Skip less-than symbol that marks trailing comments.
+      if (BufferPtr != BufferEnd && *BufferPtr == '<')
+        BufferPtr++;
+
+      CommentState = LCS_InsideCComment;
+      State = LS_Normal;
+      CommentEnd = findCCommentEnd(BufferPtr, BufferEnd);
+      goto again;
+    }
+    default:
+      llvm_unreachable("second character of comment should be '/' or '*'");
+    }
+
+  case LCS_BetweenComments: {
+    // Consecutive comments are extracted only if there is only whitespace
+    // between them.  So we can search for the start of the next comment.
+    const char *EndWhitespace = BufferPtr;
+    while(EndWhitespace != BufferEnd && *EndWhitespace != '/')
+      EndWhitespace++;
+
+    // Turn any whitespace between comments (and there is only whitespace
+    // between them -- guaranteed by comment extraction) into a newline.  We
+    // have two newlines between C comments in total (first one was synthesized
+    // after a comment).
+    formTokenWithChars(T, EndWhitespace, tok::newline);
+
+    CommentState = LCS_BeforeComment;
+    break;
+  }
+
+  case LCS_InsideBCPLComment:
+  case LCS_InsideCComment:
+    if (BufferPtr != CommentEnd) {
+      lexCommentText(T);
+      break;
+    } else {
+      // Skip C comment closing sequence.
+      if (CommentState == LCS_InsideCComment) {
+        assert(BufferPtr[0] == '*' && BufferPtr[1] == '/');
+        BufferPtr += 2;
+        assert(BufferPtr <= BufferEnd);
+
+        // Synthenize newline just after the C comment, regardless if there is
+        // actually a newline.
+        formTokenWithChars(T, BufferPtr, tok::newline);
+
+        CommentState = LCS_BetweenComments;
+        break;
+      } else {
+        // Don't synthesized a newline after BCPL comment.
+        CommentState = LCS_BetweenComments;
+        goto again;
+      }
+    }
+  }
+}
+
+StringRef Lexer::getSpelling(const Token &Tok,
+                             const SourceManager &SourceMgr) const {
+  SourceLocation Loc = Tok.getLocation();
+  std::pair<FileID, unsigned> LocInfo = SourceMgr.getDecomposedLoc(Loc);
+
+  bool InvalidTemp = false;
+  StringRef File = SourceMgr.getBufferData(LocInfo.first, &InvalidTemp);
+  if (InvalidTemp)
+    return StringRef();
+
+  const char *Begin = File.data() + LocInfo.second;
+  return StringRef(Begin, Tok.getLength());
+}
+
+} // end namespace comments
+} // end namespace clang