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      1 #include "clang/AST/CommentLexer.h"
      2 #include "clang/AST/CommentCommandTraits.h"
      3 #include "clang/AST/CommentDiagnostic.h"
      4 #include "clang/Basic/CharInfo.h"
      5 #include "llvm/ADT/StringExtras.h"
      6 #include "llvm/ADT/StringSwitch.h"
      7 #include "llvm/Support/ConvertUTF.h"
      8 #include "llvm/Support/ErrorHandling.h"
      9 
     10 namespace clang {
     11 namespace comments {
     12 
     13 void Token::dump(const Lexer &L, const SourceManager &SM) const {
     14   llvm::errs() << "comments::Token Kind=" << Kind << " ";
     15   Loc.dump(SM);
     16   llvm::errs() << " " << Length << " \"" << L.getSpelling(*this, SM) << "\"\n";
     17 }
     18 
     19 static inline bool isHTMLNamedCharacterReferenceCharacter(char C) {
     20   return isLetter(C);
     21 }
     22 
     23 static inline bool isHTMLDecimalCharacterReferenceCharacter(char C) {
     24   return isDigit(C);
     25 }
     26 
     27 static inline bool isHTMLHexCharacterReferenceCharacter(char C) {
     28   return isHexDigit(C);
     29 }
     30 
     31 static inline StringRef convertCodePointToUTF8(
     32                                       llvm::BumpPtrAllocator &Allocator,
     33                                       unsigned CodePoint) {
     34   char *Resolved = Allocator.Allocate<char>(UNI_MAX_UTF8_BYTES_PER_CODE_POINT);
     35   char *ResolvedPtr = Resolved;
     36   if (llvm::ConvertCodePointToUTF8(CodePoint, ResolvedPtr))
     37     return StringRef(Resolved, ResolvedPtr - Resolved);
     38   else
     39     return StringRef();
     40 }
     41 
     42 namespace {
     43 
     44 #include "clang/AST/CommentHTMLTags.inc"
     45 #include "clang/AST/CommentHTMLNamedCharacterReferences.inc"
     46 
     47 } // unnamed namespace
     48 
     49 StringRef Lexer::resolveHTMLNamedCharacterReference(StringRef Name) const {
     50   // Fast path, first check a few most widely used named character references.
     51   return llvm::StringSwitch<StringRef>(Name)
     52       .Case("amp", "&")
     53       .Case("lt", "<")
     54       .Case("gt", ">")
     55       .Case("quot", "\"")
     56       .Case("apos", "\'")
     57       // Slow path.
     58       .Default(translateHTMLNamedCharacterReferenceToUTF8(Name));
     59 }
     60 
     61 StringRef Lexer::resolveHTMLDecimalCharacterReference(StringRef Name) const {
     62   unsigned CodePoint = 0;
     63   for (unsigned i = 0, e = Name.size(); i != e; ++i) {
     64     assert(isHTMLDecimalCharacterReferenceCharacter(Name[i]));
     65     CodePoint *= 10;
     66     CodePoint += Name[i] - '0';
     67   }
     68   return convertCodePointToUTF8(Allocator, CodePoint);
     69 }
     70 
     71 StringRef Lexer::resolveHTMLHexCharacterReference(StringRef Name) const {
     72   unsigned CodePoint = 0;
     73   for (unsigned i = 0, e = Name.size(); i != e; ++i) {
     74     CodePoint *= 16;
     75     const char C = Name[i];
     76     assert(isHTMLHexCharacterReferenceCharacter(C));
     77     CodePoint += llvm::hexDigitValue(C);
     78   }
     79   return convertCodePointToUTF8(Allocator, CodePoint);
     80 }
     81 
     82 void Lexer::skipLineStartingDecorations() {
     83   // This function should be called only for C comments
     84   assert(CommentState == LCS_InsideCComment);
     85 
     86   if (BufferPtr == CommentEnd)
     87     return;
     88 
     89   switch (*BufferPtr) {
     90   case ' ':
     91   case '\t':
     92   case '\f':
     93   case '\v': {
     94     const char *NewBufferPtr = BufferPtr;
     95     NewBufferPtr++;
     96     if (NewBufferPtr == CommentEnd)
     97       return;
     98 
     99     char C = *NewBufferPtr;
    100     while (isHorizontalWhitespace(C)) {
    101       NewBufferPtr++;
    102       if (NewBufferPtr == CommentEnd)
    103         return;
    104       C = *NewBufferPtr;
    105     }
    106     if (C == '*')
    107       BufferPtr = NewBufferPtr + 1;
    108     break;
    109   }
    110   case '*':
    111     BufferPtr++;
    112     break;
    113   }
    114 }
    115 
    116 namespace {
    117 /// Returns pointer to the first newline character in the string.
    118 const char *findNewline(const char *BufferPtr, const char *BufferEnd) {
    119   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    120     if (isVerticalWhitespace(*BufferPtr))
    121       return BufferPtr;
    122   }
    123   return BufferEnd;
    124 }
    125 
    126 const char *skipNewline(const char *BufferPtr, const char *BufferEnd) {
    127   if (BufferPtr == BufferEnd)
    128     return BufferPtr;
    129 
    130   if (*BufferPtr == '\n')
    131     BufferPtr++;
    132   else {
    133     assert(*BufferPtr == '\r');
    134     BufferPtr++;
    135     if (BufferPtr != BufferEnd && *BufferPtr == '\n')
    136       BufferPtr++;
    137   }
    138   return BufferPtr;
    139 }
    140 
    141 const char *skipNamedCharacterReference(const char *BufferPtr,
    142                                         const char *BufferEnd) {
    143   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    144     if (!isHTMLNamedCharacterReferenceCharacter(*BufferPtr))
    145       return BufferPtr;
    146   }
    147   return BufferEnd;
    148 }
    149 
    150 const char *skipDecimalCharacterReference(const char *BufferPtr,
    151                                           const char *BufferEnd) {
    152   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    153     if (!isHTMLDecimalCharacterReferenceCharacter(*BufferPtr))
    154       return BufferPtr;
    155   }
    156   return BufferEnd;
    157 }
    158 
    159 const char *skipHexCharacterReference(const char *BufferPtr,
    160                                           const char *BufferEnd) {
    161   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    162     if (!isHTMLHexCharacterReferenceCharacter(*BufferPtr))
    163       return BufferPtr;
    164   }
    165   return BufferEnd;
    166 }
    167 
    168 bool isHTMLIdentifierStartingCharacter(char C) {
    169   return isLetter(C);
    170 }
    171 
    172 bool isHTMLIdentifierCharacter(char C) {
    173   return isAlphanumeric(C);
    174 }
    175 
    176 const char *skipHTMLIdentifier(const char *BufferPtr, const char *BufferEnd) {
    177   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    178     if (!isHTMLIdentifierCharacter(*BufferPtr))
    179       return BufferPtr;
    180   }
    181   return BufferEnd;
    182 }
    183 
    184 /// Skip HTML string quoted in single or double quotes.  Escaping quotes inside
    185 /// string allowed.
    186 ///
    187 /// Returns pointer to closing quote.
    188 const char *skipHTMLQuotedString(const char *BufferPtr, const char *BufferEnd)
    189 {
    190   const char Quote = *BufferPtr;
    191   assert(Quote == '\"' || Quote == '\'');
    192 
    193   BufferPtr++;
    194   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    195     const char C = *BufferPtr;
    196     if (C == Quote && BufferPtr[-1] != '\\')
    197       return BufferPtr;
    198   }
    199   return BufferEnd;
    200 }
    201 
    202 const char *skipWhitespace(const char *BufferPtr, const char *BufferEnd) {
    203   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    204     if (!isWhitespace(*BufferPtr))
    205       return BufferPtr;
    206   }
    207   return BufferEnd;
    208 }
    209 
    210 bool isWhitespace(const char *BufferPtr, const char *BufferEnd) {
    211   return skipWhitespace(BufferPtr, BufferEnd) == BufferEnd;
    212 }
    213 
    214 bool isCommandNameStartCharacter(char C) {
    215   return isLetter(C);
    216 }
    217 
    218 bool isCommandNameCharacter(char C) {
    219   return isAlphanumeric(C);
    220 }
    221 
    222 const char *skipCommandName(const char *BufferPtr, const char *BufferEnd) {
    223   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    224     if (!isCommandNameCharacter(*BufferPtr))
    225       return BufferPtr;
    226   }
    227   return BufferEnd;
    228 }
    229 
    230 /// Return the one past end pointer for BCPL comments.
    231 /// Handles newlines escaped with backslash or trigraph for backslahs.
    232 const char *findBCPLCommentEnd(const char *BufferPtr, const char *BufferEnd) {
    233   const char *CurPtr = BufferPtr;
    234   while (CurPtr != BufferEnd) {
    235     while (!isVerticalWhitespace(*CurPtr)) {
    236       CurPtr++;
    237       if (CurPtr == BufferEnd)
    238         return BufferEnd;
    239     }
    240     // We found a newline, check if it is escaped.
    241     const char *EscapePtr = CurPtr - 1;
    242     while(isHorizontalWhitespace(*EscapePtr))
    243       EscapePtr--;
    244 
    245     if (*EscapePtr == '\\' ||
    246         (EscapePtr - 2 >= BufferPtr && EscapePtr[0] == '/' &&
    247          EscapePtr[-1] == '?' && EscapePtr[-2] == '?')) {
    248       // We found an escaped newline.
    249       CurPtr = skipNewline(CurPtr, BufferEnd);
    250     } else
    251       return CurPtr; // Not an escaped newline.
    252   }
    253   return BufferEnd;
    254 }
    255 
    256 /// Return the one past end pointer for C comments.
    257 /// Very dumb, does not handle escaped newlines or trigraphs.
    258 const char *findCCommentEnd(const char *BufferPtr, const char *BufferEnd) {
    259   for ( ; BufferPtr != BufferEnd; ++BufferPtr) {
    260     if (*BufferPtr == '*') {
    261       assert(BufferPtr + 1 != BufferEnd);
    262       if (*(BufferPtr + 1) == '/')
    263         return BufferPtr;
    264     }
    265   }
    266   llvm_unreachable("buffer end hit before '*/' was seen");
    267 }
    268 
    269 } // unnamed namespace
    270 
    271 void Lexer::lexCommentText(Token &T) {
    272   assert(CommentState == LCS_InsideBCPLComment ||
    273          CommentState == LCS_InsideCComment);
    274 
    275   switch (State) {
    276   case LS_Normal:
    277     break;
    278   case LS_VerbatimBlockFirstLine:
    279     lexVerbatimBlockFirstLine(T);
    280     return;
    281   case LS_VerbatimBlockBody:
    282     lexVerbatimBlockBody(T);
    283     return;
    284   case LS_VerbatimLineText:
    285     lexVerbatimLineText(T);
    286     return;
    287   case LS_HTMLStartTag:
    288     lexHTMLStartTag(T);
    289     return;
    290   case LS_HTMLEndTag:
    291     lexHTMLEndTag(T);
    292     return;
    293   }
    294 
    295   assert(State == LS_Normal);
    296 
    297   const char *TokenPtr = BufferPtr;
    298   assert(TokenPtr < CommentEnd);
    299   while (TokenPtr != CommentEnd) {
    300     switch(*TokenPtr) {
    301       case '\\':
    302       case '@': {
    303         // Commands that start with a backslash and commands that start with
    304         // 'at' have equivalent semantics.  But we keep information about the
    305         // exact syntax in AST for comments.
    306         tok::TokenKind CommandKind =
    307             (*TokenPtr == '@') ? tok::at_command : tok::backslash_command;
    308         TokenPtr++;
    309         if (TokenPtr == CommentEnd) {
    310           formTextToken(T, TokenPtr);
    311           return;
    312         }
    313         char C = *TokenPtr;
    314         switch (C) {
    315         default:
    316           break;
    317 
    318         case '\\': case '@': case '&': case '$':
    319         case '#':  case '<': case '>': case '%':
    320         case '\"': case '.': case ':':
    321           // This is one of \\ \@ \& \$ etc escape sequences.
    322           TokenPtr++;
    323           if (C == ':' && TokenPtr != CommentEnd && *TokenPtr == ':') {
    324             // This is the \:: escape sequence.
    325             TokenPtr++;
    326           }
    327           StringRef UnescapedText(BufferPtr + 1, TokenPtr - (BufferPtr + 1));
    328           formTokenWithChars(T, TokenPtr, tok::text);
    329           T.setText(UnescapedText);
    330           return;
    331         }
    332 
    333         // Don't make zero-length commands.
    334         if (!isCommandNameStartCharacter(*TokenPtr)) {
    335           formTextToken(T, TokenPtr);
    336           return;
    337         }
    338 
    339         TokenPtr = skipCommandName(TokenPtr, CommentEnd);
    340         unsigned Length = TokenPtr - (BufferPtr + 1);
    341 
    342         // Hardcoded support for lexing LaTeX formula commands
    343         // \f$ \f[ \f] \f{ \f} as a single command.
    344         if (Length == 1 && TokenPtr[-1] == 'f' && TokenPtr != CommentEnd) {
    345           C = *TokenPtr;
    346           if (C == '$' || C == '[' || C == ']' || C == '{' || C == '}') {
    347             TokenPtr++;
    348             Length++;
    349           }
    350         }
    351 
    352         const StringRef CommandName(BufferPtr + 1, Length);
    353 
    354         const CommandInfo *Info = Traits.getCommandInfoOrNULL(CommandName);
    355         if (!Info) {
    356           formTokenWithChars(T, TokenPtr, tok::unknown_command);
    357           T.setUnknownCommandName(CommandName);
    358           if ((Info = Traits.getTypoCorrectCommandInfo(CommandName))) {
    359             StringRef CorrectedName = Info->Name;
    360             SourceRange CommandRange(T.getLocation().getLocWithOffset(1),
    361                                      T.getEndLocation());
    362             Diag(T.getLocation(), diag::warn_correct_comment_command_name)
    363               << CommandName << CorrectedName
    364               << FixItHint::CreateReplacement(CommandRange, CorrectedName);
    365           } else {
    366             Diag(T.getLocation(), diag::warn_unknown_comment_command_name);
    367             return;
    368           }
    369         }
    370         if (Info->IsVerbatimBlockCommand) {
    371           setupAndLexVerbatimBlock(T, TokenPtr, *BufferPtr, Info);
    372           return;
    373         }
    374         if (Info->IsVerbatimLineCommand) {
    375           setupAndLexVerbatimLine(T, TokenPtr, Info);
    376           return;
    377         }
    378         formTokenWithChars(T, TokenPtr, CommandKind);
    379         T.setCommandID(Info->getID());
    380         return;
    381       }
    382 
    383       case '&':
    384         lexHTMLCharacterReference(T);
    385         return;
    386 
    387       case '<': {
    388         TokenPtr++;
    389         if (TokenPtr == CommentEnd) {
    390           formTextToken(T, TokenPtr);
    391           return;
    392         }
    393         const char C = *TokenPtr;
    394         if (isHTMLIdentifierStartingCharacter(C))
    395           setupAndLexHTMLStartTag(T);
    396         else if (C == '/')
    397           setupAndLexHTMLEndTag(T);
    398         else
    399           formTextToken(T, TokenPtr);
    400 
    401         return;
    402       }
    403 
    404       case '\n':
    405       case '\r':
    406         TokenPtr = skipNewline(TokenPtr, CommentEnd);
    407         formTokenWithChars(T, TokenPtr, tok::newline);
    408 
    409         if (CommentState == LCS_InsideCComment)
    410           skipLineStartingDecorations();
    411         return;
    412 
    413       default: {
    414         size_t End = StringRef(TokenPtr, CommentEnd - TokenPtr).
    415                          find_first_of("\n\r\\@&<");
    416         if (End != StringRef::npos)
    417           TokenPtr += End;
    418         else
    419           TokenPtr = CommentEnd;
    420         formTextToken(T, TokenPtr);
    421         return;
    422       }
    423     }
    424   }
    425 }
    426 
    427 void Lexer::setupAndLexVerbatimBlock(Token &T,
    428                                      const char *TextBegin,
    429                                      char Marker, const CommandInfo *Info) {
    430   assert(Info->IsVerbatimBlockCommand);
    431 
    432   VerbatimBlockEndCommandName.clear();
    433   VerbatimBlockEndCommandName.append(Marker == '\\' ? "\\" : "@");
    434   VerbatimBlockEndCommandName.append(Info->EndCommandName);
    435 
    436   formTokenWithChars(T, TextBegin, tok::verbatim_block_begin);
    437   T.setVerbatimBlockID(Info->getID());
    438 
    439   // If there is a newline following the verbatim opening command, skip the
    440   // newline so that we don't create an tok::verbatim_block_line with empty
    441   // text content.
    442   if (BufferPtr != CommentEnd &&
    443       isVerticalWhitespace(*BufferPtr)) {
    444     BufferPtr = skipNewline(BufferPtr, CommentEnd);
    445     State = LS_VerbatimBlockBody;
    446     return;
    447   }
    448 
    449   State = LS_VerbatimBlockFirstLine;
    450 }
    451 
    452 void Lexer::lexVerbatimBlockFirstLine(Token &T) {
    453 again:
    454   assert(BufferPtr < CommentEnd);
    455 
    456   // FIXME: It would be better to scan the text once, finding either the block
    457   // end command or newline.
    458   //
    459   // Extract current line.
    460   const char *Newline = findNewline(BufferPtr, CommentEnd);
    461   StringRef Line(BufferPtr, Newline - BufferPtr);
    462 
    463   // Look for end command in current line.
    464   size_t Pos = Line.find(VerbatimBlockEndCommandName);
    465   const char *TextEnd;
    466   const char *NextLine;
    467   if (Pos == StringRef::npos) {
    468     // Current line is completely verbatim.
    469     TextEnd = Newline;
    470     NextLine = skipNewline(Newline, CommentEnd);
    471   } else if (Pos == 0) {
    472     // Current line contains just an end command.
    473     const char *End = BufferPtr + VerbatimBlockEndCommandName.size();
    474     StringRef Name(BufferPtr + 1, End - (BufferPtr + 1));
    475     formTokenWithChars(T, End, tok::verbatim_block_end);
    476     T.setVerbatimBlockID(Traits.getCommandInfo(Name)->getID());
    477     State = LS_Normal;
    478     return;
    479   } else {
    480     // There is some text, followed by end command.  Extract text first.
    481     TextEnd = BufferPtr + Pos;
    482     NextLine = TextEnd;
    483     // If there is only whitespace before end command, skip whitespace.
    484     if (isWhitespace(BufferPtr, TextEnd)) {
    485       BufferPtr = TextEnd;
    486       goto again;
    487     }
    488   }
    489 
    490   StringRef Text(BufferPtr, TextEnd - BufferPtr);
    491   formTokenWithChars(T, NextLine, tok::verbatim_block_line);
    492   T.setVerbatimBlockText(Text);
    493 
    494   State = LS_VerbatimBlockBody;
    495 }
    496 
    497 void Lexer::lexVerbatimBlockBody(Token &T) {
    498   assert(State == LS_VerbatimBlockBody);
    499 
    500   if (CommentState == LCS_InsideCComment)
    501     skipLineStartingDecorations();
    502 
    503   lexVerbatimBlockFirstLine(T);
    504 }
    505 
    506 void Lexer::setupAndLexVerbatimLine(Token &T, const char *TextBegin,
    507                                     const CommandInfo *Info) {
    508   assert(Info->IsVerbatimLineCommand);
    509   formTokenWithChars(T, TextBegin, tok::verbatim_line_name);
    510   T.setVerbatimLineID(Info->getID());
    511 
    512   State = LS_VerbatimLineText;
    513 }
    514 
    515 void Lexer::lexVerbatimLineText(Token &T) {
    516   assert(State == LS_VerbatimLineText);
    517 
    518   // Extract current line.
    519   const char *Newline = findNewline(BufferPtr, CommentEnd);
    520   const StringRef Text(BufferPtr, Newline - BufferPtr);
    521   formTokenWithChars(T, Newline, tok::verbatim_line_text);
    522   T.setVerbatimLineText(Text);
    523 
    524   State = LS_Normal;
    525 }
    526 
    527 void Lexer::lexHTMLCharacterReference(Token &T) {
    528   const char *TokenPtr = BufferPtr;
    529   assert(*TokenPtr == '&');
    530   TokenPtr++;
    531   if (TokenPtr == CommentEnd) {
    532     formTextToken(T, TokenPtr);
    533     return;
    534   }
    535   const char *NamePtr;
    536   bool isNamed = false;
    537   bool isDecimal = false;
    538   char C = *TokenPtr;
    539   if (isHTMLNamedCharacterReferenceCharacter(C)) {
    540     NamePtr = TokenPtr;
    541     TokenPtr = skipNamedCharacterReference(TokenPtr, CommentEnd);
    542     isNamed = true;
    543   } else if (C == '#') {
    544     TokenPtr++;
    545     if (TokenPtr == CommentEnd) {
    546       formTextToken(T, TokenPtr);
    547       return;
    548     }
    549     C = *TokenPtr;
    550     if (isHTMLDecimalCharacterReferenceCharacter(C)) {
    551       NamePtr = TokenPtr;
    552       TokenPtr = skipDecimalCharacterReference(TokenPtr, CommentEnd);
    553       isDecimal = true;
    554     } else if (C == 'x' || C == 'X') {
    555       TokenPtr++;
    556       NamePtr = TokenPtr;
    557       TokenPtr = skipHexCharacterReference(TokenPtr, CommentEnd);
    558     } else {
    559       formTextToken(T, TokenPtr);
    560       return;
    561     }
    562   } else {
    563     formTextToken(T, TokenPtr);
    564     return;
    565   }
    566   if (NamePtr == TokenPtr || TokenPtr == CommentEnd ||
    567       *TokenPtr != ';') {
    568     formTextToken(T, TokenPtr);
    569     return;
    570   }
    571   StringRef Name(NamePtr, TokenPtr - NamePtr);
    572   TokenPtr++; // Skip semicolon.
    573   StringRef Resolved;
    574   if (isNamed)
    575     Resolved = resolveHTMLNamedCharacterReference(Name);
    576   else if (isDecimal)
    577     Resolved = resolveHTMLDecimalCharacterReference(Name);
    578   else
    579     Resolved = resolveHTMLHexCharacterReference(Name);
    580 
    581   if (Resolved.empty()) {
    582     formTextToken(T, TokenPtr);
    583     return;
    584   }
    585   formTokenWithChars(T, TokenPtr, tok::text);
    586   T.setText(Resolved);
    587   return;
    588 }
    589 
    590 void Lexer::setupAndLexHTMLStartTag(Token &T) {
    591   assert(BufferPtr[0] == '<' &&
    592          isHTMLIdentifierStartingCharacter(BufferPtr[1]));
    593   const char *TagNameEnd = skipHTMLIdentifier(BufferPtr + 2, CommentEnd);
    594   StringRef Name(BufferPtr + 1, TagNameEnd - (BufferPtr + 1));
    595   if (!isHTMLTagName(Name)) {
    596     formTextToken(T, TagNameEnd);
    597     return;
    598   }
    599 
    600   formTokenWithChars(T, TagNameEnd, tok::html_start_tag);
    601   T.setHTMLTagStartName(Name);
    602 
    603   BufferPtr = skipWhitespace(BufferPtr, CommentEnd);
    604 
    605   const char C = *BufferPtr;
    606   if (BufferPtr != CommentEnd &&
    607       (C == '>' || C == '/' || isHTMLIdentifierStartingCharacter(C)))
    608     State = LS_HTMLStartTag;
    609 }
    610 
    611 void Lexer::lexHTMLStartTag(Token &T) {
    612   assert(State == LS_HTMLStartTag);
    613 
    614   const char *TokenPtr = BufferPtr;
    615   char C = *TokenPtr;
    616   if (isHTMLIdentifierCharacter(C)) {
    617     TokenPtr = skipHTMLIdentifier(TokenPtr, CommentEnd);
    618     StringRef Ident(BufferPtr, TokenPtr - BufferPtr);
    619     formTokenWithChars(T, TokenPtr, tok::html_ident);
    620     T.setHTMLIdent(Ident);
    621   } else {
    622     switch (C) {
    623     case '=':
    624       TokenPtr++;
    625       formTokenWithChars(T, TokenPtr, tok::html_equals);
    626       break;
    627     case '\"':
    628     case '\'': {
    629       const char *OpenQuote = TokenPtr;
    630       TokenPtr = skipHTMLQuotedString(TokenPtr, CommentEnd);
    631       const char *ClosingQuote = TokenPtr;
    632       if (TokenPtr != CommentEnd) // Skip closing quote.
    633         TokenPtr++;
    634       formTokenWithChars(T, TokenPtr, tok::html_quoted_string);
    635       T.setHTMLQuotedString(StringRef(OpenQuote + 1,
    636                                       ClosingQuote - (OpenQuote + 1)));
    637       break;
    638     }
    639     case '>':
    640       TokenPtr++;
    641       formTokenWithChars(T, TokenPtr, tok::html_greater);
    642       State = LS_Normal;
    643       return;
    644     case '/':
    645       TokenPtr++;
    646       if (TokenPtr != CommentEnd && *TokenPtr == '>') {
    647         TokenPtr++;
    648         formTokenWithChars(T, TokenPtr, tok::html_slash_greater);
    649       } else
    650         formTextToken(T, TokenPtr);
    651 
    652       State = LS_Normal;
    653       return;
    654     }
    655   }
    656 
    657   // Now look ahead and return to normal state if we don't see any HTML tokens
    658   // ahead.
    659   BufferPtr = skipWhitespace(BufferPtr, CommentEnd);
    660   if (BufferPtr == CommentEnd) {
    661     State = LS_Normal;
    662     return;
    663   }
    664 
    665   C = *BufferPtr;
    666   if (!isHTMLIdentifierStartingCharacter(C) &&
    667       C != '=' && C != '\"' && C != '\'' && C != '>') {
    668     State = LS_Normal;
    669     return;
    670   }
    671 }
    672 
    673 void Lexer::setupAndLexHTMLEndTag(Token &T) {
    674   assert(BufferPtr[0] == '<' && BufferPtr[1] == '/');
    675 
    676   const char *TagNameBegin = skipWhitespace(BufferPtr + 2, CommentEnd);
    677   const char *TagNameEnd = skipHTMLIdentifier(TagNameBegin, CommentEnd);
    678   StringRef Name(TagNameBegin, TagNameEnd - TagNameBegin);
    679   if (!isHTMLTagName(Name)) {
    680     formTextToken(T, TagNameEnd);
    681     return;
    682   }
    683 
    684   const char *End = skipWhitespace(TagNameEnd, CommentEnd);
    685 
    686   formTokenWithChars(T, End, tok::html_end_tag);
    687   T.setHTMLTagEndName(Name);
    688 
    689   if (BufferPtr != CommentEnd && *BufferPtr == '>')
    690     State = LS_HTMLEndTag;
    691 }
    692 
    693 void Lexer::lexHTMLEndTag(Token &T) {
    694   assert(BufferPtr != CommentEnd && *BufferPtr == '>');
    695 
    696   formTokenWithChars(T, BufferPtr + 1, tok::html_greater);
    697   State = LS_Normal;
    698 }
    699 
    700 Lexer::Lexer(llvm::BumpPtrAllocator &Allocator, DiagnosticsEngine &Diags,
    701              const CommandTraits &Traits,
    702              SourceLocation FileLoc,
    703              const char *BufferStart, const char *BufferEnd):
    704     Allocator(Allocator), Diags(Diags), Traits(Traits),
    705     BufferStart(BufferStart), BufferEnd(BufferEnd),
    706     FileLoc(FileLoc), BufferPtr(BufferStart),
    707     CommentState(LCS_BeforeComment), State(LS_Normal) {
    708 }
    709 
    710 void Lexer::lex(Token &T) {
    711 again:
    712   switch (CommentState) {
    713   case LCS_BeforeComment:
    714     if (BufferPtr == BufferEnd) {
    715       formTokenWithChars(T, BufferPtr, tok::eof);
    716       return;
    717     }
    718 
    719     assert(*BufferPtr == '/');
    720     BufferPtr++; // Skip first slash.
    721     switch(*BufferPtr) {
    722     case '/': { // BCPL comment.
    723       BufferPtr++; // Skip second slash.
    724 
    725       if (BufferPtr != BufferEnd) {
    726         // Skip Doxygen magic marker, if it is present.
    727         // It might be missing because of a typo //< or /*<, or because we
    728         // merged this non-Doxygen comment into a bunch of Doxygen comments
    729         // around it: /** ... */ /* ... */ /** ... */
    730         const char C = *BufferPtr;
    731         if (C == '/' || C == '!')
    732           BufferPtr++;
    733       }
    734 
    735       // Skip less-than symbol that marks trailing comments.
    736       // Skip it even if the comment is not a Doxygen one, because //< and /*<
    737       // are frequent typos.
    738       if (BufferPtr != BufferEnd && *BufferPtr == '<')
    739         BufferPtr++;
    740 
    741       CommentState = LCS_InsideBCPLComment;
    742       if (State != LS_VerbatimBlockBody && State != LS_VerbatimBlockFirstLine)
    743         State = LS_Normal;
    744       CommentEnd = findBCPLCommentEnd(BufferPtr, BufferEnd);
    745       goto again;
    746     }
    747     case '*': { // C comment.
    748       BufferPtr++; // Skip star.
    749 
    750       // Skip Doxygen magic marker.
    751       const char C = *BufferPtr;
    752       if ((C == '*' && *(BufferPtr + 1) != '/') || C == '!')
    753         BufferPtr++;
    754 
    755       // Skip less-than symbol that marks trailing comments.
    756       if (BufferPtr != BufferEnd && *BufferPtr == '<')
    757         BufferPtr++;
    758 
    759       CommentState = LCS_InsideCComment;
    760       State = LS_Normal;
    761       CommentEnd = findCCommentEnd(BufferPtr, BufferEnd);
    762       goto again;
    763     }
    764     default:
    765       llvm_unreachable("second character of comment should be '/' or '*'");
    766     }
    767 
    768   case LCS_BetweenComments: {
    769     // Consecutive comments are extracted only if there is only whitespace
    770     // between them.  So we can search for the start of the next comment.
    771     const char *EndWhitespace = BufferPtr;
    772     while(EndWhitespace != BufferEnd && *EndWhitespace != '/')
    773       EndWhitespace++;
    774 
    775     // Turn any whitespace between comments (and there is only whitespace
    776     // between them -- guaranteed by comment extraction) into a newline.  We
    777     // have two newlines between C comments in total (first one was synthesized
    778     // after a comment).
    779     formTokenWithChars(T, EndWhitespace, tok::newline);
    780 
    781     CommentState = LCS_BeforeComment;
    782     break;
    783   }
    784 
    785   case LCS_InsideBCPLComment:
    786   case LCS_InsideCComment:
    787     if (BufferPtr != CommentEnd) {
    788       lexCommentText(T);
    789       break;
    790     } else {
    791       // Skip C comment closing sequence.
    792       if (CommentState == LCS_InsideCComment) {
    793         assert(BufferPtr[0] == '*' && BufferPtr[1] == '/');
    794         BufferPtr += 2;
    795         assert(BufferPtr <= BufferEnd);
    796 
    797         // Synthenize newline just after the C comment, regardless if there is
    798         // actually a newline.
    799         formTokenWithChars(T, BufferPtr, tok::newline);
    800 
    801         CommentState = LCS_BetweenComments;
    802         break;
    803       } else {
    804         // Don't synthesized a newline after BCPL comment.
    805         CommentState = LCS_BetweenComments;
    806         goto again;
    807       }
    808     }
    809   }
    810 }
    811 
    812 StringRef Lexer::getSpelling(const Token &Tok,
    813                              const SourceManager &SourceMgr,
    814                              bool *Invalid) const {
    815   SourceLocation Loc = Tok.getLocation();
    816   std::pair<FileID, unsigned> LocInfo = SourceMgr.getDecomposedLoc(Loc);
    817 
    818   bool InvalidTemp = false;
    819   StringRef File = SourceMgr.getBufferData(LocInfo.first, &InvalidTemp);
    820   if (InvalidTemp) {
    821     *Invalid = true;
    822     return StringRef();
    823   }
    824 
    825   const char *Begin = File.data() + LocInfo.second;
    826   return StringRef(Begin, Tok.getLength());
    827 }
    828 
    829 } // end namespace comments
    830 } // end namespace clang
    831 
    832