summaryrefslogtreecommitdiff
path: root/clang/lib/Lex/TokenLexer.cpp
blob: 696754c74167fc42b63a6ce69839f6c8e7abb026 (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
//===--- TokenLexer.cpp - Lex from a token stream -------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the TokenLexer interface.
//
//===----------------------------------------------------------------------===//

#include "clang/Lex/TokenLexer.h"
#include "MacroArgs.h"
#include "clang/Lex/MacroInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Lex/LexDiagnostic.h"
#include "llvm/ADT/SmallString.h"
using namespace clang;


/// Create a TokenLexer for the specified macro with the specified actual
/// arguments.  Note that this ctor takes ownership of the ActualArgs pointer.
void TokenLexer::Init(Token &Tok, SourceLocation ELEnd, MacroArgs *Actuals) {
  // If the client is reusing a TokenLexer, make sure to free any memory
  // associated with it.
  destroy();

  Macro = PP.getMacroInfo(Tok.getIdentifierInfo());
  ActualArgs = Actuals;
  CurToken = 0;

  ExpandLocStart = Tok.getLocation();
  ExpandLocEnd = ELEnd;
  AtStartOfLine = Tok.isAtStartOfLine();
  HasLeadingSpace = Tok.hasLeadingSpace();
  Tokens = &*Macro->tokens_begin();
  OwnsTokens = false;
  DisableMacroExpansion = false;
  NumTokens = Macro->tokens_end()-Macro->tokens_begin();
  MacroExpansionStart = SourceLocation();

  SourceManager &SM = PP.getSourceManager();
  MacroStartSLocOffset = SM.getNextLocalOffset();

  if (NumTokens > 0) {
    assert(Tokens[0].getLocation().isValid());
    assert((Tokens[0].getLocation().isFileID() || Tokens[0].is(tok::comment)) &&
           "Macro defined in macro?");
    assert(ExpandLocStart.isValid());

    // Reserve a source location entry chunk for the length of the macro
    // definition. Tokens that get lexed directly from the definition will
    // have their locations pointing inside this chunk. This is to avoid
    // creating separate source location entries for each token.
    MacroDefStart = SM.getExpansionLoc(Tokens[0].getLocation());
    MacroDefLength = Macro->getDefinitionLength(SM);
    MacroExpansionStart = SM.createExpansionLoc(MacroDefStart,
                                                ExpandLocStart,
                                                ExpandLocEnd,
                                                MacroDefLength);
  }

  // If this is a function-like macro, expand the arguments and change
  // Tokens to point to the expanded tokens.
  if (Macro->isFunctionLike() && Macro->getNumArgs())
    ExpandFunctionArguments();

  // Mark the macro as currently disabled, so that it is not recursively
  // expanded.  The macro must be disabled only after argument pre-expansion of
  // function-like macro arguments occurs.
  Macro->DisableMacro();
}



/// Create a TokenLexer for the specified token stream.  This does not
/// take ownership of the specified token vector.
void TokenLexer::Init(const Token *TokArray, unsigned NumToks,
                      bool disableMacroExpansion, bool ownsTokens) {
  // If the client is reusing a TokenLexer, make sure to free any memory
  // associated with it.
  destroy();

  Macro = 0;
  ActualArgs = 0;
  Tokens = TokArray;
  OwnsTokens = ownsTokens;
  DisableMacroExpansion = disableMacroExpansion;
  NumTokens = NumToks;
  CurToken = 0;
  ExpandLocStart = ExpandLocEnd = SourceLocation();
  AtStartOfLine = false;
  HasLeadingSpace = false;
  MacroExpansionStart = SourceLocation();

  // Set HasLeadingSpace/AtStartOfLine so that the first token will be
  // returned unmodified.
  if (NumToks != 0) {
    AtStartOfLine   = TokArray[0].isAtStartOfLine();
    HasLeadingSpace = TokArray[0].hasLeadingSpace();
  }
}


void TokenLexer::destroy() {
  // If this was a function-like macro that actually uses its arguments, delete
  // the expanded tokens.
  if (OwnsTokens) {
    delete [] Tokens;
    Tokens = 0;
    OwnsTokens = false;
  }

  // TokenLexer owns its formal arguments.
  if (ActualArgs) ActualArgs->destroy(PP);
}

/// Expand the arguments of a function-like macro so that we can quickly
/// return preexpanded tokens from Tokens.
void TokenLexer::ExpandFunctionArguments() {

  SmallVector<Token, 128> ResultToks;

  // Loop through 'Tokens', expanding them into ResultToks.  Keep
  // track of whether we change anything.  If not, no need to keep them.  If so,
  // we install the newly expanded sequence as the new 'Tokens' list.
  bool MadeChange = false;

  // NextTokGetsSpace - When this is true, the next token appended to the
  // output list will get a leading space, regardless of whether it had one to
  // begin with or not.  This is used for placemarker support.
  bool NextTokGetsSpace = false;

  for (unsigned i = 0, e = NumTokens; i != e; ++i) {
    // If we found the stringify operator, get the argument stringified.  The
    // preprocessor already verified that the following token is a macro name
    // when the #define was parsed.
    const Token &CurTok = Tokens[i];
    if (CurTok.is(tok::hash) || CurTok.is(tok::hashat)) {
      int ArgNo = Macro->getArgumentNum(Tokens[i+1].getIdentifierInfo());
      assert(ArgNo != -1 && "Token following # is not an argument?");

      SourceLocation ExpansionLocStart =
          getExpansionLocForMacroDefLoc(CurTok.getLocation());
      SourceLocation ExpansionLocEnd =
          getExpansionLocForMacroDefLoc(Tokens[i+1].getLocation());

      Token Res;
      if (CurTok.is(tok::hash))  // Stringify
        Res = ActualArgs->getStringifiedArgument(ArgNo, PP,
                                                 ExpansionLocStart,
                                                 ExpansionLocEnd);
      else {
        // 'charify': don't bother caching these.
        Res = MacroArgs::StringifyArgument(ActualArgs->getUnexpArgument(ArgNo),
                                           PP, true,
                                           ExpansionLocStart,
                                           ExpansionLocEnd);
      }

      // The stringified/charified string leading space flag gets set to match
      // the #/#@ operator.
      if (CurTok.hasLeadingSpace() || NextTokGetsSpace)
        Res.setFlag(Token::LeadingSpace);

      ResultToks.push_back(Res);
      MadeChange = true;
      ++i;  // Skip arg name.
      NextTokGetsSpace = false;
      continue;
    }

    // Otherwise, if this is not an argument token, just add the token to the
    // output buffer.
    IdentifierInfo *II = CurTok.getIdentifierInfo();
    int ArgNo = II ? Macro->getArgumentNum(II) : -1;
    if (ArgNo == -1) {
      // This isn't an argument, just add it.
      ResultToks.push_back(CurTok);

      if (NextTokGetsSpace) {
        ResultToks.back().setFlag(Token::LeadingSpace);
        NextTokGetsSpace = false;
      }
      continue;
    }

    // An argument is expanded somehow, the result is different than the
    // input.
    MadeChange = true;

    // Otherwise, this is a use of the argument.  Find out if there is a paste
    // (##) operator before or after the argument.
    bool PasteBefore =
      !ResultToks.empty() && ResultToks.back().is(tok::hashhash);
    bool PasteAfter = i+1 != e && Tokens[i+1].is(tok::hashhash);

    // If it is not the LHS/RHS of a ## operator, we must pre-expand the
    // argument and substitute the expanded tokens into the result.  This is
    // C99 6.10.3.1p1.
    if (!PasteBefore && !PasteAfter) {
      const Token *ResultArgToks;

      // Only preexpand the argument if it could possibly need it.  This
      // avoids some work in common cases.
      const Token *ArgTok = ActualArgs->getUnexpArgument(ArgNo);
      if (ActualArgs->ArgNeedsPreexpansion(ArgTok, PP))
        ResultArgToks = &ActualArgs->getPreExpArgument(ArgNo, Macro, PP)[0];
      else
        ResultArgToks = ArgTok;  // Use non-preexpanded tokens.

      // If the arg token expanded into anything, append it.
      if (ResultArgToks->isNot(tok::eof)) {
        unsigned FirstResult = ResultToks.size();
        unsigned NumToks = MacroArgs::getArgLength(ResultArgToks);
        ResultToks.append(ResultArgToks, ResultArgToks+NumToks);

        // If the '##' came from expanding an argument, turn it into 'unknown'
        // to avoid pasting.
        for (unsigned i = FirstResult, e = ResultToks.size(); i != e; ++i) {
          Token &Tok = ResultToks[i];
          if (Tok.is(tok::hashhash))
            Tok.setKind(tok::unknown);
        }

        if(ExpandLocStart.isValid()) {
          updateLocForMacroArgTokens(CurTok.getLocation(),
                                     ResultToks.begin()+FirstResult,
                                     ResultToks.end());
        }

        // If any tokens were substituted from the argument, the whitespace
        // before the first token should match the whitespace of the arg
        // identifier.
        ResultToks[FirstResult].setFlagValue(Token::LeadingSpace,
                                             CurTok.hasLeadingSpace() ||
                                             NextTokGetsSpace);
        NextTokGetsSpace = false;
      } else {
        // If this is an empty argument, and if there was whitespace before the
        // formal token, make sure the next token gets whitespace before it.
        NextTokGetsSpace = CurTok.hasLeadingSpace();
      }
      continue;
    }

    // Okay, we have a token that is either the LHS or RHS of a paste (##)
    // argument.  It gets substituted as its non-pre-expanded tokens.
    const Token *ArgToks = ActualArgs->getUnexpArgument(ArgNo);
    unsigned NumToks = MacroArgs::getArgLength(ArgToks);
    if (NumToks) {  // Not an empty argument?
      // If this is the GNU ", ## __VA_ARG__" extension, and we just learned
      // that __VA_ARG__ expands to multiple tokens, avoid a pasting error when
      // the expander trys to paste ',' with the first token of the __VA_ARG__
      // expansion.
      if (PasteBefore && ResultToks.size() >= 2 &&
          ResultToks[ResultToks.size()-2].is(tok::comma) &&
          (unsigned)ArgNo == Macro->getNumArgs()-1 &&
          Macro->isVariadic()) {
        // Remove the paste operator, report use of the extension.
        PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma);
        ResultToks.pop_back();
      }

      ResultToks.append(ArgToks, ArgToks+NumToks);

      // If the '##' came from expanding an argument, turn it into 'unknown'
      // to avoid pasting.
      for (unsigned i = ResultToks.size() - NumToks, e = ResultToks.size();
             i != e; ++i) {
        Token &Tok = ResultToks[i];
        if (Tok.is(tok::hashhash))
          Tok.setKind(tok::unknown);
      }

      if (ExpandLocStart.isValid()) {
        updateLocForMacroArgTokens(CurTok.getLocation(),
                                   ResultToks.end()-NumToks, ResultToks.end());
      }

      // If this token (the macro argument) was supposed to get leading
      // whitespace, transfer this information onto the first token of the
      // expansion.
      //
      // Do not do this if the paste operator occurs before the macro argument,
      // as in "A ## MACROARG".  In valid code, the first token will get
      // smooshed onto the preceding one anyway (forming AMACROARG).  In
      // assembler-with-cpp mode, invalid pastes are allowed through: in this
      // case, we do not want the extra whitespace to be added.  For example,
      // we want ". ## foo" -> ".foo" not ". foo".
      if ((CurTok.hasLeadingSpace() || NextTokGetsSpace) &&
          !PasteBefore)
        ResultToks[ResultToks.size()-NumToks].setFlag(Token::LeadingSpace);

      NextTokGetsSpace = false;
      continue;
    }

    // If an empty argument is on the LHS or RHS of a paste, the standard (C99
    // 6.10.3.3p2,3) calls for a bunch of placemarker stuff to occur.  We
    // implement this by eating ## operators when a LHS or RHS expands to
    // empty.
    NextTokGetsSpace |= CurTok.hasLeadingSpace();
    if (PasteAfter) {
      // Discard the argument token and skip (don't copy to the expansion
      // buffer) the paste operator after it.
      NextTokGetsSpace |= Tokens[i+1].hasLeadingSpace();
      ++i;
      continue;
    }

    // If this is on the RHS of a paste operator, we've already copied the
    // paste operator to the ResultToks list.  Remove it.
    assert(PasteBefore && ResultToks.back().is(tok::hashhash));
    NextTokGetsSpace |= ResultToks.back().hasLeadingSpace();
    ResultToks.pop_back();

    // If this is the __VA_ARGS__ token, and if the argument wasn't provided,
    // and if the macro had at least one real argument, and if the token before
    // the ## was a comma, remove the comma.
    if ((unsigned)ArgNo == Macro->getNumArgs()-1 && // is __VA_ARGS__
        ActualArgs->isVarargsElidedUse() &&       // Argument elided.
        !ResultToks.empty() && ResultToks.back().is(tok::comma)) {
      // Never add a space, even if the comma, ##, or arg had a space.
      NextTokGetsSpace = false;
      // Remove the paste operator, report use of the extension.
      PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma);
      ResultToks.pop_back();
      
      // If the comma was right after another paste (e.g. "X##,##__VA_ARGS__"),
      // then removal of the comma should produce a placemarker token (in C99
      // terms) which we model by popping off the previous ##, giving us a plain
      // "X" when __VA_ARGS__ is empty.
      if (!ResultToks.empty() && ResultToks.back().is(tok::hashhash))
        ResultToks.pop_back();
    }
    continue;
  }

  // If anything changed, install this as the new Tokens list.
  if (MadeChange) {
    assert(!OwnsTokens && "This would leak if we already own the token list");
    // This is deleted in the dtor.
    NumTokens = ResultToks.size();
    // The tokens will be added to Preprocessor's cache and will be removed
    // when this TokenLexer finishes lexing them.
    Tokens = PP.cacheMacroExpandedTokens(this, ResultToks);

    // The preprocessor cache of macro expanded tokens owns these tokens,not us.
    OwnsTokens = false;
  }
}

/// Lex - Lex and return a token from this macro stream.
///
void TokenLexer::Lex(Token &Tok) {
  // Lexing off the end of the macro, pop this macro off the expansion stack.
  if (isAtEnd()) {
    // If this is a macro (not a token stream), mark the macro enabled now
    // that it is no longer being expanded.
    if (Macro) Macro->EnableMacro();

    // Pop this context off the preprocessors lexer stack and get the next
    // token.  This will delete "this" so remember the PP instance var.
    Preprocessor &PPCache = PP;
    if (PP.HandleEndOfTokenLexer(Tok))
      return;

    // HandleEndOfTokenLexer may not return a token.  If it doesn't, lex
    // whatever is next.
    return PPCache.Lex(Tok);
  }

  SourceManager &SM = PP.getSourceManager();

  // If this is the first token of the expanded result, we inherit spacing
  // properties later.
  bool isFirstToken = CurToken == 0;

  // Get the next token to return.
  Tok = Tokens[CurToken++];

  bool TokenIsFromPaste = false;

  // If this token is followed by a token paste (##) operator, paste the tokens!
  // Note that ## is a normal token when not expanding a macro.
  if (!isAtEnd() && Tokens[CurToken].is(tok::hashhash) && Macro) {
    // When handling the microsoft /##/ extension, the final token is
    // returned by PasteTokens, not the pasted token.
    if (PasteTokens(Tok))
      return;

    TokenIsFromPaste = true;
  }

  // The token's current location indicate where the token was lexed from.  We
  // need this information to compute the spelling of the token, but any
  // diagnostics for the expanded token should appear as if they came from
  // ExpansionLoc.  Pull this information together into a new SourceLocation
  // that captures all of this.
  if (ExpandLocStart.isValid() &&   // Don't do this for token streams.
      // Check that the token's location was not already set properly.
      SM.isBeforeInSLocAddrSpace(Tok.getLocation(), MacroStartSLocOffset)) {
    SourceLocation instLoc;
    if (Tok.is(tok::comment)) {
      instLoc = SM.createExpansionLoc(Tok.getLocation(),
                                      ExpandLocStart,
                                      ExpandLocEnd,
                                      Tok.getLength());
    } else {
      instLoc = getExpansionLocForMacroDefLoc(Tok.getLocation());
    }

    Tok.setLocation(instLoc);
  }

  // If this is the first token, set the lexical properties of the token to
  // match the lexical properties of the macro identifier.
  if (isFirstToken) {
    Tok.setFlagValue(Token::StartOfLine , AtStartOfLine);
    Tok.setFlagValue(Token::LeadingSpace, HasLeadingSpace);
  }

  // Handle recursive expansion!
  if (!Tok.isAnnotation() && Tok.getIdentifierInfo() != 0) {
    // Change the kind of this identifier to the appropriate token kind, e.g.
    // turning "for" into a keyword.
    IdentifierInfo *II = Tok.getIdentifierInfo();
    Tok.setKind(II->getTokenID());

    // If this identifier was poisoned and from a paste, emit an error.  This
    // won't be handled by Preprocessor::HandleIdentifier because this is coming
    // from a macro expansion.
    if (II->isPoisoned() && TokenIsFromPaste) {
      PP.HandlePoisonedIdentifier(Tok);
    }

    if (!DisableMacroExpansion && II->isHandleIdentifierCase())
      PP.HandleIdentifier(Tok);
  }

  // Otherwise, return a normal token.
}

/// PasteTokens - Tok is the LHS of a ## operator, and CurToken is the ##
/// operator.  Read the ## and RHS, and paste the LHS/RHS together.  If there
/// are more ## after it, chomp them iteratively.  Return the result as Tok.
/// If this returns true, the caller should immediately return the token.
bool TokenLexer::PasteTokens(Token &Tok) {
  SmallString<128> Buffer;
  const char *ResultTokStrPtr = 0;
  SourceLocation StartLoc = Tok.getLocation();
  SourceLocation PasteOpLoc;
  do {
    // Consume the ## operator.
    PasteOpLoc = Tokens[CurToken].getLocation();
    ++CurToken;
    assert(!isAtEnd() && "No token on the RHS of a paste operator!");

    // Get the RHS token.
    const Token &RHS = Tokens[CurToken];

    // Allocate space for the result token.  This is guaranteed to be enough for
    // the two tokens.
    Buffer.resize(Tok.getLength() + RHS.getLength());

    // Get the spelling of the LHS token in Buffer.
    const char *BufPtr = &Buffer[0];
    bool Invalid = false;
    unsigned LHSLen = PP.getSpelling(Tok, BufPtr, &Invalid);
    if (BufPtr != &Buffer[0])   // Really, we want the chars in Buffer!
      memcpy(&Buffer[0], BufPtr, LHSLen);
    if (Invalid)
      return true;
    
    BufPtr = &Buffer[LHSLen];
    unsigned RHSLen = PP.getSpelling(RHS, BufPtr, &Invalid);
    if (Invalid)
      return true;
    if (BufPtr != &Buffer[LHSLen])   // Really, we want the chars in Buffer!
      memcpy(&Buffer[LHSLen], BufPtr, RHSLen);

    // Trim excess space.
    Buffer.resize(LHSLen+RHSLen);

    // Plop the pasted result (including the trailing newline and null) into a
    // scratch buffer where we can lex it.
    Token ResultTokTmp;
    ResultTokTmp.startToken();

    // Claim that the tmp token is a string_literal so that we can get the
    // character pointer back from CreateString in getLiteralData().
    ResultTokTmp.setKind(tok::string_literal);
    PP.CreateString(&Buffer[0], Buffer.size(), ResultTokTmp);
    SourceLocation ResultTokLoc = ResultTokTmp.getLocation();
    ResultTokStrPtr = ResultTokTmp.getLiteralData();

    // Lex the resultant pasted token into Result.
    Token Result;

    if (Tok.isAnyIdentifier() && RHS.isAnyIdentifier()) {
      // Common paste case: identifier+identifier = identifier.  Avoid creating
      // a lexer and other overhead.
      PP.IncrementPasteCounter(true);
      Result.startToken();
      Result.setKind(tok::raw_identifier);
      Result.setRawIdentifierData(ResultTokStrPtr);
      Result.setLocation(ResultTokLoc);
      Result.setLength(LHSLen+RHSLen);
    } else {
      PP.IncrementPasteCounter(false);

      assert(ResultTokLoc.isFileID() &&
             "Should be a raw location into scratch buffer");
      SourceManager &SourceMgr = PP.getSourceManager();
      FileID LocFileID = SourceMgr.getFileID(ResultTokLoc);

      bool Invalid = false;
      const char *ScratchBufStart
        = SourceMgr.getBufferData(LocFileID, &Invalid).data();
      if (Invalid)
        return false;

      // Make a lexer to lex this string from.  Lex just this one token.
      // Make a lexer object so that we lex and expand the paste result.
      Lexer TL(SourceMgr.getLocForStartOfFile(LocFileID),
               PP.getLangOpts(), ScratchBufStart,
               ResultTokStrPtr, ResultTokStrPtr+LHSLen+RHSLen);

      // Lex a token in raw mode.  This way it won't look up identifiers
      // automatically, lexing off the end will return an eof token, and
      // warnings are disabled.  This returns true if the result token is the
      // entire buffer.
      bool isInvalid = !TL.LexFromRawLexer(Result);

      // If we got an EOF token, we didn't form even ONE token.  For example, we
      // did "/ ## /" to get "//".
      isInvalid |= Result.is(tok::eof);

      // If pasting the two tokens didn't form a full new token, this is an
      // error.  This occurs with "x ## +"  and other stuff.  Return with Tok
      // unmodified and with RHS as the next token to lex.
      if (isInvalid) {
        // Test for the Microsoft extension of /##/ turning into // here on the
        // error path.
        if (PP.getLangOpts().MicrosoftExt && Tok.is(tok::slash) &&
            RHS.is(tok::slash)) {
          HandleMicrosoftCommentPaste(Tok);
          return true;
        }

        // Do not emit the error when preprocessing assembler code.
        if (!PP.getLangOpts().AsmPreprocessor) {
          // Explicitly convert the token location to have proper expansion
          // information so that the user knows where it came from.
          SourceManager &SM = PP.getSourceManager();
          SourceLocation Loc =
            SM.createExpansionLoc(PasteOpLoc, ExpandLocStart, ExpandLocEnd, 2);
          // If we're in microsoft extensions mode, downgrade this from a hard
          // error to a warning that defaults to an error.  This allows
          // disabling it.
          PP.Diag(Loc,
                  PP.getLangOpts().MicrosoftExt ? diag::err_pp_bad_paste_ms 
                                                   : diag::err_pp_bad_paste)
            << Buffer.str();
        }

        // Do not consume the RHS.
        --CurToken;
      }

      // Turn ## into 'unknown' to avoid # ## # from looking like a paste
      // operator.
      if (Result.is(tok::hashhash))
        Result.setKind(tok::unknown);
    }

    // Transfer properties of the LHS over the the Result.
    Result.setFlagValue(Token::StartOfLine , Tok.isAtStartOfLine());
    Result.setFlagValue(Token::LeadingSpace, Tok.hasLeadingSpace());
    
    // Finally, replace LHS with the result, consume the RHS, and iterate.
    ++CurToken;
    Tok = Result;
  } while (!isAtEnd() && Tokens[CurToken].is(tok::hashhash));

  SourceLocation EndLoc = Tokens[CurToken - 1].getLocation();

  // The token's current location indicate where the token was lexed from.  We
  // need this information to compute the spelling of the token, but any
  // diagnostics for the expanded token should appear as if the token was
  // expanded from the full ## expression. Pull this information together into
  // a new SourceLocation that captures all of this.
  SourceManager &SM = PP.getSourceManager();
  if (StartLoc.isFileID())
    StartLoc = getExpansionLocForMacroDefLoc(StartLoc);
  if (EndLoc.isFileID())
    EndLoc = getExpansionLocForMacroDefLoc(EndLoc);
  Tok.setLocation(SM.createExpansionLoc(Tok.getLocation(), StartLoc, EndLoc,
                                        Tok.getLength()));

  // Now that we got the result token, it will be subject to expansion.  Since
  // token pasting re-lexes the result token in raw mode, identifier information
  // isn't looked up.  As such, if the result is an identifier, look up id info.
  if (Tok.is(tok::raw_identifier)) {
    // Look up the identifier info for the token.  We disabled identifier lookup
    // by saying we're skipping contents, so we need to do this manually.
    PP.LookUpIdentifierInfo(Tok);
  }
  return false;
}

/// isNextTokenLParen - If the next token lexed will pop this macro off the
/// expansion stack, return 2.  If the next unexpanded token is a '(', return
/// 1, otherwise return 0.
unsigned TokenLexer::isNextTokenLParen() const {
  // Out of tokens?
  if (isAtEnd())
    return 2;
  return Tokens[CurToken].is(tok::l_paren);
}

/// isParsingPreprocessorDirective - Return true if we are in the middle of a
/// preprocessor directive.
bool TokenLexer::isParsingPreprocessorDirective() const {
  return Tokens[NumTokens-1].is(tok::eod) && !isAtEnd();
}

/// HandleMicrosoftCommentPaste - In microsoft compatibility mode, /##/ pastes
/// together to form a comment that comments out everything in the current
/// macro, other active macros, and anything left on the current physical
/// source line of the expanded buffer.  Handle this by returning the
/// first token on the next line.
void TokenLexer::HandleMicrosoftCommentPaste(Token &Tok) {
  // We 'comment out' the rest of this macro by just ignoring the rest of the
  // tokens that have not been lexed yet, if any.

  // Since this must be a macro, mark the macro enabled now that it is no longer
  // being expanded.
  assert(Macro && "Token streams can't paste comments");
  Macro->EnableMacro();

  PP.HandleMicrosoftCommentPaste(Tok);
}

/// \brief If \arg loc is a file ID and points inside the current macro
/// definition, returns the appropriate source location pointing at the
/// macro expansion source location entry, otherwise it returns an invalid
/// SourceLocation.
SourceLocation
TokenLexer::getExpansionLocForMacroDefLoc(SourceLocation loc) const {
  assert(ExpandLocStart.isValid() && MacroExpansionStart.isValid() &&
         "Not appropriate for token streams");
  assert(loc.isValid() && loc.isFileID());
  
  SourceManager &SM = PP.getSourceManager();
  assert(SM.isInSLocAddrSpace(loc, MacroDefStart, MacroDefLength) &&
         "Expected loc to come from the macro definition");

  unsigned relativeOffset = 0;
  SM.isInSLocAddrSpace(loc, MacroDefStart, MacroDefLength, &relativeOffset);
  return MacroExpansionStart.getLocWithOffset(relativeOffset);
}

/// \brief Finds the tokens that are consecutive (from the same FileID)
/// creates a single SLocEntry, and assigns SourceLocations to each token that
/// point to that SLocEntry. e.g for
///   assert(foo == bar);
/// There will be a single SLocEntry for the "foo == bar" chunk and locations
/// for the 'foo', '==', 'bar' tokens will point inside that chunk.
///
/// \arg begin_tokens will be updated to a position past all the found
/// consecutive tokens.
static void updateConsecutiveMacroArgTokens(SourceManager &SM,
                                            SourceLocation InstLoc,
                                            Token *&begin_tokens,
                                            Token * end_tokens) {
  assert(begin_tokens < end_tokens);

  SourceLocation FirstLoc = begin_tokens->getLocation();
  SourceLocation CurLoc = FirstLoc;

  // Compare the source location offset of tokens and group together tokens that
  // are close, even if their locations point to different FileIDs. e.g.
  //
  //  |bar    |  foo | cake   |  (3 tokens from 3 consecutive FileIDs)
  //  ^                    ^
  //  |bar       foo   cake|     (one SLocEntry chunk for all tokens)
  //
  // we can perform this "merge" since the token's spelling location depends
  // on the relative offset.

  Token *NextTok = begin_tokens + 1;
  for (; NextTok < end_tokens; ++NextTok) {
    int RelOffs;
    if (!SM.isInSameSLocAddrSpace(CurLoc, NextTok->getLocation(), &RelOffs))
      break; // Token from different local/loaded location.
    // Check that token is not before the previous token or more than 50
    // "characters" away.
    if (RelOffs < 0 || RelOffs > 50)
      break;
    CurLoc = NextTok->getLocation();
  }

  // For the consecutive tokens, find the length of the SLocEntry to contain
  // all of them.
  Token &LastConsecutiveTok = *(NextTok-1);
  int LastRelOffs = 0;
  SM.isInSameSLocAddrSpace(FirstLoc, LastConsecutiveTok.getLocation(),
                           &LastRelOffs);
  unsigned FullLength = LastRelOffs + LastConsecutiveTok.getLength();

  // Create a macro expansion SLocEntry that will "contain" all of the tokens.
  SourceLocation Expansion =
      SM.createMacroArgExpansionLoc(FirstLoc, InstLoc,FullLength);

  // Change the location of the tokens from the spelling location to the new
  // expanded location.
  for (; begin_tokens < NextTok; ++begin_tokens) {
    Token &Tok = *begin_tokens;
    int RelOffs = 0;
    SM.isInSameSLocAddrSpace(FirstLoc, Tok.getLocation(), &RelOffs);
    Tok.setLocation(Expansion.getLocWithOffset(RelOffs));
  }
}

/// \brief Creates SLocEntries and updates the locations of macro argument
/// tokens to their new expanded locations.
///
/// \param ArgIdDefLoc the location of the macro argument id inside the macro
/// definition.
/// \param Tokens the macro argument tokens to update.
void TokenLexer::updateLocForMacroArgTokens(SourceLocation ArgIdSpellLoc,
                                            Token *begin_tokens,
                                            Token *end_tokens) {
  SourceManager &SM = PP.getSourceManager();

  SourceLocation InstLoc =
      getExpansionLocForMacroDefLoc(ArgIdSpellLoc);
  
  while (begin_tokens < end_tokens) {
    // If there's only one token just create a SLocEntry for it.
    if (end_tokens - begin_tokens == 1) {
      Token &Tok = *begin_tokens;
      Tok.setLocation(SM.createMacroArgExpansionLoc(Tok.getLocation(),
                                                    InstLoc,
                                                    Tok.getLength()));
      return;
    }

    updateConsecutiveMacroArgTokens(SM, InstLoc, begin_tokens, end_tokens);
  }
}