aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Tooling/Syntax/Tokens.cpp
blob: d82dc1f35c9445dc4a226152e2615ed245fe4736 (plain) (blame)
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
//===- Tokens.cpp - collect tokens from preprocessing ---------------------===//
//
// 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/Tooling/Syntax/Tokens.h"

#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TokenKinds.h"
#include "clang/Lex/PPCallbacks.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Lex/Token.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <iterator>
#include <string>
#include <utility>
#include <vector>

using namespace clang;
using namespace clang::syntax;

syntax::Token::Token(SourceLocation Location, unsigned Length,
                     tok::TokenKind Kind)
    : Location(Location), Length(Length), Kind(Kind) {
  assert(Location.isValid());
}

syntax::Token::Token(const clang::Token &T)
    : Token(T.getLocation(), T.getLength(), T.getKind()) {
  assert(!T.isAnnotation());
}

llvm::StringRef syntax::Token::text(const SourceManager &SM) const {
  bool Invalid = false;
  const char *Start = SM.getCharacterData(location(), &Invalid);
  assert(!Invalid);
  return llvm::StringRef(Start, length());
}

FileRange syntax::Token::range(const SourceManager &SM) const {
  assert(location().isFileID() && "must be a spelled token");
  FileID File;
  unsigned StartOffset;
  std::tie(File, StartOffset) = SM.getDecomposedLoc(location());
  return FileRange(File, StartOffset, StartOffset + length());
}

FileRange syntax::Token::range(const SourceManager &SM,
                               const syntax::Token &First,
                               const syntax::Token &Last) {
  auto F = First.range(SM);
  auto L = Last.range(SM);
  assert(F.file() == L.file() && "tokens from different files");
  assert(F.endOffset() <= L.beginOffset() && "wrong order of tokens");
  return FileRange(F.file(), F.beginOffset(), L.endOffset());
}

llvm::raw_ostream &syntax::operator<<(llvm::raw_ostream &OS, const Token &T) {
  return OS << T.str();
}

FileRange::FileRange(FileID File, unsigned BeginOffset, unsigned EndOffset)
    : File(File), Begin(BeginOffset), End(EndOffset) {
  assert(File.isValid());
  assert(BeginOffset <= EndOffset);
}

FileRange::FileRange(const SourceManager &SM, SourceLocation BeginLoc,
                     unsigned Length) {
  assert(BeginLoc.isValid());
  assert(BeginLoc.isFileID());

  std::tie(File, Begin) = SM.getDecomposedLoc(BeginLoc);
  End = Begin + Length;
}
FileRange::FileRange(const SourceManager &SM, SourceLocation BeginLoc,
                     SourceLocation EndLoc) {
  assert(BeginLoc.isValid());
  assert(BeginLoc.isFileID());
  assert(EndLoc.isValid());
  assert(EndLoc.isFileID());
  assert(SM.getFileID(BeginLoc) == SM.getFileID(EndLoc));
  assert(SM.getFileOffset(BeginLoc) <= SM.getFileOffset(EndLoc));

  std::tie(File, Begin) = SM.getDecomposedLoc(BeginLoc);
  End = SM.getFileOffset(EndLoc);
}

llvm::raw_ostream &syntax::operator<<(llvm::raw_ostream &OS,
                                      const FileRange &R) {
  return OS << llvm::formatv("FileRange(file = {0}, offsets = {1}-{2})",
                             R.file().getHashValue(), R.beginOffset(),
                             R.endOffset());
}

llvm::StringRef FileRange::text(const SourceManager &SM) const {
  bool Invalid = false;
  StringRef Text = SM.getBufferData(File, &Invalid);
  if (Invalid)
    return "";
  assert(Begin <= Text.size());
  assert(End <= Text.size());
  return Text.substr(Begin, length());
}

std::pair<const syntax::Token *, const TokenBuffer::Mapping *>
TokenBuffer::spelledForExpandedToken(const syntax::Token *Expanded) const {
  assert(Expanded);
  assert(ExpandedTokens.data() <= Expanded &&
         Expanded < ExpandedTokens.data() + ExpandedTokens.size());

  auto FileIt = Files.find(
      SourceMgr->getFileID(SourceMgr->getExpansionLoc(Expanded->location())));
  assert(FileIt != Files.end() && "no file for an expanded token");

  const MarkedFile &File = FileIt->second;

  unsigned ExpandedIndex = Expanded - ExpandedTokens.data();
  // Find the first mapping that produced tokens after \p Expanded.
  auto It = llvm::partition_point(File.Mappings, [&](const Mapping &M) {
    return M.BeginExpanded <= ExpandedIndex;
  });
  // Our token could only be produced by the previous mapping.
  if (It == File.Mappings.begin()) {
    // No previous mapping, no need to modify offsets.
    return {&File.SpelledTokens[ExpandedIndex - File.BeginExpanded], nullptr};
  }
  --It; // 'It' now points to last mapping that started before our token.

  // Check if the token is part of the mapping.
  if (ExpandedIndex < It->EndExpanded)
    return {&File.SpelledTokens[It->BeginSpelled], /*Mapping*/ &*It};

  // Not part of the mapping, use the index from previous mapping to compute the
  // corresponding spelled token.
  return {
      &File.SpelledTokens[It->EndSpelled + (ExpandedIndex - It->EndExpanded)],
      /*Mapping*/ nullptr};
}

llvm::ArrayRef<syntax::Token> TokenBuffer::spelledTokens(FileID FID) const {
  auto It = Files.find(FID);
  assert(It != Files.end());
  return It->second.SpelledTokens;
}

std::string TokenBuffer::Mapping::str() const {
  return llvm::formatv("spelled tokens: [{0},{1}), expanded tokens: [{2},{3})",
                       BeginSpelled, EndSpelled, BeginExpanded, EndExpanded);
}

llvm::Optional<llvm::ArrayRef<syntax::Token>>
TokenBuffer::spelledForExpanded(llvm::ArrayRef<syntax::Token> Expanded) const {
  // Mapping an empty range is ambiguous in case of empty mappings at either end
  // of the range, bail out in that case.
  if (Expanded.empty())
    return llvm::None;

  // FIXME: also allow changes uniquely mapping to macro arguments.

  const syntax::Token *BeginSpelled;
  const Mapping *BeginMapping;
  std::tie(BeginSpelled, BeginMapping) =
      spelledForExpandedToken(&Expanded.front());

  const syntax::Token *LastSpelled;
  const Mapping *LastMapping;
  std::tie(LastSpelled, LastMapping) =
      spelledForExpandedToken(&Expanded.back());

  FileID FID = SourceMgr->getFileID(BeginSpelled->location());
  // FIXME: Handle multi-file changes by trying to map onto a common root.
  if (FID != SourceMgr->getFileID(LastSpelled->location()))
    return llvm::None;

  const MarkedFile &File = Files.find(FID)->second;

  // Do not allow changes that cross macro expansion boundaries.
  unsigned BeginExpanded = Expanded.begin() - ExpandedTokens.data();
  unsigned EndExpanded = Expanded.end() - ExpandedTokens.data();
  if (BeginMapping && BeginMapping->BeginExpanded < BeginExpanded)
    return llvm::None;
  if (LastMapping && EndExpanded < LastMapping->EndExpanded)
    return llvm::None;
  // All is good, return the result.
  return llvm::makeArrayRef(
      BeginMapping ? File.SpelledTokens.data() + BeginMapping->BeginSpelled
                   : BeginSpelled,
      LastMapping ? File.SpelledTokens.data() + LastMapping->EndSpelled
                  : LastSpelled + 1);
}

llvm::Optional<TokenBuffer::Expansion>
TokenBuffer::expansionStartingAt(const syntax::Token *Spelled) const {
  assert(Spelled);
  assert(Spelled->location().isFileID() && "not a spelled token");
  auto FileIt = Files.find(SourceMgr->getFileID(Spelled->location()));
  assert(FileIt != Files.end() && "file not tracked by token buffer");

  auto &File = FileIt->second;
  assert(File.SpelledTokens.data() <= Spelled &&
         Spelled < (File.SpelledTokens.data() + File.SpelledTokens.size()));

  unsigned SpelledIndex = Spelled - File.SpelledTokens.data();
  auto M = llvm::partition_point(File.Mappings, [&](const Mapping &M) {
    return M.BeginSpelled < SpelledIndex;
  });
  if (M == File.Mappings.end() || M->BeginSpelled != SpelledIndex)
    return llvm::None;

  Expansion E;
  E.Spelled = llvm::makeArrayRef(File.SpelledTokens.data() + M->BeginSpelled,
                                 File.SpelledTokens.data() + M->EndSpelled);
  E.Expanded = llvm::makeArrayRef(ExpandedTokens.data() + M->BeginExpanded,
                                  ExpandedTokens.data() + M->EndExpanded);
  return E;
}

std::vector<syntax::Token> syntax::tokenize(FileID FID, const SourceManager &SM,
                                            const LangOptions &LO) {
  std::vector<syntax::Token> Tokens;
  IdentifierTable Identifiers(LO);
  auto AddToken = [&](clang::Token T) {
    // Fill the proper token kind for keywords, etc.
    if (T.getKind() == tok::raw_identifier && !T.needsCleaning() &&
        !T.hasUCN()) { // FIXME: support needsCleaning and hasUCN cases.
      clang::IdentifierInfo &II = Identifiers.get(T.getRawIdentifier());
      T.setIdentifierInfo(&II);
      T.setKind(II.getTokenID());
    }
    Tokens.push_back(syntax::Token(T));
  };

  Lexer L(FID, SM.getBuffer(FID), SM, LO);

  clang::Token T;
  while (!L.LexFromRawLexer(T))
    AddToken(T);
  // 'eof' is only the last token if the input is null-terminated. Never store
  // it, for consistency.
  if (T.getKind() != tok::eof)
    AddToken(T);
  return Tokens;
}

/// Records information reqired to construct mappings for the token buffer that
/// we are collecting.
class TokenCollector::CollectPPExpansions : public PPCallbacks {
public:
  CollectPPExpansions(TokenCollector &C) : Collector(&C) {}

  /// Disabled instance will stop reporting anything to TokenCollector.
  /// This ensures that uses of the preprocessor after TokenCollector::consume()
  /// is called do not access the (possibly invalid) collector instance.
  void disable() { Collector = nullptr; }

  void MacroExpands(const clang::Token &MacroNameTok, const MacroDefinition &MD,
                    SourceRange Range, const MacroArgs *Args) override {
    if (!Collector)
      return;
    // Only record top-level expansions, not those where:
    //   - the macro use is inside a macro body,
    //   - the macro appears in an argument to another macro.
    if (!MacroNameTok.getLocation().isFileID() ||
        (LastExpansionEnd.isValid() &&
         Collector->PP.getSourceManager().isBeforeInTranslationUnit(
             Range.getBegin(), LastExpansionEnd)))
      return;
    Collector->Expansions[Range.getBegin().getRawEncoding()] = Range.getEnd();
    LastExpansionEnd = Range.getEnd();
  }
  // FIXME: handle directives like #pragma, #include, etc.
private:
  TokenCollector *Collector;
  /// Used to detect recursive macro expansions.
  SourceLocation LastExpansionEnd;
};

/// Fills in the TokenBuffer by tracing the run of a preprocessor. The
/// implementation tracks the tokens, macro expansions and directives coming
/// from the preprocessor and:
/// - for each token, figures out if it is a part of an expanded token stream,
///   spelled token stream or both. Stores the tokens appropriately.
/// - records mappings from the spelled to expanded token ranges, e.g. for macro
///   expansions.
/// FIXME: also properly record:
///          - #include directives,
///          - #pragma, #line and other PP directives,
///          - skipped pp regions,
///          - ...

TokenCollector::TokenCollector(Preprocessor &PP) : PP(PP) {
  // Collect the expanded token stream during preprocessing.
  PP.setTokenWatcher([this](const clang::Token &T) {
    if (T.isAnnotation())
      return;
    DEBUG_WITH_TYPE("collect-tokens", llvm::dbgs()
                                          << "Token: "
                                          << syntax::Token(T).dumpForTests(
                                                 this->PP.getSourceManager())
                                          << "\n"

    );
    Expanded.push_back(syntax::Token(T));
  });
  // And locations of macro calls, to properly recover boundaries of those in
  // case of empty expansions.
  auto CB = llvm::make_unique<CollectPPExpansions>(*this);
  this->Collector = CB.get();
  PP.addPPCallbacks(std::move(CB));
}

/// Builds mappings and spelled tokens in the TokenBuffer based on the expanded
/// token stream.
class TokenCollector::Builder {
public:
  Builder(std::vector<syntax::Token> Expanded, PPExpansions CollectedExpansions,
          const SourceManager &SM, const LangOptions &LangOpts)
      : Result(SM), CollectedExpansions(std::move(CollectedExpansions)), SM(SM),
        LangOpts(LangOpts) {
    Result.ExpandedTokens = std::move(Expanded);
  }

  TokenBuffer build() && {
    buildSpelledTokens();

    // Walk over expanded tokens and spelled tokens in parallel, building the
    // mappings between those using source locations.
    // To correctly recover empty macro expansions, we also take locations
    // reported to PPCallbacks::MacroExpands into account as we do not have any
    // expanded tokens with source locations to guide us.

    // The 'eof' token is special, it is not part of spelled token stream. We
    // handle it separately at the end.
    assert(!Result.ExpandedTokens.empty());
    assert(Result.ExpandedTokens.back().kind() == tok::eof);
    for (unsigned I = 0; I < Result.ExpandedTokens.size() - 1; ++I) {
      // (!) I might be updated by the following call.
      processExpandedToken(I);
    }

    // 'eof' not handled in the loop, do it here.
    assert(SM.getMainFileID() ==
           SM.getFileID(Result.ExpandedTokens.back().location()));
    fillGapUntil(Result.Files[SM.getMainFileID()],
                 Result.ExpandedTokens.back().location(),
                 Result.ExpandedTokens.size() - 1);
    Result.Files[SM.getMainFileID()].EndExpanded = Result.ExpandedTokens.size();

    // Some files might have unaccounted spelled tokens at the end, add an empty
    // mapping for those as they did not have expanded counterparts.
    fillGapsAtEndOfFiles();

    return std::move(Result);
  }

private:
  /// Process the next token in an expanded stream and move corresponding
  /// spelled tokens, record any mapping if needed.
  /// (!) \p I will be updated if this had to skip tokens, e.g. for macros.
  void processExpandedToken(unsigned &I) {
    auto L = Result.ExpandedTokens[I].location();
    if (L.isMacroID()) {
      processMacroExpansion(SM.getExpansionRange(L), I);
      return;
    }
    if (L.isFileID()) {
      auto FID = SM.getFileID(L);
      TokenBuffer::MarkedFile &File = Result.Files[FID];

      fillGapUntil(File, L, I);

      // Skip the token.
      assert(File.SpelledTokens[NextSpelled[FID]].location() == L &&
             "no corresponding token in the spelled stream");
      ++NextSpelled[FID];
      return;
    }
  }

  /// Skipped expanded and spelled tokens of a macro expansion that covers \p
  /// SpelledRange. Add a corresponding mapping.
  /// (!) \p I will be the index of the last token in an expansion after this
  /// function returns.
  void processMacroExpansion(CharSourceRange SpelledRange, unsigned &I) {
    auto FID = SM.getFileID(SpelledRange.getBegin());
    assert(FID == SM.getFileID(SpelledRange.getEnd()));
    TokenBuffer::MarkedFile &File = Result.Files[FID];

    fillGapUntil(File, SpelledRange.getBegin(), I);

    // Skip all expanded tokens from the same macro expansion.
    unsigned BeginExpanded = I;
    for (; I + 1 < Result.ExpandedTokens.size(); ++I) {
      auto NextL = Result.ExpandedTokens[I + 1].location();
      if (!NextL.isMacroID() ||
          SM.getExpansionLoc(NextL) != SpelledRange.getBegin())
        break;
    }
    unsigned EndExpanded = I + 1;
    consumeMapping(File, SM.getFileOffset(SpelledRange.getEnd()), BeginExpanded,
                   EndExpanded, NextSpelled[FID]);
  }

  /// Initializes TokenBuffer::Files and fills spelled tokens and expanded
  /// ranges for each of the files.
  void buildSpelledTokens() {
    for (unsigned I = 0; I < Result.ExpandedTokens.size(); ++I) {
      auto FID =
          SM.getFileID(SM.getExpansionLoc(Result.ExpandedTokens[I].location()));
      auto It = Result.Files.try_emplace(FID);
      TokenBuffer::MarkedFile &File = It.first->second;

      File.EndExpanded = I + 1;
      if (!It.second)
        continue; // we have seen this file before.

      // This is the first time we see this file.
      File.BeginExpanded = I;
      File.SpelledTokens = tokenize(FID, SM, LangOpts);
    }
  }

  void consumeEmptyMapping(TokenBuffer::MarkedFile &File, unsigned EndOffset,
                           unsigned ExpandedIndex, unsigned &SpelledIndex) {
    consumeMapping(File, EndOffset, ExpandedIndex, ExpandedIndex, SpelledIndex);
  }

  /// Consumes spelled tokens that form a macro expansion and adds a entry to
  /// the resulting token buffer.
  /// (!) SpelledIndex is updated in-place.
  void consumeMapping(TokenBuffer::MarkedFile &File, unsigned EndOffset,
                      unsigned BeginExpanded, unsigned EndExpanded,
                      unsigned &SpelledIndex) {
    // We need to record this mapping before continuing.
    unsigned MappingBegin = SpelledIndex;
    ++SpelledIndex;

    bool HitMapping =
        tryConsumeSpelledUntil(File, EndOffset + 1, SpelledIndex).hasValue();
    (void)HitMapping;
    assert(!HitMapping && "recursive macro expansion?");

    TokenBuffer::Mapping M;
    M.BeginExpanded = BeginExpanded;
    M.EndExpanded = EndExpanded;
    M.BeginSpelled = MappingBegin;
    M.EndSpelled = SpelledIndex;

    File.Mappings.push_back(M);
  }

  /// Consumes spelled tokens until location \p L is reached and adds a mapping
  /// covering the consumed tokens. The mapping will point to an empty expanded
  /// range at position \p ExpandedIndex.
  void fillGapUntil(TokenBuffer::MarkedFile &File, SourceLocation L,
                    unsigned ExpandedIndex) {
    assert(L.isFileID());
    FileID FID;
    unsigned Offset;
    std::tie(FID, Offset) = SM.getDecomposedLoc(L);

    unsigned &SpelledIndex = NextSpelled[FID];
    unsigned MappingBegin = SpelledIndex;
    while (true) {
      auto EndLoc = tryConsumeSpelledUntil(File, Offset, SpelledIndex);
      if (SpelledIndex != MappingBegin) {
        TokenBuffer::Mapping M;
        M.BeginSpelled = MappingBegin;
        M.EndSpelled = SpelledIndex;
        M.BeginExpanded = M.EndExpanded = ExpandedIndex;
        File.Mappings.push_back(M);
      }
      if (!EndLoc)
        break;
      consumeEmptyMapping(File, SM.getFileOffset(*EndLoc), ExpandedIndex,
                          SpelledIndex);

      MappingBegin = SpelledIndex;
    }
  };

  /// Consumes spelled tokens until it reaches Offset or a mapping boundary,
  /// i.e. a name of a macro expansion or the start '#' token of a PP directive.
  /// (!) NextSpelled is updated in place.
  ///
  /// returns None if \p Offset was reached, otherwise returns the end location
  /// of a mapping that starts at \p NextSpelled.
  llvm::Optional<SourceLocation>
  tryConsumeSpelledUntil(TokenBuffer::MarkedFile &File, unsigned Offset,
                         unsigned &NextSpelled) {
    for (; NextSpelled < File.SpelledTokens.size(); ++NextSpelled) {
      auto L = File.SpelledTokens[NextSpelled].location();
      if (Offset <= SM.getFileOffset(L))
        return llvm::None; // reached the offset we are looking for.
      auto Mapping = CollectedExpansions.find(L.getRawEncoding());
      if (Mapping != CollectedExpansions.end())
        return Mapping->second; // found a mapping before the offset.
    }
    return llvm::None; // no more tokens, we "reached" the offset.
  }

  /// Adds empty mappings for unconsumed spelled tokens at the end of each file.
  void fillGapsAtEndOfFiles() {
    for (auto &F : Result.Files) {
      if (F.second.SpelledTokens.empty())
        continue;
      fillGapUntil(F.second, F.second.SpelledTokens.back().endLocation(),
                   F.second.EndExpanded);
    }
  }

  TokenBuffer Result;
  /// For each file, a position of the next spelled token we will consume.
  llvm::DenseMap<FileID, unsigned> NextSpelled;
  PPExpansions CollectedExpansions;
  const SourceManager &SM;
  const LangOptions &LangOpts;
};

TokenBuffer TokenCollector::consume() && {
  PP.setTokenWatcher(nullptr);
  Collector->disable();
  return Builder(std::move(Expanded), std::move(Expansions),
                 PP.getSourceManager(), PP.getLangOpts())
      .build();
}

std::string syntax::Token::str() const {
  return llvm::formatv("Token({0}, length = {1})", tok::getTokenName(kind()),
                       length());
}

std::string syntax::Token::dumpForTests(const SourceManager &SM) const {
  return llvm::formatv("{0}   {1}", tok::getTokenName(kind()), text(SM));
}

std::string TokenBuffer::dumpForTests() const {
  auto PrintToken = [this](const syntax::Token &T) -> std::string {
    if (T.kind() == tok::eof)
      return "<eof>";
    return T.text(*SourceMgr);
  };

  auto DumpTokens = [this, &PrintToken](llvm::raw_ostream &OS,
                                        llvm::ArrayRef<syntax::Token> Tokens) {
    if (Tokens.empty()) {
      OS << "<empty>";
      return;
    }
    OS << Tokens[0].text(*SourceMgr);
    for (unsigned I = 1; I < Tokens.size(); ++I) {
      if (Tokens[I].kind() == tok::eof)
        continue;
      OS << " " << PrintToken(Tokens[I]);
    }
  };

  std::string Dump;
  llvm::raw_string_ostream OS(Dump);

  OS << "expanded tokens:\n"
     << "  ";
  // (!) we do not show '<eof>'.
  DumpTokens(OS, llvm::makeArrayRef(ExpandedTokens).drop_back());
  OS << "\n";

  std::vector<FileID> Keys;
  for (auto F : Files)
    Keys.push_back(F.first);
  llvm::sort(Keys);

  for (FileID ID : Keys) {
    const MarkedFile &File = Files.find(ID)->second;
    auto *Entry = SourceMgr->getFileEntryForID(ID);
    if (!Entry)
      continue; // Skip builtin files.
    OS << llvm::formatv("file '{0}'\n", Entry->getName())
       << "  spelled tokens:\n"
       << "    ";
    DumpTokens(OS, File.SpelledTokens);
    OS << "\n";

    if (File.Mappings.empty()) {
      OS << "  no mappings.\n";
      continue;
    }
    OS << "  mappings:\n";
    for (auto &M : File.Mappings) {
      OS << llvm::formatv(
          "    ['{0}'_{1}, '{2}'_{3}) => ['{4}'_{5}, '{6}'_{7})\n",
          PrintToken(File.SpelledTokens[M.BeginSpelled]), M.BeginSpelled,
          M.EndSpelled == File.SpelledTokens.size()
              ? "<eof>"
              : PrintToken(File.SpelledTokens[M.EndSpelled]),
          M.EndSpelled, PrintToken(ExpandedTokens[M.BeginExpanded]),
          M.BeginExpanded, PrintToken(ExpandedTokens[M.EndExpanded]),
          M.EndExpanded);
    }
  }
  return OS.str();
}