1 //===--- PPCallbacksTracker.cpp - Preprocessor tracker -*--*---------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// \brief Implementations for preprocessor tracking.
11 ///
12 /// See the header for details.
13 ///
14 //===----------------------------------------------------------------------===//
15 
16 #include "PPCallbacksTracker.h"
17 #include "clang/Lex/MacroArgs.h"
18 #include "llvm/Support/raw_ostream.h"
19 
20 // Utility functions.
21 
22 // Get a "file:line:column" source location string.
23 static std::string getSourceLocationString(clang::Preprocessor &PP,
24                                            clang::SourceLocation Loc) {
25   if (Loc.isInvalid())
26     return std::string("(none)");
27 
28   if (Loc.isFileID()) {
29     clang::PresumedLoc PLoc = PP.getSourceManager().getPresumedLoc(Loc);
30 
31     if (PLoc.isInvalid()) {
32       return std::string("(invalid)");
33     }
34 
35     std::string Str;
36     llvm::raw_string_ostream SS(Str);
37 
38     // The macro expansion and spelling pos is identical for file locs.
39     SS << "\"" << PLoc.getFilename() << ':' << PLoc.getLine() << ':'
40        << PLoc.getColumn() << "\"";
41 
42     std::string Result = SS.str();
43 
44     // YAML treats backslash as escape, so use forward slashes.
45     std::replace(Result.begin(), Result.end(), '\\', '/');
46 
47     return Result;
48   }
49 
50   return std::string("(nonfile)");
51 }
52 
53 // Enum string tables.
54 
55 // FileChangeReason strings.
56 static const char *const FileChangeReasonStrings[] = {
57   "EnterFile", "ExitFile", "SystemHeaderPragma", "RenameFile"
58 };
59 
60 // CharacteristicKind strings.
61 static const char *const CharacteristicKindStrings[] = { "C_User", "C_System",
62                                                          "C_ExternCSystem" };
63 
64 // MacroDirective::Kind strings.
65 static const char *const MacroDirectiveKindStrings[] = {
66   "MD_Define","MD_Undefine", "MD_Visibility"
67 };
68 
69 // PragmaIntroducerKind strings.
70 static const char *const PragmaIntroducerKindStrings[] = { "PIK_HashPragma",
71                                                            "PIK__Pragma",
72                                                            "PIK___pragma" };
73 
74 // PragmaMessageKind strings.
75 static const char *const PragmaMessageKindStrings[] = {
76   "PMK_Message", "PMK_Warning", "PMK_Error"
77 };
78 
79 // ConditionValueKind strings.
80 static const char *const ConditionValueKindStrings[] = {
81   "CVK_NotEvaluated", "CVK_False", "CVK_True"
82 };
83 
84 // Mapping strings.
85 static const char *const MappingStrings[] = { "0",          "MAP_IGNORE",
86                                               "MAP_REMARK", "MAP_WARNING",
87                                               "MAP_ERROR",  "MAP_FATAL" };
88 
89 // PPCallbacksTracker functions.
90 
91 PPCallbacksTracker::PPCallbacksTracker(const FilterType &Filters,
92                                        std::vector<CallbackCall> &CallbackCalls,
93                                        clang::Preprocessor &PP)
94     : CallbackCalls(CallbackCalls), Filters(Filters), PP(PP) {}
95 
96 PPCallbacksTracker::~PPCallbacksTracker() {}
97 
98 // Callback functions.
99 
100 // Callback invoked whenever a source file is entered or exited.
101 void PPCallbacksTracker::FileChanged(
102     clang::SourceLocation Loc, clang::PPCallbacks::FileChangeReason Reason,
103     clang::SrcMgr::CharacteristicKind FileType, clang::FileID PrevFID) {
104   beginCallback("FileChanged");
105   appendArgument("Loc", Loc);
106   appendArgument("Reason", Reason, FileChangeReasonStrings);
107   appendArgument("FileType", FileType, CharacteristicKindStrings);
108   appendArgument("PrevFID", PrevFID);
109 }
110 
111 // Callback invoked whenever a source file is skipped as the result
112 // of header guard optimization.
113 void
114 PPCallbacksTracker::FileSkipped(const clang::FileEntry &SkippedFile,
115                                 const clang::Token &FilenameTok,
116                                 clang::SrcMgr::CharacteristicKind FileType) {
117   beginCallback("FileSkipped");
118   appendArgument("ParentFile", &SkippedFile);
119   appendArgument("FilenameTok", FilenameTok);
120   appendArgument("FileType", FileType, CharacteristicKindStrings);
121 }
122 
123 // Callback invoked whenever an inclusion directive results in a
124 // file-not-found error.
125 bool
126 PPCallbacksTracker::FileNotFound(llvm::StringRef FileName,
127                                  llvm::SmallVectorImpl<char> &RecoveryPath) {
128   beginCallback("FileNotFound");
129   appendFilePathArgument("FileName", FileName);
130   return false;
131 }
132 
133 // Callback invoked whenever an inclusion directive of
134 // any kind (#include, #import, etc.) has been processed, regardless
135 // of whether the inclusion will actually result in an inclusion.
136 void PPCallbacksTracker::InclusionDirective(
137     clang::SourceLocation HashLoc, const clang::Token &IncludeTok,
138     llvm::StringRef FileName, bool IsAngled,
139     clang::CharSourceRange FilenameRange, const clang::FileEntry *File,
140     llvm::StringRef SearchPath, llvm::StringRef RelativePath,
141     const clang::Module *Imported, clang::SrcMgr::CharacteristicKind FileType) {
142   beginCallback("InclusionDirective");
143   appendArgument("IncludeTok", IncludeTok);
144   appendFilePathArgument("FileName", FileName);
145   appendArgument("IsAngled", IsAngled);
146   appendArgument("FilenameRange", FilenameRange);
147   appendArgument("File", File);
148   appendFilePathArgument("SearchPath", SearchPath);
149   appendFilePathArgument("RelativePath", RelativePath);
150   appendArgument("Imported", Imported);
151 }
152 
153 // Callback invoked whenever there was an explicit module-import
154 // syntax.
155 void PPCallbacksTracker::moduleImport(clang::SourceLocation ImportLoc,
156                                       clang::ModuleIdPath Path,
157                                       const clang::Module *Imported) {
158   beginCallback("moduleImport");
159   appendArgument("ImportLoc", ImportLoc);
160   appendArgument("Path", Path);
161   appendArgument("Imported", Imported);
162 }
163 
164 // Callback invoked when the end of the main file is reached.
165 // No subsequent callbacks will be made.
166 void PPCallbacksTracker::EndOfMainFile() { beginCallback("EndOfMainFile"); }
167 
168 // Callback invoked when a #ident or #sccs directive is read.
169 void PPCallbacksTracker::Ident(clang::SourceLocation Loc, llvm::StringRef Str) {
170   beginCallback("Ident");
171   appendArgument("Loc", Loc);
172   appendArgument("Str", Str);
173 }
174 
175 // Callback invoked when start reading any pragma directive.
176 void
177 PPCallbacksTracker::PragmaDirective(clang::SourceLocation Loc,
178                                     clang::PragmaIntroducerKind Introducer) {
179   beginCallback("PragmaDirective");
180   appendArgument("Loc", Loc);
181   appendArgument("Introducer", Introducer, PragmaIntroducerKindStrings);
182 }
183 
184 // Callback invoked when a #pragma comment directive is read.
185 void PPCallbacksTracker::PragmaComment(clang::SourceLocation Loc,
186                                        const clang::IdentifierInfo *Kind,
187                                        llvm::StringRef Str) {
188   beginCallback("PragmaComment");
189   appendArgument("Loc", Loc);
190   appendArgument("Kind", Kind);
191   appendArgument("Str", Str);
192 }
193 
194 // Callback invoked when a #pragma detect_mismatch directive is
195 // read.
196 void PPCallbacksTracker::PragmaDetectMismatch(clang::SourceLocation Loc,
197                                               llvm::StringRef Name,
198                                               llvm::StringRef Value) {
199   beginCallback("PragmaDetectMismatch");
200   appendArgument("Loc", Loc);
201   appendArgument("Name", Name);
202   appendArgument("Value", Value);
203 }
204 
205 // Callback invoked when a #pragma clang __debug directive is read.
206 void PPCallbacksTracker::PragmaDebug(clang::SourceLocation Loc,
207                                      llvm::StringRef DebugType) {
208   beginCallback("PragmaDebug");
209   appendArgument("Loc", Loc);
210   appendArgument("DebugType", DebugType);
211 }
212 
213 // Callback invoked when a #pragma message directive is read.
214 void PPCallbacksTracker::PragmaMessage(
215     clang::SourceLocation Loc, llvm::StringRef Namespace,
216     clang::PPCallbacks::PragmaMessageKind Kind, llvm::StringRef Str) {
217   beginCallback("PragmaMessage");
218   appendArgument("Loc", Loc);
219   appendArgument("Namespace", Namespace);
220   appendArgument("Kind", Kind, PragmaMessageKindStrings);
221   appendArgument("Str", Str);
222 }
223 
224 // Callback invoked when a #pragma gcc dianostic push directive
225 // is read.
226 void PPCallbacksTracker::PragmaDiagnosticPush(clang::SourceLocation Loc,
227                                               llvm::StringRef Namespace) {
228   beginCallback("PragmaDiagnosticPush");
229   appendArgument("Loc", Loc);
230   appendArgument("Namespace", Namespace);
231 }
232 
233 // Callback invoked when a #pragma gcc dianostic pop directive
234 // is read.
235 void PPCallbacksTracker::PragmaDiagnosticPop(clang::SourceLocation Loc,
236                                              llvm::StringRef Namespace) {
237   beginCallback("PragmaDiagnosticPop");
238   appendArgument("Loc", Loc);
239   appendArgument("Namespace", Namespace);
240 }
241 
242 // Callback invoked when a #pragma gcc dianostic directive is read.
243 void PPCallbacksTracker::PragmaDiagnostic(clang::SourceLocation Loc,
244                                           llvm::StringRef Namespace,
245                                           clang::diag::Severity Mapping,
246                                           llvm::StringRef Str) {
247   beginCallback("PragmaDiagnostic");
248   appendArgument("Loc", Loc);
249   appendArgument("Namespace", Namespace);
250   appendArgument("Mapping", (unsigned)Mapping, MappingStrings);
251   appendArgument("Str", Str);
252 }
253 
254 // Called when an OpenCL extension is either disabled or
255 // enabled with a pragma.
256 void PPCallbacksTracker::PragmaOpenCLExtension(
257     clang::SourceLocation NameLoc, const clang::IdentifierInfo *Name,
258     clang::SourceLocation StateLoc, unsigned State) {
259   beginCallback("PragmaOpenCLExtension");
260   appendArgument("NameLoc", NameLoc);
261   appendArgument("Name", Name);
262   appendArgument("StateLoc", StateLoc);
263   appendArgument("State", (int)State);
264 }
265 
266 // Callback invoked when a #pragma warning directive is read.
267 void PPCallbacksTracker::PragmaWarning(clang::SourceLocation Loc,
268                                        llvm::StringRef WarningSpec,
269                                        llvm::ArrayRef<int> Ids) {
270   beginCallback("PragmaWarning");
271   appendArgument("Loc", Loc);
272   appendArgument("WarningSpec", WarningSpec);
273 
274   std::string Str;
275   llvm::raw_string_ostream SS(Str);
276   SS << "[";
277   for (int i = 0, e = Ids.size(); i != e; ++i) {
278     if (i)
279       SS << ", ";
280     SS << Ids[i];
281   }
282   SS << "]";
283   appendArgument("Ids", SS.str());
284 }
285 
286 // Callback invoked when a #pragma warning(push) directive is read.
287 void PPCallbacksTracker::PragmaWarningPush(clang::SourceLocation Loc,
288                                            int Level) {
289   beginCallback("PragmaWarningPush");
290   appendArgument("Loc", Loc);
291   appendArgument("Level", Level);
292 }
293 
294 // Callback invoked when a #pragma warning(pop) directive is read.
295 void PPCallbacksTracker::PragmaWarningPop(clang::SourceLocation Loc) {
296   beginCallback("PragmaWarningPop");
297   appendArgument("Loc", Loc);
298 }
299 
300 // Callback invoked when a #pragma execution_character_set(push) directive
301 // is read.
302 void PPCallbacksTracker::PragmaExecCharsetPush(clang::SourceLocation Loc,
303                                                clang::StringRef Str) {
304   beginCallback("PragmaExecCharsetPush");
305   appendArgument("Loc", Loc);
306   appendArgument("Charset", Str);
307 }
308 
309 // Callback invoked when a #pragma execution_character_set(pop) directive
310 // is read.
311 void PPCallbacksTracker::PragmaExecCharsetPop(clang::SourceLocation Loc) {
312   beginCallback("PragmaExecCharsetPop");
313   appendArgument("Loc", Loc);
314 }
315 
316 // Called by Preprocessor::HandleMacroExpandedIdentifier when a
317 // macro invocation is found.
318 void
319 PPCallbacksTracker::MacroExpands(const clang::Token &MacroNameTok,
320                                  const clang::MacroDefinition &MacroDefinition,
321                                  clang::SourceRange Range,
322                                  const clang::MacroArgs *Args) {
323   beginCallback("MacroExpands");
324   appendArgument("MacroNameTok", MacroNameTok);
325   appendArgument("MacroDefinition", MacroDefinition);
326   appendArgument("Range", Range);
327   appendArgument("Args", Args);
328 }
329 
330 // Hook called whenever a macro definition is seen.
331 void
332 PPCallbacksTracker::MacroDefined(const clang::Token &MacroNameTok,
333                                  const clang::MacroDirective *MacroDirective) {
334   beginCallback("MacroDefined");
335   appendArgument("MacroNameTok", MacroNameTok);
336   appendArgument("MacroDirective", MacroDirective);
337 }
338 
339 // Hook called whenever a macro #undef is seen.
340 void PPCallbacksTracker::MacroUndefined(
341     const clang::Token &MacroNameTok,
342     const clang::MacroDefinition &MacroDefinition,
343     const clang::MacroDirective *Undef) {
344   beginCallback("MacroUndefined");
345   appendArgument("MacroNameTok", MacroNameTok);
346   appendArgument("MacroDefinition", MacroDefinition);
347 }
348 
349 // Hook called whenever the 'defined' operator is seen.
350 void PPCallbacksTracker::Defined(const clang::Token &MacroNameTok,
351                                  const clang::MacroDefinition &MacroDefinition,
352                                  clang::SourceRange Range) {
353   beginCallback("Defined");
354   appendArgument("MacroNameTok", MacroNameTok);
355   appendArgument("MacroDefinition", MacroDefinition);
356   appendArgument("Range", Range);
357 }
358 
359 // Hook called when a source range is skipped.
360 void PPCallbacksTracker::SourceRangeSkipped(clang::SourceRange Range,
361                                             clang::SourceLocation EndifLoc) {
362   beginCallback("SourceRangeSkipped");
363   appendArgument("Range", clang::SourceRange(Range.getBegin(), EndifLoc));
364 }
365 
366 // Hook called whenever an #if is seen.
367 void PPCallbacksTracker::If(clang::SourceLocation Loc,
368                             clang::SourceRange ConditionRange,
369                             ConditionValueKind ConditionValue) {
370   beginCallback("If");
371   appendArgument("Loc", Loc);
372   appendArgument("ConditionRange", ConditionRange);
373   appendArgument("ConditionValue", ConditionValue, ConditionValueKindStrings);
374 }
375 
376 // Hook called whenever an #elif is seen.
377 void PPCallbacksTracker::Elif(clang::SourceLocation Loc,
378                               clang::SourceRange ConditionRange,
379                               ConditionValueKind ConditionValue,
380                               clang::SourceLocation IfLoc) {
381   beginCallback("Elif");
382   appendArgument("Loc", Loc);
383   appendArgument("ConditionRange", ConditionRange);
384   appendArgument("ConditionValue", ConditionValue, ConditionValueKindStrings);
385   appendArgument("IfLoc", IfLoc);
386 }
387 
388 // Hook called whenever an #ifdef is seen.
389 void PPCallbacksTracker::Ifdef(clang::SourceLocation Loc,
390                                const clang::Token &MacroNameTok,
391                                const clang::MacroDefinition &MacroDefinition) {
392   beginCallback("Ifdef");
393   appendArgument("Loc", Loc);
394   appendArgument("MacroNameTok", MacroNameTok);
395   appendArgument("MacroDefinition", MacroDefinition);
396 }
397 
398 // Hook called whenever an #ifndef is seen.
399 void PPCallbacksTracker::Ifndef(clang::SourceLocation Loc,
400                                 const clang::Token &MacroNameTok,
401                                 const clang::MacroDefinition &MacroDefinition) {
402   beginCallback("Ifndef");
403   appendArgument("Loc", Loc);
404   appendArgument("MacroNameTok", MacroNameTok);
405   appendArgument("MacroDefinition", MacroDefinition);
406 }
407 
408 // Hook called whenever an #else is seen.
409 void PPCallbacksTracker::Else(clang::SourceLocation Loc,
410                               clang::SourceLocation IfLoc) {
411   beginCallback("Else");
412   appendArgument("Loc", Loc);
413   appendArgument("IfLoc", IfLoc);
414 }
415 
416 // Hook called whenever an #endif is seen.
417 void PPCallbacksTracker::Endif(clang::SourceLocation Loc,
418                                clang::SourceLocation IfLoc) {
419   beginCallback("Endif");
420   appendArgument("Loc", Loc);
421   appendArgument("IfLoc", IfLoc);
422 }
423 
424 // Helper functions.
425 
426 // Start a new callback.
427 void PPCallbacksTracker::beginCallback(const char *Name) {
428   auto R = CallbackIsEnabled.try_emplace(Name, false);
429   if (R.second) {
430     llvm::StringRef N(Name);
431     for (const std::pair<llvm::GlobPattern, bool> &Filter : Filters)
432       if (Filter.first.match(N))
433         R.first->second = Filter.second;
434   }
435   DisableTrace = !R.first->second;
436   if (DisableTrace)
437     return;
438   CallbackCalls.push_back(CallbackCall(Name));
439 }
440 
441 // Append a bool argument to the top trace item.
442 void PPCallbacksTracker::appendArgument(const char *Name, bool Value) {
443   appendArgument(Name, (Value ? "true" : "false"));
444 }
445 
446 // Append an int argument to the top trace item.
447 void PPCallbacksTracker::appendArgument(const char *Name, int Value) {
448   std::string Str;
449   llvm::raw_string_ostream SS(Str);
450   SS << Value;
451   appendArgument(Name, SS.str());
452 }
453 
454 // Append a string argument to the top trace item.
455 void PPCallbacksTracker::appendArgument(const char *Name, const char *Value) {
456   if (DisableTrace)
457     return;
458   CallbackCalls.back().Arguments.push_back(Argument(Name, Value));
459 }
460 
461 // Append a string object argument to the top trace item.
462 void PPCallbacksTracker::appendArgument(const char *Name,
463                                         llvm::StringRef Value) {
464   appendArgument(Name, Value.str());
465 }
466 
467 // Append a string object argument to the top trace item.
468 void PPCallbacksTracker::appendArgument(const char *Name,
469                                         const std::string &Value) {
470   appendArgument(Name, Value.c_str());
471 }
472 
473 // Append a token argument to the top trace item.
474 void PPCallbacksTracker::appendArgument(const char *Name,
475                                         const clang::Token &Value) {
476   appendArgument(Name, PP.getSpelling(Value));
477 }
478 
479 // Append an enum argument to the top trace item.
480 void PPCallbacksTracker::appendArgument(const char *Name, int Value,
481                                         const char *const Strings[]) {
482   appendArgument(Name, Strings[Value]);
483 }
484 
485 // Append a FileID argument to the top trace item.
486 void PPCallbacksTracker::appendArgument(const char *Name, clang::FileID Value) {
487   if (Value.isInvalid()) {
488     appendArgument(Name, "(invalid)");
489     return;
490   }
491   const clang::FileEntry *FileEntry =
492       PP.getSourceManager().getFileEntryForID(Value);
493   if (!FileEntry) {
494     appendArgument(Name, "(getFileEntryForID failed)");
495     return;
496   }
497   appendFilePathArgument(Name, FileEntry->getName());
498 }
499 
500 // Append a FileEntry argument to the top trace item.
501 void PPCallbacksTracker::appendArgument(const char *Name,
502                                         const clang::FileEntry *Value) {
503   if (!Value) {
504     appendArgument(Name, "(null)");
505     return;
506   }
507   appendFilePathArgument(Name, Value->getName());
508 }
509 
510 // Append a SourceLocation argument to the top trace item.
511 void PPCallbacksTracker::appendArgument(const char *Name,
512                                         clang::SourceLocation Value) {
513   if (Value.isInvalid()) {
514     appendArgument(Name, "(invalid)");
515     return;
516   }
517   appendArgument(Name, getSourceLocationString(PP, Value).c_str());
518 }
519 
520 // Append a SourceRange argument to the top trace item.
521 void PPCallbacksTracker::appendArgument(const char *Name,
522                                         clang::SourceRange Value) {
523   if (DisableTrace)
524     return;
525   if (Value.isInvalid()) {
526     appendArgument(Name, "(invalid)");
527     return;
528   }
529   std::string Str;
530   llvm::raw_string_ostream SS(Str);
531   SS << "[" << getSourceLocationString(PP, Value.getBegin()) << ", "
532      << getSourceLocationString(PP, Value.getEnd()) << "]";
533   appendArgument(Name, SS.str());
534 }
535 
536 // Append a CharSourceRange argument to the top trace item.
537 void PPCallbacksTracker::appendArgument(const char *Name,
538                                         clang::CharSourceRange Value) {
539   if (Value.isInvalid()) {
540     appendArgument(Name, "(invalid)");
541     return;
542   }
543   appendArgument(Name, getSourceString(Value).str().c_str());
544 }
545 
546 // Append a SourceLocation argument to the top trace item.
547 void PPCallbacksTracker::appendArgument(const char *Name,
548                                         clang::ModuleIdPath Value) {
549   if (DisableTrace)
550     return;
551   std::string Str;
552   llvm::raw_string_ostream SS(Str);
553   SS << "[";
554   for (int I = 0, E = Value.size(); I != E; ++I) {
555     if (I)
556       SS << ", ";
557     SS << "{"
558        << "Name: " << Value[I].first->getName() << ", "
559        << "Loc: " << getSourceLocationString(PP, Value[I].second) << "}";
560   }
561   SS << "]";
562   appendArgument(Name, SS.str());
563 }
564 
565 // Append an IdentifierInfo argument to the top trace item.
566 void PPCallbacksTracker::appendArgument(const char *Name,
567                                         const clang::IdentifierInfo *Value) {
568   if (!Value) {
569     appendArgument(Name, "(null)");
570     return;
571   }
572   appendArgument(Name, Value->getName().str().c_str());
573 }
574 
575 // Append a MacroDirective argument to the top trace item.
576 void PPCallbacksTracker::appendArgument(const char *Name,
577                                         const clang::MacroDirective *Value) {
578   if (!Value) {
579     appendArgument(Name, "(null)");
580     return;
581   }
582   appendArgument(Name, MacroDirectiveKindStrings[Value->getKind()]);
583 }
584 
585 // Append a MacroDefinition argument to the top trace item.
586 void PPCallbacksTracker::appendArgument(const char *Name,
587                                         const clang::MacroDefinition &Value) {
588   std::string Str;
589   llvm::raw_string_ostream SS(Str);
590   SS << "[";
591   bool Any = false;
592   if (Value.getLocalDirective()) {
593     SS << "(local)";
594     Any = true;
595   }
596   for (auto *MM : Value.getModuleMacros()) {
597     if (Any) SS << ", ";
598     SS << MM->getOwningModule()->getFullModuleName();
599   }
600   SS << "]";
601   appendArgument(Name, SS.str());
602 }
603 
604 // Append a MacroArgs argument to the top trace item.
605 void PPCallbacksTracker::appendArgument(const char *Name,
606                                         const clang::MacroArgs *Value) {
607   if (!Value) {
608     appendArgument(Name, "(null)");
609     return;
610   }
611   std::string Str;
612   llvm::raw_string_ostream SS(Str);
613   SS << "[";
614 
615   // Each argument is is a series of contiguous Tokens, terminated by a eof.
616   // Go through each argument printing tokens until we reach eof.
617   for (unsigned I = 0; I < Value->getNumMacroArguments(); ++I) {
618     const clang::Token *Current = Value->getUnexpArgument(I);
619     if (I)
620       SS << ", ";
621     bool First = true;
622     while (Current->isNot(clang::tok::eof)) {
623       if (!First)
624         SS << " ";
625       // We need to be careful here because the arguments might not be legal in
626       // YAML, so we use the token name for anything but identifiers and
627       // numeric literals.
628       if (Current->isAnyIdentifier() ||
629           Current->is(clang::tok::numeric_constant)) {
630         SS << PP.getSpelling(*Current);
631       } else {
632         SS << "<" << Current->getName() << ">";
633       }
634       ++Current;
635       First = false;
636     }
637   }
638   SS << "]";
639   appendArgument(Name, SS.str());
640 }
641 
642 // Append a Module argument to the top trace item.
643 void PPCallbacksTracker::appendArgument(const char *Name,
644                                         const clang::Module *Value) {
645   if (!Value) {
646     appendArgument(Name, "(null)");
647     return;
648   }
649   appendArgument(Name, Value->Name.c_str());
650 }
651 
652 // Append a double-quoted argument to the top trace item.
653 void PPCallbacksTracker::appendQuotedArgument(const char *Name,
654                                               const std::string &Value) {
655   std::string Str;
656   llvm::raw_string_ostream SS(Str);
657   SS << "\"" << Value << "\"";
658   appendArgument(Name, SS.str());
659 }
660 
661 // Append a double-quoted file path argument to the top trace item.
662 void PPCallbacksTracker::appendFilePathArgument(const char *Name,
663                                                 llvm::StringRef Value) {
664   std::string Path(Value);
665   // YAML treats backslash as escape, so use forward slashes.
666   std::replace(Path.begin(), Path.end(), '\\', '/');
667   appendQuotedArgument(Name, Path);
668 }
669 
670 // Get the raw source string of the range.
671 llvm::StringRef
672 PPCallbacksTracker::getSourceString(clang::CharSourceRange Range) {
673   const char *B = PP.getSourceManager().getCharacterData(Range.getBegin());
674   const char *E = PP.getSourceManager().getCharacterData(Range.getEnd());
675   return llvm::StringRef(B, E - B);
676 }
677