1 //===--- IdentifierTable.cpp - Hash table for identifier lookup -----------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the IdentifierInfo, IdentifierVisitor, and
11 // IdentifierTable interfaces.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Basic/CharInfo.h"
16 #include "clang/Basic/IdentifierTable.h"
17 #include "clang/Basic/LangOptions.h"
18 #include "clang/Basic/OperatorKinds.h"
19 #include "clang/Basic/Specifiers.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/FoldingSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include <cstdio>
26 
27 using namespace clang;
28 
29 //===----------------------------------------------------------------------===//
30 // IdentifierInfo Implementation
31 //===----------------------------------------------------------------------===//
32 
33 IdentifierInfo::IdentifierInfo() {
34   TokenID = tok::identifier;
35   ObjCOrBuiltinID = 0;
36   HasMacro = false;
37   HadMacro = false;
38   IsExtension = false;
39   IsFutureCompatKeyword = false;
40   IsPoisoned = false;
41   IsCPPOperatorKeyword = false;
42   NeedsHandleIdentifier = false;
43   IsFromAST = false;
44   ChangedAfterLoad = false;
45   FEChangedAfterLoad = false;
46   RevertedTokenID = false;
47   OutOfDate = false;
48   IsModulesImport = false;
49   FETokenInfo = nullptr;
50   Entry = nullptr;
51 }
52 
53 //===----------------------------------------------------------------------===//
54 // IdentifierTable Implementation
55 //===----------------------------------------------------------------------===//
56 
57 IdentifierIterator::~IdentifierIterator() { }
58 
59 IdentifierInfoLookup::~IdentifierInfoLookup() {}
60 
61 namespace {
62   /// \brief A simple identifier lookup iterator that represents an
63   /// empty sequence of identifiers.
64   class EmptyLookupIterator : public IdentifierIterator
65   {
66   public:
67     StringRef Next() override { return StringRef(); }
68   };
69 }
70 
71 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() {
72   return new EmptyLookupIterator();
73 }
74 
75 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
76                                  IdentifierInfoLookup* externalLookup)
77   : HashTable(8192), // Start with space for 8K identifiers.
78     ExternalLookup(externalLookup) {
79 
80   // Populate the identifier table with info about keywords for the current
81   // language.
82   AddKeywords(LangOpts);
83 
84 
85   // Add the '_experimental_modules_import' contextual keyword.
86   get("import").setModulesImport(true);
87 }
88 
89 //===----------------------------------------------------------------------===//
90 // Language Keyword Implementation
91 //===----------------------------------------------------------------------===//
92 
93 // Constants for TokenKinds.def
94 namespace {
95   enum {
96     KEYC99 = 0x1,
97     KEYCXX = 0x2,
98     KEYCXX11 = 0x4,
99     KEYGNU = 0x8,
100     KEYMS = 0x10,
101     BOOLSUPPORT = 0x20,
102     KEYALTIVEC = 0x40,
103     KEYNOCXX = 0x80,
104     KEYBORLAND = 0x100,
105     KEYOPENCL = 0x200,
106     KEYC11 = 0x400,
107     KEYARC = 0x800,
108     KEYNOMS18 = 0x01000,
109     KEYNOOPENCL = 0x02000,
110     WCHARSUPPORT = 0x04000,
111     HALFSUPPORT = 0x08000,
112     KEYCONCEPTS = 0x10000,
113     KEYOBJC2    = 0x20000,
114     KEYZVECTOR  = 0x40000,
115     KEYCOROUTINES = 0x80000,
116     KEYMODULES = 0x100000,
117     KEYALL = (0x1fffff & ~KEYNOMS18 &
118               ~KEYNOOPENCL) // KEYNOMS18 and KEYNOOPENCL are used to exclude.
119   };
120 
121   /// \brief How a keyword is treated in the selected standard.
122   enum KeywordStatus {
123     KS_Disabled,    // Disabled
124     KS_Extension,   // Is an extension
125     KS_Enabled,     // Enabled
126     KS_Future       // Is a keyword in future standard
127   };
128 }
129 
130 /// \brief Translates flags as specified in TokenKinds.def into keyword status
131 /// in the given language standard.
132 static KeywordStatus getKeywordStatus(const LangOptions &LangOpts,
133                                       unsigned Flags) {
134   if (Flags == KEYALL) return KS_Enabled;
135   if (LangOpts.CPlusPlus && (Flags & KEYCXX)) return KS_Enabled;
136   if (LangOpts.CPlusPlus11 && (Flags & KEYCXX11)) return KS_Enabled;
137   if (LangOpts.C99 && (Flags & KEYC99)) return KS_Enabled;
138   if (LangOpts.GNUKeywords && (Flags & KEYGNU)) return KS_Extension;
139   if (LangOpts.MicrosoftExt && (Flags & KEYMS)) return KS_Extension;
140   if (LangOpts.Borland && (Flags & KEYBORLAND)) return KS_Extension;
141   if (LangOpts.Bool && (Flags & BOOLSUPPORT)) return KS_Enabled;
142   if (LangOpts.Half && (Flags & HALFSUPPORT)) return KS_Enabled;
143   if (LangOpts.WChar && (Flags & WCHARSUPPORT)) return KS_Enabled;
144   if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) return KS_Enabled;
145   if (LangOpts.OpenCL && (Flags & KEYOPENCL)) return KS_Enabled;
146   if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) return KS_Enabled;
147   if (LangOpts.C11 && (Flags & KEYC11)) return KS_Enabled;
148   // We treat bridge casts as objective-C keywords so we can warn on them
149   // in non-arc mode.
150   if (LangOpts.ObjC2 && (Flags & KEYARC)) return KS_Enabled;
151   if (LangOpts.ObjC2 && (Flags & KEYOBJC2)) return KS_Enabled;
152   if (LangOpts.ConceptsTS && (Flags & KEYCONCEPTS)) return KS_Enabled;
153   if (LangOpts.CoroutinesTS && (Flags & KEYCOROUTINES)) return KS_Enabled;
154   if (LangOpts.ModulesTS && (Flags & KEYMODULES)) return KS_Enabled;
155   if (LangOpts.CPlusPlus && (Flags & KEYCXX11)) return KS_Future;
156   return KS_Disabled;
157 }
158 
159 /// AddKeyword - This method is used to associate a token ID with specific
160 /// identifiers because they are language keywords.  This causes the lexer to
161 /// automatically map matching identifiers to specialized token codes.
162 static void AddKeyword(StringRef Keyword,
163                        tok::TokenKind TokenCode, unsigned Flags,
164                        const LangOptions &LangOpts, IdentifierTable &Table) {
165   KeywordStatus AddResult = getKeywordStatus(LangOpts, Flags);
166 
167   // Don't add this keyword under MSVCCompat.
168   if (LangOpts.MSVCCompat && (Flags & KEYNOMS18) &&
169       !LangOpts.isCompatibleWithMSVC(LangOptions::MSVC2015))
170     return;
171 
172   // Don't add this keyword under OpenCL.
173   if (LangOpts.OpenCL && (Flags & KEYNOOPENCL))
174     return;
175 
176   // Don't add this keyword if disabled in this language.
177   if (AddResult == KS_Disabled) return;
178 
179   IdentifierInfo &Info =
180       Table.get(Keyword, AddResult == KS_Future ? tok::identifier : TokenCode);
181   Info.setIsExtensionToken(AddResult == KS_Extension);
182   Info.setIsFutureCompatKeyword(AddResult == KS_Future);
183 }
184 
185 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
186 /// representations.
187 static void AddCXXOperatorKeyword(StringRef Keyword,
188                                   tok::TokenKind TokenCode,
189                                   IdentifierTable &Table) {
190   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
191   Info.setIsCPlusPlusOperatorKeyword();
192 }
193 
194 /// AddObjCKeyword - Register an Objective-C \@keyword like "class" "selector"
195 /// or "property".
196 static void AddObjCKeyword(StringRef Name,
197                            tok::ObjCKeywordKind ObjCID,
198                            IdentifierTable &Table) {
199   Table.get(Name).setObjCKeywordID(ObjCID);
200 }
201 
202 /// AddKeywords - Add all keywords to the symbol table.
203 ///
204 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
205   // Add keywords and tokens for the current language.
206 #define KEYWORD(NAME, FLAGS) \
207   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
208              FLAGS, LangOpts, *this);
209 #define ALIAS(NAME, TOK, FLAGS) \
210   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
211              FLAGS, LangOpts, *this);
212 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
213   if (LangOpts.CXXOperatorNames)          \
214     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
215 #define OBJC1_AT_KEYWORD(NAME) \
216   if (LangOpts.ObjC1)          \
217     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
218 #define OBJC2_AT_KEYWORD(NAME) \
219   if (LangOpts.ObjC2)          \
220     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
221 #define TESTING_KEYWORD(NAME, FLAGS)
222 #include "clang/Basic/TokenKinds.def"
223 
224   if (LangOpts.ParseUnknownAnytype)
225     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
226                LangOpts, *this);
227 
228   if (LangOpts.DeclSpecKeyword)
229     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
230 }
231 
232 /// \brief Checks if the specified token kind represents a keyword in the
233 /// specified language.
234 /// \returns Status of the keyword in the language.
235 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
236                                       tok::TokenKind K) {
237   switch (K) {
238 #define KEYWORD(NAME, FLAGS) \
239   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
240 #include "clang/Basic/TokenKinds.def"
241   default: return KS_Disabled;
242   }
243 }
244 
245 /// \brief Returns true if the identifier represents a keyword in the
246 /// specified language.
247 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) const {
248   switch (getTokenKwStatus(LangOpts, getTokenID())) {
249   case KS_Enabled:
250   case KS_Extension:
251     return true;
252   default:
253     return false;
254   }
255 }
256 
257 /// \brief Returns true if the identifier represents a C++ keyword in the
258 /// specified language.
259 bool IdentifierInfo::isCPlusPlusKeyword(const LangOptions &LangOpts) const {
260   if (!LangOpts.CPlusPlus || !isKeyword(LangOpts))
261     return false;
262   // This is a C++ keyword if this identifier is not a keyword when checked
263   // using LangOptions without C++ support.
264   LangOptions LangOptsNoCPP = LangOpts;
265   LangOptsNoCPP.CPlusPlus = false;
266   LangOptsNoCPP.CPlusPlus11 = false;
267   return !isKeyword(LangOptsNoCPP);
268 }
269 
270 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
271   // We use a perfect hash function here involving the length of the keyword,
272   // the first and third character.  For preprocessor ID's there are no
273   // collisions (if there were, the switch below would complain about duplicate
274   // case values).  Note that this depends on 'if' being null terminated.
275 
276 #define HASH(LEN, FIRST, THIRD) \
277   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
278 #define CASE(LEN, FIRST, THIRD, NAME) \
279   case HASH(LEN, FIRST, THIRD): \
280     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
281 
282   unsigned Len = getLength();
283   if (Len < 2) return tok::pp_not_keyword;
284   const char *Name = getNameStart();
285   switch (HASH(Len, Name[0], Name[2])) {
286   default: return tok::pp_not_keyword;
287   CASE( 2, 'i', '\0', if);
288   CASE( 4, 'e', 'i', elif);
289   CASE( 4, 'e', 's', else);
290   CASE( 4, 'l', 'n', line);
291   CASE( 4, 's', 'c', sccs);
292   CASE( 5, 'e', 'd', endif);
293   CASE( 5, 'e', 'r', error);
294   CASE( 5, 'i', 'e', ident);
295   CASE( 5, 'i', 'd', ifdef);
296   CASE( 5, 'u', 'd', undef);
297 
298   CASE( 6, 'a', 's', assert);
299   CASE( 6, 'd', 'f', define);
300   CASE( 6, 'i', 'n', ifndef);
301   CASE( 6, 'i', 'p', import);
302   CASE( 6, 'p', 'a', pragma);
303 
304   CASE( 7, 'd', 'f', defined);
305   CASE( 7, 'i', 'c', include);
306   CASE( 7, 'w', 'r', warning);
307 
308   CASE( 8, 'u', 'a', unassert);
309   CASE(12, 'i', 'c', include_next);
310 
311   CASE(14, '_', 'p', __public_macro);
312 
313   CASE(15, '_', 'p', __private_macro);
314 
315   CASE(16, '_', 'i', __include_macros);
316 #undef CASE
317 #undef HASH
318   }
319 }
320 
321 //===----------------------------------------------------------------------===//
322 // Stats Implementation
323 //===----------------------------------------------------------------------===//
324 
325 /// PrintStats - Print statistics about how well the identifier table is doing
326 /// at hashing identifiers.
327 void IdentifierTable::PrintStats() const {
328   unsigned NumBuckets = HashTable.getNumBuckets();
329   unsigned NumIdentifiers = HashTable.getNumItems();
330   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
331   unsigned AverageIdentifierSize = 0;
332   unsigned MaxIdentifierLength = 0;
333 
334   // TODO: Figure out maximum times an identifier had to probe for -stats.
335   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
336        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
337     unsigned IdLen = I->getKeyLength();
338     AverageIdentifierSize += IdLen;
339     if (MaxIdentifierLength < IdLen)
340       MaxIdentifierLength = IdLen;
341   }
342 
343   fprintf(stderr, "\n*** Identifier Table Stats:\n");
344   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
345   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
346   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
347           NumIdentifiers/(double)NumBuckets);
348   fprintf(stderr, "Ave identifier length: %f\n",
349           (AverageIdentifierSize/(double)NumIdentifiers));
350   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
351 
352   // Compute statistics about the memory allocated for identifiers.
353   HashTable.getAllocator().PrintStats();
354 }
355 
356 //===----------------------------------------------------------------------===//
357 // SelectorTable Implementation
358 //===----------------------------------------------------------------------===//
359 
360 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
361   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
362 }
363 
364 namespace clang {
365 /// MultiKeywordSelector - One of these variable length records is kept for each
366 /// selector containing more than one keyword. We use a folding set
367 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
368 /// this class is provided strictly through Selector.
369 class MultiKeywordSelector
370   : public DeclarationNameExtra, public llvm::FoldingSetNode {
371   MultiKeywordSelector(unsigned nKeys) {
372     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
373   }
374 public:
375   // Constructor for keyword selectors.
376   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV) {
377     assert((nKeys > 1) && "not a multi-keyword selector");
378     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
379 
380     // Fill in the trailing keyword array.
381     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this+1);
382     for (unsigned i = 0; i != nKeys; ++i)
383       KeyInfo[i] = IIV[i];
384   }
385 
386   // getName - Derive the full selector name and return it.
387   std::string getName() const;
388 
389   unsigned getNumArgs() const { return ExtraKindOrNumArgs - NUM_EXTRA_KINDS; }
390 
391   typedef IdentifierInfo *const *keyword_iterator;
392   keyword_iterator keyword_begin() const {
393     return reinterpret_cast<keyword_iterator>(this+1);
394   }
395   keyword_iterator keyword_end() const {
396     return keyword_begin()+getNumArgs();
397   }
398   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
399     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
400     return keyword_begin()[i];
401   }
402   static void Profile(llvm::FoldingSetNodeID &ID,
403                       keyword_iterator ArgTys, unsigned NumArgs) {
404     ID.AddInteger(NumArgs);
405     for (unsigned i = 0; i != NumArgs; ++i)
406       ID.AddPointer(ArgTys[i]);
407   }
408   void Profile(llvm::FoldingSetNodeID &ID) {
409     Profile(ID, keyword_begin(), getNumArgs());
410   }
411 };
412 } // end namespace clang.
413 
414 unsigned Selector::getNumArgs() const {
415   unsigned IIF = getIdentifierInfoFlag();
416   if (IIF <= ZeroArg)
417     return 0;
418   if (IIF == OneArg)
419     return 1;
420   // We point to a MultiKeywordSelector.
421   MultiKeywordSelector *SI = getMultiKeywordSelector();
422   return SI->getNumArgs();
423 }
424 
425 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
426   if (getIdentifierInfoFlag() < MultiArg) {
427     assert(argIndex == 0 && "illegal keyword index");
428     return getAsIdentifierInfo();
429   }
430   // We point to a MultiKeywordSelector.
431   MultiKeywordSelector *SI = getMultiKeywordSelector();
432   return SI->getIdentifierInfoForSlot(argIndex);
433 }
434 
435 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
436   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
437   return II? II->getName() : StringRef();
438 }
439 
440 std::string MultiKeywordSelector::getName() const {
441   SmallString<256> Str;
442   llvm::raw_svector_ostream OS(Str);
443   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
444     if (*I)
445       OS << (*I)->getName();
446     OS << ':';
447   }
448 
449   return OS.str();
450 }
451 
452 std::string Selector::getAsString() const {
453   if (InfoPtr == 0)
454     return "<null selector>";
455 
456   if (getIdentifierInfoFlag() < MultiArg) {
457     IdentifierInfo *II = getAsIdentifierInfo();
458 
459     if (getNumArgs() == 0) {
460       assert(II && "If the number of arguments is 0 then II is guaranteed to "
461                    "not be null.");
462       return II->getName();
463     }
464 
465     if (!II)
466       return ":";
467 
468     return II->getName().str() + ":";
469   }
470 
471   // We have a multiple keyword selector.
472   return getMultiKeywordSelector()->getName();
473 }
474 
475 void Selector::print(llvm::raw_ostream &OS) const {
476   OS << getAsString();
477 }
478 
479 /// Interpreting the given string using the normal CamelCase
480 /// conventions, determine whether the given string starts with the
481 /// given "word", which is assumed to end in a lowercase letter.
482 static bool startsWithWord(StringRef name, StringRef word) {
483   if (name.size() < word.size()) return false;
484   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
485           name.startswith(word));
486 }
487 
488 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
489   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
490   if (!first) return OMF_None;
491 
492   StringRef name = first->getName();
493   if (sel.isUnarySelector()) {
494     if (name == "autorelease") return OMF_autorelease;
495     if (name == "dealloc") return OMF_dealloc;
496     if (name == "finalize") return OMF_finalize;
497     if (name == "release") return OMF_release;
498     if (name == "retain") return OMF_retain;
499     if (name == "retainCount") return OMF_retainCount;
500     if (name == "self") return OMF_self;
501     if (name == "initialize") return OMF_initialize;
502   }
503 
504   if (name == "performSelector" || name == "performSelectorInBackground" ||
505       name == "performSelectorOnMainThread")
506     return OMF_performSelector;
507 
508   // The other method families may begin with a prefix of underscores.
509   while (!name.empty() && name.front() == '_')
510     name = name.substr(1);
511 
512   if (name.empty()) return OMF_None;
513   switch (name.front()) {
514   case 'a':
515     if (startsWithWord(name, "alloc")) return OMF_alloc;
516     break;
517   case 'c':
518     if (startsWithWord(name, "copy")) return OMF_copy;
519     break;
520   case 'i':
521     if (startsWithWord(name, "init")) return OMF_init;
522     break;
523   case 'm':
524     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
525     break;
526   case 'n':
527     if (startsWithWord(name, "new")) return OMF_new;
528     break;
529   default:
530     break;
531   }
532 
533   return OMF_None;
534 }
535 
536 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
537   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
538   if (!first) return OIT_None;
539 
540   StringRef name = first->getName();
541 
542   if (name.empty()) return OIT_None;
543   switch (name.front()) {
544     case 'a':
545       if (startsWithWord(name, "array")) return OIT_Array;
546       break;
547     case 'd':
548       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
549       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
550       break;
551     case 's':
552       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
553       if (startsWithWord(name, "standard")) return OIT_Singleton;
554     case 'i':
555       if (startsWithWord(name, "init")) return OIT_Init;
556     default:
557       break;
558   }
559   return OIT_None;
560 }
561 
562 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
563   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
564   if (!first) return SFF_None;
565 
566   StringRef name = first->getName();
567 
568   switch (name.front()) {
569     case 'a':
570       if (name == "appendFormat") return SFF_NSString;
571       break;
572 
573     case 'i':
574       if (name == "initWithFormat") return SFF_NSString;
575       break;
576 
577     case 'l':
578       if (name == "localizedStringWithFormat") return SFF_NSString;
579       break;
580 
581     case 's':
582       if (name == "stringByAppendingFormat" ||
583           name == "stringWithFormat") return SFF_NSString;
584       break;
585   }
586   return SFF_None;
587 }
588 
589 namespace {
590   struct SelectorTableImpl {
591     llvm::FoldingSet<MultiKeywordSelector> Table;
592     llvm::BumpPtrAllocator Allocator;
593   };
594 } // end anonymous namespace.
595 
596 static SelectorTableImpl &getSelectorTableImpl(void *P) {
597   return *static_cast<SelectorTableImpl*>(P);
598 }
599 
600 SmallString<64>
601 SelectorTable::constructSetterName(StringRef Name) {
602   SmallString<64> SetterName("set");
603   SetterName += Name;
604   SetterName[3] = toUppercase(SetterName[3]);
605   return SetterName;
606 }
607 
608 Selector
609 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
610                                        SelectorTable &SelTable,
611                                        const IdentifierInfo *Name) {
612   IdentifierInfo *SetterName =
613     &Idents.get(constructSetterName(Name->getName()));
614   return SelTable.getUnarySelector(SetterName);
615 }
616 
617 size_t SelectorTable::getTotalMemory() const {
618   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
619   return SelTabImpl.Allocator.getTotalMemory();
620 }
621 
622 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
623   if (nKeys < 2)
624     return Selector(IIV[0], nKeys);
625 
626   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
627 
628   // Unique selector, to guarantee there is one per name.
629   llvm::FoldingSetNodeID ID;
630   MultiKeywordSelector::Profile(ID, IIV, nKeys);
631 
632   void *InsertPos = nullptr;
633   if (MultiKeywordSelector *SI =
634         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
635     return Selector(SI);
636 
637   // MultiKeywordSelector objects are not allocated with new because they have a
638   // variable size array (for parameter types) at the end of them.
639   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
640   MultiKeywordSelector *SI =
641       (MultiKeywordSelector *)SelTabImpl.Allocator.Allocate(
642           Size, alignof(MultiKeywordSelector));
643   new (SI) MultiKeywordSelector(nKeys, IIV);
644   SelTabImpl.Table.InsertNode(SI, InsertPos);
645   return Selector(SI);
646 }
647 
648 SelectorTable::SelectorTable() {
649   Impl = new SelectorTableImpl();
650 }
651 
652 SelectorTable::~SelectorTable() {
653   delete &getSelectorTableImpl(Impl);
654 }
655 
656 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
657   switch (Operator) {
658   case OO_None:
659   case NUM_OVERLOADED_OPERATORS:
660     return nullptr;
661 
662 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
663   case OO_##Name: return Spelling;
664 #include "clang/Basic/OperatorKinds.def"
665   }
666 
667   llvm_unreachable("Invalid OverloadedOperatorKind!");
668 }
669 
670 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
671                                         bool isContextSensitive) {
672   switch (kind) {
673   case NullabilityKind::NonNull:
674     return isContextSensitive ? "nonnull" : "_Nonnull";
675 
676   case NullabilityKind::Nullable:
677     return isContextSensitive ? "nullable" : "_Nullable";
678 
679   case NullabilityKind::Unspecified:
680     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
681   }
682   llvm_unreachable("Unknown nullability kind.");
683 }
684