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/IdentifierTable.h"
16 #include "clang/Basic/CharInfo.h"
17 #include "clang/Basic/LangOptions.h"
18 #include "clang/Basic/OperatorKinds.h"
19 #include "clang/Basic/Specifiers.h"
20 #include "clang/Basic/TokenKinds.h"
21 #include "llvm/ADT/DenseMapInfo.h"
22 #include "llvm/ADT/FoldingSet.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/StringMap.h"
25 #include "llvm/ADT/StringRef.h"
26 #include "llvm/Support/Allocator.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include <cassert>
30 #include <cstdio>
31 #include <cstring>
32 #include <string>
33 
34 using namespace clang;
35 
36 //===----------------------------------------------------------------------===//
37 // IdentifierTable Implementation
38 //===----------------------------------------------------------------------===//
39 
40 IdentifierIterator::~IdentifierIterator() = default;
41 
42 IdentifierInfoLookup::~IdentifierInfoLookup() = default;
43 
44 namespace {
45 
46 /// A simple identifier lookup iterator that represents an
47 /// empty sequence of identifiers.
48 class EmptyLookupIterator : public IdentifierIterator
49 {
50 public:
51   StringRef Next() override { return StringRef(); }
52 };
53 
54 } // namespace
55 
56 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() {
57   return new EmptyLookupIterator();
58 }
59 
60 IdentifierTable::IdentifierTable(IdentifierInfoLookup *ExternalLookup)
61     : HashTable(8192), // Start with space for 8K identifiers.
62       ExternalLookup(ExternalLookup) {}
63 
64 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
65                                  IdentifierInfoLookup *ExternalLookup)
66     : IdentifierTable(ExternalLookup) {
67   // Populate the identifier table with info about keywords for the current
68   // language.
69   AddKeywords(LangOpts);
70 }
71 
72 //===----------------------------------------------------------------------===//
73 // Language Keyword Implementation
74 //===----------------------------------------------------------------------===//
75 
76 // Constants for TokenKinds.def
77 namespace {
78 
79   enum {
80     KEYC99        = 0x1,
81     KEYCXX        = 0x2,
82     KEYCXX11      = 0x4,
83     KEYGNU        = 0x8,
84     KEYMS         = 0x10,
85     BOOLSUPPORT   = 0x20,
86     KEYALTIVEC    = 0x40,
87     KEYNOCXX      = 0x80,
88     KEYBORLAND    = 0x100,
89     KEYOPENCLC    = 0x200,
90     KEYC11        = 0x400,
91     KEYNOMS18     = 0x800,
92     KEYNOOPENCL   = 0x1000,
93     WCHARSUPPORT  = 0x2000,
94     HALFSUPPORT   = 0x4000,
95     CHAR8SUPPORT  = 0x8000,
96     KEYCONCEPTS   = 0x10000,
97     KEYOBJC       = 0x20000,
98     KEYZVECTOR    = 0x40000,
99     KEYCOROUTINES = 0x80000,
100     KEYMODULES    = 0x100000,
101     KEYCXX2A      = 0x200000,
102     KEYOPENCLCXX  = 0x400000,
103     KEYALLCXX = KEYCXX | KEYCXX11 | KEYCXX2A,
104     KEYALL = (0xffffff & ~KEYNOMS18 &
105               ~KEYNOOPENCL) // KEYNOMS18 and KEYNOOPENCL are used to exclude.
106   };
107 
108   /// How a keyword is treated in the selected standard.
109   enum KeywordStatus {
110     KS_Disabled,    // Disabled
111     KS_Extension,   // Is an extension
112     KS_Enabled,     // Enabled
113     KS_Future       // Is a keyword in future standard
114   };
115 
116 } // namespace
117 
118 /// Translates flags as specified in TokenKinds.def into keyword status
119 /// in the given language standard.
120 static KeywordStatus getKeywordStatus(const LangOptions &LangOpts,
121                                       unsigned Flags) {
122   if (Flags == KEYALL) return KS_Enabled;
123   if (LangOpts.CPlusPlus && (Flags & KEYCXX)) return KS_Enabled;
124   if (LangOpts.CPlusPlus11 && (Flags & KEYCXX11)) return KS_Enabled;
125   if (LangOpts.CPlusPlus2a && (Flags & KEYCXX2A)) return KS_Enabled;
126   if (LangOpts.C99 && (Flags & KEYC99)) return KS_Enabled;
127   if (LangOpts.GNUKeywords && (Flags & KEYGNU)) return KS_Extension;
128   if (LangOpts.MicrosoftExt && (Flags & KEYMS)) return KS_Extension;
129   if (LangOpts.Borland && (Flags & KEYBORLAND)) return KS_Extension;
130   if (LangOpts.Bool && (Flags & BOOLSUPPORT)) return KS_Enabled;
131   if (LangOpts.Half && (Flags & HALFSUPPORT)) return KS_Enabled;
132   if (LangOpts.WChar && (Flags & WCHARSUPPORT)) return KS_Enabled;
133   if (LangOpts.Char8 && (Flags & CHAR8SUPPORT)) return KS_Enabled;
134   if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) return KS_Enabled;
135   if (LangOpts.ZVector && (Flags & KEYZVECTOR)) return KS_Enabled;
136   if (LangOpts.OpenCL && !LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLC))
137     return KS_Enabled;
138   if (LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLCXX)) return KS_Enabled;
139   if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) return KS_Enabled;
140   if (LangOpts.C11 && (Flags & KEYC11)) return KS_Enabled;
141   // We treat bridge casts as objective-C keywords so we can warn on them
142   // in non-arc mode.
143   if (LangOpts.ObjC && (Flags & KEYOBJC)) return KS_Enabled;
144   if (LangOpts.ConceptsTS && (Flags & KEYCONCEPTS)) return KS_Enabled;
145   if (LangOpts.CoroutinesTS && (Flags & KEYCOROUTINES)) return KS_Enabled;
146   if (LangOpts.ModulesTS && (Flags & KEYMODULES)) return KS_Enabled;
147   if (LangOpts.CPlusPlus && (Flags & KEYALLCXX)) return KS_Future;
148   return KS_Disabled;
149 }
150 
151 /// AddKeyword - This method is used to associate a token ID with specific
152 /// identifiers because they are language keywords.  This causes the lexer to
153 /// automatically map matching identifiers to specialized token codes.
154 static void AddKeyword(StringRef Keyword,
155                        tok::TokenKind TokenCode, unsigned Flags,
156                        const LangOptions &LangOpts, IdentifierTable &Table) {
157   KeywordStatus AddResult = getKeywordStatus(LangOpts, Flags);
158 
159   // Don't add this keyword under MSVCCompat.
160   if (LangOpts.MSVCCompat && (Flags & KEYNOMS18) &&
161       !LangOpts.isCompatibleWithMSVC(LangOptions::MSVC2015))
162     return;
163 
164   // Don't add this keyword under OpenCL.
165   if (LangOpts.OpenCL && (Flags & KEYNOOPENCL))
166     return;
167 
168   // Don't add this keyword if disabled in this language.
169   if (AddResult == KS_Disabled) return;
170 
171   IdentifierInfo &Info =
172       Table.get(Keyword, AddResult == KS_Future ? tok::identifier : TokenCode);
173   Info.setIsExtensionToken(AddResult == KS_Extension);
174   Info.setIsFutureCompatKeyword(AddResult == KS_Future);
175 }
176 
177 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
178 /// representations.
179 static void AddCXXOperatorKeyword(StringRef Keyword,
180                                   tok::TokenKind TokenCode,
181                                   IdentifierTable &Table) {
182   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
183   Info.setIsCPlusPlusOperatorKeyword();
184 }
185 
186 /// AddObjCKeyword - Register an Objective-C \@keyword like "class" "selector"
187 /// or "property".
188 static void AddObjCKeyword(StringRef Name,
189                            tok::ObjCKeywordKind ObjCID,
190                            IdentifierTable &Table) {
191   Table.get(Name).setObjCKeywordID(ObjCID);
192 }
193 
194 /// AddKeywords - Add all keywords to the symbol table.
195 ///
196 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
197   // Add keywords and tokens for the current language.
198 #define KEYWORD(NAME, FLAGS) \
199   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
200              FLAGS, LangOpts, *this);
201 #define ALIAS(NAME, TOK, FLAGS) \
202   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
203              FLAGS, LangOpts, *this);
204 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
205   if (LangOpts.CXXOperatorNames)          \
206     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
207 #define OBJC_AT_KEYWORD(NAME)  \
208   if (LangOpts.ObjC)           \
209     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
210 #define TESTING_KEYWORD(NAME, FLAGS)
211 #include "clang/Basic/TokenKinds.def"
212 
213   if (LangOpts.ParseUnknownAnytype)
214     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
215                LangOpts, *this);
216 
217   if (LangOpts.DeclSpecKeyword)
218     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
219 
220   // Add the '_experimental_modules_import' contextual keyword.
221   get("import").setModulesImport(true);
222 }
223 
224 /// Checks if the specified token kind represents a keyword in the
225 /// specified language.
226 /// \returns Status of the keyword in the language.
227 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
228                                       tok::TokenKind K) {
229   switch (K) {
230 #define KEYWORD(NAME, FLAGS) \
231   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
232 #include "clang/Basic/TokenKinds.def"
233   default: return KS_Disabled;
234   }
235 }
236 
237 /// Returns true if the identifier represents a keyword in the
238 /// specified language.
239 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) const {
240   switch (getTokenKwStatus(LangOpts, getTokenID())) {
241   case KS_Enabled:
242   case KS_Extension:
243     return true;
244   default:
245     return false;
246   }
247 }
248 
249 /// Returns true if the identifier represents a C++ keyword in the
250 /// specified language.
251 bool IdentifierInfo::isCPlusPlusKeyword(const LangOptions &LangOpts) const {
252   if (!LangOpts.CPlusPlus || !isKeyword(LangOpts))
253     return false;
254   // This is a C++ keyword if this identifier is not a keyword when checked
255   // using LangOptions without C++ support.
256   LangOptions LangOptsNoCPP = LangOpts;
257   LangOptsNoCPP.CPlusPlus = false;
258   LangOptsNoCPP.CPlusPlus11 = false;
259   LangOptsNoCPP.CPlusPlus2a = false;
260   return !isKeyword(LangOptsNoCPP);
261 }
262 
263 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
264   // We use a perfect hash function here involving the length of the keyword,
265   // the first and third character.  For preprocessor ID's there are no
266   // collisions (if there were, the switch below would complain about duplicate
267   // case values).  Note that this depends on 'if' being null terminated.
268 
269 #define HASH(LEN, FIRST, THIRD) \
270   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
271 #define CASE(LEN, FIRST, THIRD, NAME) \
272   case HASH(LEN, FIRST, THIRD): \
273     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
274 
275   unsigned Len = getLength();
276   if (Len < 2) return tok::pp_not_keyword;
277   const char *Name = getNameStart();
278   switch (HASH(Len, Name[0], Name[2])) {
279   default: return tok::pp_not_keyword;
280   CASE( 2, 'i', '\0', if);
281   CASE( 4, 'e', 'i', elif);
282   CASE( 4, 'e', 's', else);
283   CASE( 4, 'l', 'n', line);
284   CASE( 4, 's', 'c', sccs);
285   CASE( 5, 'e', 'd', endif);
286   CASE( 5, 'e', 'r', error);
287   CASE( 5, 'i', 'e', ident);
288   CASE( 5, 'i', 'd', ifdef);
289   CASE( 5, 'u', 'd', undef);
290 
291   CASE( 6, 'a', 's', assert);
292   CASE( 6, 'd', 'f', define);
293   CASE( 6, 'i', 'n', ifndef);
294   CASE( 6, 'i', 'p', import);
295   CASE( 6, 'p', 'a', pragma);
296 
297   CASE( 7, 'd', 'f', defined);
298   CASE( 7, 'i', 'c', include);
299   CASE( 7, 'w', 'r', warning);
300 
301   CASE( 8, 'u', 'a', unassert);
302   CASE(12, 'i', 'c', include_next);
303 
304   CASE(14, '_', 'p', __public_macro);
305 
306   CASE(15, '_', 'p', __private_macro);
307 
308   CASE(16, '_', 'i', __include_macros);
309 #undef CASE
310 #undef HASH
311   }
312 }
313 
314 //===----------------------------------------------------------------------===//
315 // Stats Implementation
316 //===----------------------------------------------------------------------===//
317 
318 /// PrintStats - Print statistics about how well the identifier table is doing
319 /// at hashing identifiers.
320 void IdentifierTable::PrintStats() const {
321   unsigned NumBuckets = HashTable.getNumBuckets();
322   unsigned NumIdentifiers = HashTable.getNumItems();
323   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
324   unsigned AverageIdentifierSize = 0;
325   unsigned MaxIdentifierLength = 0;
326 
327   // TODO: Figure out maximum times an identifier had to probe for -stats.
328   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
329        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
330     unsigned IdLen = I->getKeyLength();
331     AverageIdentifierSize += IdLen;
332     if (MaxIdentifierLength < IdLen)
333       MaxIdentifierLength = IdLen;
334   }
335 
336   fprintf(stderr, "\n*** Identifier Table Stats:\n");
337   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
338   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
339   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
340           NumIdentifiers/(double)NumBuckets);
341   fprintf(stderr, "Ave identifier length: %f\n",
342           (AverageIdentifierSize/(double)NumIdentifiers));
343   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
344 
345   // Compute statistics about the memory allocated for identifiers.
346   HashTable.getAllocator().PrintStats();
347 }
348 
349 //===----------------------------------------------------------------------===//
350 // SelectorTable Implementation
351 //===----------------------------------------------------------------------===//
352 
353 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
354   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
355 }
356 
357 namespace clang {
358 
359 /// One of these variable length records is kept for each
360 /// selector containing more than one keyword. We use a folding set
361 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
362 /// this class is provided strictly through Selector.
363 class alignas(IdentifierInfoAlignment) MultiKeywordSelector
364     : public detail::DeclarationNameExtra,
365       public llvm::FoldingSetNode {
366   MultiKeywordSelector(unsigned nKeys) : DeclarationNameExtra(nKeys) {}
367 
368 public:
369   // Constructor for keyword selectors.
370   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV)
371       : DeclarationNameExtra(nKeys) {
372     assert((nKeys > 1) && "not a multi-keyword selector");
373 
374     // Fill in the trailing keyword array.
375     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this + 1);
376     for (unsigned i = 0; i != nKeys; ++i)
377       KeyInfo[i] = IIV[i];
378   }
379 
380   // getName - Derive the full selector name and return it.
381   std::string getName() const;
382 
383   using DeclarationNameExtra::getNumArgs;
384 
385   using keyword_iterator = IdentifierInfo *const *;
386 
387   keyword_iterator keyword_begin() const {
388     return reinterpret_cast<keyword_iterator>(this + 1);
389   }
390 
391   keyword_iterator keyword_end() const {
392     return keyword_begin() + getNumArgs();
393   }
394 
395   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
396     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
397     return keyword_begin()[i];
398   }
399 
400   static void Profile(llvm::FoldingSetNodeID &ID, keyword_iterator ArgTys,
401                       unsigned NumArgs) {
402     ID.AddInteger(NumArgs);
403     for (unsigned i = 0; i != NumArgs; ++i)
404       ID.AddPointer(ArgTys[i]);
405   }
406 
407   void Profile(llvm::FoldingSetNodeID &ID) {
408     Profile(ID, keyword_begin(), getNumArgs());
409   }
410 };
411 
412 } // 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 
431   // We point to a MultiKeywordSelector.
432   MultiKeywordSelector *SI = getMultiKeywordSelector();
433   return SI->getIdentifierInfoForSlot(argIndex);
434 }
435 
436 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
437   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
438   return II ? II->getName() : StringRef();
439 }
440 
441 std::string MultiKeywordSelector::getName() const {
442   SmallString<256> Str;
443   llvm::raw_svector_ostream OS(Str);
444   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
445     if (*I)
446       OS << (*I)->getName();
447     OS << ':';
448   }
449 
450   return OS.str();
451 }
452 
453 std::string Selector::getAsString() const {
454   if (InfoPtr == 0)
455     return "<null selector>";
456 
457   if (getIdentifierInfoFlag() < MultiArg) {
458     IdentifierInfo *II = getAsIdentifierInfo();
459 
460     if (getNumArgs() == 0) {
461       assert(II && "If the number of arguments is 0 then II is guaranteed to "
462                    "not be null.");
463       return II->getName();
464     }
465 
466     if (!II)
467       return ":";
468 
469     return II->getName().str() + ":";
470   }
471 
472   // We have a multiple keyword selector.
473   return getMultiKeywordSelector()->getName();
474 }
475 
476 void Selector::print(llvm::raw_ostream &OS) const {
477   OS << getAsString();
478 }
479 
480 LLVM_DUMP_METHOD void Selector::dump() const { print(llvm::errs()); }
481 
482 /// Interpreting the given string using the normal CamelCase
483 /// conventions, determine whether the given string starts with the
484 /// given "word", which is assumed to end in a lowercase letter.
485 static bool startsWithWord(StringRef name, StringRef word) {
486   if (name.size() < word.size()) return false;
487   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
488           name.startswith(word));
489 }
490 
491 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
492   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
493   if (!first) return OMF_None;
494 
495   StringRef name = first->getName();
496   if (sel.isUnarySelector()) {
497     if (name == "autorelease") return OMF_autorelease;
498     if (name == "dealloc") return OMF_dealloc;
499     if (name == "finalize") return OMF_finalize;
500     if (name == "release") return OMF_release;
501     if (name == "retain") return OMF_retain;
502     if (name == "retainCount") return OMF_retainCount;
503     if (name == "self") return OMF_self;
504     if (name == "initialize") return OMF_initialize;
505   }
506 
507   if (name == "performSelector" || name == "performSelectorInBackground" ||
508       name == "performSelectorOnMainThread")
509     return OMF_performSelector;
510 
511   // The other method families may begin with a prefix of underscores.
512   while (!name.empty() && name.front() == '_')
513     name = name.substr(1);
514 
515   if (name.empty()) return OMF_None;
516   switch (name.front()) {
517   case 'a':
518     if (startsWithWord(name, "alloc")) return OMF_alloc;
519     break;
520   case 'c':
521     if (startsWithWord(name, "copy")) return OMF_copy;
522     break;
523   case 'i':
524     if (startsWithWord(name, "init")) return OMF_init;
525     break;
526   case 'm':
527     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
528     break;
529   case 'n':
530     if (startsWithWord(name, "new")) return OMF_new;
531     break;
532   default:
533     break;
534   }
535 
536   return OMF_None;
537 }
538 
539 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
540   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
541   if (!first) return OIT_None;
542 
543   StringRef name = first->getName();
544 
545   if (name.empty()) return OIT_None;
546   switch (name.front()) {
547     case 'a':
548       if (startsWithWord(name, "array")) return OIT_Array;
549       break;
550     case 'd':
551       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
552       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
553       break;
554     case 's':
555       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
556       if (startsWithWord(name, "standard")) return OIT_Singleton;
557       break;
558     case 'i':
559       if (startsWithWord(name, "init")) return OIT_Init;
560       break;
561     default:
562       break;
563   }
564   return OIT_None;
565 }
566 
567 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
568   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
569   if (!first) return SFF_None;
570 
571   StringRef name = first->getName();
572 
573   switch (name.front()) {
574     case 'a':
575       if (name == "appendFormat") return SFF_NSString;
576       break;
577 
578     case 'i':
579       if (name == "initWithFormat") return SFF_NSString;
580       break;
581 
582     case 'l':
583       if (name == "localizedStringWithFormat") return SFF_NSString;
584       break;
585 
586     case 's':
587       if (name == "stringByAppendingFormat" ||
588           name == "stringWithFormat") return SFF_NSString;
589       break;
590   }
591   return SFF_None;
592 }
593 
594 namespace {
595 
596 struct SelectorTableImpl {
597   llvm::FoldingSet<MultiKeywordSelector> Table;
598   llvm::BumpPtrAllocator Allocator;
599 };
600 
601 } // namespace
602 
603 static SelectorTableImpl &getSelectorTableImpl(void *P) {
604   return *static_cast<SelectorTableImpl*>(P);
605 }
606 
607 SmallString<64>
608 SelectorTable::constructSetterName(StringRef Name) {
609   SmallString<64> SetterName("set");
610   SetterName += Name;
611   SetterName[3] = toUppercase(SetterName[3]);
612   return SetterName;
613 }
614 
615 Selector
616 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
617                                        SelectorTable &SelTable,
618                                        const IdentifierInfo *Name) {
619   IdentifierInfo *SetterName =
620     &Idents.get(constructSetterName(Name->getName()));
621   return SelTable.getUnarySelector(SetterName);
622 }
623 
624 std::string SelectorTable::getPropertyNameFromSetterSelector(Selector Sel) {
625   StringRef Name = Sel.getNameForSlot(0);
626   assert(Name.startswith("set") && "invalid setter name");
627   return (Twine(toLowercase(Name[3])) + Name.drop_front(4)).str();
628 }
629 
630 size_t SelectorTable::getTotalMemory() const {
631   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
632   return SelTabImpl.Allocator.getTotalMemory();
633 }
634 
635 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
636   if (nKeys < 2)
637     return Selector(IIV[0], nKeys);
638 
639   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
640 
641   // Unique selector, to guarantee there is one per name.
642   llvm::FoldingSetNodeID ID;
643   MultiKeywordSelector::Profile(ID, IIV, nKeys);
644 
645   void *InsertPos = nullptr;
646   if (MultiKeywordSelector *SI =
647         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
648     return Selector(SI);
649 
650   // MultiKeywordSelector objects are not allocated with new because they have a
651   // variable size array (for parameter types) at the end of them.
652   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
653   MultiKeywordSelector *SI =
654       (MultiKeywordSelector *)SelTabImpl.Allocator.Allocate(
655           Size, alignof(MultiKeywordSelector));
656   new (SI) MultiKeywordSelector(nKeys, IIV);
657   SelTabImpl.Table.InsertNode(SI, InsertPos);
658   return Selector(SI);
659 }
660 
661 SelectorTable::SelectorTable() {
662   Impl = new SelectorTableImpl();
663 }
664 
665 SelectorTable::~SelectorTable() {
666   delete &getSelectorTableImpl(Impl);
667 }
668 
669 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
670   switch (Operator) {
671   case OO_None:
672   case NUM_OVERLOADED_OPERATORS:
673     return nullptr;
674 
675 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
676   case OO_##Name: return Spelling;
677 #include "clang/Basic/OperatorKinds.def"
678   }
679 
680   llvm_unreachable("Invalid OverloadedOperatorKind!");
681 }
682 
683 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
684                                         bool isContextSensitive) {
685   switch (kind) {
686   case NullabilityKind::NonNull:
687     return isContextSensitive ? "nonnull" : "_Nonnull";
688 
689   case NullabilityKind::Nullable:
690     return isContextSensitive ? "nullable" : "_Nullable";
691 
692   case NullabilityKind::Unspecified:
693     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
694   }
695   llvm_unreachable("Unknown nullability kind.");
696 }
697