1 //===- IdentifierTable.cpp - Hash table for identifier lookup -------------===//
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 // This file implements the IdentifierInfo, IdentifierVisitor, and
10 // IdentifierTable interfaces.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Basic/IdentifierTable.h"
15 #include "clang/Basic/CharInfo.h"
16 #include "clang/Basic/LangOptions.h"
17 #include "clang/Basic/OperatorKinds.h"
18 #include "clang/Basic/Specifiers.h"
19 #include "clang/Basic/TokenKinds.h"
20 #include "llvm/ADT/DenseMapInfo.h"
21 #include "llvm/ADT/FoldingSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/StringMap.h"
24 #include "llvm/ADT/StringRef.h"
25 #include "llvm/Support/Allocator.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include <cassert>
29 #include <cstdio>
30 #include <cstring>
31 #include <string>
32 
33 using namespace clang;
34 
35 //===----------------------------------------------------------------------===//
36 // IdentifierTable Implementation
37 //===----------------------------------------------------------------------===//
38 
39 IdentifierIterator::~IdentifierIterator() = default;
40 
41 IdentifierInfoLookup::~IdentifierInfoLookup() = default;
42 
43 namespace {
44 
45 /// A simple identifier lookup iterator that represents an
46 /// empty sequence of identifiers.
47 class EmptyLookupIterator : public IdentifierIterator
48 {
49 public:
50   StringRef Next() override { return StringRef(); }
51 };
52 
53 } // namespace
54 
55 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() {
56   return new EmptyLookupIterator();
57 }
58 
59 IdentifierTable::IdentifierTable(IdentifierInfoLookup *ExternalLookup)
60     : HashTable(8192), // Start with space for 8K identifiers.
61       ExternalLookup(ExternalLookup) {}
62 
63 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
64                                  IdentifierInfoLookup *ExternalLookup)
65     : IdentifierTable(ExternalLookup) {
66   // Populate the identifier table with info about keywords for the current
67   // language.
68   AddKeywords(LangOpts);
69 }
70 
71 //===----------------------------------------------------------------------===//
72 // Language Keyword Implementation
73 //===----------------------------------------------------------------------===//
74 
75 // Constants for TokenKinds.def
76 namespace {
77 
78   enum {
79     KEYC99        = 0x1,
80     KEYCXX        = 0x2,
81     KEYCXX11      = 0x4,
82     KEYGNU        = 0x8,
83     KEYMS         = 0x10,
84     BOOLSUPPORT   = 0x20,
85     KEYALTIVEC    = 0x40,
86     KEYNOCXX      = 0x80,
87     KEYBORLAND    = 0x100,
88     KEYOPENCLC    = 0x200,
89     KEYC11        = 0x400,
90     KEYNOMS18     = 0x800,
91     KEYNOOPENCL   = 0x1000,
92     WCHARSUPPORT  = 0x2000,
93     HALFSUPPORT   = 0x4000,
94     CHAR8SUPPORT  = 0x8000,
95     KEYCONCEPTS   = 0x10000,
96     KEYOBJC       = 0x20000,
97     KEYZVECTOR    = 0x40000,
98     KEYCOROUTINES = 0x80000,
99     KEYMODULES    = 0x100000,
100     KEYCXX2A      = 0x200000,
101     KEYOPENCLCXX  = 0x400000,
102     KEYALLCXX = KEYCXX | KEYCXX11 | KEYCXX2A,
103     KEYALL = (0xffffff & ~KEYNOMS18 &
104               ~KEYNOOPENCL) // KEYNOMS18 and KEYNOOPENCL are used to exclude.
105   };
106 
107   /// How a keyword is treated in the selected standard.
108   enum KeywordStatus {
109     KS_Disabled,    // Disabled
110     KS_Extension,   // Is an extension
111     KS_Enabled,     // Enabled
112     KS_Future       // Is a keyword in future standard
113   };
114 
115 } // namespace
116 
117 /// Translates flags as specified in TokenKinds.def into keyword status
118 /// in the given language standard.
119 static KeywordStatus getKeywordStatus(const LangOptions &LangOpts,
120                                       unsigned Flags) {
121   if (Flags == KEYALL) return KS_Enabled;
122   if (LangOpts.CPlusPlus && (Flags & KEYCXX)) return KS_Enabled;
123   if (LangOpts.CPlusPlus11 && (Flags & KEYCXX11)) return KS_Enabled;
124   if (LangOpts.CPlusPlus2a && (Flags & KEYCXX2A)) return KS_Enabled;
125   if (LangOpts.C99 && (Flags & KEYC99)) return KS_Enabled;
126   if (LangOpts.GNUKeywords && (Flags & KEYGNU)) return KS_Extension;
127   if (LangOpts.MicrosoftExt && (Flags & KEYMS)) return KS_Extension;
128   if (LangOpts.Borland && (Flags & KEYBORLAND)) return KS_Extension;
129   if (LangOpts.Bool && (Flags & BOOLSUPPORT)) return KS_Enabled;
130   if (LangOpts.Half && (Flags & HALFSUPPORT)) return KS_Enabled;
131   if (LangOpts.WChar && (Flags & WCHARSUPPORT)) return KS_Enabled;
132   if (LangOpts.Char8 && (Flags & CHAR8SUPPORT)) return KS_Enabled;
133   if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) return KS_Enabled;
134   if (LangOpts.ZVector && (Flags & KEYZVECTOR)) return KS_Enabled;
135   if (LangOpts.OpenCL && !LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLC))
136     return KS_Enabled;
137   if (LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLCXX)) return KS_Enabled;
138   if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) return KS_Enabled;
139   if (LangOpts.C11 && (Flags & KEYC11)) return KS_Enabled;
140   // We treat bridge casts as objective-C keywords so we can warn on them
141   // in non-arc mode.
142   if (LangOpts.ObjC && (Flags & KEYOBJC)) return KS_Enabled;
143   if (LangOpts.ConceptsTS && (Flags & KEYCONCEPTS)) return KS_Enabled;
144   if (LangOpts.CoroutinesTS && (Flags & KEYCOROUTINES)) return KS_Enabled;
145   if (LangOpts.ModulesTS && (Flags & KEYMODULES)) return KS_Enabled;
146   if (LangOpts.CPlusPlus && (Flags & KEYALLCXX)) return KS_Future;
147   return KS_Disabled;
148 }
149 
150 /// AddKeyword - This method is used to associate a token ID with specific
151 /// identifiers because they are language keywords.  This causes the lexer to
152 /// automatically map matching identifiers to specialized token codes.
153 static void AddKeyword(StringRef Keyword,
154                        tok::TokenKind TokenCode, unsigned Flags,
155                        const LangOptions &LangOpts, IdentifierTable &Table) {
156   KeywordStatus AddResult = getKeywordStatus(LangOpts, Flags);
157 
158   // Don't add this keyword under MSVCCompat.
159   if (LangOpts.MSVCCompat && (Flags & KEYNOMS18) &&
160       !LangOpts.isCompatibleWithMSVC(LangOptions::MSVC2015))
161     return;
162 
163   // Don't add this keyword under OpenCL.
164   if (LangOpts.OpenCL && (Flags & KEYNOOPENCL))
165     return;
166 
167   // Don't add this keyword if disabled in this language.
168   if (AddResult == KS_Disabled) return;
169 
170   IdentifierInfo &Info =
171       Table.get(Keyword, AddResult == KS_Future ? tok::identifier : TokenCode);
172   Info.setIsExtensionToken(AddResult == KS_Extension);
173   Info.setIsFutureCompatKeyword(AddResult == KS_Future);
174 }
175 
176 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
177 /// representations.
178 static void AddCXXOperatorKeyword(StringRef Keyword,
179                                   tok::TokenKind TokenCode,
180                                   IdentifierTable &Table) {
181   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
182   Info.setIsCPlusPlusOperatorKeyword();
183 }
184 
185 /// AddObjCKeyword - Register an Objective-C \@keyword like "class" "selector"
186 /// or "property".
187 static void AddObjCKeyword(StringRef Name,
188                            tok::ObjCKeywordKind ObjCID,
189                            IdentifierTable &Table) {
190   Table.get(Name).setObjCKeywordID(ObjCID);
191 }
192 
193 /// AddKeywords - Add all keywords to the symbol table.
194 ///
195 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
196   // Add keywords and tokens for the current language.
197 #define KEYWORD(NAME, FLAGS) \
198   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
199              FLAGS, LangOpts, *this);
200 #define ALIAS(NAME, TOK, FLAGS) \
201   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
202              FLAGS, LangOpts, *this);
203 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
204   if (LangOpts.CXXOperatorNames)          \
205     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
206 #define OBJC_AT_KEYWORD(NAME)  \
207   if (LangOpts.ObjC)           \
208     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
209 #define TESTING_KEYWORD(NAME, FLAGS)
210 #include "clang/Basic/TokenKinds.def"
211 
212   if (LangOpts.ParseUnknownAnytype)
213     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
214                LangOpts, *this);
215 
216   if (LangOpts.DeclSpecKeyword)
217     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
218 
219   // Add the '_experimental_modules_import' contextual keyword.
220   get("import").setModulesImport(true);
221 }
222 
223 /// Checks if the specified token kind represents a keyword in the
224 /// specified language.
225 /// \returns Status of the keyword in the language.
226 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
227                                       tok::TokenKind K) {
228   switch (K) {
229 #define KEYWORD(NAME, FLAGS) \
230   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
231 #include "clang/Basic/TokenKinds.def"
232   default: return KS_Disabled;
233   }
234 }
235 
236 /// Returns true if the identifier represents a keyword in the
237 /// specified language.
238 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) const {
239   switch (getTokenKwStatus(LangOpts, getTokenID())) {
240   case KS_Enabled:
241   case KS_Extension:
242     return true;
243   default:
244     return false;
245   }
246 }
247 
248 /// Returns true if the identifier represents a C++ keyword in the
249 /// specified language.
250 bool IdentifierInfo::isCPlusPlusKeyword(const LangOptions &LangOpts) const {
251   if (!LangOpts.CPlusPlus || !isKeyword(LangOpts))
252     return false;
253   // This is a C++ keyword if this identifier is not a keyword when checked
254   // using LangOptions without C++ support.
255   LangOptions LangOptsNoCPP = LangOpts;
256   LangOptsNoCPP.CPlusPlus = false;
257   LangOptsNoCPP.CPlusPlus11 = false;
258   LangOptsNoCPP.CPlusPlus2a = false;
259   return !isKeyword(LangOptsNoCPP);
260 }
261 
262 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
263   // We use a perfect hash function here involving the length of the keyword,
264   // the first and third character.  For preprocessor ID's there are no
265   // collisions (if there were, the switch below would complain about duplicate
266   // case values).  Note that this depends on 'if' being null terminated.
267 
268 #define HASH(LEN, FIRST, THIRD) \
269   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
270 #define CASE(LEN, FIRST, THIRD, NAME) \
271   case HASH(LEN, FIRST, THIRD): \
272     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
273 
274   unsigned Len = getLength();
275   if (Len < 2) return tok::pp_not_keyword;
276   const char *Name = getNameStart();
277   switch (HASH(Len, Name[0], Name[2])) {
278   default: return tok::pp_not_keyword;
279   CASE( 2, 'i', '\0', if);
280   CASE( 4, 'e', 'i', elif);
281   CASE( 4, 'e', 's', else);
282   CASE( 4, 'l', 'n', line);
283   CASE( 4, 's', 'c', sccs);
284   CASE( 5, 'e', 'd', endif);
285   CASE( 5, 'e', 'r', error);
286   CASE( 5, 'i', 'e', ident);
287   CASE( 5, 'i', 'd', ifdef);
288   CASE( 5, 'u', 'd', undef);
289 
290   CASE( 6, 'a', 's', assert);
291   CASE( 6, 'd', 'f', define);
292   CASE( 6, 'i', 'n', ifndef);
293   CASE( 6, 'i', 'p', import);
294   CASE( 6, 'p', 'a', pragma);
295 
296   CASE( 7, 'd', 'f', defined);
297   CASE( 7, 'i', 'c', include);
298   CASE( 7, 'w', 'r', warning);
299 
300   CASE( 8, 'u', 'a', unassert);
301   CASE(12, 'i', 'c', include_next);
302 
303   CASE(14, '_', 'p', __public_macro);
304 
305   CASE(15, '_', 'p', __private_macro);
306 
307   CASE(16, '_', 'i', __include_macros);
308 #undef CASE
309 #undef HASH
310   }
311 }
312 
313 //===----------------------------------------------------------------------===//
314 // Stats Implementation
315 //===----------------------------------------------------------------------===//
316 
317 /// PrintStats - Print statistics about how well the identifier table is doing
318 /// at hashing identifiers.
319 void IdentifierTable::PrintStats() const {
320   unsigned NumBuckets = HashTable.getNumBuckets();
321   unsigned NumIdentifiers = HashTable.getNumItems();
322   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
323   unsigned AverageIdentifierSize = 0;
324   unsigned MaxIdentifierLength = 0;
325 
326   // TODO: Figure out maximum times an identifier had to probe for -stats.
327   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
328        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
329     unsigned IdLen = I->getKeyLength();
330     AverageIdentifierSize += IdLen;
331     if (MaxIdentifierLength < IdLen)
332       MaxIdentifierLength = IdLen;
333   }
334 
335   fprintf(stderr, "\n*** Identifier Table Stats:\n");
336   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
337   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
338   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
339           NumIdentifiers/(double)NumBuckets);
340   fprintf(stderr, "Ave identifier length: %f\n",
341           (AverageIdentifierSize/(double)NumIdentifiers));
342   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
343 
344   // Compute statistics about the memory allocated for identifiers.
345   HashTable.getAllocator().PrintStats();
346 }
347 
348 //===----------------------------------------------------------------------===//
349 // SelectorTable Implementation
350 //===----------------------------------------------------------------------===//
351 
352 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
353   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
354 }
355 
356 namespace clang {
357 
358 /// One of these variable length records is kept for each
359 /// selector containing more than one keyword. We use a folding set
360 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
361 /// this class is provided strictly through Selector.
362 class alignas(IdentifierInfoAlignment) MultiKeywordSelector
363     : public detail::DeclarationNameExtra,
364       public llvm::FoldingSetNode {
365   MultiKeywordSelector(unsigned nKeys) : DeclarationNameExtra(nKeys) {}
366 
367 public:
368   // Constructor for keyword selectors.
369   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV)
370       : DeclarationNameExtra(nKeys) {
371     assert((nKeys > 1) && "not a multi-keyword selector");
372 
373     // Fill in the trailing keyword array.
374     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this + 1);
375     for (unsigned i = 0; i != nKeys; ++i)
376       KeyInfo[i] = IIV[i];
377   }
378 
379   // getName - Derive the full selector name and return it.
380   std::string getName() const;
381 
382   using DeclarationNameExtra::getNumArgs;
383 
384   using keyword_iterator = IdentifierInfo *const *;
385 
386   keyword_iterator keyword_begin() const {
387     return reinterpret_cast<keyword_iterator>(this + 1);
388   }
389 
390   keyword_iterator keyword_end() const {
391     return keyword_begin() + getNumArgs();
392   }
393 
394   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
395     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
396     return keyword_begin()[i];
397   }
398 
399   static void Profile(llvm::FoldingSetNodeID &ID, keyword_iterator ArgTys,
400                       unsigned NumArgs) {
401     ID.AddInteger(NumArgs);
402     for (unsigned i = 0; i != NumArgs; ++i)
403       ID.AddPointer(ArgTys[i]);
404   }
405 
406   void Profile(llvm::FoldingSetNodeID &ID) {
407     Profile(ID, keyword_begin(), getNumArgs());
408   }
409 };
410 
411 } // namespace clang.
412 
413 unsigned Selector::getNumArgs() const {
414   unsigned IIF = getIdentifierInfoFlag();
415   if (IIF <= ZeroArg)
416     return 0;
417   if (IIF == OneArg)
418     return 1;
419   // We point to a MultiKeywordSelector.
420   MultiKeywordSelector *SI = getMultiKeywordSelector();
421   return SI->getNumArgs();
422 }
423 
424 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
425   if (getIdentifierInfoFlag() < MultiArg) {
426     assert(argIndex == 0 && "illegal keyword index");
427     return getAsIdentifierInfo();
428   }
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 LLVM_DUMP_METHOD void Selector::dump() const { print(llvm::errs()); }
480 
481 /// Interpreting the given string using the normal CamelCase
482 /// conventions, determine whether the given string starts with the
483 /// given "word", which is assumed to end in a lowercase letter.
484 static bool startsWithWord(StringRef name, StringRef word) {
485   if (name.size() < word.size()) return false;
486   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
487           name.startswith(word));
488 }
489 
490 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
491   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
492   if (!first) return OMF_None;
493 
494   StringRef name = first->getName();
495   if (sel.isUnarySelector()) {
496     if (name == "autorelease") return OMF_autorelease;
497     if (name == "dealloc") return OMF_dealloc;
498     if (name == "finalize") return OMF_finalize;
499     if (name == "release") return OMF_release;
500     if (name == "retain") return OMF_retain;
501     if (name == "retainCount") return OMF_retainCount;
502     if (name == "self") return OMF_self;
503     if (name == "initialize") return OMF_initialize;
504   }
505 
506   if (name == "performSelector" || name == "performSelectorInBackground" ||
507       name == "performSelectorOnMainThread")
508     return OMF_performSelector;
509 
510   // The other method families may begin with a prefix of underscores.
511   while (!name.empty() && name.front() == '_')
512     name = name.substr(1);
513 
514   if (name.empty()) return OMF_None;
515   switch (name.front()) {
516   case 'a':
517     if (startsWithWord(name, "alloc")) return OMF_alloc;
518     break;
519   case 'c':
520     if (startsWithWord(name, "copy")) return OMF_copy;
521     break;
522   case 'i':
523     if (startsWithWord(name, "init")) return OMF_init;
524     break;
525   case 'm':
526     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
527     break;
528   case 'n':
529     if (startsWithWord(name, "new")) return OMF_new;
530     break;
531   default:
532     break;
533   }
534 
535   return OMF_None;
536 }
537 
538 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
539   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
540   if (!first) return OIT_None;
541 
542   StringRef name = first->getName();
543 
544   if (name.empty()) return OIT_None;
545   switch (name.front()) {
546     case 'a':
547       if (startsWithWord(name, "array")) return OIT_Array;
548       break;
549     case 'd':
550       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
551       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
552       break;
553     case 's':
554       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
555       if (startsWithWord(name, "standard")) return OIT_Singleton;
556       break;
557     case 'i':
558       if (startsWithWord(name, "init")) return OIT_Init;
559       break;
560     default:
561       break;
562   }
563   return OIT_None;
564 }
565 
566 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
567   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
568   if (!first) return SFF_None;
569 
570   StringRef name = first->getName();
571 
572   switch (name.front()) {
573     case 'a':
574       if (name == "appendFormat") return SFF_NSString;
575       break;
576 
577     case 'i':
578       if (name == "initWithFormat") return SFF_NSString;
579       break;
580 
581     case 'l':
582       if (name == "localizedStringWithFormat") return SFF_NSString;
583       break;
584 
585     case 's':
586       if (name == "stringByAppendingFormat" ||
587           name == "stringWithFormat") return SFF_NSString;
588       break;
589   }
590   return SFF_None;
591 }
592 
593 namespace {
594 
595 struct SelectorTableImpl {
596   llvm::FoldingSet<MultiKeywordSelector> Table;
597   llvm::BumpPtrAllocator Allocator;
598 };
599 
600 } // namespace
601 
602 static SelectorTableImpl &getSelectorTableImpl(void *P) {
603   return *static_cast<SelectorTableImpl*>(P);
604 }
605 
606 SmallString<64>
607 SelectorTable::constructSetterName(StringRef Name) {
608   SmallString<64> SetterName("set");
609   SetterName += Name;
610   SetterName[3] = toUppercase(SetterName[3]);
611   return SetterName;
612 }
613 
614 Selector
615 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
616                                        SelectorTable &SelTable,
617                                        const IdentifierInfo *Name) {
618   IdentifierInfo *SetterName =
619     &Idents.get(constructSetterName(Name->getName()));
620   return SelTable.getUnarySelector(SetterName);
621 }
622 
623 std::string SelectorTable::getPropertyNameFromSetterSelector(Selector Sel) {
624   StringRef Name = Sel.getNameForSlot(0);
625   assert(Name.startswith("set") && "invalid setter name");
626   return (Twine(toLowercase(Name[3])) + Name.drop_front(4)).str();
627 }
628 
629 size_t SelectorTable::getTotalMemory() const {
630   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
631   return SelTabImpl.Allocator.getTotalMemory();
632 }
633 
634 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
635   if (nKeys < 2)
636     return Selector(IIV[0], nKeys);
637 
638   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
639 
640   // Unique selector, to guarantee there is one per name.
641   llvm::FoldingSetNodeID ID;
642   MultiKeywordSelector::Profile(ID, IIV, nKeys);
643 
644   void *InsertPos = nullptr;
645   if (MultiKeywordSelector *SI =
646         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
647     return Selector(SI);
648 
649   // MultiKeywordSelector objects are not allocated with new because they have a
650   // variable size array (for parameter types) at the end of them.
651   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
652   MultiKeywordSelector *SI =
653       (MultiKeywordSelector *)SelTabImpl.Allocator.Allocate(
654           Size, alignof(MultiKeywordSelector));
655   new (SI) MultiKeywordSelector(nKeys, IIV);
656   SelTabImpl.Table.InsertNode(SI, InsertPos);
657   return Selector(SI);
658 }
659 
660 SelectorTable::SelectorTable() {
661   Impl = new SelectorTableImpl();
662 }
663 
664 SelectorTable::~SelectorTable() {
665   delete &getSelectorTableImpl(Impl);
666 }
667 
668 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
669   switch (Operator) {
670   case OO_None:
671   case NUM_OVERLOADED_OPERATORS:
672     return nullptr;
673 
674 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
675   case OO_##Name: return Spelling;
676 #include "clang/Basic/OperatorKinds.def"
677   }
678 
679   llvm_unreachable("Invalid OverloadedOperatorKind!");
680 }
681 
682 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
683                                         bool isContextSensitive) {
684   switch (kind) {
685   case NullabilityKind::NonNull:
686     return isContextSensitive ? "nonnull" : "_Nonnull";
687 
688   case NullabilityKind::Nullable:
689     return isContextSensitive ? "nullable" : "_Nullable";
690 
691   case NullabilityKind::Unspecified:
692     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
693   }
694   llvm_unreachable("Unknown nullability kind.");
695 }
696