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/TargetBuiltins.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 // A check to make sure the ObjCOrBuiltinID has sufficient room to store the
37 // largest possible target/aux-target combination. If we exceed this, we likely
38 // need to just change the ObjCOrBuiltinIDBits value in IdentifierTable.h.
39 static_assert(2 * LargestBuiltinID < (2 << (ObjCOrBuiltinIDBits - 1)),
40               "Insufficient ObjCOrBuiltinID Bits");
41 
42 //===----------------------------------------------------------------------===//
43 // IdentifierTable Implementation
44 //===----------------------------------------------------------------------===//
45 
46 IdentifierIterator::~IdentifierIterator() = default;
47 
48 IdentifierInfoLookup::~IdentifierInfoLookup() = default;
49 
50 namespace {
51 
52 /// A simple identifier lookup iterator that represents an
53 /// empty sequence of identifiers.
54 class EmptyLookupIterator : public IdentifierIterator
55 {
56 public:
57   StringRef Next() override { return StringRef(); }
58 };
59 
60 } // namespace
61 
62 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() {
63   return new EmptyLookupIterator();
64 }
65 
66 IdentifierTable::IdentifierTable(IdentifierInfoLookup *ExternalLookup)
67     : HashTable(8192), // Start with space for 8K identifiers.
68       ExternalLookup(ExternalLookup) {}
69 
70 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
71                                  IdentifierInfoLookup *ExternalLookup)
72     : IdentifierTable(ExternalLookup) {
73   // Populate the identifier table with info about keywords for the current
74   // language.
75   AddKeywords(LangOpts);
76 }
77 
78 //===----------------------------------------------------------------------===//
79 // Language Keyword Implementation
80 //===----------------------------------------------------------------------===//
81 
82 // Constants for TokenKinds.def
83 namespace {
84 
85   enum {
86     KEYC99        = 0x1,
87     KEYCXX        = 0x2,
88     KEYCXX11      = 0x4,
89     KEYGNU        = 0x8,
90     KEYMS         = 0x10,
91     BOOLSUPPORT   = 0x20,
92     KEYALTIVEC    = 0x40,
93     KEYNOCXX      = 0x80,
94     KEYBORLAND    = 0x100,
95     KEYOPENCLC    = 0x200,
96     KEYC11        = 0x400,
97     KEYNOMS18     = 0x800,
98     KEYNOOPENCL   = 0x1000,
99     WCHARSUPPORT  = 0x2000,
100     HALFSUPPORT   = 0x4000,
101     CHAR8SUPPORT  = 0x8000,
102     KEYCONCEPTS   = 0x10000,
103     KEYOBJC       = 0x20000,
104     KEYZVECTOR    = 0x40000,
105     KEYCOROUTINES = 0x80000,
106     KEYMODULES    = 0x100000,
107     KEYCXX20      = 0x200000,
108     KEYOPENCLCXX  = 0x400000,
109     KEYMSCOMPAT   = 0x800000,
110     KEYALLCXX = KEYCXX | KEYCXX11 | KEYCXX20,
111     KEYALL = (0xffffff & ~KEYNOMS18 &
112               ~KEYNOOPENCL) // KEYNOMS18 and KEYNOOPENCL are used to exclude.
113   };
114 
115   /// How a keyword is treated in the selected standard.
116   enum KeywordStatus {
117     KS_Disabled,    // Disabled
118     KS_Extension,   // Is an extension
119     KS_Enabled,     // Enabled
120     KS_Future       // Is a keyword in future standard
121   };
122 
123 } // namespace
124 
125 /// Translates flags as specified in TokenKinds.def into keyword status
126 /// in the given language standard.
127 static KeywordStatus getKeywordStatus(const LangOptions &LangOpts,
128                                       unsigned Flags) {
129   if (Flags == KEYALL) return KS_Enabled;
130   if (LangOpts.CPlusPlus && (Flags & KEYCXX)) return KS_Enabled;
131   if (LangOpts.CPlusPlus11 && (Flags & KEYCXX11)) return KS_Enabled;
132   if (LangOpts.CPlusPlus20 && (Flags & KEYCXX20)) return KS_Enabled;
133   if (LangOpts.C99 && (Flags & KEYC99)) return KS_Enabled;
134   if (LangOpts.GNUKeywords && (Flags & KEYGNU)) return KS_Extension;
135   if (LangOpts.MicrosoftExt && (Flags & KEYMS)) return KS_Extension;
136   if (LangOpts.MSVCCompat && (Flags & KEYMSCOMPAT)) return KS_Enabled;
137   if (LangOpts.Borland && (Flags & KEYBORLAND)) return KS_Extension;
138   if (LangOpts.Bool && (Flags & BOOLSUPPORT)) return KS_Enabled;
139   if (LangOpts.Half && (Flags & HALFSUPPORT)) return KS_Enabled;
140   if (LangOpts.WChar && (Flags & WCHARSUPPORT)) return KS_Enabled;
141   if (LangOpts.Char8 && (Flags & CHAR8SUPPORT)) return KS_Enabled;
142   if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) return KS_Enabled;
143   if (LangOpts.ZVector && (Flags & KEYZVECTOR)) return KS_Enabled;
144   if (LangOpts.OpenCL && !LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLC))
145     return KS_Enabled;
146   if (LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLCXX)) return KS_Enabled;
147   if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) return KS_Enabled;
148   if (LangOpts.C11 && (Flags & KEYC11)) return KS_Enabled;
149   // We treat bridge casts as objective-C keywords so we can warn on them
150   // in non-arc mode.
151   if (LangOpts.ObjC && (Flags & KEYOBJC)) return KS_Enabled;
152   if (LangOpts.CPlusPlus20 && (Flags & KEYCONCEPTS)) return KS_Enabled;
153   if (LangOpts.Coroutines && (Flags & KEYCOROUTINES)) return KS_Enabled;
154   if (LangOpts.ModulesTS && (Flags & KEYMODULES)) return KS_Enabled;
155   if (LangOpts.CPlusPlus && (Flags & KEYALLCXX)) return KS_Future;
156   if (LangOpts.CPlusPlus && !LangOpts.CPlusPlus20 && (Flags & CHAR8SUPPORT))
157     return KS_Future;
158   return KS_Disabled;
159 }
160 
161 /// AddKeyword - This method is used to associate a token ID with specific
162 /// identifiers because they are language keywords.  This causes the lexer to
163 /// automatically map matching identifiers to specialized token codes.
164 static void AddKeyword(StringRef Keyword,
165                        tok::TokenKind TokenCode, unsigned Flags,
166                        const LangOptions &LangOpts, IdentifierTable &Table) {
167   KeywordStatus AddResult = getKeywordStatus(LangOpts, Flags);
168 
169   // Don't add this keyword under MSVCCompat.
170   if (LangOpts.MSVCCompat && (Flags & KEYNOMS18) &&
171       !LangOpts.isCompatibleWithMSVC(LangOptions::MSVC2015))
172     return;
173 
174   // Don't add this keyword under OpenCL.
175   if (LangOpts.OpenCL && (Flags & KEYNOOPENCL))
176     return;
177 
178   // Don't add this keyword if disabled in this language.
179   if (AddResult == KS_Disabled) return;
180 
181   IdentifierInfo &Info =
182       Table.get(Keyword, AddResult == KS_Future ? tok::identifier : TokenCode);
183   Info.setIsExtensionToken(AddResult == KS_Extension);
184   Info.setIsFutureCompatKeyword(AddResult == KS_Future);
185 }
186 
187 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
188 /// representations.
189 static void AddCXXOperatorKeyword(StringRef Keyword,
190                                   tok::TokenKind TokenCode,
191                                   IdentifierTable &Table) {
192   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
193   Info.setIsCPlusPlusOperatorKeyword();
194 }
195 
196 /// AddObjCKeyword - Register an Objective-C \@keyword like "class" "selector"
197 /// or "property".
198 static void AddObjCKeyword(StringRef Name,
199                            tok::ObjCKeywordKind ObjCID,
200                            IdentifierTable &Table) {
201   Table.get(Name).setObjCKeywordID(ObjCID);
202 }
203 
204 /// AddKeywords - Add all keywords to the symbol table.
205 ///
206 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
207   // Add keywords and tokens for the current language.
208 #define KEYWORD(NAME, FLAGS) \
209   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
210              FLAGS, LangOpts, *this);
211 #define ALIAS(NAME, TOK, FLAGS) \
212   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
213              FLAGS, LangOpts, *this);
214 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
215   if (LangOpts.CXXOperatorNames)          \
216     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
217 #define OBJC_AT_KEYWORD(NAME)  \
218   if (LangOpts.ObjC)           \
219     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
220 #define TESTING_KEYWORD(NAME, FLAGS)
221 #include "clang/Basic/TokenKinds.def"
222 
223   if (LangOpts.ParseUnknownAnytype)
224     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
225                LangOpts, *this);
226 
227   if (LangOpts.DeclSpecKeyword)
228     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
229 
230   if (LangOpts.IEEE128)
231     AddKeyword("__ieee128", tok::kw___float128, KEYALL, LangOpts, *this);
232 
233   // Add the 'import' contextual keyword.
234   get("import").setModulesImport(true);
235 }
236 
237 /// Checks if the specified token kind represents a keyword in the
238 /// specified language.
239 /// \returns Status of the keyword in the language.
240 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
241                                       tok::TokenKind K) {
242   switch (K) {
243 #define KEYWORD(NAME, FLAGS) \
244   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
245 #include "clang/Basic/TokenKinds.def"
246   default: return KS_Disabled;
247   }
248 }
249 
250 /// Returns true if the identifier represents a keyword in the
251 /// specified language.
252 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) const {
253   switch (getTokenKwStatus(LangOpts, getTokenID())) {
254   case KS_Enabled:
255   case KS_Extension:
256     return true;
257   default:
258     return false;
259   }
260 }
261 
262 /// Returns true if the identifier represents a C++ keyword in the
263 /// specified language.
264 bool IdentifierInfo::isCPlusPlusKeyword(const LangOptions &LangOpts) const {
265   if (!LangOpts.CPlusPlus || !isKeyword(LangOpts))
266     return false;
267   // This is a C++ keyword if this identifier is not a keyword when checked
268   // using LangOptions without C++ support.
269   LangOptions LangOptsNoCPP = LangOpts;
270   LangOptsNoCPP.CPlusPlus = false;
271   LangOptsNoCPP.CPlusPlus11 = false;
272   LangOptsNoCPP.CPlusPlus20 = false;
273   return !isKeyword(LangOptsNoCPP);
274 }
275 
276 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
277   // We use a perfect hash function here involving the length of the keyword,
278   // the first and third character.  For preprocessor ID's there are no
279   // collisions (if there were, the switch below would complain about duplicate
280   // case values).  Note that this depends on 'if' being null terminated.
281 
282 #define HASH(LEN, FIRST, THIRD) \
283   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
284 #define CASE(LEN, FIRST, THIRD, NAME) \
285   case HASH(LEN, FIRST, THIRD): \
286     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
287 
288   unsigned Len = getLength();
289   if (Len < 2) return tok::pp_not_keyword;
290   const char *Name = getNameStart();
291   switch (HASH(Len, Name[0], Name[2])) {
292   default: return tok::pp_not_keyword;
293   CASE( 2, 'i', '\0', if);
294   CASE( 4, 'e', 'i', elif);
295   CASE( 4, 'e', 's', else);
296   CASE( 4, 'l', 'n', line);
297   CASE( 4, 's', 'c', sccs);
298   CASE( 5, 'e', 'd', endif);
299   CASE( 5, 'e', 'r', error);
300   CASE( 5, 'i', 'e', ident);
301   CASE( 5, 'i', 'd', ifdef);
302   CASE( 5, 'u', 'd', undef);
303 
304   CASE( 6, 'a', 's', assert);
305   CASE( 6, 'd', 'f', define);
306   CASE( 6, 'i', 'n', ifndef);
307   CASE( 6, 'i', 'p', import);
308   CASE( 6, 'p', 'a', pragma);
309 
310   CASE( 7, 'd', 'f', defined);
311   CASE( 7, 'i', 'c', include);
312   CASE( 7, 'w', 'r', warning);
313 
314   CASE( 8, 'u', 'a', unassert);
315   CASE(12, 'i', 'c', include_next);
316 
317   CASE(14, '_', 'p', __public_macro);
318 
319   CASE(15, '_', 'p', __private_macro);
320 
321   CASE(16, '_', 'i', __include_macros);
322 #undef CASE
323 #undef HASH
324   }
325 }
326 
327 //===----------------------------------------------------------------------===//
328 // Stats Implementation
329 //===----------------------------------------------------------------------===//
330 
331 /// PrintStats - Print statistics about how well the identifier table is doing
332 /// at hashing identifiers.
333 void IdentifierTable::PrintStats() const {
334   unsigned NumBuckets = HashTable.getNumBuckets();
335   unsigned NumIdentifiers = HashTable.getNumItems();
336   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
337   unsigned AverageIdentifierSize = 0;
338   unsigned MaxIdentifierLength = 0;
339 
340   // TODO: Figure out maximum times an identifier had to probe for -stats.
341   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
342        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
343     unsigned IdLen = I->getKeyLength();
344     AverageIdentifierSize += IdLen;
345     if (MaxIdentifierLength < IdLen)
346       MaxIdentifierLength = IdLen;
347   }
348 
349   fprintf(stderr, "\n*** Identifier Table Stats:\n");
350   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
351   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
352   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
353           NumIdentifiers/(double)NumBuckets);
354   fprintf(stderr, "Ave identifier length: %f\n",
355           (AverageIdentifierSize/(double)NumIdentifiers));
356   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
357 
358   // Compute statistics about the memory allocated for identifiers.
359   HashTable.getAllocator().PrintStats();
360 }
361 
362 //===----------------------------------------------------------------------===//
363 // SelectorTable Implementation
364 //===----------------------------------------------------------------------===//
365 
366 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
367   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
368 }
369 
370 namespace clang {
371 
372 /// One of these variable length records is kept for each
373 /// selector containing more than one keyword. We use a folding set
374 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
375 /// this class is provided strictly through Selector.
376 class alignas(IdentifierInfoAlignment) MultiKeywordSelector
377     : public detail::DeclarationNameExtra,
378       public llvm::FoldingSetNode {
379   MultiKeywordSelector(unsigned nKeys) : DeclarationNameExtra(nKeys) {}
380 
381 public:
382   // Constructor for keyword selectors.
383   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV)
384       : DeclarationNameExtra(nKeys) {
385     assert((nKeys > 1) && "not a multi-keyword selector");
386 
387     // Fill in the trailing keyword array.
388     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this + 1);
389     for (unsigned i = 0; i != nKeys; ++i)
390       KeyInfo[i] = IIV[i];
391   }
392 
393   // getName - Derive the full selector name and return it.
394   std::string getName() const;
395 
396   using DeclarationNameExtra::getNumArgs;
397 
398   using keyword_iterator = IdentifierInfo *const *;
399 
400   keyword_iterator keyword_begin() const {
401     return reinterpret_cast<keyword_iterator>(this + 1);
402   }
403 
404   keyword_iterator keyword_end() const {
405     return keyword_begin() + getNumArgs();
406   }
407 
408   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
409     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
410     return keyword_begin()[i];
411   }
412 
413   static void Profile(llvm::FoldingSetNodeID &ID, keyword_iterator ArgTys,
414                       unsigned NumArgs) {
415     ID.AddInteger(NumArgs);
416     for (unsigned i = 0; i != NumArgs; ++i)
417       ID.AddPointer(ArgTys[i]);
418   }
419 
420   void Profile(llvm::FoldingSetNodeID &ID) {
421     Profile(ID, keyword_begin(), getNumArgs());
422   }
423 };
424 
425 } // namespace clang.
426 
427 bool Selector::isKeywordSelector(ArrayRef<StringRef> Names) const {
428   assert(!Names.empty() && "must have >= 1 selector slots");
429   if (getNumArgs() != Names.size())
430     return false;
431   for (unsigned I = 0, E = Names.size(); I != E; ++I) {
432     if (getNameForSlot(I) != Names[I])
433       return false;
434   }
435   return true;
436 }
437 
438 bool Selector::isUnarySelector(StringRef Name) const {
439   return isUnarySelector() && getNameForSlot(0) == Name;
440 }
441 
442 unsigned Selector::getNumArgs() const {
443   unsigned IIF = getIdentifierInfoFlag();
444   if (IIF <= ZeroArg)
445     return 0;
446   if (IIF == OneArg)
447     return 1;
448   // We point to a MultiKeywordSelector.
449   MultiKeywordSelector *SI = getMultiKeywordSelector();
450   return SI->getNumArgs();
451 }
452 
453 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
454   if (getIdentifierInfoFlag() < MultiArg) {
455     assert(argIndex == 0 && "illegal keyword index");
456     return getAsIdentifierInfo();
457   }
458 
459   // We point to a MultiKeywordSelector.
460   MultiKeywordSelector *SI = getMultiKeywordSelector();
461   return SI->getIdentifierInfoForSlot(argIndex);
462 }
463 
464 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
465   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
466   return II ? II->getName() : StringRef();
467 }
468 
469 std::string MultiKeywordSelector::getName() const {
470   SmallString<256> Str;
471   llvm::raw_svector_ostream OS(Str);
472   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
473     if (*I)
474       OS << (*I)->getName();
475     OS << ':';
476   }
477 
478   return std::string(OS.str());
479 }
480 
481 std::string Selector::getAsString() const {
482   if (InfoPtr == 0)
483     return "<null selector>";
484 
485   if (getIdentifierInfoFlag() < MultiArg) {
486     IdentifierInfo *II = getAsIdentifierInfo();
487 
488     if (getNumArgs() == 0) {
489       assert(II && "If the number of arguments is 0 then II is guaranteed to "
490                    "not be null.");
491       return std::string(II->getName());
492     }
493 
494     if (!II)
495       return ":";
496 
497     return II->getName().str() + ":";
498   }
499 
500   // We have a multiple keyword selector.
501   return getMultiKeywordSelector()->getName();
502 }
503 
504 void Selector::print(llvm::raw_ostream &OS) const {
505   OS << getAsString();
506 }
507 
508 LLVM_DUMP_METHOD void Selector::dump() const { print(llvm::errs()); }
509 
510 /// Interpreting the given string using the normal CamelCase
511 /// conventions, determine whether the given string starts with the
512 /// given "word", which is assumed to end in a lowercase letter.
513 static bool startsWithWord(StringRef name, StringRef word) {
514   if (name.size() < word.size()) return false;
515   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
516           name.startswith(word));
517 }
518 
519 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
520   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
521   if (!first) return OMF_None;
522 
523   StringRef name = first->getName();
524   if (sel.isUnarySelector()) {
525     if (name == "autorelease") return OMF_autorelease;
526     if (name == "dealloc") return OMF_dealloc;
527     if (name == "finalize") return OMF_finalize;
528     if (name == "release") return OMF_release;
529     if (name == "retain") return OMF_retain;
530     if (name == "retainCount") return OMF_retainCount;
531     if (name == "self") return OMF_self;
532     if (name == "initialize") return OMF_initialize;
533   }
534 
535   if (name == "performSelector" || name == "performSelectorInBackground" ||
536       name == "performSelectorOnMainThread")
537     return OMF_performSelector;
538 
539   // The other method families may begin with a prefix of underscores.
540   while (!name.empty() && name.front() == '_')
541     name = name.substr(1);
542 
543   if (name.empty()) return OMF_None;
544   switch (name.front()) {
545   case 'a':
546     if (startsWithWord(name, "alloc")) return OMF_alloc;
547     break;
548   case 'c':
549     if (startsWithWord(name, "copy")) return OMF_copy;
550     break;
551   case 'i':
552     if (startsWithWord(name, "init")) return OMF_init;
553     break;
554   case 'm':
555     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
556     break;
557   case 'n':
558     if (startsWithWord(name, "new")) return OMF_new;
559     break;
560   default:
561     break;
562   }
563 
564   return OMF_None;
565 }
566 
567 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
568   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
569   if (!first) return OIT_None;
570 
571   StringRef name = first->getName();
572 
573   if (name.empty()) return OIT_None;
574   switch (name.front()) {
575     case 'a':
576       if (startsWithWord(name, "array")) return OIT_Array;
577       break;
578     case 'd':
579       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
580       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
581       break;
582     case 's':
583       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
584       if (startsWithWord(name, "standard")) return OIT_Singleton;
585       break;
586     case 'i':
587       if (startsWithWord(name, "init")) return OIT_Init;
588       break;
589     default:
590       break;
591   }
592   return OIT_None;
593 }
594 
595 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
596   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
597   if (!first) return SFF_None;
598 
599   StringRef name = first->getName();
600 
601   switch (name.front()) {
602     case 'a':
603       if (name == "appendFormat") return SFF_NSString;
604       break;
605 
606     case 'i':
607       if (name == "initWithFormat") return SFF_NSString;
608       break;
609 
610     case 'l':
611       if (name == "localizedStringWithFormat") return SFF_NSString;
612       break;
613 
614     case 's':
615       if (name == "stringByAppendingFormat" ||
616           name == "stringWithFormat") return SFF_NSString;
617       break;
618   }
619   return SFF_None;
620 }
621 
622 namespace {
623 
624 struct SelectorTableImpl {
625   llvm::FoldingSet<MultiKeywordSelector> Table;
626   llvm::BumpPtrAllocator Allocator;
627 };
628 
629 } // namespace
630 
631 static SelectorTableImpl &getSelectorTableImpl(void *P) {
632   return *static_cast<SelectorTableImpl*>(P);
633 }
634 
635 SmallString<64>
636 SelectorTable::constructSetterName(StringRef Name) {
637   SmallString<64> SetterName("set");
638   SetterName += Name;
639   SetterName[3] = toUppercase(SetterName[3]);
640   return SetterName;
641 }
642 
643 Selector
644 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
645                                        SelectorTable &SelTable,
646                                        const IdentifierInfo *Name) {
647   IdentifierInfo *SetterName =
648     &Idents.get(constructSetterName(Name->getName()));
649   return SelTable.getUnarySelector(SetterName);
650 }
651 
652 std::string SelectorTable::getPropertyNameFromSetterSelector(Selector Sel) {
653   StringRef Name = Sel.getNameForSlot(0);
654   assert(Name.startswith("set") && "invalid setter name");
655   return (Twine(toLowercase(Name[3])) + Name.drop_front(4)).str();
656 }
657 
658 size_t SelectorTable::getTotalMemory() const {
659   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
660   return SelTabImpl.Allocator.getTotalMemory();
661 }
662 
663 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
664   if (nKeys < 2)
665     return Selector(IIV[0], nKeys);
666 
667   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
668 
669   // Unique selector, to guarantee there is one per name.
670   llvm::FoldingSetNodeID ID;
671   MultiKeywordSelector::Profile(ID, IIV, nKeys);
672 
673   void *InsertPos = nullptr;
674   if (MultiKeywordSelector *SI =
675         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
676     return Selector(SI);
677 
678   // MultiKeywordSelector objects are not allocated with new because they have a
679   // variable size array (for parameter types) at the end of them.
680   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
681   MultiKeywordSelector *SI =
682       (MultiKeywordSelector *)SelTabImpl.Allocator.Allocate(
683           Size, alignof(MultiKeywordSelector));
684   new (SI) MultiKeywordSelector(nKeys, IIV);
685   SelTabImpl.Table.InsertNode(SI, InsertPos);
686   return Selector(SI);
687 }
688 
689 SelectorTable::SelectorTable() {
690   Impl = new SelectorTableImpl();
691 }
692 
693 SelectorTable::~SelectorTable() {
694   delete &getSelectorTableImpl(Impl);
695 }
696 
697 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
698   switch (Operator) {
699   case OO_None:
700   case NUM_OVERLOADED_OPERATORS:
701     return nullptr;
702 
703 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
704   case OO_##Name: return Spelling;
705 #include "clang/Basic/OperatorKinds.def"
706   }
707 
708   llvm_unreachable("Invalid OverloadedOperatorKind!");
709 }
710 
711 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
712                                         bool isContextSensitive) {
713   switch (kind) {
714   case NullabilityKind::NonNull:
715     return isContextSensitive ? "nonnull" : "_Nonnull";
716 
717   case NullabilityKind::Nullable:
718     return isContextSensitive ? "nullable" : "_Nullable";
719 
720   case NullabilityKind::NullableResult:
721     assert(!isContextSensitive &&
722            "_Nullable_result isn't supported as context-sensitive keyword");
723     return "_Nullable_result";
724 
725   case NullabilityKind::Unspecified:
726     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
727   }
728   llvm_unreachable("Unknown nullability kind.");
729 }
730