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     KEYMSCOMPAT   = 0x800000,
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.MSVCCompat && (Flags & KEYMSCOMPAT)) return KS_Enabled;
130   if (LangOpts.Borland && (Flags & KEYBORLAND)) return KS_Extension;
131   if (LangOpts.Bool && (Flags & BOOLSUPPORT)) return KS_Enabled;
132   if (LangOpts.Half && (Flags & HALFSUPPORT)) return KS_Enabled;
133   if (LangOpts.WChar && (Flags & WCHARSUPPORT)) return KS_Enabled;
134   if (LangOpts.Char8 && (Flags & CHAR8SUPPORT)) return KS_Enabled;
135   if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) return KS_Enabled;
136   if (LangOpts.ZVector && (Flags & KEYZVECTOR)) return KS_Enabled;
137   if (LangOpts.OpenCL && !LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLC))
138     return KS_Enabled;
139   if (LangOpts.OpenCLCPlusPlus && (Flags & KEYOPENCLCXX)) return KS_Enabled;
140   if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) return KS_Enabled;
141   if (LangOpts.C11 && (Flags & KEYC11)) return KS_Enabled;
142   // We treat bridge casts as objective-C keywords so we can warn on them
143   // in non-arc mode.
144   if (LangOpts.ObjC && (Flags & KEYOBJC)) return KS_Enabled;
145   if (LangOpts.CPlusPlus2a && (Flags & KEYCONCEPTS)) return KS_Enabled;
146   if (LangOpts.Coroutines && (Flags & KEYCOROUTINES)) return KS_Enabled;
147   if (LangOpts.ModulesTS && (Flags & KEYMODULES)) return KS_Enabled;
148   if (LangOpts.CPlusPlus && (Flags & KEYALLCXX)) return KS_Future;
149   return KS_Disabled;
150 }
151 
152 /// AddKeyword - This method is used to associate a token ID with specific
153 /// identifiers because they are language keywords.  This causes the lexer to
154 /// automatically map matching identifiers to specialized token codes.
155 static void AddKeyword(StringRef Keyword,
156                        tok::TokenKind TokenCode, unsigned Flags,
157                        const LangOptions &LangOpts, IdentifierTable &Table) {
158   KeywordStatus AddResult = getKeywordStatus(LangOpts, Flags);
159 
160   // Don't add this keyword under MSVCCompat.
161   if (LangOpts.MSVCCompat && (Flags & KEYNOMS18) &&
162       !LangOpts.isCompatibleWithMSVC(LangOptions::MSVC2015))
163     return;
164 
165   // Don't add this keyword under OpenCL.
166   if (LangOpts.OpenCL && (Flags & KEYNOOPENCL))
167     return;
168 
169   // Don't add this keyword if disabled in this language.
170   if (AddResult == KS_Disabled) return;
171 
172   IdentifierInfo &Info =
173       Table.get(Keyword, AddResult == KS_Future ? tok::identifier : TokenCode);
174   Info.setIsExtensionToken(AddResult == KS_Extension);
175   Info.setIsFutureCompatKeyword(AddResult == KS_Future);
176 }
177 
178 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
179 /// representations.
180 static void AddCXXOperatorKeyword(StringRef Keyword,
181                                   tok::TokenKind TokenCode,
182                                   IdentifierTable &Table) {
183   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
184   Info.setIsCPlusPlusOperatorKeyword();
185 }
186 
187 /// AddObjCKeyword - Register an Objective-C \@keyword like "class" "selector"
188 /// or "property".
189 static void AddObjCKeyword(StringRef Name,
190                            tok::ObjCKeywordKind ObjCID,
191                            IdentifierTable &Table) {
192   Table.get(Name).setObjCKeywordID(ObjCID);
193 }
194 
195 /// AddKeywords - Add all keywords to the symbol table.
196 ///
197 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
198   // Add keywords and tokens for the current language.
199 #define KEYWORD(NAME, FLAGS) \
200   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
201              FLAGS, LangOpts, *this);
202 #define ALIAS(NAME, TOK, FLAGS) \
203   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
204              FLAGS, LangOpts, *this);
205 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
206   if (LangOpts.CXXOperatorNames)          \
207     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
208 #define OBJC_AT_KEYWORD(NAME)  \
209   if (LangOpts.ObjC)           \
210     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
211 #define TESTING_KEYWORD(NAME, FLAGS)
212 #include "clang/Basic/TokenKinds.def"
213 
214   if (LangOpts.ParseUnknownAnytype)
215     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
216                LangOpts, *this);
217 
218   if (LangOpts.DeclSpecKeyword)
219     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
220 
221   // Add the 'import' contextual keyword.
222   get("import").setModulesImport(true);
223 }
224 
225 /// Checks if the specified token kind represents a keyword in the
226 /// specified language.
227 /// \returns Status of the keyword in the language.
228 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
229                                       tok::TokenKind K) {
230   switch (K) {
231 #define KEYWORD(NAME, FLAGS) \
232   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
233 #include "clang/Basic/TokenKinds.def"
234   default: return KS_Disabled;
235   }
236 }
237 
238 /// Returns true if the identifier represents a keyword in the
239 /// specified language.
240 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) const {
241   switch (getTokenKwStatus(LangOpts, getTokenID())) {
242   case KS_Enabled:
243   case KS_Extension:
244     return true;
245   default:
246     return false;
247   }
248 }
249 
250 /// Returns true if the identifier represents a C++ keyword in the
251 /// specified language.
252 bool IdentifierInfo::isCPlusPlusKeyword(const LangOptions &LangOpts) const {
253   if (!LangOpts.CPlusPlus || !isKeyword(LangOpts))
254     return false;
255   // This is a C++ keyword if this identifier is not a keyword when checked
256   // using LangOptions without C++ support.
257   LangOptions LangOptsNoCPP = LangOpts;
258   LangOptsNoCPP.CPlusPlus = false;
259   LangOptsNoCPP.CPlusPlus11 = false;
260   LangOptsNoCPP.CPlusPlus2a = false;
261   return !isKeyword(LangOptsNoCPP);
262 }
263 
264 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
265   // We use a perfect hash function here involving the length of the keyword,
266   // the first and third character.  For preprocessor ID's there are no
267   // collisions (if there were, the switch below would complain about duplicate
268   // case values).  Note that this depends on 'if' being null terminated.
269 
270 #define HASH(LEN, FIRST, THIRD) \
271   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
272 #define CASE(LEN, FIRST, THIRD, NAME) \
273   case HASH(LEN, FIRST, THIRD): \
274     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
275 
276   unsigned Len = getLength();
277   if (Len < 2) return tok::pp_not_keyword;
278   const char *Name = getNameStart();
279   switch (HASH(Len, Name[0], Name[2])) {
280   default: return tok::pp_not_keyword;
281   CASE( 2, 'i', '\0', if);
282   CASE( 4, 'e', 'i', elif);
283   CASE( 4, 'e', 's', else);
284   CASE( 4, 'l', 'n', line);
285   CASE( 4, 's', 'c', sccs);
286   CASE( 5, 'e', 'd', endif);
287   CASE( 5, 'e', 'r', error);
288   CASE( 5, 'i', 'e', ident);
289   CASE( 5, 'i', 'd', ifdef);
290   CASE( 5, 'u', 'd', undef);
291 
292   CASE( 6, 'a', 's', assert);
293   CASE( 6, 'd', 'f', define);
294   CASE( 6, 'i', 'n', ifndef);
295   CASE( 6, 'i', 'p', import);
296   CASE( 6, 'p', 'a', pragma);
297 
298   CASE( 7, 'd', 'f', defined);
299   CASE( 7, 'i', 'c', include);
300   CASE( 7, 'w', 'r', warning);
301 
302   CASE( 8, 'u', 'a', unassert);
303   CASE(12, 'i', 'c', include_next);
304 
305   CASE(14, '_', 'p', __public_macro);
306 
307   CASE(15, '_', 'p', __private_macro);
308 
309   CASE(16, '_', 'i', __include_macros);
310 #undef CASE
311 #undef HASH
312   }
313 }
314 
315 //===----------------------------------------------------------------------===//
316 // Stats Implementation
317 //===----------------------------------------------------------------------===//
318 
319 /// PrintStats - Print statistics about how well the identifier table is doing
320 /// at hashing identifiers.
321 void IdentifierTable::PrintStats() const {
322   unsigned NumBuckets = HashTable.getNumBuckets();
323   unsigned NumIdentifiers = HashTable.getNumItems();
324   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
325   unsigned AverageIdentifierSize = 0;
326   unsigned MaxIdentifierLength = 0;
327 
328   // TODO: Figure out maximum times an identifier had to probe for -stats.
329   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
330        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
331     unsigned IdLen = I->getKeyLength();
332     AverageIdentifierSize += IdLen;
333     if (MaxIdentifierLength < IdLen)
334       MaxIdentifierLength = IdLen;
335   }
336 
337   fprintf(stderr, "\n*** Identifier Table Stats:\n");
338   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
339   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
340   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
341           NumIdentifiers/(double)NumBuckets);
342   fprintf(stderr, "Ave identifier length: %f\n",
343           (AverageIdentifierSize/(double)NumIdentifiers));
344   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
345 
346   // Compute statistics about the memory allocated for identifiers.
347   HashTable.getAllocator().PrintStats();
348 }
349 
350 //===----------------------------------------------------------------------===//
351 // SelectorTable Implementation
352 //===----------------------------------------------------------------------===//
353 
354 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
355   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
356 }
357 
358 namespace clang {
359 
360 /// One of these variable length records is kept for each
361 /// selector containing more than one keyword. We use a folding set
362 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
363 /// this class is provided strictly through Selector.
364 class alignas(IdentifierInfoAlignment) MultiKeywordSelector
365     : public detail::DeclarationNameExtra,
366       public llvm::FoldingSetNode {
367   MultiKeywordSelector(unsigned nKeys) : DeclarationNameExtra(nKeys) {}
368 
369 public:
370   // Constructor for keyword selectors.
371   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV)
372       : DeclarationNameExtra(nKeys) {
373     assert((nKeys > 1) && "not a multi-keyword selector");
374 
375     // Fill in the trailing keyword array.
376     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this + 1);
377     for (unsigned i = 0; i != nKeys; ++i)
378       KeyInfo[i] = IIV[i];
379   }
380 
381   // getName - Derive the full selector name and return it.
382   std::string getName() const;
383 
384   using DeclarationNameExtra::getNumArgs;
385 
386   using keyword_iterator = IdentifierInfo *const *;
387 
388   keyword_iterator keyword_begin() const {
389     return reinterpret_cast<keyword_iterator>(this + 1);
390   }
391 
392   keyword_iterator keyword_end() const {
393     return keyword_begin() + getNumArgs();
394   }
395 
396   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
397     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
398     return keyword_begin()[i];
399   }
400 
401   static void Profile(llvm::FoldingSetNodeID &ID, keyword_iterator ArgTys,
402                       unsigned NumArgs) {
403     ID.AddInteger(NumArgs);
404     for (unsigned i = 0; i != NumArgs; ++i)
405       ID.AddPointer(ArgTys[i]);
406   }
407 
408   void Profile(llvm::FoldingSetNodeID &ID) {
409     Profile(ID, keyword_begin(), getNumArgs());
410   }
411 };
412 
413 } // namespace clang.
414 
415 bool Selector::isKeywordSelector(ArrayRef<StringRef> Names) const {
416   assert(!Names.empty() && "must have >= 1 selector slots");
417   if (getNumArgs() != Names.size())
418     return false;
419   for (unsigned I = 0, E = Names.size(); I != E; ++I) {
420     if (getNameForSlot(I) != Names[I])
421       return false;
422   }
423   return true;
424 }
425 
426 bool Selector::isUnarySelector(StringRef Name) const {
427   return isUnarySelector() && getNameForSlot(0) == Name;
428 }
429 
430 unsigned Selector::getNumArgs() const {
431   unsigned IIF = getIdentifierInfoFlag();
432   if (IIF <= ZeroArg)
433     return 0;
434   if (IIF == OneArg)
435     return 1;
436   // We point to a MultiKeywordSelector.
437   MultiKeywordSelector *SI = getMultiKeywordSelector();
438   return SI->getNumArgs();
439 }
440 
441 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
442   if (getIdentifierInfoFlag() < MultiArg) {
443     assert(argIndex == 0 && "illegal keyword index");
444     return getAsIdentifierInfo();
445   }
446 
447   // We point to a MultiKeywordSelector.
448   MultiKeywordSelector *SI = getMultiKeywordSelector();
449   return SI->getIdentifierInfoForSlot(argIndex);
450 }
451 
452 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
453   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
454   return II ? II->getName() : StringRef();
455 }
456 
457 std::string MultiKeywordSelector::getName() const {
458   SmallString<256> Str;
459   llvm::raw_svector_ostream OS(Str);
460   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
461     if (*I)
462       OS << (*I)->getName();
463     OS << ':';
464   }
465 
466   return OS.str();
467 }
468 
469 std::string Selector::getAsString() const {
470   if (InfoPtr == 0)
471     return "<null selector>";
472 
473   if (getIdentifierInfoFlag() < MultiArg) {
474     IdentifierInfo *II = getAsIdentifierInfo();
475 
476     if (getNumArgs() == 0) {
477       assert(II && "If the number of arguments is 0 then II is guaranteed to "
478                    "not be null.");
479       return II->getName();
480     }
481 
482     if (!II)
483       return ":";
484 
485     return II->getName().str() + ":";
486   }
487 
488   // We have a multiple keyword selector.
489   return getMultiKeywordSelector()->getName();
490 }
491 
492 void Selector::print(llvm::raw_ostream &OS) const {
493   OS << getAsString();
494 }
495 
496 LLVM_DUMP_METHOD void Selector::dump() const { print(llvm::errs()); }
497 
498 /// Interpreting the given string using the normal CamelCase
499 /// conventions, determine whether the given string starts with the
500 /// given "word", which is assumed to end in a lowercase letter.
501 static bool startsWithWord(StringRef name, StringRef word) {
502   if (name.size() < word.size()) return false;
503   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
504           name.startswith(word));
505 }
506 
507 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
508   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
509   if (!first) return OMF_None;
510 
511   StringRef name = first->getName();
512   if (sel.isUnarySelector()) {
513     if (name == "autorelease") return OMF_autorelease;
514     if (name == "dealloc") return OMF_dealloc;
515     if (name == "finalize") return OMF_finalize;
516     if (name == "release") return OMF_release;
517     if (name == "retain") return OMF_retain;
518     if (name == "retainCount") return OMF_retainCount;
519     if (name == "self") return OMF_self;
520     if (name == "initialize") return OMF_initialize;
521   }
522 
523   if (name == "performSelector" || name == "performSelectorInBackground" ||
524       name == "performSelectorOnMainThread")
525     return OMF_performSelector;
526 
527   // The other method families may begin with a prefix of underscores.
528   while (!name.empty() && name.front() == '_')
529     name = name.substr(1);
530 
531   if (name.empty()) return OMF_None;
532   switch (name.front()) {
533   case 'a':
534     if (startsWithWord(name, "alloc")) return OMF_alloc;
535     break;
536   case 'c':
537     if (startsWithWord(name, "copy")) return OMF_copy;
538     break;
539   case 'i':
540     if (startsWithWord(name, "init")) return OMF_init;
541     break;
542   case 'm':
543     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
544     break;
545   case 'n':
546     if (startsWithWord(name, "new")) return OMF_new;
547     break;
548   default:
549     break;
550   }
551 
552   return OMF_None;
553 }
554 
555 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
556   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
557   if (!first) return OIT_None;
558 
559   StringRef name = first->getName();
560 
561   if (name.empty()) return OIT_None;
562   switch (name.front()) {
563     case 'a':
564       if (startsWithWord(name, "array")) return OIT_Array;
565       break;
566     case 'd':
567       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
568       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
569       break;
570     case 's':
571       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
572       if (startsWithWord(name, "standard")) return OIT_Singleton;
573       break;
574     case 'i':
575       if (startsWithWord(name, "init")) return OIT_Init;
576       break;
577     default:
578       break;
579   }
580   return OIT_None;
581 }
582 
583 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
584   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
585   if (!first) return SFF_None;
586 
587   StringRef name = first->getName();
588 
589   switch (name.front()) {
590     case 'a':
591       if (name == "appendFormat") return SFF_NSString;
592       break;
593 
594     case 'i':
595       if (name == "initWithFormat") return SFF_NSString;
596       break;
597 
598     case 'l':
599       if (name == "localizedStringWithFormat") return SFF_NSString;
600       break;
601 
602     case 's':
603       if (name == "stringByAppendingFormat" ||
604           name == "stringWithFormat") return SFF_NSString;
605       break;
606   }
607   return SFF_None;
608 }
609 
610 namespace {
611 
612 struct SelectorTableImpl {
613   llvm::FoldingSet<MultiKeywordSelector> Table;
614   llvm::BumpPtrAllocator Allocator;
615 };
616 
617 } // namespace
618 
619 static SelectorTableImpl &getSelectorTableImpl(void *P) {
620   return *static_cast<SelectorTableImpl*>(P);
621 }
622 
623 SmallString<64>
624 SelectorTable::constructSetterName(StringRef Name) {
625   SmallString<64> SetterName("set");
626   SetterName += Name;
627   SetterName[3] = toUppercase(SetterName[3]);
628   return SetterName;
629 }
630 
631 Selector
632 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
633                                        SelectorTable &SelTable,
634                                        const IdentifierInfo *Name) {
635   IdentifierInfo *SetterName =
636     &Idents.get(constructSetterName(Name->getName()));
637   return SelTable.getUnarySelector(SetterName);
638 }
639 
640 std::string SelectorTable::getPropertyNameFromSetterSelector(Selector Sel) {
641   StringRef Name = Sel.getNameForSlot(0);
642   assert(Name.startswith("set") && "invalid setter name");
643   return (Twine(toLowercase(Name[3])) + Name.drop_front(4)).str();
644 }
645 
646 size_t SelectorTable::getTotalMemory() const {
647   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
648   return SelTabImpl.Allocator.getTotalMemory();
649 }
650 
651 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
652   if (nKeys < 2)
653     return Selector(IIV[0], nKeys);
654 
655   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
656 
657   // Unique selector, to guarantee there is one per name.
658   llvm::FoldingSetNodeID ID;
659   MultiKeywordSelector::Profile(ID, IIV, nKeys);
660 
661   void *InsertPos = nullptr;
662   if (MultiKeywordSelector *SI =
663         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
664     return Selector(SI);
665 
666   // MultiKeywordSelector objects are not allocated with new because they have a
667   // variable size array (for parameter types) at the end of them.
668   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
669   MultiKeywordSelector *SI =
670       (MultiKeywordSelector *)SelTabImpl.Allocator.Allocate(
671           Size, alignof(MultiKeywordSelector));
672   new (SI) MultiKeywordSelector(nKeys, IIV);
673   SelTabImpl.Table.InsertNode(SI, InsertPos);
674   return Selector(SI);
675 }
676 
677 SelectorTable::SelectorTable() {
678   Impl = new SelectorTableImpl();
679 }
680 
681 SelectorTable::~SelectorTable() {
682   delete &getSelectorTableImpl(Impl);
683 }
684 
685 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
686   switch (Operator) {
687   case OO_None:
688   case NUM_OVERLOADED_OPERATORS:
689     return nullptr;
690 
691 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
692   case OO_##Name: return Spelling;
693 #include "clang/Basic/OperatorKinds.def"
694   }
695 
696   llvm_unreachable("Invalid OverloadedOperatorKind!");
697 }
698 
699 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
700                                         bool isContextSensitive) {
701   switch (kind) {
702   case NullabilityKind::NonNull:
703     return isContextSensitive ? "nonnull" : "_Nonnull";
704 
705   case NullabilityKind::Nullable:
706     return isContextSensitive ? "nullable" : "_Nullable";
707 
708   case NullabilityKind::Unspecified:
709     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
710   }
711   llvm_unreachable("Unknown nullability kind.");
712 }
713