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