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      1 //===--- IdentifierTable.cpp - Hash table for identifier lookup -----------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file implements the IdentifierInfo, IdentifierVisitor, and
     11 // IdentifierTable interfaces.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "clang/Basic/CharInfo.h"
     16 #include "clang/Basic/IdentifierTable.h"
     17 #include "clang/Basic/LangOptions.h"
     18 #include "clang/Basic/OperatorKinds.h"
     19 #include "clang/Basic/Specifiers.h"
     20 #include "llvm/ADT/DenseMap.h"
     21 #include "llvm/ADT/FoldingSet.h"
     22 #include "llvm/ADT/SmallString.h"
     23 #include "llvm/Support/ErrorHandling.h"
     24 #include "llvm/Support/raw_ostream.h"
     25 #include <cstdio>
     26 
     27 using namespace clang;
     28 
     29 //===----------------------------------------------------------------------===//
     30 // IdentifierInfo Implementation
     31 //===----------------------------------------------------------------------===//
     32 
     33 IdentifierInfo::IdentifierInfo() {
     34   TokenID = tok::identifier;
     35   ObjCOrBuiltinID = 0;
     36   HasMacro = false;
     37   HadMacro = false;
     38   IsExtension = false;
     39   IsFutureCompatKeyword = false;
     40   IsPoisoned = false;
     41   IsCPPOperatorKeyword = false;
     42   NeedsHandleIdentifier = false;
     43   IsFromAST = false;
     44   ChangedAfterLoad = false;
     45   RevertedTokenID = false;
     46   OutOfDate = false;
     47   IsModulesImport = false;
     48   FETokenInfo = nullptr;
     49   Entry = nullptr;
     50 }
     51 
     52 //===----------------------------------------------------------------------===//
     53 // IdentifierTable Implementation
     54 //===----------------------------------------------------------------------===//
     55 
     56 IdentifierIterator::~IdentifierIterator() { }
     57 
     58 IdentifierInfoLookup::~IdentifierInfoLookup() {}
     59 
     60 namespace {
     61   /// \brief A simple identifier lookup iterator that represents an
     62   /// empty sequence of identifiers.
     63   class EmptyLookupIterator : public IdentifierIterator
     64   {
     65   public:
     66     StringRef Next() override { return StringRef(); }
     67   };
     68 }
     69 
     70 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() {
     71   return new EmptyLookupIterator();
     72 }
     73 
     74 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
     75                                  IdentifierInfoLookup* externalLookup)
     76   : HashTable(8192), // Start with space for 8K identifiers.
     77     ExternalLookup(externalLookup) {
     78 
     79   // Populate the identifier table with info about keywords for the current
     80   // language.
     81   AddKeywords(LangOpts);
     82 
     83 
     84   // Add the '_experimental_modules_import' contextual keyword.
     85   get("import").setModulesImport(true);
     86 }
     87 
     88 //===----------------------------------------------------------------------===//
     89 // Language Keyword Implementation
     90 //===----------------------------------------------------------------------===//
     91 
     92 // Constants for TokenKinds.def
     93 namespace {
     94   enum {
     95     KEYC99 = 0x1,
     96     KEYCXX = 0x2,
     97     KEYCXX11 = 0x4,
     98     KEYGNU = 0x8,
     99     KEYMS = 0x10,
    100     BOOLSUPPORT = 0x20,
    101     KEYALTIVEC = 0x40,
    102     KEYNOCXX = 0x80,
    103     KEYBORLAND = 0x100,
    104     KEYOPENCL = 0x200,
    105     KEYC11 = 0x400,
    106     KEYARC = 0x800,
    107     KEYNOMS18 = 0x01000,
    108     KEYNOOPENCL = 0x02000,
    109     WCHARSUPPORT = 0x04000,
    110     HALFSUPPORT = 0x08000,
    111     KEYCONCEPTS = 0x10000,
    112     KEYOBJC2    = 0x20000,
    113     KEYZVECTOR  = 0x40000,
    114     KEYCOROUTINES = 0x80000,
    115     KEYALL = (0xfffff & ~KEYNOMS18 &
    116               ~KEYNOOPENCL) // KEYNOMS18 and KEYNOOPENCL are used to exclude.
    117   };
    118 
    119   /// \brief How a keyword is treated in the selected standard.
    120   enum KeywordStatus {
    121     KS_Disabled,    // Disabled
    122     KS_Extension,   // Is an extension
    123     KS_Enabled,     // Enabled
    124     KS_Future       // Is a keyword in future standard
    125   };
    126 }
    127 
    128 /// \brief Translates flags as specified in TokenKinds.def into keyword status
    129 /// in the given language standard.
    130 static KeywordStatus getKeywordStatus(const LangOptions &LangOpts,
    131                                       unsigned Flags) {
    132   if (Flags == KEYALL) return KS_Enabled;
    133   if (LangOpts.CPlusPlus && (Flags & KEYCXX)) return KS_Enabled;
    134   if (LangOpts.CPlusPlus11 && (Flags & KEYCXX11)) return KS_Enabled;
    135   if (LangOpts.C99 && (Flags & KEYC99)) return KS_Enabled;
    136   if (LangOpts.GNUKeywords && (Flags & KEYGNU)) return KS_Extension;
    137   if (LangOpts.MicrosoftExt && (Flags & KEYMS)) return KS_Extension;
    138   if (LangOpts.Borland && (Flags & KEYBORLAND)) return KS_Extension;
    139   if (LangOpts.Bool && (Flags & BOOLSUPPORT)) return KS_Enabled;
    140   if (LangOpts.Half && (Flags & HALFSUPPORT)) return KS_Enabled;
    141   if (LangOpts.WChar && (Flags & WCHARSUPPORT)) return KS_Enabled;
    142   if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) return KS_Enabled;
    143   if (LangOpts.OpenCL && (Flags & KEYOPENCL)) return KS_Enabled;
    144   if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) return KS_Enabled;
    145   if (LangOpts.C11 && (Flags & KEYC11)) return KS_Enabled;
    146   // We treat bridge casts as objective-C keywords so we can warn on them
    147   // in non-arc mode.
    148   if (LangOpts.ObjC2 && (Flags & KEYARC)) return KS_Enabled;
    149   if (LangOpts.ConceptsTS && (Flags & KEYCONCEPTS)) return KS_Enabled;
    150   if (LangOpts.ObjC2 && (Flags & KEYOBJC2)) return KS_Enabled;
    151   if (LangOpts.Coroutines && (Flags & KEYCOROUTINES)) return KS_Enabled;
    152   if (LangOpts.CPlusPlus && (Flags & KEYCXX11)) return KS_Future;
    153   return KS_Disabled;
    154 }
    155 
    156 /// AddKeyword - This method is used to associate a token ID with specific
    157 /// identifiers because they are language keywords.  This causes the lexer to
    158 /// automatically map matching identifiers to specialized token codes.
    159 static void AddKeyword(StringRef Keyword,
    160                        tok::TokenKind TokenCode, unsigned Flags,
    161                        const LangOptions &LangOpts, IdentifierTable &Table) {
    162   KeywordStatus AddResult = getKeywordStatus(LangOpts, Flags);
    163 
    164   // Don't add this keyword under MSVCCompat.
    165   if (LangOpts.MSVCCompat && (Flags & KEYNOMS18) &&
    166       !LangOpts.isCompatibleWithMSVC(LangOptions::MSVC2015))
    167     return;
    168 
    169   // Don't add this keyword under OpenCL.
    170   if (LangOpts.OpenCL && (Flags & KEYNOOPENCL))
    171     return;
    172 
    173   // Don't add this keyword if disabled in this language.
    174   if (AddResult == KS_Disabled) return;
    175 
    176   IdentifierInfo &Info =
    177       Table.get(Keyword, AddResult == KS_Future ? tok::identifier : TokenCode);
    178   Info.setIsExtensionToken(AddResult == KS_Extension);
    179   Info.setIsFutureCompatKeyword(AddResult == KS_Future);
    180 }
    181 
    182 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
    183 /// representations.
    184 static void AddCXXOperatorKeyword(StringRef Keyword,
    185                                   tok::TokenKind TokenCode,
    186                                   IdentifierTable &Table) {
    187   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
    188   Info.setIsCPlusPlusOperatorKeyword();
    189 }
    190 
    191 /// AddObjCKeyword - Register an Objective-C \@keyword like "class" "selector"
    192 /// or "property".
    193 static void AddObjCKeyword(StringRef Name,
    194                            tok::ObjCKeywordKind ObjCID,
    195                            IdentifierTable &Table) {
    196   Table.get(Name).setObjCKeywordID(ObjCID);
    197 }
    198 
    199 /// AddKeywords - Add all keywords to the symbol table.
    200 ///
    201 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
    202   // Add keywords and tokens for the current language.
    203 #define KEYWORD(NAME, FLAGS) \
    204   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
    205              FLAGS, LangOpts, *this);
    206 #define ALIAS(NAME, TOK, FLAGS) \
    207   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
    208              FLAGS, LangOpts, *this);
    209 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
    210   if (LangOpts.CXXOperatorNames)          \
    211     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
    212 #define OBJC1_AT_KEYWORD(NAME) \
    213   if (LangOpts.ObjC1)          \
    214     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
    215 #define OBJC2_AT_KEYWORD(NAME) \
    216   if (LangOpts.ObjC2)          \
    217     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
    218 #define TESTING_KEYWORD(NAME, FLAGS)
    219 #include "clang/Basic/TokenKinds.def"
    220 
    221   if (LangOpts.ParseUnknownAnytype)
    222     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
    223                LangOpts, *this);
    224 
    225   if (LangOpts.DeclSpecKeyword)
    226     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
    227 }
    228 
    229 /// \brief Checks if the specified token kind represents a keyword in the
    230 /// specified language.
    231 /// \returns Status of the keyword in the language.
    232 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
    233                                       tok::TokenKind K) {
    234   switch (K) {
    235 #define KEYWORD(NAME, FLAGS) \
    236   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
    237 #include "clang/Basic/TokenKinds.def"
    238   default: return KS_Disabled;
    239   }
    240 }
    241 
    242 /// \brief Returns true if the identifier represents a keyword in the
    243 /// specified language.
    244 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) {
    245   switch (getTokenKwStatus(LangOpts, getTokenID())) {
    246   case KS_Enabled:
    247   case KS_Extension:
    248     return true;
    249   default:
    250     return false;
    251   }
    252 }
    253 
    254 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
    255   // We use a perfect hash function here involving the length of the keyword,
    256   // the first and third character.  For preprocessor ID's there are no
    257   // collisions (if there were, the switch below would complain about duplicate
    258   // case values).  Note that this depends on 'if' being null terminated.
    259 
    260 #define HASH(LEN, FIRST, THIRD) \
    261   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
    262 #define CASE(LEN, FIRST, THIRD, NAME) \
    263   case HASH(LEN, FIRST, THIRD): \
    264     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
    265 
    266   unsigned Len = getLength();
    267   if (Len < 2) return tok::pp_not_keyword;
    268   const char *Name = getNameStart();
    269   switch (HASH(Len, Name[0], Name[2])) {
    270   default: return tok::pp_not_keyword;
    271   CASE( 2, 'i', '\0', if);
    272   CASE( 4, 'e', 'i', elif);
    273   CASE( 4, 'e', 's', else);
    274   CASE( 4, 'l', 'n', line);
    275   CASE( 4, 's', 'c', sccs);
    276   CASE( 5, 'e', 'd', endif);
    277   CASE( 5, 'e', 'r', error);
    278   CASE( 5, 'i', 'e', ident);
    279   CASE( 5, 'i', 'd', ifdef);
    280   CASE( 5, 'u', 'd', undef);
    281 
    282   CASE( 6, 'a', 's', assert);
    283   CASE( 6, 'd', 'f', define);
    284   CASE( 6, 'i', 'n', ifndef);
    285   CASE( 6, 'i', 'p', import);
    286   CASE( 6, 'p', 'a', pragma);
    287 
    288   CASE( 7, 'd', 'f', defined);
    289   CASE( 7, 'i', 'c', include);
    290   CASE( 7, 'w', 'r', warning);
    291 
    292   CASE( 8, 'u', 'a', unassert);
    293   CASE(12, 'i', 'c', include_next);
    294 
    295   CASE(14, '_', 'p', __public_macro);
    296 
    297   CASE(15, '_', 'p', __private_macro);
    298 
    299   CASE(16, '_', 'i', __include_macros);
    300 #undef CASE
    301 #undef HASH
    302   }
    303 }
    304 
    305 //===----------------------------------------------------------------------===//
    306 // Stats Implementation
    307 //===----------------------------------------------------------------------===//
    308 
    309 /// PrintStats - Print statistics about how well the identifier table is doing
    310 /// at hashing identifiers.
    311 void IdentifierTable::PrintStats() const {
    312   unsigned NumBuckets = HashTable.getNumBuckets();
    313   unsigned NumIdentifiers = HashTable.getNumItems();
    314   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
    315   unsigned AverageIdentifierSize = 0;
    316   unsigned MaxIdentifierLength = 0;
    317 
    318   // TODO: Figure out maximum times an identifier had to probe for -stats.
    319   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
    320        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
    321     unsigned IdLen = I->getKeyLength();
    322     AverageIdentifierSize += IdLen;
    323     if (MaxIdentifierLength < IdLen)
    324       MaxIdentifierLength = IdLen;
    325   }
    326 
    327   fprintf(stderr, "\n*** Identifier Table Stats:\n");
    328   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
    329   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
    330   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
    331           NumIdentifiers/(double)NumBuckets);
    332   fprintf(stderr, "Ave identifier length: %f\n",
    333           (AverageIdentifierSize/(double)NumIdentifiers));
    334   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
    335 
    336   // Compute statistics about the memory allocated for identifiers.
    337   HashTable.getAllocator().PrintStats();
    338 }
    339 
    340 //===----------------------------------------------------------------------===//
    341 // SelectorTable Implementation
    342 //===----------------------------------------------------------------------===//
    343 
    344 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
    345   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
    346 }
    347 
    348 namespace clang {
    349 /// MultiKeywordSelector - One of these variable length records is kept for each
    350 /// selector containing more than one keyword. We use a folding set
    351 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
    352 /// this class is provided strictly through Selector.
    353 class MultiKeywordSelector
    354   : public DeclarationNameExtra, public llvm::FoldingSetNode {
    355   MultiKeywordSelector(unsigned nKeys) {
    356     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
    357   }
    358 public:
    359   // Constructor for keyword selectors.
    360   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV) {
    361     assert((nKeys > 1) && "not a multi-keyword selector");
    362     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
    363 
    364     // Fill in the trailing keyword array.
    365     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this+1);
    366     for (unsigned i = 0; i != nKeys; ++i)
    367       KeyInfo[i] = IIV[i];
    368   }
    369 
    370   // getName - Derive the full selector name and return it.
    371   std::string getName() const;
    372 
    373   unsigned getNumArgs() const { return ExtraKindOrNumArgs - NUM_EXTRA_KINDS; }
    374 
    375   typedef IdentifierInfo *const *keyword_iterator;
    376   keyword_iterator keyword_begin() const {
    377     return reinterpret_cast<keyword_iterator>(this+1);
    378   }
    379   keyword_iterator keyword_end() const {
    380     return keyword_begin()+getNumArgs();
    381   }
    382   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
    383     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
    384     return keyword_begin()[i];
    385   }
    386   static void Profile(llvm::FoldingSetNodeID &ID,
    387                       keyword_iterator ArgTys, unsigned NumArgs) {
    388     ID.AddInteger(NumArgs);
    389     for (unsigned i = 0; i != NumArgs; ++i)
    390       ID.AddPointer(ArgTys[i]);
    391   }
    392   void Profile(llvm::FoldingSetNodeID &ID) {
    393     Profile(ID, keyword_begin(), getNumArgs());
    394   }
    395 };
    396 } // end namespace clang.
    397 
    398 unsigned Selector::getNumArgs() const {
    399   unsigned IIF = getIdentifierInfoFlag();
    400   if (IIF <= ZeroArg)
    401     return 0;
    402   if (IIF == OneArg)
    403     return 1;
    404   // We point to a MultiKeywordSelector.
    405   MultiKeywordSelector *SI = getMultiKeywordSelector();
    406   return SI->getNumArgs();
    407 }
    408 
    409 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
    410   if (getIdentifierInfoFlag() < MultiArg) {
    411     assert(argIndex == 0 && "illegal keyword index");
    412     return getAsIdentifierInfo();
    413   }
    414   // We point to a MultiKeywordSelector.
    415   MultiKeywordSelector *SI = getMultiKeywordSelector();
    416   return SI->getIdentifierInfoForSlot(argIndex);
    417 }
    418 
    419 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
    420   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
    421   return II? II->getName() : StringRef();
    422 }
    423 
    424 std::string MultiKeywordSelector::getName() const {
    425   SmallString<256> Str;
    426   llvm::raw_svector_ostream OS(Str);
    427   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
    428     if (*I)
    429       OS << (*I)->getName();
    430     OS << ':';
    431   }
    432 
    433   return OS.str();
    434 }
    435 
    436 std::string Selector::getAsString() const {
    437   if (InfoPtr == 0)
    438     return "<null selector>";
    439 
    440   if (getIdentifierInfoFlag() < MultiArg) {
    441     IdentifierInfo *II = getAsIdentifierInfo();
    442 
    443     // If the number of arguments is 0 then II is guaranteed to not be null.
    444     if (getNumArgs() == 0)
    445       return II->getName();
    446 
    447     if (!II)
    448       return ":";
    449 
    450     return II->getName().str() + ":";
    451   }
    452 
    453   // We have a multiple keyword selector.
    454   return getMultiKeywordSelector()->getName();
    455 }
    456 
    457 void Selector::print(llvm::raw_ostream &OS) const {
    458   OS << getAsString();
    459 }
    460 
    461 /// Interpreting the given string using the normal CamelCase
    462 /// conventions, determine whether the given string starts with the
    463 /// given "word", which is assumed to end in a lowercase letter.
    464 static bool startsWithWord(StringRef name, StringRef word) {
    465   if (name.size() < word.size()) return false;
    466   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
    467           name.startswith(word));
    468 }
    469 
    470 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
    471   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
    472   if (!first) return OMF_None;
    473 
    474   StringRef name = first->getName();
    475   if (sel.isUnarySelector()) {
    476     if (name == "autorelease") return OMF_autorelease;
    477     if (name == "dealloc") return OMF_dealloc;
    478     if (name == "finalize") return OMF_finalize;
    479     if (name == "release") return OMF_release;
    480     if (name == "retain") return OMF_retain;
    481     if (name == "retainCount") return OMF_retainCount;
    482     if (name == "self") return OMF_self;
    483     if (name == "initialize") return OMF_initialize;
    484   }
    485 
    486   if (name == "performSelector") return OMF_performSelector;
    487 
    488   // The other method families may begin with a prefix of underscores.
    489   while (!name.empty() && name.front() == '_')
    490     name = name.substr(1);
    491 
    492   if (name.empty()) return OMF_None;
    493   switch (name.front()) {
    494   case 'a':
    495     if (startsWithWord(name, "alloc")) return OMF_alloc;
    496     break;
    497   case 'c':
    498     if (startsWithWord(name, "copy")) return OMF_copy;
    499     break;
    500   case 'i':
    501     if (startsWithWord(name, "init")) return OMF_init;
    502     break;
    503   case 'm':
    504     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
    505     break;
    506   case 'n':
    507     if (startsWithWord(name, "new")) return OMF_new;
    508     break;
    509   default:
    510     break;
    511   }
    512 
    513   return OMF_None;
    514 }
    515 
    516 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
    517   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
    518   if (!first) return OIT_None;
    519 
    520   StringRef name = first->getName();
    521 
    522   if (name.empty()) return OIT_None;
    523   switch (name.front()) {
    524     case 'a':
    525       if (startsWithWord(name, "array")) return OIT_Array;
    526       break;
    527     case 'd':
    528       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
    529       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
    530       break;
    531     case 's':
    532       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
    533       if (startsWithWord(name, "standard")) return OIT_Singleton;
    534     case 'i':
    535       if (startsWithWord(name, "init")) return OIT_Init;
    536     default:
    537       break;
    538   }
    539   return OIT_None;
    540 }
    541 
    542 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
    543   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
    544   if (!first) return SFF_None;
    545 
    546   StringRef name = first->getName();
    547 
    548   switch (name.front()) {
    549     case 'a':
    550       if (name == "appendFormat") return SFF_NSString;
    551       break;
    552 
    553     case 'i':
    554       if (name == "initWithFormat") return SFF_NSString;
    555       break;
    556 
    557     case 'l':
    558       if (name == "localizedStringWithFormat") return SFF_NSString;
    559       break;
    560 
    561     case 's':
    562       if (name == "stringByAppendingFormat" ||
    563           name == "stringWithFormat") return SFF_NSString;
    564       break;
    565   }
    566   return SFF_None;
    567 }
    568 
    569 namespace {
    570   struct SelectorTableImpl {
    571     llvm::FoldingSet<MultiKeywordSelector> Table;
    572     llvm::BumpPtrAllocator Allocator;
    573   };
    574 } // end anonymous namespace.
    575 
    576 static SelectorTableImpl &getSelectorTableImpl(void *P) {
    577   return *static_cast<SelectorTableImpl*>(P);
    578 }
    579 
    580 SmallString<64>
    581 SelectorTable::constructSetterName(StringRef Name) {
    582   SmallString<64> SetterName("set");
    583   SetterName += Name;
    584   SetterName[3] = toUppercase(SetterName[3]);
    585   return SetterName;
    586 }
    587 
    588 Selector
    589 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
    590                                        SelectorTable &SelTable,
    591                                        const IdentifierInfo *Name) {
    592   IdentifierInfo *SetterName =
    593     &Idents.get(constructSetterName(Name->getName()));
    594   return SelTable.getUnarySelector(SetterName);
    595 }
    596 
    597 size_t SelectorTable::getTotalMemory() const {
    598   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
    599   return SelTabImpl.Allocator.getTotalMemory();
    600 }
    601 
    602 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
    603   if (nKeys < 2)
    604     return Selector(IIV[0], nKeys);
    605 
    606   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
    607 
    608   // Unique selector, to guarantee there is one per name.
    609   llvm::FoldingSetNodeID ID;
    610   MultiKeywordSelector::Profile(ID, IIV, nKeys);
    611 
    612   void *InsertPos = nullptr;
    613   if (MultiKeywordSelector *SI =
    614         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
    615     return Selector(SI);
    616 
    617   // MultiKeywordSelector objects are not allocated with new because they have a
    618   // variable size array (for parameter types) at the end of them.
    619   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
    620   MultiKeywordSelector *SI =
    621     (MultiKeywordSelector*)SelTabImpl.Allocator.Allocate(Size,
    622                                          llvm::alignOf<MultiKeywordSelector>());
    623   new (SI) MultiKeywordSelector(nKeys, IIV);
    624   SelTabImpl.Table.InsertNode(SI, InsertPos);
    625   return Selector(SI);
    626 }
    627 
    628 SelectorTable::SelectorTable() {
    629   Impl = new SelectorTableImpl();
    630 }
    631 
    632 SelectorTable::~SelectorTable() {
    633   delete &getSelectorTableImpl(Impl);
    634 }
    635 
    636 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
    637   switch (Operator) {
    638   case OO_None:
    639   case NUM_OVERLOADED_OPERATORS:
    640     return nullptr;
    641 
    642 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
    643   case OO_##Name: return Spelling;
    644 #include "clang/Basic/OperatorKinds.def"
    645   }
    646 
    647   llvm_unreachable("Invalid OverloadedOperatorKind!");
    648 }
    649 
    650 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
    651                                         bool isContextSensitive) {
    652   switch (kind) {
    653   case NullabilityKind::NonNull:
    654     return isContextSensitive ? "nonnull" : "_Nonnull";
    655 
    656   case NullabilityKind::Nullable:
    657     return isContextSensitive ? "nullable" : "_Nullable";
    658 
    659   case NullabilityKind::Unspecified:
    660     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
    661   }
    662   llvm_unreachable("Unknown nullability kind.");
    663 }
    664