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/DiagnosticLex.h"
17 #include "clang/Basic/LangOptions.h"
18 #include "clang/Basic/OperatorKinds.h"
19 #include "clang/Basic/Specifiers.h"
20 #include "clang/Basic/TargetBuiltins.h"
21 #include "clang/Basic/TokenKinds.h"
22 #include "llvm/ADT/DenseMapInfo.h"
23 #include "llvm/ADT/FoldingSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/StringMap.h"
26 #include "llvm/ADT/StringRef.h"
27 #include "llvm/Support/Allocator.h"
28 #include "llvm/Support/ErrorHandling.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include <cassert>
31 #include <cstdio>
32 #include <cstring>
33 #include <string>
34 
35 using namespace clang;
36 
37 // A check to make sure the ObjCOrBuiltinID has sufficient room to store the
38 // largest possible target/aux-target combination. If we exceed this, we likely
39 // need to just change the ObjCOrBuiltinIDBits value in IdentifierTable.h.
40 static_assert(2 * LargestBuiltinID < (2 << (ObjCOrBuiltinIDBits - 1)),
41               "Insufficient ObjCOrBuiltinID Bits");
42 
43 //===----------------------------------------------------------------------===//
44 // IdentifierTable Implementation
45 //===----------------------------------------------------------------------===//
46 
47 IdentifierIterator::~IdentifierIterator() = default;
48 
49 IdentifierInfoLookup::~IdentifierInfoLookup() = default;
50 
51 namespace {
52 
53 /// A simple identifier lookup iterator that represents an
54 /// empty sequence of identifiers.
55 class EmptyLookupIterator : public IdentifierIterator
56 {
57 public:
58   StringRef Next() override { return StringRef(); }
59 };
60 
61 } // namespace
62 
63 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() {
64   return new EmptyLookupIterator();
65 }
66 
67 IdentifierTable::IdentifierTable(IdentifierInfoLookup *ExternalLookup)
68     : HashTable(8192), // Start with space for 8K identifiers.
69       ExternalLookup(ExternalLookup) {}
70 
71 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
72                                  IdentifierInfoLookup *ExternalLookup)
73     : IdentifierTable(ExternalLookup) {
74   // Populate the identifier table with info about keywords for the current
75   // language.
76   AddKeywords(LangOpts);
77 }
78 
79 //===----------------------------------------------------------------------===//
80 // Language Keyword Implementation
81 //===----------------------------------------------------------------------===//
82 
83 // Constants for TokenKinds.def
84 namespace {
85 
86   enum TokenKey : unsigned {
87     KEYC99        = 0x1,
88     KEYCXX        = 0x2,
89     KEYCXX11      = 0x4,
90     KEYGNU        = 0x8,
91     KEYMS         = 0x10,
92     BOOLSUPPORT   = 0x20,
93     KEYALTIVEC    = 0x40,
94     KEYNOCXX      = 0x80,
95     KEYBORLAND    = 0x100,
96     KEYOPENCLC    = 0x200,
97     KEYC2X        = 0x400,
98     KEYNOMS18     = 0x800,
99     KEYNOOPENCL   = 0x1000,
100     WCHARSUPPORT  = 0x2000,
101     HALFSUPPORT   = 0x4000,
102     CHAR8SUPPORT  = 0x8000,
103     KEYOBJC       = 0x10000,
104     KEYZVECTOR    = 0x20000,
105     KEYCOROUTINES = 0x40000,
106     KEYMODULES    = 0x80000,
107     KEYCXX20      = 0x100000,
108     KEYOPENCLCXX  = 0x200000,
109     KEYMSCOMPAT   = 0x400000,
110     KEYSYCL       = 0x800000,
111     KEYCUDA       = 0x1000000,
112     KEYHLSL       = 0x2000000,
113     KEYMAX        = KEYHLSL, // The maximum key
114     KEYALLCXX = KEYCXX | KEYCXX11 | KEYCXX20,
115     KEYALL = (KEYMAX | (KEYMAX-1)) & ~KEYNOMS18 &
116              ~KEYNOOPENCL // KEYNOMS18 and KEYNOOPENCL are used to exclude.
117   };
118 
119   /// How a keyword is treated in the selected standard. This enum is ordered
120   /// intentionally so that the value that 'wins' is the most 'permissive'.
121   enum KeywordStatus {
122     KS_Unknown,     // Not yet calculated. Used when figuring out the status.
123     KS_Disabled,    // Disabled
124     KS_Future,      // Is a keyword in future standard
125     KS_Extension,   // Is an extension
126     KS_Enabled,     // Enabled
127   };
128 
129 } // namespace
130 
131 // This works on a single TokenKey flag and checks the LangOpts to get the
132 // KeywordStatus based exclusively on this flag, so that it can be merged in
133 // getKeywordStatus. Most should be enabled/disabled, but some might imply
134 // 'future' versions, or extensions. Returns 'unknown' unless this is KNOWN to
135 // be disabled, and the calling function makes it 'disabled' if no other flag
136 // changes it. This is necessary for the KEYNOCXX and KEYNOOPENCL flags.
137 static KeywordStatus getKeywordStatusHelper(const LangOptions &LangOpts,
138                                             TokenKey Flag) {
139   // Flag is a single bit version of TokenKey (that is, not
140   // KEYALL/KEYALLCXX/etc), so we can check with == throughout this function.
141   assert((Flag & ~(Flag - 1)) == Flag && "Multiple bits set?");
142 
143   switch (Flag) {
144   case KEYC99:
145     if (LangOpts.C99)
146       return KS_Enabled;
147     return !LangOpts.CPlusPlus ? KS_Future : KS_Unknown;
148   case KEYC2X:
149     if (LangOpts.C2x)
150       return KS_Enabled;
151     return !LangOpts.CPlusPlus ? KS_Future : KS_Unknown;
152   case KEYCXX:
153     return LangOpts.CPlusPlus ? KS_Enabled : KS_Unknown;
154   case KEYCXX11:
155     if (LangOpts.CPlusPlus11)
156       return KS_Enabled;
157     return LangOpts.CPlusPlus ? KS_Future : KS_Unknown;
158   case KEYCXX20:
159     if (LangOpts.CPlusPlus20)
160       return KS_Enabled;
161     return LangOpts.CPlusPlus ? KS_Future : KS_Unknown;
162   case KEYGNU:
163     return LangOpts.GNUKeywords ? KS_Extension : KS_Unknown;
164   case KEYMS:
165     return LangOpts.MicrosoftExt ? KS_Extension : KS_Unknown;
166   case BOOLSUPPORT:
167     if (LangOpts.Bool)      return KS_Enabled;
168     return !LangOpts.CPlusPlus ? KS_Future : KS_Unknown;
169   case KEYALTIVEC:
170     return LangOpts.AltiVec ? KS_Enabled : KS_Unknown;
171   case KEYBORLAND:
172     return LangOpts.Borland ? KS_Extension : KS_Unknown;
173   case KEYOPENCLC:
174     return LangOpts.OpenCL && !LangOpts.OpenCLCPlusPlus ? KS_Enabled
175                                                         : KS_Unknown;
176   case WCHARSUPPORT:
177     return LangOpts.WChar ? KS_Enabled : KS_Unknown;
178   case HALFSUPPORT:
179     return LangOpts.Half ? KS_Enabled : KS_Unknown;
180   case CHAR8SUPPORT:
181     if (LangOpts.Char8) return KS_Enabled;
182     if (LangOpts.CPlusPlus20) return KS_Unknown;
183     if (LangOpts.CPlusPlus) return KS_Future;
184     return KS_Unknown;
185   case KEYOBJC:
186     // We treat bridge casts as objective-C keywords so we can warn on them
187     // in non-arc mode.
188     return LangOpts.ObjC ? KS_Enabled : KS_Unknown;
189   case KEYZVECTOR:
190     return LangOpts.ZVector ? KS_Enabled : KS_Unknown;
191   case KEYCOROUTINES:
192     return LangOpts.Coroutines ? KS_Enabled : KS_Unknown;
193   case KEYMODULES:
194     return LangOpts.ModulesTS ? KS_Enabled : KS_Unknown;
195   case KEYOPENCLCXX:
196     return LangOpts.OpenCLCPlusPlus ? KS_Enabled : KS_Unknown;
197   case KEYMSCOMPAT:
198     return LangOpts.MSVCCompat ? KS_Enabled : KS_Unknown;
199   case KEYSYCL:
200     return LangOpts.isSYCL() ? KS_Enabled : KS_Unknown;
201   case KEYCUDA:
202     return LangOpts.CUDA ? KS_Enabled : KS_Unknown;
203   case KEYHLSL:
204     return LangOpts.HLSL ? KS_Enabled : KS_Unknown;
205   case KEYNOCXX:
206     // This is enabled in all non-C++ modes, but might be enabled for other
207     // reasons as well.
208     return LangOpts.CPlusPlus ? KS_Unknown : KS_Enabled;
209   case KEYNOOPENCL:
210     // The disable behavior for this is handled in getKeywordStatus.
211     return KS_Unknown;
212   case KEYNOMS18:
213     // The disable behavior for this is handled in getKeywordStatus.
214     return KS_Unknown;
215   default:
216     llvm_unreachable("Unknown KeywordStatus flag");
217   }
218 }
219 
220 /// Translates flags as specified in TokenKinds.def into keyword status
221 /// in the given language standard.
222 static KeywordStatus getKeywordStatus(const LangOptions &LangOpts,
223                                       unsigned Flags) {
224   // KEYALL means always enabled, so special case this one.
225   if (Flags == KEYALL) return KS_Enabled;
226   // These are tests that need to 'always win', as they are special in that they
227   // disable based on certain conditions.
228   if (LangOpts.OpenCL && (Flags & KEYNOOPENCL)) return KS_Disabled;
229   if (LangOpts.MSVCCompat && (Flags & KEYNOMS18) &&
230       !LangOpts.isCompatibleWithMSVC(LangOptions::MSVC2015))
231     return KS_Disabled;
232 
233   KeywordStatus CurStatus = KS_Unknown;
234 
235   while (Flags != 0) {
236     unsigned CurFlag = Flags & ~(Flags - 1);
237     Flags = Flags & ~CurFlag;
238     CurStatus = std::max(
239         CurStatus,
240         getKeywordStatusHelper(LangOpts, static_cast<TokenKey>(CurFlag)));
241   }
242 
243   if (CurStatus == KS_Unknown)
244     return KS_Disabled;
245   return CurStatus;
246 }
247 
248 /// AddKeyword - This method is used to associate a token ID with specific
249 /// identifiers because they are language keywords.  This causes the lexer to
250 /// automatically map matching identifiers to specialized token codes.
251 static void AddKeyword(StringRef Keyword,
252                        tok::TokenKind TokenCode, unsigned Flags,
253                        const LangOptions &LangOpts, IdentifierTable &Table) {
254   KeywordStatus AddResult = getKeywordStatus(LangOpts, Flags);
255 
256   // Don't add this keyword if disabled in this language.
257   if (AddResult == KS_Disabled) return;
258 
259   IdentifierInfo &Info =
260       Table.get(Keyword, AddResult == KS_Future ? tok::identifier : TokenCode);
261   Info.setIsExtensionToken(AddResult == KS_Extension);
262   Info.setIsFutureCompatKeyword(AddResult == KS_Future);
263 }
264 
265 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
266 /// representations.
267 static void AddCXXOperatorKeyword(StringRef Keyword,
268                                   tok::TokenKind TokenCode,
269                                   IdentifierTable &Table) {
270   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
271   Info.setIsCPlusPlusOperatorKeyword();
272 }
273 
274 /// AddObjCKeyword - Register an Objective-C \@keyword like "class" "selector"
275 /// or "property".
276 static void AddObjCKeyword(StringRef Name,
277                            tok::ObjCKeywordKind ObjCID,
278                            IdentifierTable &Table) {
279   Table.get(Name).setObjCKeywordID(ObjCID);
280 }
281 
282 /// AddKeywords - Add all keywords to the symbol table.
283 ///
284 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
285   // Add keywords and tokens for the current language.
286 #define KEYWORD(NAME, FLAGS) \
287   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
288              FLAGS, LangOpts, *this);
289 #define ALIAS(NAME, TOK, FLAGS) \
290   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
291              FLAGS, LangOpts, *this);
292 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
293   if (LangOpts.CXXOperatorNames)          \
294     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
295 #define OBJC_AT_KEYWORD(NAME)  \
296   if (LangOpts.ObjC)           \
297     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
298 #define TESTING_KEYWORD(NAME, FLAGS)
299 #include "clang/Basic/TokenKinds.def"
300 
301   if (LangOpts.ParseUnknownAnytype)
302     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
303                LangOpts, *this);
304 
305   if (LangOpts.DeclSpecKeyword)
306     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
307 
308   if (LangOpts.IEEE128)
309     AddKeyword("__ieee128", tok::kw___float128, KEYALL, LangOpts, *this);
310 
311   // Add the 'import' contextual keyword.
312   get("import").setModulesImport(true);
313 }
314 
315 /// Checks if the specified token kind represents a keyword in the
316 /// specified language.
317 /// \returns Status of the keyword in the language.
318 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
319                                       tok::TokenKind K) {
320   switch (K) {
321 #define KEYWORD(NAME, FLAGS) \
322   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
323 #include "clang/Basic/TokenKinds.def"
324   default: return KS_Disabled;
325   }
326 }
327 
328 /// Returns true if the identifier represents a keyword in the
329 /// specified language.
330 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) const {
331   switch (getTokenKwStatus(LangOpts, getTokenID())) {
332   case KS_Enabled:
333   case KS_Extension:
334     return true;
335   default:
336     return false;
337   }
338 }
339 
340 /// Returns true if the identifier represents a C++ keyword in the
341 /// specified language.
342 bool IdentifierInfo::isCPlusPlusKeyword(const LangOptions &LangOpts) const {
343   if (!LangOpts.CPlusPlus || !isKeyword(LangOpts))
344     return false;
345   // This is a C++ keyword if this identifier is not a keyword when checked
346   // using LangOptions without C++ support.
347   LangOptions LangOptsNoCPP = LangOpts;
348   LangOptsNoCPP.CPlusPlus = false;
349   LangOptsNoCPP.CPlusPlus11 = false;
350   LangOptsNoCPP.CPlusPlus20 = false;
351   return !isKeyword(LangOptsNoCPP);
352 }
353 
354 ReservedIdentifierStatus
355 IdentifierInfo::isReserved(const LangOptions &LangOpts) const {
356   StringRef Name = getName();
357 
358   // '_' is a reserved identifier, but its use is so common (e.g. to store
359   // ignored values) that we don't warn on it.
360   if (Name.size() <= 1)
361     return ReservedIdentifierStatus::NotReserved;
362 
363   // [lex.name] p3
364   if (Name[0] == '_') {
365 
366     // Each name that begins with an underscore followed by an uppercase letter
367     // or another underscore is reserved.
368     if (Name[1] == '_')
369       return ReservedIdentifierStatus::StartsWithDoubleUnderscore;
370 
371     if ('A' <= Name[1] && Name[1] <= 'Z')
372       return ReservedIdentifierStatus::
373           StartsWithUnderscoreFollowedByCapitalLetter;
374 
375     // This is a bit misleading: it actually means it's only reserved if we're
376     // at global scope because it starts with an underscore.
377     return ReservedIdentifierStatus::StartsWithUnderscoreAtGlobalScope;
378   }
379 
380   // Each name that contains a double underscore (__) is reserved.
381   if (LangOpts.CPlusPlus && Name.contains("__"))
382     return ReservedIdentifierStatus::ContainsDoubleUnderscore;
383 
384   return ReservedIdentifierStatus::NotReserved;
385 }
386 
387 StringRef IdentifierInfo::deuglifiedName() const {
388   StringRef Name = getName();
389   if (Name.size() >= 2 && Name.front() == '_' &&
390       (Name[1] == '_' || (Name[1] >= 'A' && Name[1] <= 'Z')))
391     return Name.ltrim('_');
392   return Name;
393 }
394 
395 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
396   // We use a perfect hash function here involving the length of the keyword,
397   // the first and third character.  For preprocessor ID's there are no
398   // collisions (if there were, the switch below would complain about duplicate
399   // case values).  Note that this depends on 'if' being null terminated.
400 
401 #define HASH(LEN, FIRST, THIRD) \
402   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
403 #define CASE(LEN, FIRST, THIRD, NAME) \
404   case HASH(LEN, FIRST, THIRD): \
405     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
406 
407   unsigned Len = getLength();
408   if (Len < 2) return tok::pp_not_keyword;
409   const char *Name = getNameStart();
410   switch (HASH(Len, Name[0], Name[2])) {
411   default: return tok::pp_not_keyword;
412   CASE( 2, 'i', '\0', if);
413   CASE( 4, 'e', 'i', elif);
414   CASE( 4, 'e', 's', else);
415   CASE( 4, 'l', 'n', line);
416   CASE( 4, 's', 'c', sccs);
417   CASE( 5, 'e', 'd', endif);
418   CASE( 5, 'e', 'r', error);
419   CASE( 5, 'i', 'e', ident);
420   CASE( 5, 'i', 'd', ifdef);
421   CASE( 5, 'u', 'd', undef);
422 
423   CASE( 6, 'a', 's', assert);
424   CASE( 6, 'd', 'f', define);
425   CASE( 6, 'i', 'n', ifndef);
426   CASE( 6, 'i', 'p', import);
427   CASE( 6, 'p', 'a', pragma);
428 
429   CASE( 7, 'd', 'f', defined);
430   CASE( 7, 'e', 'i', elifdef);
431   CASE( 7, 'i', 'c', include);
432   CASE( 7, 'w', 'r', warning);
433 
434   CASE( 8, 'e', 'i', elifndef);
435   CASE( 8, 'u', 'a', unassert);
436   CASE(12, 'i', 'c', include_next);
437 
438   CASE(14, '_', 'p', __public_macro);
439 
440   CASE(15, '_', 'p', __private_macro);
441 
442   CASE(16, '_', 'i', __include_macros);
443 #undef CASE
444 #undef HASH
445   }
446 }
447 
448 //===----------------------------------------------------------------------===//
449 // Stats Implementation
450 //===----------------------------------------------------------------------===//
451 
452 /// PrintStats - Print statistics about how well the identifier table is doing
453 /// at hashing identifiers.
454 void IdentifierTable::PrintStats() const {
455   unsigned NumBuckets = HashTable.getNumBuckets();
456   unsigned NumIdentifiers = HashTable.getNumItems();
457   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
458   unsigned AverageIdentifierSize = 0;
459   unsigned MaxIdentifierLength = 0;
460 
461   // TODO: Figure out maximum times an identifier had to probe for -stats.
462   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
463        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
464     unsigned IdLen = I->getKeyLength();
465     AverageIdentifierSize += IdLen;
466     if (MaxIdentifierLength < IdLen)
467       MaxIdentifierLength = IdLen;
468   }
469 
470   fprintf(stderr, "\n*** Identifier Table Stats:\n");
471   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
472   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
473   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
474           NumIdentifiers/(double)NumBuckets);
475   fprintf(stderr, "Ave identifier length: %f\n",
476           (AverageIdentifierSize/(double)NumIdentifiers));
477   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
478 
479   // Compute statistics about the memory allocated for identifiers.
480   HashTable.getAllocator().PrintStats();
481 }
482 
483 //===----------------------------------------------------------------------===//
484 // SelectorTable Implementation
485 //===----------------------------------------------------------------------===//
486 
487 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
488   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
489 }
490 
491 namespace clang {
492 
493 /// One of these variable length records is kept for each
494 /// selector containing more than one keyword. We use a folding set
495 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
496 /// this class is provided strictly through Selector.
497 class alignas(IdentifierInfoAlignment) MultiKeywordSelector
498     : public detail::DeclarationNameExtra,
499       public llvm::FoldingSetNode {
500   MultiKeywordSelector(unsigned nKeys) : DeclarationNameExtra(nKeys) {}
501 
502 public:
503   // Constructor for keyword selectors.
504   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV)
505       : DeclarationNameExtra(nKeys) {
506     assert((nKeys > 1) && "not a multi-keyword selector");
507 
508     // Fill in the trailing keyword array.
509     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this + 1);
510     for (unsigned i = 0; i != nKeys; ++i)
511       KeyInfo[i] = IIV[i];
512   }
513 
514   // getName - Derive the full selector name and return it.
515   std::string getName() const;
516 
517   using DeclarationNameExtra::getNumArgs;
518 
519   using keyword_iterator = IdentifierInfo *const *;
520 
521   keyword_iterator keyword_begin() const {
522     return reinterpret_cast<keyword_iterator>(this + 1);
523   }
524 
525   keyword_iterator keyword_end() const {
526     return keyword_begin() + getNumArgs();
527   }
528 
529   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
530     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
531     return keyword_begin()[i];
532   }
533 
534   static void Profile(llvm::FoldingSetNodeID &ID, keyword_iterator ArgTys,
535                       unsigned NumArgs) {
536     ID.AddInteger(NumArgs);
537     for (unsigned i = 0; i != NumArgs; ++i)
538       ID.AddPointer(ArgTys[i]);
539   }
540 
541   void Profile(llvm::FoldingSetNodeID &ID) {
542     Profile(ID, keyword_begin(), getNumArgs());
543   }
544 };
545 
546 } // namespace clang.
547 
548 bool Selector::isKeywordSelector(ArrayRef<StringRef> Names) const {
549   assert(!Names.empty() && "must have >= 1 selector slots");
550   if (getNumArgs() != Names.size())
551     return false;
552   for (unsigned I = 0, E = Names.size(); I != E; ++I) {
553     if (getNameForSlot(I) != Names[I])
554       return false;
555   }
556   return true;
557 }
558 
559 bool Selector::isUnarySelector(StringRef Name) const {
560   return isUnarySelector() && getNameForSlot(0) == Name;
561 }
562 
563 unsigned Selector::getNumArgs() const {
564   unsigned IIF = getIdentifierInfoFlag();
565   if (IIF <= ZeroArg)
566     return 0;
567   if (IIF == OneArg)
568     return 1;
569   // We point to a MultiKeywordSelector.
570   MultiKeywordSelector *SI = getMultiKeywordSelector();
571   return SI->getNumArgs();
572 }
573 
574 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
575   if (getIdentifierInfoFlag() < MultiArg) {
576     assert(argIndex == 0 && "illegal keyword index");
577     return getAsIdentifierInfo();
578   }
579 
580   // We point to a MultiKeywordSelector.
581   MultiKeywordSelector *SI = getMultiKeywordSelector();
582   return SI->getIdentifierInfoForSlot(argIndex);
583 }
584 
585 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
586   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
587   return II ? II->getName() : StringRef();
588 }
589 
590 std::string MultiKeywordSelector::getName() const {
591   SmallString<256> Str;
592   llvm::raw_svector_ostream OS(Str);
593   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
594     if (*I)
595       OS << (*I)->getName();
596     OS << ':';
597   }
598 
599   return std::string(OS.str());
600 }
601 
602 std::string Selector::getAsString() const {
603   if (InfoPtr == 0)
604     return "<null selector>";
605 
606   if (getIdentifierInfoFlag() < MultiArg) {
607     IdentifierInfo *II = getAsIdentifierInfo();
608 
609     if (getNumArgs() == 0) {
610       assert(II && "If the number of arguments is 0 then II is guaranteed to "
611                    "not be null.");
612       return std::string(II->getName());
613     }
614 
615     if (!II)
616       return ":";
617 
618     return II->getName().str() + ":";
619   }
620 
621   // We have a multiple keyword selector.
622   return getMultiKeywordSelector()->getName();
623 }
624 
625 void Selector::print(llvm::raw_ostream &OS) const {
626   OS << getAsString();
627 }
628 
629 LLVM_DUMP_METHOD void Selector::dump() const { print(llvm::errs()); }
630 
631 /// Interpreting the given string using the normal CamelCase
632 /// conventions, determine whether the given string starts with the
633 /// given "word", which is assumed to end in a lowercase letter.
634 static bool startsWithWord(StringRef name, StringRef word) {
635   if (name.size() < word.size()) return false;
636   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
637           name.startswith(word));
638 }
639 
640 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
641   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
642   if (!first) return OMF_None;
643 
644   StringRef name = first->getName();
645   if (sel.isUnarySelector()) {
646     if (name == "autorelease") return OMF_autorelease;
647     if (name == "dealloc") return OMF_dealloc;
648     if (name == "finalize") return OMF_finalize;
649     if (name == "release") return OMF_release;
650     if (name == "retain") return OMF_retain;
651     if (name == "retainCount") return OMF_retainCount;
652     if (name == "self") return OMF_self;
653     if (name == "initialize") return OMF_initialize;
654   }
655 
656   if (name == "performSelector" || name == "performSelectorInBackground" ||
657       name == "performSelectorOnMainThread")
658     return OMF_performSelector;
659 
660   // The other method families may begin with a prefix of underscores.
661   while (!name.empty() && name.front() == '_')
662     name = name.substr(1);
663 
664   if (name.empty()) return OMF_None;
665   switch (name.front()) {
666   case 'a':
667     if (startsWithWord(name, "alloc")) return OMF_alloc;
668     break;
669   case 'c':
670     if (startsWithWord(name, "copy")) return OMF_copy;
671     break;
672   case 'i':
673     if (startsWithWord(name, "init")) return OMF_init;
674     break;
675   case 'm':
676     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
677     break;
678   case 'n':
679     if (startsWithWord(name, "new")) return OMF_new;
680     break;
681   default:
682     break;
683   }
684 
685   return OMF_None;
686 }
687 
688 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
689   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
690   if (!first) return OIT_None;
691 
692   StringRef name = first->getName();
693 
694   if (name.empty()) return OIT_None;
695   switch (name.front()) {
696     case 'a':
697       if (startsWithWord(name, "array")) return OIT_Array;
698       break;
699     case 'd':
700       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
701       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
702       break;
703     case 's':
704       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
705       if (startsWithWord(name, "standard")) return OIT_Singleton;
706       break;
707     case 'i':
708       if (startsWithWord(name, "init")) return OIT_Init;
709       break;
710     default:
711       break;
712   }
713   return OIT_None;
714 }
715 
716 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
717   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
718   if (!first) return SFF_None;
719 
720   StringRef name = first->getName();
721 
722   switch (name.front()) {
723     case 'a':
724       if (name == "appendFormat") return SFF_NSString;
725       break;
726 
727     case 'i':
728       if (name == "initWithFormat") return SFF_NSString;
729       break;
730 
731     case 'l':
732       if (name == "localizedStringWithFormat") return SFF_NSString;
733       break;
734 
735     case 's':
736       if (name == "stringByAppendingFormat" ||
737           name == "stringWithFormat") return SFF_NSString;
738       break;
739   }
740   return SFF_None;
741 }
742 
743 namespace {
744 
745 struct SelectorTableImpl {
746   llvm::FoldingSet<MultiKeywordSelector> Table;
747   llvm::BumpPtrAllocator Allocator;
748 };
749 
750 } // namespace
751 
752 static SelectorTableImpl &getSelectorTableImpl(void *P) {
753   return *static_cast<SelectorTableImpl*>(P);
754 }
755 
756 SmallString<64>
757 SelectorTable::constructSetterName(StringRef Name) {
758   SmallString<64> SetterName("set");
759   SetterName += Name;
760   SetterName[3] = toUppercase(SetterName[3]);
761   return SetterName;
762 }
763 
764 Selector
765 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
766                                        SelectorTable &SelTable,
767                                        const IdentifierInfo *Name) {
768   IdentifierInfo *SetterName =
769     &Idents.get(constructSetterName(Name->getName()));
770   return SelTable.getUnarySelector(SetterName);
771 }
772 
773 std::string SelectorTable::getPropertyNameFromSetterSelector(Selector Sel) {
774   StringRef Name = Sel.getNameForSlot(0);
775   assert(Name.startswith("set") && "invalid setter name");
776   return (Twine(toLowercase(Name[3])) + Name.drop_front(4)).str();
777 }
778 
779 size_t SelectorTable::getTotalMemory() const {
780   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
781   return SelTabImpl.Allocator.getTotalMemory();
782 }
783 
784 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
785   if (nKeys < 2)
786     return Selector(IIV[0], nKeys);
787 
788   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
789 
790   // Unique selector, to guarantee there is one per name.
791   llvm::FoldingSetNodeID ID;
792   MultiKeywordSelector::Profile(ID, IIV, nKeys);
793 
794   void *InsertPos = nullptr;
795   if (MultiKeywordSelector *SI =
796         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
797     return Selector(SI);
798 
799   // MultiKeywordSelector objects are not allocated with new because they have a
800   // variable size array (for parameter types) at the end of them.
801   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
802   MultiKeywordSelector *SI =
803       (MultiKeywordSelector *)SelTabImpl.Allocator.Allocate(
804           Size, alignof(MultiKeywordSelector));
805   new (SI) MultiKeywordSelector(nKeys, IIV);
806   SelTabImpl.Table.InsertNode(SI, InsertPos);
807   return Selector(SI);
808 }
809 
810 SelectorTable::SelectorTable() {
811   Impl = new SelectorTableImpl();
812 }
813 
814 SelectorTable::~SelectorTable() {
815   delete &getSelectorTableImpl(Impl);
816 }
817 
818 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
819   switch (Operator) {
820   case OO_None:
821   case NUM_OVERLOADED_OPERATORS:
822     return nullptr;
823 
824 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
825   case OO_##Name: return Spelling;
826 #include "clang/Basic/OperatorKinds.def"
827   }
828 
829   llvm_unreachable("Invalid OverloadedOperatorKind!");
830 }
831 
832 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
833                                         bool isContextSensitive) {
834   switch (kind) {
835   case NullabilityKind::NonNull:
836     return isContextSensitive ? "nonnull" : "_Nonnull";
837 
838   case NullabilityKind::Nullable:
839     return isContextSensitive ? "nullable" : "_Nullable";
840 
841   case NullabilityKind::NullableResult:
842     assert(!isContextSensitive &&
843            "_Nullable_result isn't supported as context-sensitive keyword");
844     return "_Nullable_result";
845 
846   case NullabilityKind::Unspecified:
847     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
848   }
849   llvm_unreachable("Unknown nullability kind.");
850 }
851 
852 diag::kind
853 IdentifierTable::getFutureCompatDiagKind(const IdentifierInfo &II,
854                                          const LangOptions &LangOpts) {
855   assert(II.isFutureCompatKeyword() && "diagnostic should not be needed");
856 
857   unsigned Flags = llvm::StringSwitch<unsigned>(II.getName())
858 #define KEYWORD(NAME, FLAGS) .Case(#NAME, FLAGS)
859 #include "clang/Basic/TokenKinds.def"
860 #undef KEYWORD
861       ;
862 
863   if (LangOpts.CPlusPlus) {
864     if ((Flags & KEYCXX11) == KEYCXX11)
865       return diag::warn_cxx11_keyword;
866 
867     // char8_t is not modeled as a CXX20_KEYWORD because it's not
868     // unconditionally enabled in C++20 mode. (It can be disabled
869     // by -fno-char8_t.)
870     if (((Flags & KEYCXX20) == KEYCXX20) ||
871         ((Flags & CHAR8SUPPORT) == CHAR8SUPPORT))
872       return diag::warn_cxx20_keyword;
873   } else {
874     if ((Flags & KEYC99) == KEYC99)
875       return diag::warn_c99_keyword;
876     if ((Flags & KEYC2X) == KEYC2X)
877       return diag::warn_c2x_keyword;
878   }
879 
880   llvm_unreachable(
881       "Keyword not known to come from a newer Standard or proposed Standard");
882 }
883