xref: /llvm-project/clang/lib/Basic/IdentifierTable.cpp (revision 9fc3b4acbc920dc93f4b6eefb4e2b3f795fa9aac)
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 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 static void AddInterestingIdentifier(StringRef Name,
283                                      tok::InterestingIdentifierKind BTID,
284                                      IdentifierTable &Table) {
285   // Don't add 'not_interesting' identifier.
286   if (BTID != tok::not_interesting) {
287     IdentifierInfo &Info = Table.get(Name, tok::identifier);
288     Info.setInterestingIdentifierID(BTID);
289   }
290 }
291 
292 /// AddKeywords - Add all keywords to the symbol table.
293 ///
294 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
295   // Add keywords and tokens for the current language.
296 #define KEYWORD(NAME, FLAGS) \
297   AddKeyword(StringRef(#NAME), tok::kw_ ## NAME,  \
298              FLAGS, LangOpts, *this);
299 #define ALIAS(NAME, TOK, FLAGS) \
300   AddKeyword(StringRef(NAME), tok::kw_ ## TOK,  \
301              FLAGS, LangOpts, *this);
302 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
303   if (LangOpts.CXXOperatorNames)          \
304     AddCXXOperatorKeyword(StringRef(#NAME), tok::ALIAS, *this);
305 #define OBJC_AT_KEYWORD(NAME)  \
306   if (LangOpts.ObjC)           \
307     AddObjCKeyword(StringRef(#NAME), tok::objc_##NAME, *this);
308 #define INTERESTING_IDENTIFIER(NAME)                                           \
309   AddInterestingIdentifier(StringRef(#NAME), tok::NAME, *this);
310 
311 #define TESTING_KEYWORD(NAME, FLAGS)
312 #include "clang/Basic/TokenKinds.def"
313 
314   if (LangOpts.ParseUnknownAnytype)
315     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
316                LangOpts, *this);
317 
318   if (LangOpts.DeclSpecKeyword)
319     AddKeyword("__declspec", tok::kw___declspec, KEYALL, LangOpts, *this);
320 
321   if (LangOpts.IEEE128)
322     AddKeyword("__ieee128", tok::kw___float128, KEYALL, LangOpts, *this);
323 
324   // Add the 'import' contextual keyword.
325   get("import").setModulesImport(true);
326 }
327 
328 /// Checks if the specified token kind represents a keyword in the
329 /// specified language.
330 /// \returns Status of the keyword in the language.
331 static KeywordStatus getTokenKwStatus(const LangOptions &LangOpts,
332                                       tok::TokenKind K) {
333   switch (K) {
334 #define KEYWORD(NAME, FLAGS) \
335   case tok::kw_##NAME: return getKeywordStatus(LangOpts, FLAGS);
336 #include "clang/Basic/TokenKinds.def"
337   default: return KS_Disabled;
338   }
339 }
340 
341 /// Returns true if the identifier represents a keyword in the
342 /// specified language.
343 bool IdentifierInfo::isKeyword(const LangOptions &LangOpts) const {
344   switch (getTokenKwStatus(LangOpts, getTokenID())) {
345   case KS_Enabled:
346   case KS_Extension:
347     return true;
348   default:
349     return false;
350   }
351 }
352 
353 /// Returns true if the identifier represents a C++ keyword in the
354 /// specified language.
355 bool IdentifierInfo::isCPlusPlusKeyword(const LangOptions &LangOpts) const {
356   if (!LangOpts.CPlusPlus || !isKeyword(LangOpts))
357     return false;
358   // This is a C++ keyword if this identifier is not a keyword when checked
359   // using LangOptions without C++ support.
360   LangOptions LangOptsNoCPP = LangOpts;
361   LangOptsNoCPP.CPlusPlus = false;
362   LangOptsNoCPP.CPlusPlus11 = false;
363   LangOptsNoCPP.CPlusPlus20 = false;
364   return !isKeyword(LangOptsNoCPP);
365 }
366 
367 ReservedIdentifierStatus
368 IdentifierInfo::isReserved(const LangOptions &LangOpts) const {
369   StringRef Name = getName();
370 
371   // '_' is a reserved identifier, but its use is so common (e.g. to store
372   // ignored values) that we don't warn on it.
373   if (Name.size() <= 1)
374     return ReservedIdentifierStatus::NotReserved;
375 
376   // [lex.name] p3
377   if (Name[0] == '_') {
378 
379     // Each name that begins with an underscore followed by an uppercase letter
380     // or another underscore is reserved.
381     if (Name[1] == '_')
382       return ReservedIdentifierStatus::StartsWithDoubleUnderscore;
383 
384     if ('A' <= Name[1] && Name[1] <= 'Z')
385       return ReservedIdentifierStatus::
386           StartsWithUnderscoreFollowedByCapitalLetter;
387 
388     // This is a bit misleading: it actually means it's only reserved if we're
389     // at global scope because it starts with an underscore.
390     return ReservedIdentifierStatus::StartsWithUnderscoreAtGlobalScope;
391   }
392 
393   // Each name that contains a double underscore (__) is reserved.
394   if (LangOpts.CPlusPlus && Name.contains("__"))
395     return ReservedIdentifierStatus::ContainsDoubleUnderscore;
396 
397   return ReservedIdentifierStatus::NotReserved;
398 }
399 
400 StringRef IdentifierInfo::deuglifiedName() const {
401   StringRef Name = getName();
402   if (Name.size() >= 2 && Name.front() == '_' &&
403       (Name[1] == '_' || (Name[1] >= 'A' && Name[1] <= 'Z')))
404     return Name.ltrim('_');
405   return Name;
406 }
407 
408 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
409   // We use a perfect hash function here involving the length of the keyword,
410   // the first and third character.  For preprocessor ID's there are no
411   // collisions (if there were, the switch below would complain about duplicate
412   // case values).  Note that this depends on 'if' being null terminated.
413 
414 #define HASH(LEN, FIRST, THIRD) \
415   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
416 #define CASE(LEN, FIRST, THIRD, NAME) \
417   case HASH(LEN, FIRST, THIRD): \
418     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
419 
420   unsigned Len = getLength();
421   if (Len < 2) return tok::pp_not_keyword;
422   const char *Name = getNameStart();
423   switch (HASH(Len, Name[0], Name[2])) {
424   default: return tok::pp_not_keyword;
425   CASE( 2, 'i', '\0', if);
426   CASE( 4, 'e', 'i', elif);
427   CASE( 4, 'e', 's', else);
428   CASE( 4, 'l', 'n', line);
429   CASE( 4, 's', 'c', sccs);
430   CASE( 5, 'e', 'd', endif);
431   CASE( 5, 'e', 'r', error);
432   CASE( 5, 'i', 'e', ident);
433   CASE( 5, 'i', 'd', ifdef);
434   CASE( 5, 'u', 'd', undef);
435 
436   CASE( 6, 'a', 's', assert);
437   CASE( 6, 'd', 'f', define);
438   CASE( 6, 'i', 'n', ifndef);
439   CASE( 6, 'i', 'p', import);
440   CASE( 6, 'p', 'a', pragma);
441 
442   CASE( 7, 'd', 'f', defined);
443   CASE( 7, 'e', 'i', elifdef);
444   CASE( 7, 'i', 'c', include);
445   CASE( 7, 'w', 'r', warning);
446 
447   CASE( 8, 'e', 'i', elifndef);
448   CASE( 8, 'u', 'a', unassert);
449   CASE(12, 'i', 'c', include_next);
450 
451   CASE(14, '_', 'p', __public_macro);
452 
453   CASE(15, '_', 'p', __private_macro);
454 
455   CASE(16, '_', 'i', __include_macros);
456 #undef CASE
457 #undef HASH
458   }
459 }
460 
461 //===----------------------------------------------------------------------===//
462 // Stats Implementation
463 //===----------------------------------------------------------------------===//
464 
465 /// PrintStats - Print statistics about how well the identifier table is doing
466 /// at hashing identifiers.
467 void IdentifierTable::PrintStats() const {
468   unsigned NumBuckets = HashTable.getNumBuckets();
469   unsigned NumIdentifiers = HashTable.getNumItems();
470   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
471   unsigned AverageIdentifierSize = 0;
472   unsigned MaxIdentifierLength = 0;
473 
474   // TODO: Figure out maximum times an identifier had to probe for -stats.
475   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
476        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
477     unsigned IdLen = I->getKeyLength();
478     AverageIdentifierSize += IdLen;
479     if (MaxIdentifierLength < IdLen)
480       MaxIdentifierLength = IdLen;
481   }
482 
483   fprintf(stderr, "\n*** Identifier Table Stats:\n");
484   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
485   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
486   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
487           NumIdentifiers/(double)NumBuckets);
488   fprintf(stderr, "Ave identifier length: %f\n",
489           (AverageIdentifierSize/(double)NumIdentifiers));
490   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
491 
492   // Compute statistics about the memory allocated for identifiers.
493   HashTable.getAllocator().PrintStats();
494 }
495 
496 //===----------------------------------------------------------------------===//
497 // SelectorTable Implementation
498 //===----------------------------------------------------------------------===//
499 
500 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
501   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
502 }
503 
504 namespace clang {
505 
506 /// One of these variable length records is kept for each
507 /// selector containing more than one keyword. We use a folding set
508 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
509 /// this class is provided strictly through Selector.
510 class alignas(IdentifierInfoAlignment) MultiKeywordSelector
511     : public detail::DeclarationNameExtra,
512       public llvm::FoldingSetNode {
513   MultiKeywordSelector(unsigned nKeys) : DeclarationNameExtra(nKeys) {}
514 
515 public:
516   // Constructor for keyword selectors.
517   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV)
518       : DeclarationNameExtra(nKeys) {
519     assert((nKeys > 1) && "not a multi-keyword selector");
520 
521     // Fill in the trailing keyword array.
522     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this + 1);
523     for (unsigned i = 0; i != nKeys; ++i)
524       KeyInfo[i] = IIV[i];
525   }
526 
527   // getName - Derive the full selector name and return it.
528   std::string getName() const;
529 
530   using DeclarationNameExtra::getNumArgs;
531 
532   using keyword_iterator = IdentifierInfo *const *;
533 
534   keyword_iterator keyword_begin() const {
535     return reinterpret_cast<keyword_iterator>(this + 1);
536   }
537 
538   keyword_iterator keyword_end() const {
539     return keyword_begin() + getNumArgs();
540   }
541 
542   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
543     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
544     return keyword_begin()[i];
545   }
546 
547   static void Profile(llvm::FoldingSetNodeID &ID, keyword_iterator ArgTys,
548                       unsigned NumArgs) {
549     ID.AddInteger(NumArgs);
550     for (unsigned i = 0; i != NumArgs; ++i)
551       ID.AddPointer(ArgTys[i]);
552   }
553 
554   void Profile(llvm::FoldingSetNodeID &ID) {
555     Profile(ID, keyword_begin(), getNumArgs());
556   }
557 };
558 
559 } // namespace clang.
560 
561 bool Selector::isKeywordSelector(ArrayRef<StringRef> Names) const {
562   assert(!Names.empty() && "must have >= 1 selector slots");
563   if (getNumArgs() != Names.size())
564     return false;
565   for (unsigned I = 0, E = Names.size(); I != E; ++I) {
566     if (getNameForSlot(I) != Names[I])
567       return false;
568   }
569   return true;
570 }
571 
572 bool Selector::isUnarySelector(StringRef Name) const {
573   return isUnarySelector() && getNameForSlot(0) == Name;
574 }
575 
576 unsigned Selector::getNumArgs() const {
577   unsigned IIF = getIdentifierInfoFlag();
578   if (IIF <= ZeroArg)
579     return 0;
580   if (IIF == OneArg)
581     return 1;
582   // We point to a MultiKeywordSelector.
583   MultiKeywordSelector *SI = getMultiKeywordSelector();
584   return SI->getNumArgs();
585 }
586 
587 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
588   if (getIdentifierInfoFlag() < MultiArg) {
589     assert(argIndex == 0 && "illegal keyword index");
590     return getAsIdentifierInfo();
591   }
592 
593   // We point to a MultiKeywordSelector.
594   MultiKeywordSelector *SI = getMultiKeywordSelector();
595   return SI->getIdentifierInfoForSlot(argIndex);
596 }
597 
598 StringRef Selector::getNameForSlot(unsigned int argIndex) const {
599   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
600   return II ? II->getName() : StringRef();
601 }
602 
603 std::string MultiKeywordSelector::getName() const {
604   SmallString<256> Str;
605   llvm::raw_svector_ostream OS(Str);
606   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
607     if (*I)
608       OS << (*I)->getName();
609     OS << ':';
610   }
611 
612   return std::string(OS.str());
613 }
614 
615 std::string Selector::getAsString() const {
616   if (InfoPtr == 0)
617     return "<null selector>";
618 
619   if (getIdentifierInfoFlag() < MultiArg) {
620     IdentifierInfo *II = getAsIdentifierInfo();
621 
622     if (getNumArgs() == 0) {
623       assert(II && "If the number of arguments is 0 then II is guaranteed to "
624                    "not be null.");
625       return std::string(II->getName());
626     }
627 
628     if (!II)
629       return ":";
630 
631     return II->getName().str() + ":";
632   }
633 
634   // We have a multiple keyword selector.
635   return getMultiKeywordSelector()->getName();
636 }
637 
638 void Selector::print(llvm::raw_ostream &OS) const {
639   OS << getAsString();
640 }
641 
642 LLVM_DUMP_METHOD void Selector::dump() const { print(llvm::errs()); }
643 
644 /// Interpreting the given string using the normal CamelCase
645 /// conventions, determine whether the given string starts with the
646 /// given "word", which is assumed to end in a lowercase letter.
647 static bool startsWithWord(StringRef name, StringRef word) {
648   if (name.size() < word.size()) return false;
649   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
650           name.startswith(word));
651 }
652 
653 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
654   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
655   if (!first) return OMF_None;
656 
657   StringRef name = first->getName();
658   if (sel.isUnarySelector()) {
659     if (name == "autorelease") return OMF_autorelease;
660     if (name == "dealloc") return OMF_dealloc;
661     if (name == "finalize") return OMF_finalize;
662     if (name == "release") return OMF_release;
663     if (name == "retain") return OMF_retain;
664     if (name == "retainCount") return OMF_retainCount;
665     if (name == "self") return OMF_self;
666     if (name == "initialize") return OMF_initialize;
667   }
668 
669   if (name == "performSelector" || name == "performSelectorInBackground" ||
670       name == "performSelectorOnMainThread")
671     return OMF_performSelector;
672 
673   // The other method families may begin with a prefix of underscores.
674   while (!name.empty() && name.front() == '_')
675     name = name.substr(1);
676 
677   if (name.empty()) return OMF_None;
678   switch (name.front()) {
679   case 'a':
680     if (startsWithWord(name, "alloc")) return OMF_alloc;
681     break;
682   case 'c':
683     if (startsWithWord(name, "copy")) return OMF_copy;
684     break;
685   case 'i':
686     if (startsWithWord(name, "init")) return OMF_init;
687     break;
688   case 'm':
689     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
690     break;
691   case 'n':
692     if (startsWithWord(name, "new")) return OMF_new;
693     break;
694   default:
695     break;
696   }
697 
698   return OMF_None;
699 }
700 
701 ObjCInstanceTypeFamily Selector::getInstTypeMethodFamily(Selector sel) {
702   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
703   if (!first) return OIT_None;
704 
705   StringRef name = first->getName();
706 
707   if (name.empty()) return OIT_None;
708   switch (name.front()) {
709     case 'a':
710       if (startsWithWord(name, "array")) return OIT_Array;
711       break;
712     case 'd':
713       if (startsWithWord(name, "default")) return OIT_ReturnsSelf;
714       if (startsWithWord(name, "dictionary")) return OIT_Dictionary;
715       break;
716     case 's':
717       if (startsWithWord(name, "shared")) return OIT_ReturnsSelf;
718       if (startsWithWord(name, "standard")) return OIT_Singleton;
719       break;
720     case 'i':
721       if (startsWithWord(name, "init")) return OIT_Init;
722       break;
723     default:
724       break;
725   }
726   return OIT_None;
727 }
728 
729 ObjCStringFormatFamily Selector::getStringFormatFamilyImpl(Selector sel) {
730   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
731   if (!first) return SFF_None;
732 
733   StringRef name = first->getName();
734 
735   switch (name.front()) {
736     case 'a':
737       if (name == "appendFormat") return SFF_NSString;
738       break;
739 
740     case 'i':
741       if (name == "initWithFormat") return SFF_NSString;
742       break;
743 
744     case 'l':
745       if (name == "localizedStringWithFormat") return SFF_NSString;
746       break;
747 
748     case 's':
749       if (name == "stringByAppendingFormat" ||
750           name == "stringWithFormat") return SFF_NSString;
751       break;
752   }
753   return SFF_None;
754 }
755 
756 namespace {
757 
758 struct SelectorTableImpl {
759   llvm::FoldingSet<MultiKeywordSelector> Table;
760   llvm::BumpPtrAllocator Allocator;
761 };
762 
763 } // namespace
764 
765 static SelectorTableImpl &getSelectorTableImpl(void *P) {
766   return *static_cast<SelectorTableImpl*>(P);
767 }
768 
769 SmallString<64>
770 SelectorTable::constructSetterName(StringRef Name) {
771   SmallString<64> SetterName("set");
772   SetterName += Name;
773   SetterName[3] = toUppercase(SetterName[3]);
774   return SetterName;
775 }
776 
777 Selector
778 SelectorTable::constructSetterSelector(IdentifierTable &Idents,
779                                        SelectorTable &SelTable,
780                                        const IdentifierInfo *Name) {
781   IdentifierInfo *SetterName =
782     &Idents.get(constructSetterName(Name->getName()));
783   return SelTable.getUnarySelector(SetterName);
784 }
785 
786 std::string SelectorTable::getPropertyNameFromSetterSelector(Selector Sel) {
787   StringRef Name = Sel.getNameForSlot(0);
788   assert(Name.startswith("set") && "invalid setter name");
789   return (Twine(toLowercase(Name[3])) + Name.drop_front(4)).str();
790 }
791 
792 size_t SelectorTable::getTotalMemory() const {
793   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
794   return SelTabImpl.Allocator.getTotalMemory();
795 }
796 
797 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
798   if (nKeys < 2)
799     return Selector(IIV[0], nKeys);
800 
801   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
802 
803   // Unique selector, to guarantee there is one per name.
804   llvm::FoldingSetNodeID ID;
805   MultiKeywordSelector::Profile(ID, IIV, nKeys);
806 
807   void *InsertPos = nullptr;
808   if (MultiKeywordSelector *SI =
809         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
810     return Selector(SI);
811 
812   // MultiKeywordSelector objects are not allocated with new because they have a
813   // variable size array (for parameter types) at the end of them.
814   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
815   MultiKeywordSelector *SI =
816       (MultiKeywordSelector *)SelTabImpl.Allocator.Allocate(
817           Size, alignof(MultiKeywordSelector));
818   new (SI) MultiKeywordSelector(nKeys, IIV);
819   SelTabImpl.Table.InsertNode(SI, InsertPos);
820   return Selector(SI);
821 }
822 
823 SelectorTable::SelectorTable() {
824   Impl = new SelectorTableImpl();
825 }
826 
827 SelectorTable::~SelectorTable() {
828   delete &getSelectorTableImpl(Impl);
829 }
830 
831 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
832   switch (Operator) {
833   case OO_None:
834   case NUM_OVERLOADED_OPERATORS:
835     return nullptr;
836 
837 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
838   case OO_##Name: return Spelling;
839 #include "clang/Basic/OperatorKinds.def"
840   }
841 
842   llvm_unreachable("Invalid OverloadedOperatorKind!");
843 }
844 
845 StringRef clang::getNullabilitySpelling(NullabilityKind kind,
846                                         bool isContextSensitive) {
847   switch (kind) {
848   case NullabilityKind::NonNull:
849     return isContextSensitive ? "nonnull" : "_Nonnull";
850 
851   case NullabilityKind::Nullable:
852     return isContextSensitive ? "nullable" : "_Nullable";
853 
854   case NullabilityKind::NullableResult:
855     assert(!isContextSensitive &&
856            "_Nullable_result isn't supported as context-sensitive keyword");
857     return "_Nullable_result";
858 
859   case NullabilityKind::Unspecified:
860     return isContextSensitive ? "null_unspecified" : "_Null_unspecified";
861   }
862   llvm_unreachable("Unknown nullability kind.");
863 }
864 
865 llvm::raw_ostream &clang::operator<<(llvm::raw_ostream &OS,
866                                      NullabilityKind NK) {
867   switch (NK) {
868   case NullabilityKind::NonNull:
869     return OS << "NonNull";
870   case NullabilityKind::Nullable:
871     return OS << "Nullable";
872   case NullabilityKind::NullableResult:
873     return OS << "NullableResult";
874   case NullabilityKind::Unspecified:
875     return OS << "Unspecified";
876   }
877   llvm_unreachable("Unknown nullability kind.");
878 }
879 
880 diag::kind
881 IdentifierTable::getFutureCompatDiagKind(const IdentifierInfo &II,
882                                          const LangOptions &LangOpts) {
883   assert(II.isFutureCompatKeyword() && "diagnostic should not be needed");
884 
885   unsigned Flags = llvm::StringSwitch<unsigned>(II.getName())
886 #define KEYWORD(NAME, FLAGS) .Case(#NAME, FLAGS)
887 #include "clang/Basic/TokenKinds.def"
888 #undef KEYWORD
889       ;
890 
891   if (LangOpts.CPlusPlus) {
892     if ((Flags & KEYCXX11) == KEYCXX11)
893       return diag::warn_cxx11_keyword;
894 
895     // char8_t is not modeled as a CXX20_KEYWORD because it's not
896     // unconditionally enabled in C++20 mode. (It can be disabled
897     // by -fno-char8_t.)
898     if (((Flags & KEYCXX20) == KEYCXX20) ||
899         ((Flags & CHAR8SUPPORT) == CHAR8SUPPORT))
900       return diag::warn_cxx20_keyword;
901   } else {
902     if ((Flags & KEYC99) == KEYC99)
903       return diag::warn_c99_keyword;
904     if ((Flags & KEYC2X) == KEYC2X)
905       return diag::warn_c2x_keyword;
906   }
907 
908   llvm_unreachable(
909       "Keyword not known to come from a newer Standard or proposed Standard");
910 }
911