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/IdentifierTable.h"
16 #include "clang/Basic/LangOptions.h"
17 #include "llvm/ADT/FoldingSet.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <cstdio>
22 
23 using namespace clang;
24 
25 //===----------------------------------------------------------------------===//
26 // IdentifierInfo Implementation
27 //===----------------------------------------------------------------------===//
28 
29 IdentifierInfo::IdentifierInfo() {
30   TokenID = tok::identifier;
31   ObjCOrBuiltinID = 0;
32   HasMacro = false;
33   IsExtension = false;
34   IsPoisoned = false;
35   IsCPPOperatorKeyword = false;
36   NeedsHandleIdentifier = false;
37   IsFromAST = false;
38   RevertedTokenID = false;
39   FETokenInfo = 0;
40   Entry = 0;
41 }
42 
43 //===----------------------------------------------------------------------===//
44 // IdentifierTable Implementation
45 //===----------------------------------------------------------------------===//
46 
47 IdentifierIterator::~IdentifierIterator() { }
48 
49 IdentifierInfoLookup::~IdentifierInfoLookup() {}
50 
51 namespace {
52   /// \brief A simple identifier lookup iterator that represents an
53   /// empty sequence of identifiers.
54   class EmptyLookupIterator : public IdentifierIterator
55   {
56   public:
57     virtual llvm::StringRef Next() { return llvm::StringRef(); }
58   };
59 }
60 
61 IdentifierIterator *IdentifierInfoLookup::getIdentifiers() const {
62   return new EmptyLookupIterator();
63 }
64 
65 ExternalIdentifierLookup::~ExternalIdentifierLookup() {}
66 
67 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
68                                  IdentifierInfoLookup* externalLookup)
69   : HashTable(8192), // Start with space for 8K identifiers.
70     ExternalLookup(externalLookup) {
71 
72   // Populate the identifier table with info about keywords for the current
73   // language.
74   AddKeywords(LangOpts);
75 }
76 
77 //===----------------------------------------------------------------------===//
78 // Language Keyword Implementation
79 //===----------------------------------------------------------------------===//
80 
81 // Constants for TokenKinds.def
82 namespace {
83   enum {
84     KEYC99 = 0x1,
85     KEYCXX = 0x2,
86     KEYCXX0X = 0x4,
87     KEYGNU = 0x8,
88     KEYMS = 0x10,
89     BOOLSUPPORT = 0x20,
90     KEYALTIVEC = 0x40,
91     KEYNOCXX = 0x80,
92     KEYBORLAND = 0x100,
93     KEYOPENCL = 0x200,
94     KEYALL = 0x3ff
95   };
96 }
97 
98 /// AddKeyword - This method is used to associate a token ID with specific
99 /// identifiers because they are language keywords.  This causes the lexer to
100 /// automatically map matching identifiers to specialized token codes.
101 ///
102 /// The C90/C99/CPP/CPP0x flags are set to 2 if the token should be
103 /// enabled in the specified langauge, set to 1 if it is an extension
104 /// in the specified language, and set to 0 if disabled in the
105 /// specified language.
106 static void AddKeyword(llvm::StringRef Keyword,
107                        tok::TokenKind TokenCode, unsigned Flags,
108                        const LangOptions &LangOpts, IdentifierTable &Table) {
109   unsigned AddResult = 0;
110   if (Flags == KEYALL) AddResult = 2;
111   else if (LangOpts.CPlusPlus && (Flags & KEYCXX)) AddResult = 2;
112   else if (LangOpts.CPlusPlus0x && (Flags & KEYCXX0X)) AddResult = 2;
113   else if (LangOpts.C99 && (Flags & KEYC99)) AddResult = 2;
114   else if (LangOpts.GNUKeywords && (Flags & KEYGNU)) AddResult = 1;
115   else if (LangOpts.Microsoft && (Flags & KEYMS)) AddResult = 1;
116   else if (LangOpts.Borland && (Flags & KEYBORLAND)) AddResult = 1;
117   else if (LangOpts.Bool && (Flags & BOOLSUPPORT)) AddResult = 2;
118   else if (LangOpts.AltiVec && (Flags & KEYALTIVEC)) AddResult = 2;
119   else if (LangOpts.OpenCL && (Flags & KEYOPENCL)) AddResult = 2;
120   else if (!LangOpts.CPlusPlus && (Flags & KEYNOCXX)) AddResult = 2;
121 
122   // Don't add this keyword if disabled in this language.
123   if (AddResult == 0) return;
124 
125   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
126   Info.setIsExtensionToken(AddResult == 1);
127 }
128 
129 /// AddCXXOperatorKeyword - Register a C++ operator keyword alternative
130 /// representations.
131 static void AddCXXOperatorKeyword(llvm::StringRef Keyword,
132                                   tok::TokenKind TokenCode,
133                                   IdentifierTable &Table) {
134   IdentifierInfo &Info = Table.get(Keyword, TokenCode);
135   Info.setIsCPlusPlusOperatorKeyword();
136 }
137 
138 /// AddObjCKeyword - Register an Objective-C @keyword like "class" "selector" or
139 /// "property".
140 static void AddObjCKeyword(llvm::StringRef Name,
141                            tok::ObjCKeywordKind ObjCID,
142                            IdentifierTable &Table) {
143   Table.get(Name).setObjCKeywordID(ObjCID);
144 }
145 
146 /// AddKeywords - Add all keywords to the symbol table.
147 ///
148 void IdentifierTable::AddKeywords(const LangOptions &LangOpts) {
149   // Add keywords and tokens for the current language.
150 #define KEYWORD(NAME, FLAGS) \
151   AddKeyword(llvm::StringRef(#NAME), tok::kw_ ## NAME,  \
152              FLAGS, LangOpts, *this);
153 #define ALIAS(NAME, TOK, FLAGS) \
154   AddKeyword(llvm::StringRef(NAME), tok::kw_ ## TOK,  \
155              FLAGS, LangOpts, *this);
156 #define CXX_KEYWORD_OPERATOR(NAME, ALIAS) \
157   if (LangOpts.CXXOperatorNames)          \
158     AddCXXOperatorKeyword(llvm::StringRef(#NAME), tok::ALIAS, *this);
159 #define OBJC1_AT_KEYWORD(NAME) \
160   if (LangOpts.ObjC1)          \
161     AddObjCKeyword(llvm::StringRef(#NAME), tok::objc_##NAME, *this);
162 #define OBJC2_AT_KEYWORD(NAME) \
163   if (LangOpts.ObjC2)          \
164     AddObjCKeyword(llvm::StringRef(#NAME), tok::objc_##NAME, *this);
165 #define TESTING_KEYWORD(NAME, FLAGS)
166 #include "clang/Basic/TokenKinds.def"
167 
168   if (LangOpts.ParseUnknownAnytype)
169     AddKeyword("__unknown_anytype", tok::kw___unknown_anytype, KEYALL,
170                LangOpts, *this);
171 }
172 
173 tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
174   // We use a perfect hash function here involving the length of the keyword,
175   // the first and third character.  For preprocessor ID's there are no
176   // collisions (if there were, the switch below would complain about duplicate
177   // case values).  Note that this depends on 'if' being null terminated.
178 
179 #define HASH(LEN, FIRST, THIRD) \
180   (LEN << 5) + (((FIRST-'a') + (THIRD-'a')) & 31)
181 #define CASE(LEN, FIRST, THIRD, NAME) \
182   case HASH(LEN, FIRST, THIRD): \
183     return memcmp(Name, #NAME, LEN) ? tok::pp_not_keyword : tok::pp_ ## NAME
184 
185   unsigned Len = getLength();
186   if (Len < 2) return tok::pp_not_keyword;
187   const char *Name = getNameStart();
188   switch (HASH(Len, Name[0], Name[2])) {
189   default: return tok::pp_not_keyword;
190   CASE( 2, 'i', '\0', if);
191   CASE( 4, 'e', 'i', elif);
192   CASE( 4, 'e', 's', else);
193   CASE( 4, 'l', 'n', line);
194   CASE( 4, 's', 'c', sccs);
195   CASE( 5, 'e', 'd', endif);
196   CASE( 5, 'e', 'r', error);
197   CASE( 5, 'i', 'e', ident);
198   CASE( 5, 'i', 'd', ifdef);
199   CASE( 5, 'u', 'd', undef);
200 
201   CASE( 6, 'a', 's', assert);
202   CASE( 6, 'd', 'f', define);
203   CASE( 6, 'i', 'n', ifndef);
204   CASE( 6, 'i', 'p', import);
205   CASE( 6, 'p', 'a', pragma);
206 
207   CASE( 7, 'd', 'f', defined);
208   CASE( 7, 'i', 'c', include);
209   CASE( 7, 'w', 'r', warning);
210 
211   CASE( 8, 'u', 'a', unassert);
212   CASE(12, 'i', 'c', include_next);
213 
214   CASE(16, '_', 'i', __include_macros);
215 #undef CASE
216 #undef HASH
217   }
218 }
219 
220 //===----------------------------------------------------------------------===//
221 // Stats Implementation
222 //===----------------------------------------------------------------------===//
223 
224 /// PrintStats - Print statistics about how well the identifier table is doing
225 /// at hashing identifiers.
226 void IdentifierTable::PrintStats() const {
227   unsigned NumBuckets = HashTable.getNumBuckets();
228   unsigned NumIdentifiers = HashTable.getNumItems();
229   unsigned NumEmptyBuckets = NumBuckets-NumIdentifiers;
230   unsigned AverageIdentifierSize = 0;
231   unsigned MaxIdentifierLength = 0;
232 
233   // TODO: Figure out maximum times an identifier had to probe for -stats.
234   for (llvm::StringMap<IdentifierInfo*, llvm::BumpPtrAllocator>::const_iterator
235        I = HashTable.begin(), E = HashTable.end(); I != E; ++I) {
236     unsigned IdLen = I->getKeyLength();
237     AverageIdentifierSize += IdLen;
238     if (MaxIdentifierLength < IdLen)
239       MaxIdentifierLength = IdLen;
240   }
241 
242   fprintf(stderr, "\n*** Identifier Table Stats:\n");
243   fprintf(stderr, "# Identifiers:   %d\n", NumIdentifiers);
244   fprintf(stderr, "# Empty Buckets: %d\n", NumEmptyBuckets);
245   fprintf(stderr, "Hash density (#identifiers per bucket): %f\n",
246           NumIdentifiers/(double)NumBuckets);
247   fprintf(stderr, "Ave identifier length: %f\n",
248           (AverageIdentifierSize/(double)NumIdentifiers));
249   fprintf(stderr, "Max identifier length: %d\n", MaxIdentifierLength);
250 
251   // Compute statistics about the memory allocated for identifiers.
252   HashTable.getAllocator().PrintStats();
253 }
254 
255 //===----------------------------------------------------------------------===//
256 // SelectorTable Implementation
257 //===----------------------------------------------------------------------===//
258 
259 unsigned llvm::DenseMapInfo<clang::Selector>::getHashValue(clang::Selector S) {
260   return DenseMapInfo<void*>::getHashValue(S.getAsOpaquePtr());
261 }
262 
263 namespace clang {
264 /// MultiKeywordSelector - One of these variable length records is kept for each
265 /// selector containing more than one keyword. We use a folding set
266 /// to unique aggregate names (keyword selectors in ObjC parlance). Access to
267 /// this class is provided strictly through Selector.
268 class MultiKeywordSelector
269   : public DeclarationNameExtra, public llvm::FoldingSetNode {
270   MultiKeywordSelector(unsigned nKeys) {
271     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
272   }
273 public:
274   // Constructor for keyword selectors.
275   MultiKeywordSelector(unsigned nKeys, IdentifierInfo **IIV) {
276     assert((nKeys > 1) && "not a multi-keyword selector");
277     ExtraKindOrNumArgs = NUM_EXTRA_KINDS + nKeys;
278 
279     // Fill in the trailing keyword array.
280     IdentifierInfo **KeyInfo = reinterpret_cast<IdentifierInfo **>(this+1);
281     for (unsigned i = 0; i != nKeys; ++i)
282       KeyInfo[i] = IIV[i];
283   }
284 
285   // getName - Derive the full selector name and return it.
286   std::string getName() const;
287 
288   unsigned getNumArgs() const { return ExtraKindOrNumArgs - NUM_EXTRA_KINDS; }
289 
290   typedef IdentifierInfo *const *keyword_iterator;
291   keyword_iterator keyword_begin() const {
292     return reinterpret_cast<keyword_iterator>(this+1);
293   }
294   keyword_iterator keyword_end() const {
295     return keyword_begin()+getNumArgs();
296   }
297   IdentifierInfo *getIdentifierInfoForSlot(unsigned i) const {
298     assert(i < getNumArgs() && "getIdentifierInfoForSlot(): illegal index");
299     return keyword_begin()[i];
300   }
301   static void Profile(llvm::FoldingSetNodeID &ID,
302                       keyword_iterator ArgTys, unsigned NumArgs) {
303     ID.AddInteger(NumArgs);
304     for (unsigned i = 0; i != NumArgs; ++i)
305       ID.AddPointer(ArgTys[i]);
306   }
307   void Profile(llvm::FoldingSetNodeID &ID) {
308     Profile(ID, keyword_begin(), getNumArgs());
309   }
310 };
311 } // end namespace clang.
312 
313 unsigned Selector::getNumArgs() const {
314   unsigned IIF = getIdentifierInfoFlag();
315   if (IIF == ZeroArg)
316     return 0;
317   if (IIF == OneArg)
318     return 1;
319   // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
320   MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
321   return SI->getNumArgs();
322 }
323 
324 IdentifierInfo *Selector::getIdentifierInfoForSlot(unsigned argIndex) const {
325   if (getIdentifierInfoFlag()) {
326     assert(argIndex == 0 && "illegal keyword index");
327     return getAsIdentifierInfo();
328   }
329   // We point to a MultiKeywordSelector (pointer doesn't contain any flags).
330   MultiKeywordSelector *SI = reinterpret_cast<MultiKeywordSelector *>(InfoPtr);
331   return SI->getIdentifierInfoForSlot(argIndex);
332 }
333 
334 llvm::StringRef Selector::getNameForSlot(unsigned int argIndex) const {
335   IdentifierInfo *II = getIdentifierInfoForSlot(argIndex);
336   return II? II->getName() : llvm::StringRef();
337 }
338 
339 std::string MultiKeywordSelector::getName() const {
340   llvm::SmallString<256> Str;
341   llvm::raw_svector_ostream OS(Str);
342   for (keyword_iterator I = keyword_begin(), E = keyword_end(); I != E; ++I) {
343     if (*I)
344       OS << (*I)->getName();
345     OS << ':';
346   }
347 
348   return OS.str();
349 }
350 
351 std::string Selector::getAsString() const {
352   if (InfoPtr == 0)
353     return "<null selector>";
354 
355   if (InfoPtr & ArgFlags) {
356     IdentifierInfo *II = getAsIdentifierInfo();
357 
358     // If the number of arguments is 0 then II is guaranteed to not be null.
359     if (getNumArgs() == 0)
360       return II->getName();
361 
362     if (!II)
363       return ":";
364 
365     return II->getName().str() + ":";
366   }
367 
368   // We have a multiple keyword selector (no embedded flags).
369   return reinterpret_cast<MultiKeywordSelector *>(InfoPtr)->getName();
370 }
371 
372 /// Interpreting the given string using the normal CamelCase
373 /// conventions, determine whether the given string starts with the
374 /// given "word", which is assumed to end in a lowercase letter.
375 static bool startsWithWord(llvm::StringRef name, llvm::StringRef word) {
376   if (name.size() < word.size()) return false;
377   return ((name.size() == word.size() ||
378            !islower(name[word.size()]))
379           && name.startswith(word));
380 }
381 
382 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
383   IdentifierInfo *first = sel.getIdentifierInfoForSlot(0);
384   if (!first) return OMF_None;
385 
386   llvm::StringRef name = first->getName();
387   if (sel.isUnarySelector()) {
388     if (name == "autorelease") return OMF_autorelease;
389     if (name == "dealloc") return OMF_dealloc;
390     if (name == "release") return OMF_release;
391     if (name == "retain") return OMF_retain;
392     if (name == "retainCount") return OMF_retainCount;
393   }
394 
395   // The other method families may begin with a prefix of underscores.
396   while (!name.empty() && name.front() == '_')
397     name = name.substr(1);
398 
399   if (name.empty()) return OMF_None;
400   switch (name.front()) {
401   case 'a':
402     if (startsWithWord(name, "alloc")) return OMF_alloc;
403     break;
404   case 'c':
405     if (startsWithWord(name, "copy")) return OMF_copy;
406     break;
407   case 'i':
408     if (startsWithWord(name, "init")) return OMF_init;
409     break;
410   case 'm':
411     if (startsWithWord(name, "mutableCopy")) return OMF_mutableCopy;
412     break;
413   case 'n':
414     if (startsWithWord(name, "new")) return OMF_new;
415     break;
416   default:
417     break;
418   }
419 
420   return OMF_None;
421 }
422 
423 namespace {
424   struct SelectorTableImpl {
425     llvm::FoldingSet<MultiKeywordSelector> Table;
426     llvm::BumpPtrAllocator Allocator;
427   };
428 } // end anonymous namespace.
429 
430 static SelectorTableImpl &getSelectorTableImpl(void *P) {
431   return *static_cast<SelectorTableImpl*>(P);
432 }
433 
434 
435 Selector SelectorTable::getSelector(unsigned nKeys, IdentifierInfo **IIV) {
436   if (nKeys < 2)
437     return Selector(IIV[0], nKeys);
438 
439   SelectorTableImpl &SelTabImpl = getSelectorTableImpl(Impl);
440 
441   // Unique selector, to guarantee there is one per name.
442   llvm::FoldingSetNodeID ID;
443   MultiKeywordSelector::Profile(ID, IIV, nKeys);
444 
445   void *InsertPos = 0;
446   if (MultiKeywordSelector *SI =
447         SelTabImpl.Table.FindNodeOrInsertPos(ID, InsertPos))
448     return Selector(SI);
449 
450   // MultiKeywordSelector objects are not allocated with new because they have a
451   // variable size array (for parameter types) at the end of them.
452   unsigned Size = sizeof(MultiKeywordSelector) + nKeys*sizeof(IdentifierInfo *);
453   MultiKeywordSelector *SI =
454     (MultiKeywordSelector*)SelTabImpl.Allocator.Allocate(Size,
455                                          llvm::alignOf<MultiKeywordSelector>());
456   new (SI) MultiKeywordSelector(nKeys, IIV);
457   SelTabImpl.Table.InsertNode(SI, InsertPos);
458   return Selector(SI);
459 }
460 
461 SelectorTable::SelectorTable() {
462   Impl = new SelectorTableImpl();
463 }
464 
465 SelectorTable::~SelectorTable() {
466   delete &getSelectorTableImpl(Impl);
467 }
468 
469 const char *clang::getOperatorSpelling(OverloadedOperatorKind Operator) {
470   switch (Operator) {
471   case OO_None:
472   case NUM_OVERLOADED_OPERATORS:
473     return 0;
474 
475 #define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
476   case OO_##Name: return Spelling;
477 #include "clang/Basic/OperatorKinds.def"
478   }
479 
480   return 0;
481 }
482 
483