1//===- IdentifierResolver.cpp - Lexical Scope Name lookup -------*- C++ -*-===//
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 IdentifierResolver class, which is used for lexical
11// scoped lookup, based on declaration names.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/IdentifierResolver.h"
16#include "clang/AST/Decl.h"
17#include "clang/Basic/LangOptions.h"
18#include "clang/Lex/ExternalPreprocessorSource.h"
19#include "clang/Lex/Preprocessor.h"
20#include "clang/Sema/Scope.h"
21
22using namespace clang;
23
24//===----------------------------------------------------------------------===//
25// IdDeclInfoMap class
26//===----------------------------------------------------------------------===//
27
28/// IdDeclInfoMap - Associates IdDeclInfos with declaration names.
29/// Allocates 'pools' (vectors of IdDeclInfos) to avoid allocating each
30/// individual IdDeclInfo to heap.
31class IdentifierResolver::IdDeclInfoMap {
32  static const unsigned int POOL_SIZE = 512;
33
34  /// We use our own linked-list implementation because it is sadly
35  /// impossible to add something to a pre-C++0x STL container without
36  /// a completely unnecessary copy.
37  struct IdDeclInfoPool {
38    IdDeclInfoPool(IdDeclInfoPool *Next) : Next(Next) {}
39
40    IdDeclInfoPool *Next;
41    IdDeclInfo Pool[POOL_SIZE];
42  };
43
44  IdDeclInfoPool *CurPool;
45  unsigned int CurIndex;
46
47public:
48  IdDeclInfoMap() : CurPool(0), CurIndex(POOL_SIZE) {}
49
50  ~IdDeclInfoMap() {
51    IdDeclInfoPool *Cur = CurPool;
52    while (IdDeclInfoPool *P = Cur) {
53      Cur = Cur->Next;
54      delete P;
55    }
56  }
57
58  /// Returns the IdDeclInfo associated to the DeclarationName.
59  /// It creates a new IdDeclInfo if one was not created before for this id.
60  IdDeclInfo &operator[](DeclarationName Name);
61};
62
63
64//===----------------------------------------------------------------------===//
65// IdDeclInfo Implementation
66//===----------------------------------------------------------------------===//
67
68/// RemoveDecl - Remove the decl from the scope chain.
69/// The decl must already be part of the decl chain.
70void IdentifierResolver::IdDeclInfo::RemoveDecl(NamedDecl *D) {
71  for (DeclsTy::iterator I = Decls.end(); I != Decls.begin(); --I) {
72    if (D == *(I-1)) {
73      Decls.erase(I-1);
74      return;
75    }
76  }
77
78  llvm_unreachable("Didn't find this decl on its identifier's chain!");
79}
80
81bool
82IdentifierResolver::IdDeclInfo::ReplaceDecl(NamedDecl *Old, NamedDecl *New) {
83  for (DeclsTy::iterator I = Decls.end(); I != Decls.begin(); --I) {
84    if (Old == *(I-1)) {
85      *(I - 1) = New;
86      return true;
87    }
88  }
89
90  return false;
91}
92
93
94//===----------------------------------------------------------------------===//
95// IdentifierResolver Implementation
96//===----------------------------------------------------------------------===//
97
98IdentifierResolver::IdentifierResolver(Preprocessor &PP)
99  : LangOpt(PP.getLangOpts()), PP(PP),
100    IdDeclInfos(new IdDeclInfoMap) {
101}
102
103IdentifierResolver::~IdentifierResolver() {
104  delete IdDeclInfos;
105}
106
107/// isDeclInScope - If 'Ctx' is a function/method, isDeclInScope returns true
108/// if 'D' is in Scope 'S', otherwise 'S' is ignored and isDeclInScope returns
109/// true if 'D' belongs to the given declaration context.
110bool IdentifierResolver::isDeclInScope(Decl *D, DeclContext *Ctx, Scope *S,
111                             bool ExplicitInstantiationOrSpecialization) const {
112  Ctx = Ctx->getRedeclContext();
113
114  if (Ctx->isFunctionOrMethod() || S->isFunctionPrototypeScope()) {
115    // Ignore the scopes associated within transparent declaration contexts.
116    while (S->getEntity() &&
117           ((DeclContext *)S->getEntity())->isTransparentContext())
118      S = S->getParent();
119
120    if (S->isDeclScope(D))
121      return true;
122    if (LangOpt.CPlusPlus) {
123      // C++ 3.3.2p3:
124      // The name declared in a catch exception-declaration is local to the
125      // handler and shall not be redeclared in the outermost block of the
126      // handler.
127      // C++ 3.3.2p4:
128      // Names declared in the for-init-statement, and in the condition of if,
129      // while, for, and switch statements are local to the if, while, for, or
130      // switch statement (including the controlled statement), and shall not be
131      // redeclared in a subsequent condition of that statement nor in the
132      // outermost block (or, for the if statement, any of the outermost blocks)
133      // of the controlled statement.
134      //
135      assert(S->getParent() && "No TUScope?");
136      if (S->getParent()->getFlags() & Scope::ControlScope) {
137        S = S->getParent();
138        if (S->isDeclScope(D))
139          return true;
140      }
141      if (S->getFlags() & Scope::FnTryCatchScope)
142        return S->getParent()->isDeclScope(D);
143    }
144    return false;
145  }
146
147  DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
148  return ExplicitInstantiationOrSpecialization
149           ? Ctx->InEnclosingNamespaceSetOf(DCtx)
150           : Ctx->Equals(DCtx);
151}
152
153/// AddDecl - Link the decl to its shadowed decl chain.
154void IdentifierResolver::AddDecl(NamedDecl *D) {
155  DeclarationName Name = D->getDeclName();
156  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
157    updatingIdentifier(*II);
158
159  void *Ptr = Name.getFETokenInfo<void>();
160
161  if (!Ptr) {
162    Name.setFETokenInfo(D);
163    return;
164  }
165
166  IdDeclInfo *IDI;
167
168  if (isDeclPtr(Ptr)) {
169    Name.setFETokenInfo(NULL);
170    IDI = &(*IdDeclInfos)[Name];
171    NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
172    IDI->AddDecl(PrevD);
173  } else
174    IDI = toIdDeclInfo(Ptr);
175
176  IDI->AddDecl(D);
177}
178
179void IdentifierResolver::InsertDeclAfter(iterator Pos, NamedDecl *D) {
180  DeclarationName Name = D->getDeclName();
181  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
182    updatingIdentifier(*II);
183
184  void *Ptr = Name.getFETokenInfo<void>();
185
186  if (!Ptr) {
187    AddDecl(D);
188    return;
189  }
190
191  if (isDeclPtr(Ptr)) {
192    // We only have a single declaration: insert before or after it,
193    // as appropriate.
194    if (Pos == iterator()) {
195      // Add the new declaration before the existing declaration.
196      NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
197      RemoveDecl(PrevD);
198      AddDecl(D);
199      AddDecl(PrevD);
200    } else {
201      // Add new declaration after the existing declaration.
202      AddDecl(D);
203    }
204
205    return;
206  }
207
208  // General case: insert the declaration at the appropriate point in the
209  // list, which already has at least two elements.
210  IdDeclInfo *IDI = toIdDeclInfo(Ptr);
211  if (Pos.isIterator()) {
212    IDI->InsertDecl(Pos.getIterator() + 1, D);
213  } else
214    IDI->InsertDecl(IDI->decls_begin(), D);
215}
216
217/// RemoveDecl - Unlink the decl from its shadowed decl chain.
218/// The decl must already be part of the decl chain.
219void IdentifierResolver::RemoveDecl(NamedDecl *D) {
220  assert(D && "null param passed");
221  DeclarationName Name = D->getDeclName();
222  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
223    updatingIdentifier(*II);
224
225  void *Ptr = Name.getFETokenInfo<void>();
226
227  assert(Ptr && "Didn't find this decl on its identifier's chain!");
228
229  if (isDeclPtr(Ptr)) {
230    assert(D == Ptr && "Didn't find this decl on its identifier's chain!");
231    Name.setFETokenInfo(NULL);
232    return;
233  }
234
235  return toIdDeclInfo(Ptr)->RemoveDecl(D);
236}
237
238bool IdentifierResolver::ReplaceDecl(NamedDecl *Old, NamedDecl *New) {
239  assert(Old->getDeclName() == New->getDeclName() &&
240         "Cannot replace a decl with another decl of a different name");
241
242  DeclarationName Name = Old->getDeclName();
243  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
244    updatingIdentifier(*II);
245
246  void *Ptr = Name.getFETokenInfo<void>();
247
248  if (!Ptr)
249    return false;
250
251  if (isDeclPtr(Ptr)) {
252    if (Ptr == Old) {
253      Name.setFETokenInfo(New);
254      return true;
255    }
256    return false;
257  }
258
259  return toIdDeclInfo(Ptr)->ReplaceDecl(Old, New);
260}
261
262/// begin - Returns an iterator for decls with name 'Name'.
263IdentifierResolver::iterator
264IdentifierResolver::begin(DeclarationName Name) {
265  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
266    readingIdentifier(*II);
267
268  void *Ptr = Name.getFETokenInfo<void>();
269  if (!Ptr) return end();
270
271  if (isDeclPtr(Ptr))
272    return iterator(static_cast<NamedDecl*>(Ptr));
273
274  IdDeclInfo *IDI = toIdDeclInfo(Ptr);
275
276  IdDeclInfo::DeclsTy::iterator I = IDI->decls_end();
277  if (I != IDI->decls_begin())
278    return iterator(I-1);
279  // No decls found.
280  return end();
281}
282
283namespace {
284  enum DeclMatchKind {
285    DMK_Different,
286    DMK_Replace,
287    DMK_Ignore
288  };
289}
290
291/// \brief Compare two declarations to see whether they are different or,
292/// if they are the same, whether the new declaration should replace the
293/// existing declaration.
294static DeclMatchKind compareDeclarations(NamedDecl *Existing, NamedDecl *New) {
295  // If the declarations are identical, ignore the new one.
296  if (Existing == New)
297    return DMK_Ignore;
298
299  // If the declarations have different kinds, they're obviously different.
300  if (Existing->getKind() != New->getKind())
301    return DMK_Different;
302
303  // If the declarations are redeclarations of each other, keep the newest one.
304  if (Existing->getCanonicalDecl() == New->getCanonicalDecl()) {
305    // If either of these is the most recent declaration, use it.
306    Decl *MostRecent = Existing->getMostRecentDecl();
307    if (Existing == MostRecent)
308      return DMK_Ignore;
309
310    if (New == MostRecent)
311      return DMK_Replace;
312
313    // If the existing declaration is somewhere in the previous declaration
314    // chain of the new declaration, then prefer the new declaration.
315    for (Decl::redecl_iterator RD = New->redecls_begin(),
316                            RDEnd = New->redecls_end();
317         RD != RDEnd; ++RD) {
318      if (*RD == Existing)
319        return DMK_Replace;
320
321      if (RD->isCanonicalDecl())
322        break;
323    }
324
325    return DMK_Ignore;
326  }
327
328  return DMK_Different;
329}
330
331bool IdentifierResolver::tryAddTopLevelDecl(NamedDecl *D, DeclarationName Name){
332  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
333    readingIdentifier(*II);
334
335  void *Ptr = Name.getFETokenInfo<void>();
336
337  if (!Ptr) {
338    Name.setFETokenInfo(D);
339    return true;
340  }
341
342  IdDeclInfo *IDI;
343
344  if (isDeclPtr(Ptr)) {
345    NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
346
347    switch (compareDeclarations(PrevD, D)) {
348    case DMK_Different:
349      break;
350
351    case DMK_Ignore:
352      return false;
353
354    case DMK_Replace:
355      Name.setFETokenInfo(D);
356      return true;
357    }
358
359    Name.setFETokenInfo(NULL);
360    IDI = &(*IdDeclInfos)[Name];
361
362    // If the existing declaration is not visible in translation unit scope,
363    // then add the new top-level declaration first.
364    if (!PrevD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
365      IDI->AddDecl(D);
366      IDI->AddDecl(PrevD);
367    } else {
368      IDI->AddDecl(PrevD);
369      IDI->AddDecl(D);
370    }
371    return true;
372  }
373
374  IDI = toIdDeclInfo(Ptr);
375
376  // See whether this declaration is identical to any existing declarations.
377  // If not, find the right place to insert it.
378  for (IdDeclInfo::DeclsTy::iterator I = IDI->decls_begin(),
379                                  IEnd = IDI->decls_end();
380       I != IEnd; ++I) {
381
382    switch (compareDeclarations(*I, D)) {
383    case DMK_Different:
384      break;
385
386    case DMK_Ignore:
387      return false;
388
389    case DMK_Replace:
390      *I = D;
391      return true;
392    }
393
394    if (!(*I)->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
395      // We've found a declaration that is not visible from the translation
396      // unit (it's in an inner scope). Insert our declaration here.
397      IDI->InsertDecl(I, D);
398      return true;
399    }
400  }
401
402  // Add the declaration to the end.
403  IDI->AddDecl(D);
404  return true;
405}
406
407void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
408  if (II.isOutOfDate())
409    PP.getExternalSource()->updateOutOfDateIdentifier(II);
410}
411
412void IdentifierResolver::updatingIdentifier(IdentifierInfo &II) {
413  if (II.isOutOfDate())
414    PP.getExternalSource()->updateOutOfDateIdentifier(II);
415
416  if (II.isFromAST())
417    II.setChangedSinceDeserialization();
418}
419
420//===----------------------------------------------------------------------===//
421// IdDeclInfoMap Implementation
422//===----------------------------------------------------------------------===//
423
424/// Returns the IdDeclInfo associated to the DeclarationName.
425/// It creates a new IdDeclInfo if one was not created before for this id.
426IdentifierResolver::IdDeclInfo &
427IdentifierResolver::IdDeclInfoMap::operator[](DeclarationName Name) {
428  void *Ptr = Name.getFETokenInfo<void>();
429
430  if (Ptr) return *toIdDeclInfo(Ptr);
431
432  if (CurIndex == POOL_SIZE) {
433    CurPool = new IdDeclInfoPool(CurPool);
434    CurIndex = 0;
435  }
436  IdDeclInfo *IDI = &CurPool->Pool[CurIndex];
437  Name.setFETokenInfo(reinterpret_cast<void*>(
438                              reinterpret_cast<uintptr_t>(IDI) | 0x1)
439                                                                     );
440  ++CurIndex;
441  return *IDI;
442}
443
444void IdentifierResolver::iterator::incrementSlowCase() {
445  NamedDecl *D = **this;
446  void *InfoPtr = D->getDeclName().getFETokenInfo<void>();
447  assert(!isDeclPtr(InfoPtr) && "Decl with wrong id ?");
448  IdDeclInfo *Info = toIdDeclInfo(InfoPtr);
449
450  BaseIter I = getIterator();
451  if (I != Info->decls_begin())
452    *this = iterator(I-1);
453  else // No more decls.
454    *this = iterator();
455}
456