1 //===--- NestedNameSpecifier.cpp - C++ nested name specifiers -----*- 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 defines the NestedNameSpecifier class, which represents
11 //  a C++ nested-name-specifier.
12 //
13 //===----------------------------------------------------------------------===//
14 #include "clang/AST/NestedNameSpecifier.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/PrettyPrinter.h"
19 #include "clang/AST/Type.h"
20 #include "clang/AST/TypeLoc.h"
21 #include "llvm/Support/AlignOf.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include <cassert>
24 
25 using namespace clang;
26 
27 NestedNameSpecifier *
28 NestedNameSpecifier::FindOrInsert(const ASTContext &Context,
29                                   const NestedNameSpecifier &Mockup) {
30   llvm::FoldingSetNodeID ID;
31   Mockup.Profile(ID);
32 
33   void *InsertPos = nullptr;
34   NestedNameSpecifier *NNS
35     = Context.NestedNameSpecifiers.FindNodeOrInsertPos(ID, InsertPos);
36   if (!NNS) {
37     NNS = new (Context, llvm::alignOf<NestedNameSpecifier>())
38         NestedNameSpecifier(Mockup);
39     Context.NestedNameSpecifiers.InsertNode(NNS, InsertPos);
40   }
41 
42   return NNS;
43 }
44 
45 NestedNameSpecifier *
46 NestedNameSpecifier::Create(const ASTContext &Context,
47                             NestedNameSpecifier *Prefix, IdentifierInfo *II) {
48   assert(II && "Identifier cannot be NULL");
49   assert((!Prefix || Prefix->isDependent()) && "Prefix must be dependent");
50 
51   NestedNameSpecifier Mockup;
52   Mockup.Prefix.setPointer(Prefix);
53   Mockup.Prefix.setInt(StoredIdentifier);
54   Mockup.Specifier = II;
55   return FindOrInsert(Context, Mockup);
56 }
57 
58 NestedNameSpecifier *
59 NestedNameSpecifier::Create(const ASTContext &Context,
60                             NestedNameSpecifier *Prefix,
61                             const NamespaceDecl *NS) {
62   assert(NS && "Namespace cannot be NULL");
63   assert((!Prefix ||
64           (Prefix->getAsType() == nullptr &&
65            Prefix->getAsIdentifier() == nullptr)) &&
66          "Broken nested name specifier");
67   NestedNameSpecifier Mockup;
68   Mockup.Prefix.setPointer(Prefix);
69   Mockup.Prefix.setInt(StoredNamespaceOrAlias);
70   Mockup.Specifier = const_cast<NamespaceDecl *>(NS);
71   return FindOrInsert(Context, Mockup);
72 }
73 
74 NestedNameSpecifier *
75 NestedNameSpecifier::Create(const ASTContext &Context,
76                             NestedNameSpecifier *Prefix,
77                             NamespaceAliasDecl *Alias) {
78   assert(Alias && "Namespace alias cannot be NULL");
79   assert((!Prefix ||
80           (Prefix->getAsType() == nullptr &&
81            Prefix->getAsIdentifier() == nullptr)) &&
82          "Broken nested name specifier");
83   NestedNameSpecifier Mockup;
84   Mockup.Prefix.setPointer(Prefix);
85   Mockup.Prefix.setInt(StoredNamespaceOrAlias);
86   Mockup.Specifier = Alias;
87   return FindOrInsert(Context, Mockup);
88 }
89 
90 NestedNameSpecifier *
91 NestedNameSpecifier::Create(const ASTContext &Context,
92                             NestedNameSpecifier *Prefix,
93                             bool Template, const Type *T) {
94   assert(T && "Type cannot be NULL");
95   NestedNameSpecifier Mockup;
96   Mockup.Prefix.setPointer(Prefix);
97   Mockup.Prefix.setInt(Template? StoredTypeSpecWithTemplate : StoredTypeSpec);
98   Mockup.Specifier = const_cast<Type*>(T);
99   return FindOrInsert(Context, Mockup);
100 }
101 
102 NestedNameSpecifier *
103 NestedNameSpecifier::Create(const ASTContext &Context, IdentifierInfo *II) {
104   assert(II && "Identifier cannot be NULL");
105   NestedNameSpecifier Mockup;
106   Mockup.Prefix.setPointer(nullptr);
107   Mockup.Prefix.setInt(StoredIdentifier);
108   Mockup.Specifier = II;
109   return FindOrInsert(Context, Mockup);
110 }
111 
112 NestedNameSpecifier *
113 NestedNameSpecifier::GlobalSpecifier(const ASTContext &Context) {
114   if (!Context.GlobalNestedNameSpecifier)
115     Context.GlobalNestedNameSpecifier =
116         new (Context, llvm::alignOf<NestedNameSpecifier>())
117             NestedNameSpecifier();
118   return Context.GlobalNestedNameSpecifier;
119 }
120 
121 NestedNameSpecifier::SpecifierKind NestedNameSpecifier::getKind() const {
122   if (!Specifier)
123     return Global;
124 
125   switch (Prefix.getInt()) {
126   case StoredIdentifier:
127     return Identifier;
128 
129   case StoredNamespaceOrAlias:
130     return isa<NamespaceDecl>(static_cast<NamedDecl *>(Specifier))? Namespace
131                                                             : NamespaceAlias;
132 
133   case StoredTypeSpec:
134     return TypeSpec;
135 
136   case StoredTypeSpecWithTemplate:
137     return TypeSpecWithTemplate;
138   }
139 
140   llvm_unreachable("Invalid NNS Kind!");
141 }
142 
143 /// \brief Retrieve the namespace stored in this nested name
144 /// specifier.
145 NamespaceDecl *NestedNameSpecifier::getAsNamespace() const {
146   if (Prefix.getInt() == StoredNamespaceOrAlias)
147     return dyn_cast<NamespaceDecl>(static_cast<NamedDecl *>(Specifier));
148 
149   return nullptr;
150 }
151 
152 /// \brief Retrieve the namespace alias stored in this nested name
153 /// specifier.
154 NamespaceAliasDecl *NestedNameSpecifier::getAsNamespaceAlias() const {
155   if (Prefix.getInt() == StoredNamespaceOrAlias)
156     return dyn_cast<NamespaceAliasDecl>(static_cast<NamedDecl *>(Specifier));
157 
158   return nullptr;
159 }
160 
161 
162 /// \brief Whether this nested name specifier refers to a dependent
163 /// type or not.
164 bool NestedNameSpecifier::isDependent() const {
165   switch (getKind()) {
166   case Identifier:
167     // Identifier specifiers always represent dependent types
168     return true;
169 
170   case Namespace:
171   case NamespaceAlias:
172   case Global:
173     return false;
174 
175   case TypeSpec:
176   case TypeSpecWithTemplate:
177     return getAsType()->isDependentType();
178   }
179 
180   llvm_unreachable("Invalid NNS Kind!");
181 }
182 
183 /// \brief Whether this nested name specifier refers to a dependent
184 /// type or not.
185 bool NestedNameSpecifier::isInstantiationDependent() const {
186   switch (getKind()) {
187   case Identifier:
188     // Identifier specifiers always represent dependent types
189     return true;
190 
191   case Namespace:
192   case NamespaceAlias:
193   case Global:
194     return false;
195 
196   case TypeSpec:
197   case TypeSpecWithTemplate:
198     return getAsType()->isInstantiationDependentType();
199   }
200 
201   llvm_unreachable("Invalid NNS Kind!");
202 }
203 
204 bool NestedNameSpecifier::containsUnexpandedParameterPack() const {
205   switch (getKind()) {
206   case Identifier:
207     return getPrefix() && getPrefix()->containsUnexpandedParameterPack();
208 
209   case Namespace:
210   case NamespaceAlias:
211   case Global:
212     return false;
213 
214   case TypeSpec:
215   case TypeSpecWithTemplate:
216     return getAsType()->containsUnexpandedParameterPack();
217   }
218 
219   llvm_unreachable("Invalid NNS Kind!");
220 }
221 
222 /// \brief Print this nested name specifier to the given output
223 /// stream.
224 void
225 NestedNameSpecifier::print(raw_ostream &OS,
226                            const PrintingPolicy &Policy) const {
227   if (getPrefix())
228     getPrefix()->print(OS, Policy);
229 
230   switch (getKind()) {
231   case Identifier:
232     OS << getAsIdentifier()->getName();
233     break;
234 
235   case Namespace:
236     if (getAsNamespace()->isAnonymousNamespace())
237       return;
238 
239     OS << getAsNamespace()->getName();
240     break;
241 
242   case NamespaceAlias:
243     OS << getAsNamespaceAlias()->getName();
244     break;
245 
246   case Global:
247     break;
248 
249   case TypeSpecWithTemplate:
250     OS << "template ";
251     // Fall through to print the type.
252 
253   case TypeSpec: {
254     const Type *T = getAsType();
255 
256     PrintingPolicy InnerPolicy(Policy);
257     InnerPolicy.SuppressScope = true;
258 
259     // Nested-name-specifiers are intended to contain minimally-qualified
260     // types. An actual ElaboratedType will not occur, since we'll store
261     // just the type that is referred to in the nested-name-specifier (e.g.,
262     // a TypedefType, TagType, etc.). However, when we are dealing with
263     // dependent template-id types (e.g., Outer<T>::template Inner<U>),
264     // the type requires its own nested-name-specifier for uniqueness, so we
265     // suppress that nested-name-specifier during printing.
266     assert(!isa<ElaboratedType>(T) &&
267            "Elaborated type in nested-name-specifier");
268     if (const TemplateSpecializationType *SpecType
269           = dyn_cast<TemplateSpecializationType>(T)) {
270       // Print the template name without its corresponding
271       // nested-name-specifier.
272       SpecType->getTemplateName().print(OS, InnerPolicy, true);
273 
274       // Print the template argument list.
275       TemplateSpecializationType::PrintTemplateArgumentList(
276           OS, SpecType->getArgs(), SpecType->getNumArgs(), InnerPolicy);
277     } else {
278       // Print the type normally
279       QualType(T, 0).print(OS, InnerPolicy);
280     }
281     break;
282   }
283   }
284 
285   OS << "::";
286 }
287 
288 void NestedNameSpecifier::dump(const LangOptions &LO) {
289   print(llvm::errs(), PrintingPolicy(LO));
290 }
291 
292 unsigned
293 NestedNameSpecifierLoc::getLocalDataLength(NestedNameSpecifier *Qualifier) {
294   assert(Qualifier && "Expected a non-NULL qualifier");
295 
296   // Location of the trailing '::'.
297   unsigned Length = sizeof(unsigned);
298 
299   switch (Qualifier->getKind()) {
300   case NestedNameSpecifier::Global:
301     // Nothing more to add.
302     break;
303 
304   case NestedNameSpecifier::Identifier:
305   case NestedNameSpecifier::Namespace:
306   case NestedNameSpecifier::NamespaceAlias:
307     // The location of the identifier or namespace name.
308     Length += sizeof(unsigned);
309     break;
310 
311   case NestedNameSpecifier::TypeSpecWithTemplate:
312   case NestedNameSpecifier::TypeSpec:
313     // The "void*" that points at the TypeLoc data.
314     // Note: the 'template' keyword is part of the TypeLoc.
315     Length += sizeof(void *);
316     break;
317   }
318 
319   return Length;
320 }
321 
322 unsigned
323 NestedNameSpecifierLoc::getDataLength(NestedNameSpecifier *Qualifier) {
324   unsigned Length = 0;
325   for (; Qualifier; Qualifier = Qualifier->getPrefix())
326     Length += getLocalDataLength(Qualifier);
327   return Length;
328 }
329 
330 namespace {
331   /// \brief Load a (possibly unaligned) source location from a given address
332   /// and offset.
333   SourceLocation LoadSourceLocation(void *Data, unsigned Offset) {
334     unsigned Raw;
335     memcpy(&Raw, static_cast<char *>(Data) + Offset, sizeof(unsigned));
336     return SourceLocation::getFromRawEncoding(Raw);
337   }
338 
339   /// \brief Load a (possibly unaligned) pointer from a given address and
340   /// offset.
341   void *LoadPointer(void *Data, unsigned Offset) {
342     void *Result;
343     memcpy(&Result, static_cast<char *>(Data) + Offset, sizeof(void*));
344     return Result;
345   }
346 }
347 
348 SourceRange NestedNameSpecifierLoc::getSourceRange() const {
349   if (!Qualifier)
350     return SourceRange();
351 
352   NestedNameSpecifierLoc First = *this;
353   while (NestedNameSpecifierLoc Prefix = First.getPrefix())
354     First = Prefix;
355 
356   return SourceRange(First.getLocalSourceRange().getBegin(),
357                      getLocalSourceRange().getEnd());
358 }
359 
360 SourceRange NestedNameSpecifierLoc::getLocalSourceRange() const {
361   if (!Qualifier)
362     return SourceRange();
363 
364   unsigned Offset = getDataLength(Qualifier->getPrefix());
365   switch (Qualifier->getKind()) {
366   case NestedNameSpecifier::Global:
367     return LoadSourceLocation(Data, Offset);
368 
369   case NestedNameSpecifier::Identifier:
370   case NestedNameSpecifier::Namespace:
371   case NestedNameSpecifier::NamespaceAlias:
372     return SourceRange(LoadSourceLocation(Data, Offset),
373                        LoadSourceLocation(Data, Offset + sizeof(unsigned)));
374 
375   case NestedNameSpecifier::TypeSpecWithTemplate:
376   case NestedNameSpecifier::TypeSpec: {
377     // The "void*" that points at the TypeLoc data.
378     // Note: the 'template' keyword is part of the TypeLoc.
379     void *TypeData = LoadPointer(Data, Offset);
380     TypeLoc TL(Qualifier->getAsType(), TypeData);
381     return SourceRange(TL.getBeginLoc(),
382                        LoadSourceLocation(Data, Offset + sizeof(void*)));
383   }
384   }
385 
386   llvm_unreachable("Invalid NNS Kind!");
387 }
388 
389 TypeLoc NestedNameSpecifierLoc::getTypeLoc() const {
390   assert((Qualifier->getKind() == NestedNameSpecifier::TypeSpec ||
391           Qualifier->getKind() == NestedNameSpecifier::TypeSpecWithTemplate) &&
392          "Nested-name-specifier location is not a type");
393 
394   // The "void*" that points at the TypeLoc data.
395   unsigned Offset = getDataLength(Qualifier->getPrefix());
396   void *TypeData = LoadPointer(Data, Offset);
397   return TypeLoc(Qualifier->getAsType(), TypeData);
398 }
399 
400 namespace {
401   void Append(char *Start, char *End, char *&Buffer, unsigned &BufferSize,
402               unsigned &BufferCapacity) {
403     if (BufferSize + (End - Start) > BufferCapacity) {
404       // Reallocate the buffer.
405       unsigned NewCapacity
406       = std::max((unsigned)(BufferCapacity? BufferCapacity * 2
407                             : sizeof(void*) * 2),
408                  (unsigned)(BufferSize + (End - Start)));
409       char *NewBuffer = static_cast<char *>(malloc(NewCapacity));
410       memcpy(NewBuffer, Buffer, BufferSize);
411 
412       if (BufferCapacity)
413         free(Buffer);
414       Buffer = NewBuffer;
415       BufferCapacity = NewCapacity;
416     }
417 
418     memcpy(Buffer + BufferSize, Start, End - Start);
419     BufferSize += End-Start;
420   }
421 
422   /// \brief Save a source location to the given buffer.
423   void SaveSourceLocation(SourceLocation Loc, char *&Buffer,
424                           unsigned &BufferSize, unsigned &BufferCapacity) {
425     unsigned Raw = Loc.getRawEncoding();
426     Append(reinterpret_cast<char *>(&Raw),
427            reinterpret_cast<char *>(&Raw) + sizeof(unsigned),
428            Buffer, BufferSize, BufferCapacity);
429   }
430 
431   /// \brief Save a pointer to the given buffer.
432   void SavePointer(void *Ptr, char *&Buffer, unsigned &BufferSize,
433                    unsigned &BufferCapacity) {
434     Append(reinterpret_cast<char *>(&Ptr),
435            reinterpret_cast<char *>(&Ptr) + sizeof(void *),
436            Buffer, BufferSize, BufferCapacity);
437   }
438 }
439 
440 NestedNameSpecifierLocBuilder::
441 NestedNameSpecifierLocBuilder(const NestedNameSpecifierLocBuilder &Other)
442   : Representation(Other.Representation), Buffer(nullptr),
443     BufferSize(0), BufferCapacity(0)
444 {
445   if (!Other.Buffer)
446     return;
447 
448   if (Other.BufferCapacity == 0) {
449     // Shallow copy is okay.
450     Buffer = Other.Buffer;
451     BufferSize = Other.BufferSize;
452     return;
453   }
454 
455   // Deep copy
456   Append(Other.Buffer, Other.Buffer + Other.BufferSize, Buffer, BufferSize,
457          BufferCapacity);
458 }
459 
460 NestedNameSpecifierLocBuilder &
461 NestedNameSpecifierLocBuilder::
462 operator=(const NestedNameSpecifierLocBuilder &Other) {
463   Representation = Other.Representation;
464 
465   if (Buffer && Other.Buffer && BufferCapacity >= Other.BufferSize) {
466     // Re-use our storage.
467     BufferSize = Other.BufferSize;
468     memcpy(Buffer, Other.Buffer, BufferSize);
469     return *this;
470   }
471 
472   // Free our storage, if we have any.
473   if (BufferCapacity) {
474     free(Buffer);
475     BufferCapacity = 0;
476   }
477 
478   if (!Other.Buffer) {
479     // Empty.
480     Buffer = nullptr;
481     BufferSize = 0;
482     return *this;
483   }
484 
485   if (Other.BufferCapacity == 0) {
486     // Shallow copy is okay.
487     Buffer = Other.Buffer;
488     BufferSize = Other.BufferSize;
489     return *this;
490   }
491 
492   // Deep copy.
493   Append(Other.Buffer, Other.Buffer + Other.BufferSize, Buffer, BufferSize,
494          BufferCapacity);
495   return *this;
496 }
497 
498 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
499                                            SourceLocation TemplateKWLoc,
500                                            TypeLoc TL,
501                                            SourceLocation ColonColonLoc) {
502   Representation = NestedNameSpecifier::Create(Context, Representation,
503                                                TemplateKWLoc.isValid(),
504                                                TL.getTypePtr());
505 
506   // Push source-location info into the buffer.
507   SavePointer(TL.getOpaqueData(), Buffer, BufferSize, BufferCapacity);
508   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
509 }
510 
511 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
512                                            IdentifierInfo *Identifier,
513                                            SourceLocation IdentifierLoc,
514                                            SourceLocation ColonColonLoc) {
515   Representation = NestedNameSpecifier::Create(Context, Representation,
516                                                Identifier);
517 
518   // Push source-location info into the buffer.
519   SaveSourceLocation(IdentifierLoc, Buffer, BufferSize, BufferCapacity);
520   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
521 }
522 
523 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
524                                            NamespaceDecl *Namespace,
525                                            SourceLocation NamespaceLoc,
526                                            SourceLocation ColonColonLoc) {
527   Representation = NestedNameSpecifier::Create(Context, Representation,
528                                                Namespace);
529 
530   // Push source-location info into the buffer.
531   SaveSourceLocation(NamespaceLoc, Buffer, BufferSize, BufferCapacity);
532   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
533 }
534 
535 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
536                                            NamespaceAliasDecl *Alias,
537                                            SourceLocation AliasLoc,
538                                            SourceLocation ColonColonLoc) {
539   Representation = NestedNameSpecifier::Create(Context, Representation, Alias);
540 
541   // Push source-location info into the buffer.
542   SaveSourceLocation(AliasLoc, Buffer, BufferSize, BufferCapacity);
543   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
544 }
545 
546 void NestedNameSpecifierLocBuilder::MakeGlobal(ASTContext &Context,
547                                                SourceLocation ColonColonLoc) {
548   assert(!Representation && "Already have a nested-name-specifier!?");
549   Representation = NestedNameSpecifier::GlobalSpecifier(Context);
550 
551   // Push source-location info into the buffer.
552   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
553 }
554 
555 void NestedNameSpecifierLocBuilder::MakeTrivial(ASTContext &Context,
556                                                 NestedNameSpecifier *Qualifier,
557                                                 SourceRange R) {
558   Representation = Qualifier;
559 
560   // Construct bogus (but well-formed) source information for the
561   // nested-name-specifier.
562   BufferSize = 0;
563   SmallVector<NestedNameSpecifier *, 4> Stack;
564   for (NestedNameSpecifier *NNS = Qualifier; NNS; NNS = NNS->getPrefix())
565     Stack.push_back(NNS);
566   while (!Stack.empty()) {
567     NestedNameSpecifier *NNS = Stack.pop_back_val();
568     switch (NNS->getKind()) {
569       case NestedNameSpecifier::Identifier:
570       case NestedNameSpecifier::Namespace:
571       case NestedNameSpecifier::NamespaceAlias:
572         SaveSourceLocation(R.getBegin(), Buffer, BufferSize, BufferCapacity);
573         break;
574 
575       case NestedNameSpecifier::TypeSpec:
576       case NestedNameSpecifier::TypeSpecWithTemplate: {
577         TypeSourceInfo *TSInfo
578         = Context.getTrivialTypeSourceInfo(QualType(NNS->getAsType(), 0),
579                                            R.getBegin());
580         SavePointer(TSInfo->getTypeLoc().getOpaqueData(), Buffer, BufferSize,
581                     BufferCapacity);
582         break;
583       }
584 
585       case NestedNameSpecifier::Global:
586         break;
587     }
588 
589     // Save the location of the '::'.
590     SaveSourceLocation(Stack.empty()? R.getEnd() : R.getBegin(),
591                        Buffer, BufferSize, BufferCapacity);
592   }
593 }
594 
595 void NestedNameSpecifierLocBuilder::Adopt(NestedNameSpecifierLoc Other) {
596   if (BufferCapacity)
597     free(Buffer);
598 
599   if (!Other) {
600     Representation = nullptr;
601     BufferSize = 0;
602     return;
603   }
604 
605   // Rather than copying the data (which is wasteful), "adopt" the
606   // pointer (which points into the ASTContext) but set the capacity to zero to
607   // indicate that we don't own it.
608   Representation = Other.getNestedNameSpecifier();
609   Buffer = static_cast<char *>(Other.getOpaqueData());
610   BufferSize = Other.getDataLength();
611   BufferCapacity = 0;
612 }
613 
614 NestedNameSpecifierLoc
615 NestedNameSpecifierLocBuilder::getWithLocInContext(ASTContext &Context) const {
616   if (!Representation)
617     return NestedNameSpecifierLoc();
618 
619   // If we adopted our data pointer from elsewhere in the AST context, there's
620   // no need to copy the memory.
621   if (BufferCapacity == 0)
622     return NestedNameSpecifierLoc(Representation, Buffer);
623 
624   // FIXME: After copying the source-location information, should we free
625   // our (temporary) buffer and adopt the ASTContext-allocated memory?
626   // Doing so would optimize repeated calls to getWithLocInContext().
627   void *Mem = Context.Allocate(BufferSize, llvm::alignOf<void *>());
628   memcpy(Mem, Buffer, BufferSize);
629   return NestedNameSpecifierLoc(Representation, Mem);
630 }
631