1 //===--- NestedNameSpecifier.h - 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 #ifndef LLVM_CLANG_AST_NESTEDNAMESPECIFIER_H
15 #define LLVM_CLANG_AST_NESTEDNAMESPECIFIER_H
16 
17 #include "clang/Basic/Diagnostic.h"
18 #include "llvm/ADT/FoldingSet.h"
19 #include "llvm/ADT/PointerIntPair.h"
20 #include "llvm/Support/Compiler.h"
21 
22 namespace clang {
23 
24 class ASTContext;
25 class CXXRecordDecl;
26 class NamespaceAliasDecl;
27 class NamespaceDecl;
28 class IdentifierInfo;
29 struct PrintingPolicy;
30 class Type;
31 class TypeLoc;
32 class LangOptions;
33 
34 /// \brief Represents a C++ nested name specifier, such as
35 /// "\::std::vector<int>::".
36 ///
37 /// C++ nested name specifiers are the prefixes to qualified
38 /// namespaces. For example, "foo::" in "foo::x" is a nested name
39 /// specifier. Nested name specifiers are made up of a sequence of
40 /// specifiers, each of which can be a namespace, type, identifier
41 /// (for dependent names), decltype specifier, or the global specifier ('::').
42 /// The last two specifiers can only appear at the start of a
43 /// nested-namespace-specifier.
44 class NestedNameSpecifier : public llvm::FoldingSetNode {
45 
46   /// \brief Enumeration describing
47   enum StoredSpecifierKind {
48     StoredIdentifier = 0,
49     StoredDecl = 1,
50     StoredTypeSpec = 2,
51     StoredTypeSpecWithTemplate = 3
52   };
53 
54   /// \brief The nested name specifier that precedes this nested name
55   /// specifier.
56   ///
57   /// The pointer is the nested-name-specifier that precedes this
58   /// one. The integer stores one of the first four values of type
59   /// SpecifierKind.
60   llvm::PointerIntPair<NestedNameSpecifier *, 2, StoredSpecifierKind> Prefix;
61 
62   /// \brief The last component in the nested name specifier, which
63   /// can be an identifier, a declaration, or a type.
64   ///
65   /// When the pointer is NULL, this specifier represents the global
66   /// specifier '::'. Otherwise, the pointer is one of
67   /// IdentifierInfo*, Namespace*, or Type*, depending on the kind of
68   /// specifier as encoded within the prefix.
69   void* Specifier;
70 
71 public:
72   /// \brief The kind of specifier that completes this nested name
73   /// specifier.
74   enum SpecifierKind {
75     /// \brief An identifier, stored as an IdentifierInfo*.
76     Identifier,
77     /// \brief A namespace, stored as a NamespaceDecl*.
78     Namespace,
79     /// \brief A namespace alias, stored as a NamespaceAliasDecl*.
80     NamespaceAlias,
81     /// \brief A type, stored as a Type*.
82     TypeSpec,
83     /// \brief A type that was preceded by the 'template' keyword,
84     /// stored as a Type*.
85     TypeSpecWithTemplate,
86     /// \brief The global specifier '::'. There is no stored value.
87     Global,
88     /// \brief Microsoft's '__super' specifier, stored as a CXXRecordDecl* of
89     /// the class it appeared in.
90     Super
91   };
92 
93 private:
94   /// \brief Builds the global specifier.
NestedNameSpecifier()95   NestedNameSpecifier()
96     : Prefix(nullptr, StoredIdentifier), Specifier(nullptr) {}
97 
98   /// \brief Copy constructor used internally to clone nested name
99   /// specifiers.
NestedNameSpecifier(const NestedNameSpecifier & Other)100   NestedNameSpecifier(const NestedNameSpecifier &Other)
101     : llvm::FoldingSetNode(Other), Prefix(Other.Prefix),
102       Specifier(Other.Specifier) {
103   }
104 
105   void operator=(const NestedNameSpecifier &) = delete;
106 
107   /// \brief Either find or insert the given nested name specifier
108   /// mockup in the given context.
109   static NestedNameSpecifier *FindOrInsert(const ASTContext &Context,
110                                            const NestedNameSpecifier &Mockup);
111 
112 public:
113   /// \brief Builds a specifier combining a prefix and an identifier.
114   ///
115   /// The prefix must be dependent, since nested name specifiers
116   /// referencing an identifier are only permitted when the identifier
117   /// cannot be resolved.
118   static NestedNameSpecifier *Create(const ASTContext &Context,
119                                      NestedNameSpecifier *Prefix,
120                                      IdentifierInfo *II);
121 
122   /// \brief Builds a nested name specifier that names a namespace.
123   static NestedNameSpecifier *Create(const ASTContext &Context,
124                                      NestedNameSpecifier *Prefix,
125                                      const NamespaceDecl *NS);
126 
127   /// \brief Builds a nested name specifier that names a namespace alias.
128   static NestedNameSpecifier *Create(const ASTContext &Context,
129                                      NestedNameSpecifier *Prefix,
130                                      NamespaceAliasDecl *Alias);
131 
132   /// \brief Builds a nested name specifier that names a type.
133   static NestedNameSpecifier *Create(const ASTContext &Context,
134                                      NestedNameSpecifier *Prefix,
135                                      bool Template, const Type *T);
136 
137   /// \brief Builds a specifier that consists of just an identifier.
138   ///
139   /// The nested-name-specifier is assumed to be dependent, but has no
140   /// prefix because the prefix is implied by something outside of the
141   /// nested name specifier, e.g., in "x->Base::f", the "x" has a dependent
142   /// type.
143   static NestedNameSpecifier *Create(const ASTContext &Context,
144                                      IdentifierInfo *II);
145 
146   /// \brief Returns the nested name specifier representing the global
147   /// scope.
148   static NestedNameSpecifier *GlobalSpecifier(const ASTContext &Context);
149 
150   /// \brief Returns the nested name specifier representing the __super scope
151   /// for the given CXXRecordDecl.
152   static NestedNameSpecifier *SuperSpecifier(const ASTContext &Context,
153                                              CXXRecordDecl *RD);
154 
155   /// \brief Return the prefix of this nested name specifier.
156   ///
157   /// The prefix contains all of the parts of the nested name
158   /// specifier that preced this current specifier. For example, for a
159   /// nested name specifier that represents "foo::bar::", the current
160   /// specifier will contain "bar::" and the prefix will contain
161   /// "foo::".
getPrefix()162   NestedNameSpecifier *getPrefix() const { return Prefix.getPointer(); }
163 
164   /// \brief Determine what kind of nested name specifier is stored.
165   SpecifierKind getKind() const;
166 
167   /// \brief Retrieve the identifier stored in this nested name
168   /// specifier.
getAsIdentifier()169   IdentifierInfo *getAsIdentifier() const {
170     if (Prefix.getInt() == StoredIdentifier)
171       return (IdentifierInfo *)Specifier;
172 
173     return nullptr;
174   }
175 
176   /// \brief Retrieve the namespace stored in this nested name
177   /// specifier.
178   NamespaceDecl *getAsNamespace() const;
179 
180   /// \brief Retrieve the namespace alias stored in this nested name
181   /// specifier.
182   NamespaceAliasDecl *getAsNamespaceAlias() const;
183 
184   /// \brief Retrieve the record declaration stored in this nested name
185   /// specifier.
186   CXXRecordDecl *getAsRecordDecl() const;
187 
188   /// \brief Retrieve the type stored in this nested name specifier.
getAsType()189   const Type *getAsType() const {
190     if (Prefix.getInt() == StoredTypeSpec ||
191         Prefix.getInt() == StoredTypeSpecWithTemplate)
192       return (const Type *)Specifier;
193 
194     return nullptr;
195   }
196 
197   /// \brief Whether this nested name specifier refers to a dependent
198   /// type or not.
199   bool isDependent() const;
200 
201   /// \brief Whether this nested name specifier involves a template
202   /// parameter.
203   bool isInstantiationDependent() const;
204 
205   /// \brief Whether this nested-name-specifier contains an unexpanded
206   /// parameter pack (for C++11 variadic templates).
207   bool containsUnexpandedParameterPack() const;
208 
209   /// \brief Print this nested name specifier to the given output
210   /// stream.
211   void print(raw_ostream &OS, const PrintingPolicy &Policy) const;
212 
Profile(llvm::FoldingSetNodeID & ID)213   void Profile(llvm::FoldingSetNodeID &ID) const {
214     ID.AddPointer(Prefix.getOpaqueValue());
215     ID.AddPointer(Specifier);
216   }
217 
218   /// \brief Dump the nested name specifier to standard output to aid
219   /// in debugging.
220   void dump(const LangOptions &LO);
221 };
222 
223 /// \brief A C++ nested-name-specifier augmented with source location
224 /// information.
225 class NestedNameSpecifierLoc {
226   NestedNameSpecifier *Qualifier;
227   void *Data;
228 
229   /// \brief Determines the data length for the last component in the
230   /// given nested-name-specifier.
231   static unsigned getLocalDataLength(NestedNameSpecifier *Qualifier);
232 
233   /// \brief Determines the data length for the entire
234   /// nested-name-specifier.
235   static unsigned getDataLength(NestedNameSpecifier *Qualifier);
236 
237 public:
238   /// \brief Construct an empty nested-name-specifier.
NestedNameSpecifierLoc()239   NestedNameSpecifierLoc() : Qualifier(nullptr), Data(nullptr) { }
240 
241   /// \brief Construct a nested-name-specifier with source location information
242   /// from
NestedNameSpecifierLoc(NestedNameSpecifier * Qualifier,void * Data)243   NestedNameSpecifierLoc(NestedNameSpecifier *Qualifier, void *Data)
244     : Qualifier(Qualifier), Data(Data) { }
245 
246   /// \brief Evalutes true when this nested-name-specifier location is
247   /// non-empty.
248   explicit operator bool() const { return Qualifier; }
249 
250   /// \brief Evalutes true when this nested-name-specifier location is
251   /// empty.
hasQualifier()252   bool hasQualifier() const { return Qualifier; }
253 
254   /// \brief Retrieve the nested-name-specifier to which this instance
255   /// refers.
getNestedNameSpecifier()256   NestedNameSpecifier *getNestedNameSpecifier() const {
257     return Qualifier;
258   }
259 
260   /// \brief Retrieve the opaque pointer that refers to source-location data.
getOpaqueData()261   void *getOpaqueData() const { return Data; }
262 
263   /// \brief Retrieve the source range covering the entirety of this
264   /// nested-name-specifier.
265   ///
266   /// For example, if this instance refers to a nested-name-specifier
267   /// \c \::std::vector<int>::, the returned source range would cover
268   /// from the initial '::' to the last '::'.
269   SourceRange getSourceRange() const LLVM_READONLY;
270 
271   /// \brief Retrieve the source range covering just the last part of
272   /// this nested-name-specifier, not including the prefix.
273   ///
274   /// For example, if this instance refers to a nested-name-specifier
275   /// \c \::std::vector<int>::, the returned source range would cover
276   /// from "vector" to the last '::'.
277   SourceRange getLocalSourceRange() const;
278 
279   /// \brief Retrieve the location of the beginning of this
280   /// nested-name-specifier.
getBeginLoc()281   SourceLocation getBeginLoc() const {
282     return getSourceRange().getBegin();
283   }
284 
285   /// \brief Retrieve the location of the end of this
286   /// nested-name-specifier.
getEndLoc()287   SourceLocation getEndLoc() const {
288     return getSourceRange().getEnd();
289   }
290 
291   /// \brief Retrieve the location of the beginning of this
292   /// component of the nested-name-specifier.
getLocalBeginLoc()293   SourceLocation getLocalBeginLoc() const {
294     return getLocalSourceRange().getBegin();
295   }
296 
297   /// \brief Retrieve the location of the end of this component of the
298   /// nested-name-specifier.
getLocalEndLoc()299   SourceLocation getLocalEndLoc() const {
300     return getLocalSourceRange().getEnd();
301   }
302 
303   /// \brief Return the prefix of this nested-name-specifier.
304   ///
305   /// For example, if this instance refers to a nested-name-specifier
306   /// \c \::std::vector<int>::, the prefix is \c \::std::. Note that the
307   /// returned prefix may be empty, if this is the first component of
308   /// the nested-name-specifier.
getPrefix()309   NestedNameSpecifierLoc getPrefix() const {
310     if (!Qualifier)
311       return *this;
312 
313     return NestedNameSpecifierLoc(Qualifier->getPrefix(), Data);
314   }
315 
316   /// \brief For a nested-name-specifier that refers to a type,
317   /// retrieve the type with source-location information.
318   TypeLoc getTypeLoc() const;
319 
320   /// \brief Determines the data length for the entire
321   /// nested-name-specifier.
getDataLength()322   unsigned getDataLength() const { return getDataLength(Qualifier); }
323 
324   friend bool operator==(NestedNameSpecifierLoc X,
325                          NestedNameSpecifierLoc Y) {
326     return X.Qualifier == Y.Qualifier && X.Data == Y.Data;
327   }
328 
329   friend bool operator!=(NestedNameSpecifierLoc X,
330                          NestedNameSpecifierLoc Y) {
331     return !(X == Y);
332   }
333 };
334 
335 /// \brief Class that aids in the construction of nested-name-specifiers along
336 /// with source-location information for all of the components of the
337 /// nested-name-specifier.
338 class NestedNameSpecifierLocBuilder {
339   /// \brief The current representation of the nested-name-specifier we're
340   /// building.
341   NestedNameSpecifier *Representation;
342 
343   /// \brief Buffer used to store source-location information for the
344   /// nested-name-specifier.
345   ///
346   /// Note that we explicitly manage the buffer (rather than using a
347   /// SmallVector) because \c Declarator expects it to be possible to memcpy()
348   /// a \c CXXScopeSpec, and CXXScopeSpec uses a NestedNameSpecifierLocBuilder.
349   char *Buffer;
350 
351   /// \brief The size of the buffer used to store source-location information
352   /// for the nested-name-specifier.
353   unsigned BufferSize;
354 
355   /// \brief The capacity of the buffer used to store source-location
356   /// information for the nested-name-specifier.
357   unsigned BufferCapacity;
358 
359 public:
NestedNameSpecifierLocBuilder()360   NestedNameSpecifierLocBuilder()
361     : Representation(nullptr), Buffer(nullptr), BufferSize(0),
362       BufferCapacity(0) {}
363 
364   NestedNameSpecifierLocBuilder(const NestedNameSpecifierLocBuilder &Other);
365 
366   NestedNameSpecifierLocBuilder &
367   operator=(const NestedNameSpecifierLocBuilder &Other);
368 
~NestedNameSpecifierLocBuilder()369   ~NestedNameSpecifierLocBuilder() {
370     if (BufferCapacity)
371       free(Buffer);
372   }
373 
374   /// \brief Retrieve the representation of the nested-name-specifier.
getRepresentation()375   NestedNameSpecifier *getRepresentation() const { return Representation; }
376 
377   /// \brief Extend the current nested-name-specifier by another
378   /// nested-name-specifier component of the form 'type::'.
379   ///
380   /// \param Context The AST context in which this nested-name-specifier
381   /// resides.
382   ///
383   /// \param TemplateKWLoc The location of the 'template' keyword, if present.
384   ///
385   /// \param TL The TypeLoc that describes the type preceding the '::'.
386   ///
387   /// \param ColonColonLoc The location of the trailing '::'.
388   void Extend(ASTContext &Context, SourceLocation TemplateKWLoc, TypeLoc TL,
389               SourceLocation ColonColonLoc);
390 
391   /// \brief Extend the current nested-name-specifier by another
392   /// nested-name-specifier component of the form 'identifier::'.
393   ///
394   /// \param Context The AST context in which this nested-name-specifier
395   /// resides.
396   ///
397   /// \param Identifier The identifier.
398   ///
399   /// \param IdentifierLoc The location of the identifier.
400   ///
401   /// \param ColonColonLoc The location of the trailing '::'.
402   void Extend(ASTContext &Context, IdentifierInfo *Identifier,
403               SourceLocation IdentifierLoc, SourceLocation ColonColonLoc);
404 
405   /// \brief Extend the current nested-name-specifier by another
406   /// nested-name-specifier component of the form 'namespace::'.
407   ///
408   /// \param Context The AST context in which this nested-name-specifier
409   /// resides.
410   ///
411   /// \param Namespace The namespace.
412   ///
413   /// \param NamespaceLoc The location of the namespace name.
414   ///
415   /// \param ColonColonLoc The location of the trailing '::'.
416   void Extend(ASTContext &Context, NamespaceDecl *Namespace,
417               SourceLocation NamespaceLoc, SourceLocation ColonColonLoc);
418 
419   /// \brief Extend the current nested-name-specifier by another
420   /// nested-name-specifier component of the form 'namespace-alias::'.
421   ///
422   /// \param Context The AST context in which this nested-name-specifier
423   /// resides.
424   ///
425   /// \param Alias The namespace alias.
426   ///
427   /// \param AliasLoc The location of the namespace alias
428   /// name.
429   ///
430   /// \param ColonColonLoc The location of the trailing '::'.
431   void Extend(ASTContext &Context, NamespaceAliasDecl *Alias,
432               SourceLocation AliasLoc, SourceLocation ColonColonLoc);
433 
434   /// \brief Turn this (empty) nested-name-specifier into the global
435   /// nested-name-specifier '::'.
436   void MakeGlobal(ASTContext &Context, SourceLocation ColonColonLoc);
437 
438   /// \brief Turns this (empty) nested-name-specifier into '__super'
439   /// nested-name-specifier.
440   ///
441   /// \param Context The AST context in which this nested-name-specifier
442   /// resides.
443   ///
444   /// \param RD The declaration of the class in which nested-name-specifier
445   /// appeared.
446   ///
447   /// \param SuperLoc The location of the '__super' keyword.
448   /// name.
449   ///
450   /// \param ColonColonLoc The location of the trailing '::'.
451   void MakeSuper(ASTContext &Context, CXXRecordDecl *RD,
452                  SourceLocation SuperLoc, SourceLocation ColonColonLoc);
453   /// \brief Make a new nested-name-specifier from incomplete source-location
454   /// information.
455   ///
456   /// This routine should be used very, very rarely, in cases where we
457   /// need to synthesize a nested-name-specifier. Most code should instead use
458   /// \c Adopt() with a proper \c NestedNameSpecifierLoc.
459   void MakeTrivial(ASTContext &Context, NestedNameSpecifier *Qualifier,
460                    SourceRange R);
461 
462   /// \brief Adopt an existing nested-name-specifier (with source-range
463   /// information).
464   void Adopt(NestedNameSpecifierLoc Other);
465 
466   /// \brief Retrieve the source range covered by this nested-name-specifier.
getSourceRange()467   SourceRange getSourceRange() const LLVM_READONLY {
468     return NestedNameSpecifierLoc(Representation, Buffer).getSourceRange();
469   }
470 
471   /// \brief Retrieve a nested-name-specifier with location information,
472   /// copied into the given AST context.
473   ///
474   /// \param Context The context into which this nested-name-specifier will be
475   /// copied.
476   NestedNameSpecifierLoc getWithLocInContext(ASTContext &Context) const;
477 
478   /// \brief Retrieve a nested-name-specifier with location
479   /// information based on the information in this builder.
480   ///
481   /// This loc will contain references to the builder's internal data and may
482   /// be invalidated by any change to the builder.
getTemporary()483   NestedNameSpecifierLoc getTemporary() const {
484     return NestedNameSpecifierLoc(Representation, Buffer);
485   }
486 
487   /// \brief Clear out this builder, and prepare it to build another
488   /// nested-name-specifier with source-location information.
Clear()489   void Clear() {
490     Representation = nullptr;
491     BufferSize = 0;
492   }
493 
494   /// \brief Retrieve the underlying buffer.
495   ///
496   /// \returns A pair containing a pointer to the buffer of source-location
497   /// data and the size of the source-location data that resides in that
498   /// buffer.
getBuffer()499   std::pair<char *, unsigned> getBuffer() const {
500     return std::make_pair(Buffer, BufferSize);
501   }
502 };
503 
504 /// Insertion operator for diagnostics.  This allows sending
505 /// NestedNameSpecifiers into a diagnostic with <<.
506 inline const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB,
507                                            NestedNameSpecifier *NNS) {
508   DB.AddTaggedVal(reinterpret_cast<intptr_t>(NNS),
509                   DiagnosticsEngine::ak_nestednamespec);
510   return DB;
511 }
512 
513 }
514 
515 #endif
516