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