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