path: root/include/clang/AST/TemplateName.h

//===--- TemplateName.h - C++ Template Name Representation-------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file defines the TemplateName interface and subclasses.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_TEMPLATENAME_H
#define LLVM_CLANG_AST_TEMPLATENAME_H

#include "clang/Basic/LLVM.h"
#include "clang/Basic/OperatorKinds.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/PointerUnion.h"

namespace clang {
  
class ASTContext;
class DependentTemplateName;
class DiagnosticBuilder;
class IdentifierInfo;
class NestedNameSpecifier;
class OverloadedTemplateStorage;
struct PrintingPolicy;
class QualifiedTemplateName;
class NamedDecl;
class SubstTemplateTemplateParmStorage;
class SubstTemplateTemplateParmPackStorage;
class TemplateArgument;
class TemplateDecl;
class TemplateTemplateParmDecl;
  
/// \brief Implementation class used to describe either a set of overloaded
/// template names or an already-substituted template template parameter pack.
class UncommonTemplateNameStorage {
protected:
  enum Kind {
    Overloaded,
    SubstTemplateTemplateParm,
    SubstTemplateTemplateParmPack
  };

  struct BitsTag {
    /// \brief A Kind.
    unsigned Kind : 2;
    
    /// \brief The number of stored templates or template arguments,
    /// depending on which subclass we have.
    unsigned Size : 30;
  };

  union {
    struct BitsTag Bits;
    void *PointerAlignment;
  };
  
  UncommonTemplateNameStorage(Kind kind, unsigned size) {
    Bits.Kind = kind;
    Bits.Size = size;
  }
  
public:
  unsigned size() const { return Bits.Size; }
  
  OverloadedTemplateStorage *getAsOverloadedStorage()  {
    return Bits.Kind == Overloaded
             ? reinterpret_cast<OverloadedTemplateStorage *>(this) 
             : 0;
  }
  
  SubstTemplateTemplateParmStorage *getAsSubstTemplateTemplateParm() {
    return Bits.Kind == SubstTemplateTemplateParm
             ? reinterpret_cast<SubstTemplateTemplateParmStorage *>(this)
             : 0;
  }

  SubstTemplateTemplateParmPackStorage *getAsSubstTemplateTemplateParmPack() {
    return Bits.Kind == SubstTemplateTemplateParmPack
             ? reinterpret_cast<SubstTemplateTemplateParmPackStorage *>(this)
             : 0;
  }
};
  
/// \brief A structure for storing the information associated with an
/// overloaded template name.
class OverloadedTemplateStorage : public UncommonTemplateNameStorage {
  friend class ASTContext;

  OverloadedTemplateStorage(unsigned size) 
    : UncommonTemplateNameStorage(Overloaded, size) { }

  NamedDecl **getStorage() {
    return reinterpret_cast<NamedDecl **>(this + 1);
  }
  NamedDecl * const *getStorage() const {
    return reinterpret_cast<NamedDecl *const *>(this + 1);
  }

public:
  typedef NamedDecl *const *iterator;

  iterator begin() const { return getStorage(); }
  iterator end() const { return getStorage() + size(); }
};

/// \brief A structure for storing an already-substituted template template
/// parameter pack.
///
/// This kind of template names occurs when the parameter pack has been 
/// provided with a template template argument pack in a context where its
/// enclosing pack expansion could not be fully expanded.
class SubstTemplateTemplateParmPackStorage
  : public UncommonTemplateNameStorage, public llvm::FoldingSetNode
{
  TemplateTemplateParmDecl *Parameter;
  const TemplateArgument *Arguments;
  
public:
  SubstTemplateTemplateParmPackStorage(TemplateTemplateParmDecl *Parameter,
                                       unsigned Size, 
                                       const TemplateArgument *Arguments)
    : UncommonTemplateNameStorage(SubstTemplateTemplateParmPack, Size),
      Parameter(Parameter), Arguments(Arguments) { }
  
  /// \brief Retrieve the template template parameter pack being substituted.
  TemplateTemplateParmDecl *getParameterPack() const {
    return Parameter;
  }
  
  /// \brief Retrieve the template template argument pack with which this
  /// parameter was substituted.
  TemplateArgument getArgumentPack() const;
  
  void Profile(llvm::FoldingSetNodeID &ID, ASTContext &Context);
  
  static void Profile(llvm::FoldingSetNodeID &ID,
                      ASTContext &Context,
                      TemplateTemplateParmDecl *Parameter,
                      const TemplateArgument &ArgPack);
};

/// \brief Represents a C++ template name within the type system.
///
/// A C++ template name refers to a template within the C++ type
/// system. In most cases, a template name is simply a reference to a
/// class template, e.g.
///
/// \code
/// template<typename T> class X { };
///
/// X<int> xi;
/// \endcode
///
/// Here, the 'X' in \c X<int> is a template name that refers to the
/// declaration of the class template X, above. Template names can
/// also refer to function templates, C++0x template aliases, etc.
///
/// Some template names are dependent. For example, consider:
///
/// \code
/// template<typename MetaFun, typename T1, typename T2> struct apply2 {
///   typedef typename MetaFun::template apply<T1, T2>::type type;
/// };
/// \endcode
///
/// Here, "apply" is treated as a template name within the typename
/// specifier in the typedef. "apply" is a nested template, and can
/// only be understood in the context of
class TemplateName {
  typedef llvm::PointerUnion4<TemplateDecl *,
                              UncommonTemplateNameStorage *,
                              QualifiedTemplateName *,
                              DependentTemplateName *> StorageType;

  StorageType Storage;

  explicit TemplateName(void *Ptr) {
    Storage = StorageType::getFromOpaqueValue(Ptr);
  }

public:
  // \brief Kind of name that is actually stored.
  enum NameKind {
    /// \brief A single template declaration.
    Template,
    /// \brief A set of overloaded template declarations.
    OverloadedTemplate,
    /// \brief A qualified template name, where the qualification is kept 
    /// to describe the source code as written.
    QualifiedTemplate,
    /// \brief A dependent template name that has not been resolved to a 
    /// template (or set of templates).
    DependentTemplate,
    /// \brief A template template parameter that has been substituted
    /// for some other template name.
    SubstTemplateTemplateParm,
    /// \brief A template template parameter pack that has been substituted for 
    /// a template template argument pack, but has not yet been expanded into
    /// individual arguments.
    SubstTemplateTemplateParmPack
  };

  TemplateName() : Storage() { }
  explicit TemplateName(TemplateDecl *Template) : Storage(Template) { }
  explicit TemplateName(OverloadedTemplateStorage *Storage)
    : Storage(Storage) { }
  explicit TemplateName(SubstTemplateTemplateParmStorage *Storage);
  explicit TemplateName(SubstTemplateTemplateParmPackStorage *Storage)
    : Storage(Storage) { }
  explicit TemplateName(QualifiedTemplateName *Qual) : Storage(Qual) { }
  explicit TemplateName(DependentTemplateName *Dep) : Storage(Dep) { }

  /// \brief Determine whether this template name is NULL.
  bool isNull() const { return Storage.isNull(); }
  
  // \brief Get the kind of name that is actually stored.
  NameKind getKind() const;

  /// \brief Retrieve the underlying template declaration that
  /// this template name refers to, if known.
  ///
  /// \returns The template declaration that this template name refers
  /// to, if any. If the template name does not refer to a specific
  /// declaration because it is a dependent name, or if it refers to a
  /// set of function templates, returns NULL.
  TemplateDecl *getAsTemplateDecl() const;

  /// \brief Retrieve the underlying, overloaded function template
  // declarations that this template name refers to, if known.
  ///
  /// \returns The set of overloaded function templates that this template
  /// name refers to, if known. If the template name does not refer to a
  /// specific set of function templates because it is a dependent name or
  /// refers to a single template, returns NULL.
  OverloadedTemplateStorage *getAsOverloadedTemplate() const {
    if (UncommonTemplateNameStorage *Uncommon = 
                              Storage.dyn_cast<UncommonTemplateNameStorage *>())
      return Uncommon->getAsOverloadedStorage();
    
    return 0;
  }

  /// \brief Retrieve the substituted template template parameter, if 
  /// known.
  ///
  /// \returns The storage for the substituted template template parameter,
  /// if known. Otherwise, returns NULL.
  SubstTemplateTemplateParmStorage *getAsSubstTemplateTemplateParm() const {
    if (UncommonTemplateNameStorage *uncommon = 
          Storage.dyn_cast<UncommonTemplateNameStorage *>())
      return uncommon->getAsSubstTemplateTemplateParm();
    
    return 0;
  }

  /// \brief Retrieve the substituted template template parameter pack, if 
  /// known.
  ///
  /// \returns The storage for the substituted template template parameter pack,
  /// if known. Otherwise, returns NULL.
  SubstTemplateTemplateParmPackStorage *
  getAsSubstTemplateTemplateParmPack() const {
    if (UncommonTemplateNameStorage *Uncommon = 
        Storage.dyn_cast<UncommonTemplateNameStorage *>())
      return Uncommon->getAsSubstTemplateTemplateParmPack();
    
    return 0;
  }

  /// \brief Retrieve the underlying qualified template name
  /// structure, if any.
  QualifiedTemplateName *getAsQualifiedTemplateName() const {
    return Storage.dyn_cast<QualifiedTemplateName *>();
  }

  /// \brief Retrieve the underlying dependent template name
  /// structure, if any.
  DependentTemplateName *getAsDependentTemplateName() const {
    return Storage.dyn_cast