C++ ParsedTemplateArgument::isInvalid方法代码示例

/// ParseTemplateArgumentList - Parse a C++ template-argument-list
/// (C++ [temp.names]). Returns true if there was an error.
///
///       template-argument-list: [C++ 14.2]
///         template-argument
///         template-argument-list ',' template-argument
bool
Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs) {
  while (true) {
    ParsedTemplateArgument Arg = ParseTemplateArgument();
    if (Tok.is(tok::ellipsis)) {
      SourceLocation EllipsisLoc  = ConsumeToken();
      Arg = Actions.ActOnPackExpansion(Arg, EllipsisLoc);
    }

    if (Arg.isInvalid()) {
      SkipUntil(tok::comma, tok::greater, true, true);
      return true;
    }

    // Save this template argument.
    TemplateArgs.push_back(Arg);
      
    // If the next token is a comma, consume it and keep reading
    // arguments.
    if (Tok.isNot(tok::comma)) break;

    // Consume the comma.
    ConsumeToken();
  }

  return false;
}

/// ParseTemplateArgument - Parse a C++ template argument (C++ [temp.names]).
///
///       template-argument: [C++ 14.2]
///         constant-expression
///         type-id
///         id-expression
ParsedTemplateArgument Parser::ParseTemplateArgument() {
  // C++ [temp.arg]p2:
  //   In a template-argument, an ambiguity between a type-id and an
  //   expression is resolved to a type-id, regardless of the form of
  //   the corresponding template-parameter.
  //
  // Therefore, we initially try to parse a type-id.  
  if (isCXXTypeId(TypeIdAsTemplateArgument)) {
    SourceLocation Loc = Tok.getLocation();
    TypeResult TypeArg = ParseTypeName(/*Range=*/0, 
                                       Declarator::TemplateTypeArgContext);
    if (TypeArg.isInvalid())
      return ParsedTemplateArgument();
    
    return ParsedTemplateArgument(ParsedTemplateArgument::Type,
                                  TypeArg.get().getAsOpaquePtr(), 
                                  Loc);
  }
  
  // Try to parse a template template argument.
  {
    TentativeParsingAction TPA(*this);

    ParsedTemplateArgument TemplateTemplateArgument
      = ParseTemplateTemplateArgument();
    if (!TemplateTemplateArgument.isInvalid()) {
      TPA.Commit();
      return TemplateTemplateArgument;
    }
    
    // Revert this tentative parse to parse a non-type template argument.
    TPA.Revert();
  }
  
  // Parse a non-type template argument. 
  SourceLocation Loc = Tok.getLocation();
  ExprResult ExprArg = ParseConstantExpression();
  if (ExprArg.isInvalid() || !ExprArg.get())
    return ParsedTemplateArgument();

  return ParsedTemplateArgument(ParsedTemplateArgument::NonType, 
                                ExprArg.release(), Loc);
}

ParsedTemplateArgument 
Sema::ActOnPackExpansion(const ParsedTemplateArgument &Arg,
                         SourceLocation EllipsisLoc) {
  if (Arg.isInvalid())
    return Arg;

  switch (Arg.getKind()) {
  case ParsedTemplateArgument::Type: {
    TypeResult Result = ActOnPackExpansion(Arg.getAsType(), EllipsisLoc);
    if (Result.isInvalid())
      return ParsedTemplateArgument();

    return ParsedTemplateArgument(Arg.getKind(), Result.get().getAsOpaquePtr(), 
                                  Arg.getLocation());
  }

  case ParsedTemplateArgument::NonType: {
    ExprResult Result = ActOnPackExpansion(Arg.getAsExpr(), EllipsisLoc);
    if (Result.isInvalid())
      return ParsedTemplateArgument();
    
    return ParsedTemplateArgument(Arg.getKind(), Result.get(), 
                                  Arg.getLocation());
  }
    
  case ParsedTemplateArgument::Template:
    if (!Arg.getAsTemplate().get().containsUnexpandedParameterPack()) {
      SourceRange R(Arg.getLocation());
      if (Arg.getScopeSpec().isValid())
        R.setBegin(Arg.getScopeSpec().getBeginLoc());
      Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
        << R;
      return ParsedTemplateArgument();
    }
      
    return Arg.getTemplatePackExpansion(EllipsisLoc);
  }
  llvm_unreachable("Unhandled template argument kind?");
  return ParsedTemplateArgument();
}

/// \brief Parse a C++ template template argument.
ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
  if (!Tok.is(tok::identifier) && !Tok.is(tok::coloncolon) &&
      !Tok.is(tok::annot_cxxscope))
    return ParsedTemplateArgument();

  // C++0x [temp.arg.template]p1:
  //   A template-argument for a template template-parameter shall be the name
  //   of a class template or a template alias, expressed as id-expression.
  //   
  // We parse an id-expression that refers to a class template or template
  // alias. The grammar we parse is:
  //
  //   nested-name-specifier[opt] template[opt] identifier ...[opt]
  //
  // followed by a token that terminates a template argument, such as ',', 
  // '>', or (in some cases) '>>'.
  CXXScopeSpec SS; // nested-name-specifier, if present
  ParseOptionalCXXScopeSpecifier(SS, ParsedType(),
                                 /*EnteringContext=*/false);
  
  ParsedTemplateArgument Result;
  SourceLocation EllipsisLoc;
  if (SS.isSet() && Tok.is(tok::kw_template)) {
    // Parse the optional 'template' keyword following the 
    // nested-name-specifier.
    SourceLocation TemplateLoc = ConsumeToken();
    
    if (Tok.is(tok::identifier)) {
      // We appear to have a dependent template name.
      UnqualifiedId Name;
      Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
      ConsumeToken(); // the identifier
      
      // Parse the ellipsis.
      if (Tok.is(tok::ellipsis))
        EllipsisLoc = ConsumeToken();
      
      // If the next token signals the end of a template argument,
      // then we have a dependent template name that could be a template
      // template argument.
      TemplateTy Template;
      if (isEndOfTemplateArgument(Tok) &&
          Actions.ActOnDependentTemplateName(getCurScope(), TemplateLoc,
                                             SS, Name, 
                                             /*ObjectType=*/ ParsedType(),
                                             /*EnteringContext=*/false,
                                             Template))
        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
    }
  } else if (Tok.is(tok::identifier)) {
    // We may have a (non-dependent) template name.
    TemplateTy Template;
    UnqualifiedId Name;
    Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
    ConsumeToken(); // the identifier
    
    // Parse the ellipsis.
    if (Tok.is(tok::ellipsis))
      EllipsisLoc = ConsumeToken();

    if (isEndOfTemplateArgument(Tok)) {
      bool MemberOfUnknownSpecialization;
      TemplateNameKind TNK = Actions.isTemplateName(getCurScope(), SS,
                                               /*hasTemplateKeyword=*/false,
                                                    Name,
                                               /*ObjectType=*/ ParsedType(), 
                                                    /*EnteringContext=*/false, 
                                                    Template,
                                                MemberOfUnknownSpecialization);
      if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
        // We have an id-expression that refers to a class template or
        // (C++0x) template alias. 
        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
      }
    }
  }
  
  // If this is a pack expansion, build it as such.
  if (EllipsisLoc.isValid() && !Result.isInvalid())
    Result = Actions.ActOnPackExpansion(Result, EllipsisLoc);
  
  return Result;
}

/// ParseTemplateTemplateParameter - Handle the parsing of template
/// template parameters.
///
///       type-parameter:    [C++ temp.param]
///         'template' '<' template-parameter-list '>' 'class' 
///                  ...[opt] identifier[opt]
///         'template' '<' template-parameter-list '>' 'class' identifier[opt] 
///                  = id-expression
Decl *
Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
  assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");

  // Handle the template <...> part.
  SourceLocation TemplateLoc = ConsumeToken();
  llvm::SmallVector<Decl*,8> TemplateParams;
  SourceLocation LAngleLoc, RAngleLoc;
  {
    ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
    if (ParseTemplateParameters(Depth + 1, TemplateParams, LAngleLoc,
                               RAngleLoc)) {
      return 0;
    }
  }

  // Generate a meaningful error if the user forgot to put class before the
  // identifier, comma, or greater.
  if (!Tok.is(tok::kw_class)) {
    Diag(Tok.getLocation(), diag::err_expected_class_before)
      << PP.getSpelling(Tok);
    return 0;
  }
  ConsumeToken();

  // Parse the ellipsis, if given.
  SourceLocation EllipsisLoc;
  if (Tok.is(tok::ellipsis)) {
    EllipsisLoc = ConsumeToken();
    
    if (!getLang().CPlusPlus0x)
      Diag(EllipsisLoc, diag::ext_variadic_templates);
  }
      
  // Get the identifier, if given.
  SourceLocation NameLoc;
  IdentifierInfo* ParamName = 0;
  if (Tok.is(tok::identifier)) {
    ParamName = Tok.getIdentifierInfo();
    NameLoc = ConsumeToken();
  } else if (Tok.is(tok::equal) || Tok.is(tok::comma) || Tok.is(tok::greater)) {
    // Unnamed template parameter. Don't have to do anything here, just
    // don't consume this token.
  } else {
    Diag(Tok.getLocation(), diag::err_expected_ident);
    return 0;
  }

  TemplateParamsTy *ParamList =
    Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
                                       TemplateLoc, LAngleLoc,
                                       TemplateParams.data(),
                                       TemplateParams.size(),
                                       RAngleLoc);

  // Grab a default argument (if available).
  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
  // we introduce the template parameter into the local scope.
  SourceLocation EqualLoc;
  ParsedTemplateArgument DefaultArg;
  if (Tok.is(tok::equal)) {
    EqualLoc = ConsumeToken();
    DefaultArg = ParseTemplateTemplateArgument();
    if (DefaultArg.isInvalid()) {
      Diag(Tok.getLocation(), 
           diag::err_default_template_template_parameter_not_template);
      static const tok::TokenKind EndToks[] = { 
        tok::comma, tok::greater, tok::greatergreater
      };
      SkipUntil(EndToks, 3, true, true);
    }
  }
  
  return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
                                                ParamList, EllipsisLoc, 
                                                ParamName, NameLoc, Depth, 
                                                Position, EqualLoc, DefaultArg);
}

/// ParseTemplateTemplateParameter - Handle the parsing of template
/// template parameters.
///
///       type-parameter:    [C++ temp.param]
///         'template' '<' template-parameter-list '>' 'class' 
///                  ...[opt] identifier[opt]
///         'template' '<' template-parameter-list '>' 'class' identifier[opt] 
///                  = id-expression
Decl *
Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
  assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");

  // Handle the template <...> part.
  SourceLocation TemplateLoc = ConsumeToken();
  SmallVector<Decl*,8> TemplateParams;
  SourceLocation LAngleLoc, RAngleLoc;
  {
    ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
    if (ParseTemplateParameters(Depth + 1, TemplateParams, LAngleLoc,
                               RAngleLoc)) {
      return 0;
    }
  }

  // Generate a meaningful error if the user forgot to put class before the
  // identifier, comma, or greater. Provide a fixit if the identifier, comma,
  // or greater appear immediately or after 'typename' or 'struct'. In the
  // latter case, replace the keyword with 'class'.
  if (!Tok.is(tok::kw_class)) {
    bool Replace = Tok.is(tok::kw_typename) || Tok.is(tok::kw_struct);
    const Token& Next = Replace ? NextToken() : Tok;
    if (Next.is(tok::identifier) || Next.is(tok::comma) ||
        Next.is(tok::greater) || Next.is(tok::greatergreater) ||
        Next.is(tok::ellipsis))
      Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
        << (Replace ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
                    : FixItHint::CreateInsertion(Tok.getLocation(), "class "));
    else
      Diag(Tok.getLocation(), diag::err_class_on_template_template_param);

    if (Replace)
      ConsumeToken();
  } else
    ConsumeToken();

  // Parse the ellipsis, if given.
  SourceLocation EllipsisLoc;
  if (Tok.is(tok::ellipsis)) {
    EllipsisLoc = ConsumeToken();
    
    Diag(EllipsisLoc,
         getLangOpts().CPlusPlus0x
           ? diag::warn_cxx98_compat_variadic_templates
           : diag::ext_variadic_templates);
  }
      
  // Get the identifier, if given.
  SourceLocation NameLoc;
  IdentifierInfo* ParamName = 0;
  if (Tok.is(tok::identifier)) {
    ParamName = Tok.getIdentifierInfo();
    NameLoc = ConsumeToken();
  } else if (Tok.is(tok::equal) || Tok.is(tok::comma) ||
             Tok.is(tok::greater) || Tok.is(tok::greatergreater)) {
    // Unnamed template parameter. Don't have to do anything here, just
    // don't consume this token.
  } else {
    Diag(Tok.getLocation(), diag::err_expected_ident);
    return 0;
  }

  TemplateParameterList *ParamList =
    Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
                                       TemplateLoc, LAngleLoc,
                                       TemplateParams.data(),
                                       TemplateParams.size(),
                                       RAngleLoc);

  // Grab a default argument (if available).
  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
  // we introduce the template parameter into the local scope.
  SourceLocation EqualLoc;
  ParsedTemplateArgument DefaultArg;
  if (Tok.is(tok::equal)) {
    EqualLoc = ConsumeToken();
    DefaultArg = ParseTemplateTemplateArgument();
    if (DefaultArg.isInvalid()) {
      Diag(Tok.getLocation(), 
           diag::err_default_template_template_parameter_not_template);
      SkipUntil(tok::comma, tok::greater, tok::greatergreater, true, true);
    }
  }
  
  return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
                                                ParamList, EllipsisLoc, 
                                                ParamName, NameLoc, Depth, 
                                                Position, EqualLoc, DefaultArg);
}