classDeclaration:
     'class' Identifier ';'
   | 'class' Identifier (':' baseClassList)? structBody
   | 'class' Identifier templateParameters constraint? (structBody | ';')
   | 'class' Identifier templateParameters constraint? (':' baseClassList)? structBody
   | 'class' Identifier templateParameters (':' baseClassList)? constraint? structBody
   ;