text: // RTTI support for -*- C++ -*-
  // Copyright (C) 1994-2020 Free Software Foundation, Inc.
  //
  // This file is part of GCC.
  //
  // GCC is free software; you can redistribute it and/or modify
  // it under the terms of the GNU General Public License as published by
  // the Free Software Foundation; either version 3, or (at your option)
  // any later version.
  //
  // GCC is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  // GNU General Public License for more details.
  //
  // Under Section 7 of GPL version 3, you are granted additional
  // permissions described in the GCC Runtime Library Exception, version
  // 3.1, as published by the Free Software Foundation.
  
  // You should have received a copy of the GNU General Public License and
  // a copy of the GCC Runtime Library Exception along with this program;
  // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  // <http://www.gnu.org/licenses/>.
  
  /** @file typeinfo
   *  This is a Standard C++ Library header.
   */
  
  #ifndef _TYPEINFO
  #define _TYPEINFO
  
  #pragma GCC system_header
  
  #include <bits/exception.h>
  #if __cplusplus >= 201103L
  #include <bits/hash_bytes.h>
  #endif
  
  #pragma GCC visibility push(default)
  
  extern "C++" {
  
  namespace __cxxabiv1
  {
    class __class_type_info;
  } // namespace __cxxabiv1
  
  // Determine whether typeinfo names for the same type are merged (in which
  // case comparison can just compare pointers) or not (in which case strings
  // must be compared), and whether comparison is to be implemented inline or
  // not.  We used to do inline pointer comparison by default if weak symbols
  // are available, but even with weak symbols sometimes names are not merged
  // when objects are loaded with RTLD_LOCAL, so now we always use strcmp by
  // default.  For ABI compatibility, we do the strcmp inline if weak symbols
  // are available, and out-of-line if not.  Out-of-line pointer comparison
  // is used where the object files are to be portable to multiple systems,
  // some of which may not be able to use pointer comparison, but the
  // particular system for which libstdc++ is being built can use pointer
  // comparison; in particular for most ARM EABI systems, where the ABI
  // specifies out-of-line comparison.  The compiler's target configuration
  // can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to
  // 1 or 0 to indicate whether or not comparison is inline, and
  // __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer
  // comparison can be used.
  
  #ifndef __GXX_MERGED_TYPEINFO_NAMES
  // By default, typeinfo names are not merged.
  #define __GXX_MERGED_TYPEINFO_NAMES 0
  #endif
  
  // By default follow the old inline rules to avoid ABI changes.
  #ifndef __GXX_TYPEINFO_EQUALITY_INLINE
    #if !__GXX_WEAK__
      #define __GXX_TYPEINFO_EQUALITY_INLINE 0
    #else
      #define __GXX_TYPEINFO_EQUALITY_INLINE 1
    #endif
  #endif
  
  namespace std
  {
    /**
     *  @brief  Part of RTTI.
     *
     *  The @c type_info class describes type information generated by
     *  an implementation.
    */
    class type_info
    {
    public:
      /** Destructor first. Being the first non-inline virtual function, this
       *  controls in which translation unit the vtable is emitted. The
       *  compiler makes use of that information to know where to emit
       *  the runtime-mandated type_info structures in the new-abi.  */
      virtual ~type_info();
  
      /** Returns an @e implementation-defined byte string; this is not
       *  portable between compilers!  */
      const char* name() const _GLIBCXX_NOEXCEPT
      { return __name[0] == '*' ? __name + 1 : __name; }
  
  #if !__GXX_TYPEINFO_EQUALITY_INLINE
      // In old abi, or when weak symbols are not supported, there can
      // be multiple instances of a type_info object for one
      // type. Uniqueness must use the _name value, not object address.
      bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT;
      bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT;
  #else
    #if !__GXX_MERGED_TYPEINFO_NAMES
      /** Returns true if @c *this precedes @c __arg in the implementation's
       *  collation order.  */
      // Even with the new abi, on systems that support dlopen
      // we can run into cases where type_info names aren't merged,
      // so we still need to do string comparison.
      bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT
      { return (__name[0] == '*' && __arg.__name[0] == '*')
  	? __name < __arg.__name
  	: __builtin_strcmp (__name, __arg.__name) < 0; }
  
      bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT
      {
        return ((__name == __arg.__name)
  	      || (__name[0] != '*' &&
  		  __builtin_strcmp (__name, __arg.__name) == 0));
      }
    #else
      // On some targets we can rely on type_info's NTBS being unique,
      // and therefore address comparisons are sufficient.
      bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT
      { return __name < __arg.__name; }
  
      bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT
      { return __name == __arg.__name; }
    #endif
  #endif
  
  #if __cpp_impl_three_way_comparison < 201907L
      bool operator!=(const type_info& __arg) const _GLIBCXX_NOEXCEPT
      { return !operator==(__arg); }
  #endif
  
  #if __cplusplus >= 201103L
      size_t hash_code() const noexcept
      {
  #  if !__GXX_MERGED_TYPEINFO_NAMES
        return _Hash_bytes(name(), __builtin_strlen(name()),
  			 static_cast<size_t>(0xc70f6907UL));
  #  else
        return reinterpret_cast<size_t>(__name);
  #  endif
      }
  #endif // C++11
  
      // Return true if this is a pointer type of some kind
      virtual bool __is_pointer_p() const;
  
      // Return true if this is a function type
      virtual bool __is_function_p() const;
  
      // Try and catch a thrown type. Store an adjusted pointer to the
      // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
      // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
      // type, then THR_OBJ is the pointer itself. OUTER indicates the
      // number of outer pointers, and whether they were const
      // qualified.
      virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
  			    unsigned __outer) const;
  
      // Internally used during catch matching
      virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
  			     void **__obj_ptr) const;
  
    protected:
      const char *__name;
  
      explicit type_info(const char *__n): __name(__n) { }
  
    private:
      /// Assigning type_info is not supported.
      type_info& operator=(const type_info&);
      type_info(const type_info&);
    };
  
    /**
     *  @brief  Thrown during incorrect typecasting.
     *  @ingroup exceptions
     *
     *  If you attempt an invalid @c dynamic_cast expression, an instance of
     *  this class (or something derived from this class) is thrown.  */
    class bad_cast : public exception
    {
    public:
      bad_cast() _GLIBCXX_USE_NOEXCEPT { }
  
      // This declaration is not useless:
      // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
      virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT;
  
      // See comment in eh_exception.cc.
      virtual const char* what() const _GLIBCXX_USE_NOEXCEPT;
    };
  
    /**
     *  @brief Thrown when a NULL pointer in a @c typeid expression is used.
     *  @ingroup exceptions
     */
    class bad_typeid : public exception
    {
    public:
      bad_typeid () _GLIBCXX_USE_NOEXCEPT { }
  
      // This declaration is not useless:
      // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
      virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT;
  
      // See comment in eh_exception.cc.
      virtual const char* what() const _GLIBCXX_USE_NOEXCEPT;
    };
  } // namespace std
  
  } // extern "C++"
  
  #pragma GCC visibility pop
  
  #endif
  