The C and C++ Include Header Files

/usr/include/c++/11/typeinfo


$ cat -n /usr/include/c++/11/typeinfo

     1	// RTTI support for -*- C++ -*-
     2	// Copyright (C) 1994-2021 Free Software Foundation, Inc.
     3	//
     4	// This file is part of GCC.
     5	//
     6	// GCC is free software; you can redistribute it and/or modify
     7	// it under the terms of the GNU General Public License as published by
     8	// the Free Software Foundation; either version 3, or (at your option)
     9	// any later version.
    10	//
    11	// GCC is distributed in the hope that it will be useful,
    12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
    13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14	// GNU General Public License for more details.
    15	//
    16	// Under Section 7 of GPL version 3, you are granted additional
    17	// permissions described in the GCC Runtime Library Exception, version
    18	// 3.1, as published by the Free Software Foundation.
    19	
    20	// You should have received a copy of the GNU General Public License and
    21	// a copy of the GCC Runtime Library Exception along with this program;
    22	// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    23	// <http://www.gnu.org/licenses/>.
    24	
    25	/** @file typeinfo
    26	 *  This is a Standard C++ Library header.
    27	 */
    28	
    29	#ifndef _TYPEINFO
    30	#define _TYPEINFO
    31	
    32	#pragma GCC system_header
    33	
    34	#include <bits/exception.h>
    35	#if __cplusplus >= 201103L
    36	#include <bits/hash_bytes.h>
    37	#endif
    38	
    39	#pragma GCC visibility push(default)
    40	
    41	extern "C++" {
    42	
    43	namespace __cxxabiv1
    44	{
    45	  class __class_type_info;
    46	} // namespace __cxxabiv1
    47	
    48	// Determine whether typeinfo names for the same type are merged (in which
    49	// case comparison can just compare pointers) or not (in which case strings
    50	// must be compared), and whether comparison is to be implemented inline or
    51	// not.  We used to do inline pointer comparison by default if weak symbols
    52	// are available, but even with weak symbols sometimes names are not merged
    53	// when objects are loaded with RTLD_LOCAL, so now we always use strcmp by
    54	// default.  For ABI compatibility, we do the strcmp inline if weak symbols
    55	// are available, and out-of-line if not.  Out-of-line pointer comparison
    56	// is used where the object files are to be portable to multiple systems,
    57	// some of which may not be able to use pointer comparison, but the
    58	// particular system for which libstdc++ is being built can use pointer
    59	// comparison; in particular for most ARM EABI systems, where the ABI
    60	// specifies out-of-line comparison.  The compiler's target configuration
    61	// can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to
    62	// 1 or 0 to indicate whether or not comparison is inline, and
    63	// __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer
    64	// comparison can be used.
    65	
    66	#ifndef __GXX_MERGED_TYPEINFO_NAMES
    67	// By default, typeinfo names are not merged.
    68	#define __GXX_MERGED_TYPEINFO_NAMES 0
    69	#endif
    70	
    71	// By default follow the old inline rules to avoid ABI changes.
    72	#ifndef __GXX_TYPEINFO_EQUALITY_INLINE
    73	  #if !__GXX_WEAK__
    74	    #define __GXX_TYPEINFO_EQUALITY_INLINE 0
    75	  #else
    76	    #define __GXX_TYPEINFO_EQUALITY_INLINE 1
    77	  #endif
    78	#endif
    79	
    80	namespace std
    81	{
    82	  /**
    83	   *  @brief  Part of RTTI.
    84	   *
    85	   *  The @c type_info class describes type information generated by
    86	   *  an implementation.
    87	  */
    88	  class type_info
    89	  {
    90	  public:
    91	    /** Destructor first. Being the first non-inline virtual function, this
    92	     *  controls in which translation unit the vtable is emitted. The
    93	     *  compiler makes use of that information to know where to emit
    94	     *  the runtime-mandated type_info structures in the new-abi.  */
    95	    virtual ~type_info();
    96	
    97	    /** Returns an @e implementation-defined byte string; this is not
    98	     *  portable between compilers!  */
    99	    const char* name() const _GLIBCXX_NOEXCEPT
   100	    { return __name[0] == '*' ? __name + 1 : __name; }
   101	
   102	#if !__GXX_TYPEINFO_EQUALITY_INLINE
   103	    // In old abi, or when weak symbols are not supported, there can
   104	    // be multiple instances of a type_info object for one
   105	    // type. Uniqueness must use the _name value, not object address.
   106	    bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT;
   107	    bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT;
   108	#else
   109	  #if !__GXX_MERGED_TYPEINFO_NAMES
   110	    /** Returns true if @c *this precedes @c __arg in the implementation's
   111	     *  collation order.  */
   112	    // Even with the new abi, on systems that support dlopen
   113	    // we can run into cases where type_info names aren't merged,
   114	    // so we still need to do string comparison.
   115	    bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT
   116	    { return (__name[0] == '*' && __arg.__name[0] == '*')
   117		? __name < __arg.__name
   118		: __builtin_strcmp (__name, __arg.__name) < 0; }
   119	
   120	    bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT
   121	    {
   122	      return ((__name == __arg.__name)
   123		      || (__name[0] != '*' &&
   124			  __builtin_strcmp (__name, __arg.__name) == 0));
   125	    }
   126	  #else
   127	    // On some targets we can rely on type_info's NTBS being unique,
   128	    // and therefore address comparisons are sufficient.
   129	    bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT
   130	    { return __name < __arg.__name; }
   131	
   132	    bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT
   133	    { return __name == __arg.__name; }
   134	  #endif
   135	#endif
   136	
   137	#if __cpp_impl_three_way_comparison < 201907L
   138	    bool operator!=(const type_info& __arg) const _GLIBCXX_NOEXCEPT
   139	    { return !operator==(__arg); }
   140	#endif
   141	
   142	#if __cplusplus >= 201103L
   143	    size_t hash_code() const noexcept
   144	    {
   145	#  if !__GXX_MERGED_TYPEINFO_NAMES
   146	      return _Hash_bytes(name(), __builtin_strlen(name()),
   147				 static_cast<size_t>(0xc70f6907UL));
   148	#  else
   149	      return reinterpret_cast<size_t>(__name);
   150	#  endif
   151	    }
   152	#endif // C++11
   153	
   154	    // Return true if this is a pointer type of some kind
   155	    virtual bool __is_pointer_p() const;
   156	
   157	    // Return true if this is a function type
   158	    virtual bool __is_function_p() const;
   159	
   160	    // Try and catch a thrown type. Store an adjusted pointer to the
   161	    // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
   162	    // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
   163	    // type, then THR_OBJ is the pointer itself. OUTER indicates the
   164	    // number of outer pointers, and whether they were const
   165	    // qualified.
   166	    virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
   167				    unsigned __outer) const;
   168	
   169	    // Internally used during catch matching
   170	    virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
   171				     void **__obj_ptr) const;
   172	
   173	  protected:
   174	    const char *__name;
   175	
   176	    explicit type_info(const char *__n): __name(__n) { }
   177	
   178	  private:
   179	    /// Assigning type_info is not supported.
   180	    type_info& operator=(const type_info&);
   181	    type_info(const type_info&);
   182	  };
   183	
   184	  /**
   185	   *  @brief  Thrown during incorrect typecasting.
   186	   *  @ingroup exceptions
   187	   *
   188	   *  If you attempt an invalid @c dynamic_cast expression, an instance of
   189	   *  this class (or something derived from this class) is thrown.  */
   190	  class bad_cast : public exception
   191	  {
   192	  public:
   193	    bad_cast() _GLIBCXX_USE_NOEXCEPT { }
   194	
   195	    // This declaration is not useless:
   196	    // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
   197	    virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT;
   198	
   199	    // See comment in eh_exception.cc.
   200	    virtual const char* what() const _GLIBCXX_USE_NOEXCEPT;
   201	  };
   202	
   203	  /**
   204	   *  @brief Thrown when a NULL pointer in a @c typeid expression is used.
   205	   *  @ingroup exceptions
   206	   */
   207	  class bad_typeid : public exception
   208	  {
   209	  public:
   210	    bad_typeid () _GLIBCXX_USE_NOEXCEPT { }
   211	
   212	    // This declaration is not useless:
   213	    // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
   214	    virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT;
   215	
   216	    // See comment in eh_exception.cc.
   217	    virtual const char* what() const _GLIBCXX_USE_NOEXCEPT;
   218	  };
   219	} // namespace std
   220	
   221	} // extern "C++"
   222	
   223	#pragma GCC visibility pop
   224	
   225	#endif