gcc/libstdc++-v3/libsupc++/typeinfo

// RTTI support for -*- C++ -*-
// Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
// 2003, 2004, 2005, 2006, 2007, 2009
// Free Software Foundation
//
// 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

#include <exception>

#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 g++.dg/abi/local1.C will fail), and
// whether comparison is to be implemented inline or not.  By default we
// use inline pointer comparison if weak symbols are available, and
// out-of-line strcmp 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.  Inline strcmp is not currently supported.  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
  #if !__GXX_WEAK__
    // If weak symbols are not supported, typeinfo names are not merged.
    #define __GXX_MERGED_TYPEINFO_NAMES 0
  #else
    // On platforms that support weak symbols, typeinfo names are merged.
    #define __GXX_MERGED_TYPEINFO_NAMES 1
  #endif
#endif

// By default follow the same rules as for __GXX_MERGED_TYPEINFO_NAMES.
#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
    { return __name; }

#if !__GXX_TYPEINFO_EQUALITY_INLINE
    bool before(const type_info& __arg) const;

    // 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 operator==(const type_info& __arg) const;
#else
  #if !__GXX_MERGED_TYPEINFO_NAMES
    #error "Inline implementation of type_info comparision requires merging of type_info objects"
  #endif
    /** Returns true if @c *this precedes @c __arg in the implementation's
     *  collation order.  */
    // In new abi we can rely on type_info's NTBS being unique,
    // and therefore address comparisons are sufficient.
    bool before(const type_info& __arg) const
    { return __name < __arg.__name; }

    bool operator==(const type_info& __arg) const
    { return __name == __arg.__name; }
#endif
    bool operator!=(const type_info& __arg) const
    { return !operator==(__arg); }

    // 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() throw() { }

    // This declaration is not useless:
    // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
    virtual ~bad_cast() throw();

    // See comment in eh_exception.cc.
    virtual const char* what() const throw();
  };
  
  /** 
   *  @brief Thrown when a NULL pointer in a @c typeid expression is used.
   *  @ingroup exceptions
   */
  class bad_typeid : public exception 
  {
  public:
    bad_typeid () throw() { }

    // This declaration is not useless:
    // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
    virtual ~bad_typeid() throw();

    // See comment in eh_exception.cc.
    virtual const char* what() const throw();
  };
} // namespace std

#pragma GCC visibility pop

} // extern "C++"
#endif