p_dynamic_cast.h

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/*
 *  p_dynamic_cast.cpp - Pentagram Dynamic Cast Emulation Header
 *
 *  Copyright (C) 2003-2006  The Pentagram Team
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifndef P_DYNAMIC_CAST_H
#define P_DYNAMIC_CAST_H

// The Pentagram dynamic cast
template<class A, class B> inline A p_dynamic_cast (B *object)
{
        if (object && object->IsOfType(static_cast<A>(0)->ClassType)) return static_cast<A>(object);
        return 0;
}

// This is just a 'type' used to differentiate each class.
struct RunTimeClassType
{
        const char *    class_name;
        inline bool operator == (const RunTimeClassType &other) const { return this == &other; }
};

//
// Include this in every class. It sets up the class to be able to use 
// p_dynamic_cast. Make sure this is public!
//
#define ENABLE_RUNTIME_CLASSTYPE()                                                                                              \
        static const RunTimeClassType   ClassType;                                                                      \
        virtual bool IsOfType(const RunTimeClassType & type);                                           \
        virtual bool IsOfType(const char * type);                                                                       \
        template<class Type> inline bool IsOfType() { return IsOfType(Type::ClassType); }       \
        virtual const RunTimeClassType & GetClassType() { return ClassType; }
        


//
// Define this in the source files of base classes
//
#define DEFINE_RUNTIME_CLASSTYPE_CODE_BASE_CLASS(Classname)                     \
const RunTimeClassType Classname::ClassType = {                                         \
        #Classname                                                                                                              \
};                                                                                                                                      \
                                                                                                                                        \
bool Classname::IsOfType(const RunTimeClassType & type)                         \
{                                                                                                                                       \
        if (type == ClassType) return true;                                                             \
        return false;                                                                                                   \
}                                                                                                                                       \
                                                                                                                                        \
bool Classname::IsOfType(const char * type)                                                     \
{                                                                                                                                       \
        if (!std::strcmp(type,ClassType.class_name)) return true;               \
        return false;                                                                                                   \
}


//
// Define this in the source files of child classes, with 1 parent
//
#define DEFINE_RUNTIME_CLASSTYPE_CODE(Classname,ParentClassname)        \
const RunTimeClassType Classname::ClassType = {                                         \
        #Classname                                                                                                              \
};                                                                                                                                      \
                                                                                                                                        \
bool Classname::IsOfType(const RunTimeClassType & type)                         \
{                                                                                                                                       \
        if (type == ClassType) return true;                                                             \
        return ParentClassname::IsOfType(type);                                                 \
}                                                                                                                                       \
                                                                                                                                        \
bool Classname::IsOfType(const char * type)                                                     \
{                                                                                                                                       \
        if (!std::strcmp(type,ClassType.class_name)) return true;               \
        return ParentClassname::IsOfType(type);                                                 \
}



//
// Define this in the source files of child classes, with 2 parents
//
#define DEFINE_RUNTIME_CLASSTYPE_CODE_MULTI2(Classname,Parent1,Parent2) \
const RunTimeClassType Classname::ClassType = {                                                 \
        #Classname                                                                                                                      \
};                                                                                                                                              \
                                                                                                                                                \
bool Classname::IsOfType(const RunTimeClassType &type)                                  \
{                                                                                                                                               \
        typedef Parent1 P1;                                                                                                     \
        typedef Parent2 P2;                                                                                                     \
        if (type == ClassType) return true;                                                                     \
        bool ret = P1::IsOfType(type);                                                                          \
        if (ret) return true;                                                                                           \
        return P2::IsOfType(type);                                                                                      \
}                                                                                                                                               \
                                                                                                                                                \
bool Classname::IsOfType(const char * type)                                                             \
{                                                                                                                                               \
        typedef Parent1 P1;                                                                                                     \
        typedef Parent2 P2;                                                                                                     \
        if (!std::strcmp(type,ClassType.class_name)) return true;                       \
        bool ret = P1::IsOfType(type);                                                                          \
        if (ret) return true;                                                                                           \
        return P2::IsOfType(type);                                                                                      \
}

#endif //P_RUNTIME_CLASSTYPE

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