OpenSceneGraph/include/osgIntrospection/Converter
Robert Osfield c80313ccd0 From David Callu,
"
Found in the join file the fix for the bug found by Rafa.


    Problem :

        osgIntrospection::Value grp(new osg::Group);

        osgIntrospection::ValueList vlcall;
        vlcall.push_back(osgIntrospection::Value("toto"));

       const osgIntrospection::MethodInfo *m =
grp->getType.getCompatibleMethod("setName", vlcall, true);

       if (m)
       {
            m->invoke(grp, vlcall);      // ** SEGFAULT here
       }





    Algorithm explanation :

          The "invoke" method try to convert "grp", which reflect an
"osg::Group*", in a
          "osgIntrospection::Value", which reflect a "osg::Node*".
This because
          the "setName(const char *)" method found by
"grp->getType.getCompatibleMethod"
          is an "osg::Object" type method.

          When osgIntrospection do this conversion it try :
             - to found a "osgIntrospection::Converter"  to convert
               from "osg::Group*" to "osg::Node*"
             - to found a chain of "osgIntrospection::Converter" to convert
               from "osg::Group*" to "one or many type" to "osg::Node*"
             - to converte an Enum to int or unsigned int
             - to convert the value in its "value string representation",
               then converte this string in the destination value

          Else it throw a "TypeConversionException".







     Bug :

          1)
          When osgIntrospection try to found a chain of
"osgIntrospection::Converter"
          It could do any downcast or (Type to SuperType) or upcast
(SuperType to Type).
          This mean the the chain could be :
          osg::Group to osg::Transform to osg::Camera to
          osg::CullSettings to osg::CullStack to
osg::CollectOccludersVisitor to
          osg::NodeVisitor to osg::Referenced to osg::Object

         During the convertion with this chain, A METTRE failed and
the pointer in
         "grp" is set NULL. But the "grp" is always a valid
"osgIntrospection::Value"
         and so, osgIntrospection accept the conversion. Then it try
to use this pointer
         to call the "setName" function. And Bing SEGFAULT.


         2)
             In "bool Reflection::accum_conv_path( ... )"
             the convection path isn't accumulate in the recursive loop.
             this cause multi request of a conversion path, and a
slowdown in the
             conversion algorithm.

         3)
             Use of the last conversion way in a conversion from
pointer to pointer
             this mean you can do this :
             "osg::Node*" to " value string representation" to "osg::Material*"
             What a bad thing !!!




    Solution :

         1)
          Introduce the concept of dynamic_cast and static_cast.
          now, to do a conversion, osgIntrospection does this :

             - to found a "osgIntrospection::Converter"  to convert
               from "osg::Group*" to "osg::Node*"
             - to found a chain of "osgIntrospection::Converter" to convert
               from "osg::Group*" to "one or many type" to "osg::Node*"
               only with static_cast, downcast (Type to SuperType)

             - to found, if the source and the destination are two pointer,
               a chain of "osgIntrospection::Converter" to convert
               from "osg::Group*" to "one or many type" to "osg::Node*"
               only with dynamic_cast, upcast (SuperType to Type)

             - to convert an Enum to int or to unsigned int
             - to convert the value in its "value string representation",
               then convert this string in the destination value

          Else it throw a "TypeConversionException".


          Add the "enum CastType" to distinguish the static_cast or
dynamic_cast converter.
          Add file OpenSceneGraph/include/osgIntrospection/CastType

         2)
         add a line to accumulate converter in converter Path.

         3)
         add a line to check if source and destination are pointer.
"
2007-06-30 14:21:34 +00:00

92 lines
2.7 KiB
C++

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
*
* This library is open source and may be redistributed and/or modified under
* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
* (at your option) any later version. The full license is in LICENSE file
* included with this distribution, and on the openscenegraph.org website.
*
* This library 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
* OpenSceneGraph Public License for more details.
*/
//osgIntrospection - Copyright (C) 2005 Marco Jez
#ifndef OSGINTROSPECTION_CONVERTER_
#define OSGINTROSPECTION_CONVERTER_
#include <osgIntrospection/Value>
#include <list>
namespace osgIntrospection
{
struct Converter
{
virtual CastType getCastType() const = 0;
virtual Value convert(const Value& ) const = 0;
virtual ~Converter() {}
};
typedef std::list<const Converter* > ConverterList;
class CompositeConverter: public Converter
{
public:
CompositeConverter(const ConverterList& cvt): cvt_(cvt) {}
CompositeConverter(ConverterList& cvt) { cvt_.swap(cvt); }
virtual ~CompositeConverter() {}
virtual Value convert(const Value& src) const
{
Value accum(src);
for (ConverterList::const_iterator i=cvt_.begin(); i!=cvt_.end(); ++i)
accum = (*i)->convert(accum);
return accum;
}
virtual CastType getCastType() const { return COMPOSITE_CAST; }
private:
ConverterList cvt_;
};
template<typename S, typename D>
struct StaticConverter: Converter
{
virtual ~StaticConverter() {}
virtual Value convert(const Value& src) const
{
return static_cast<D>(variant_cast<S>(src));
}
virtual CastType getCastType() const { return STATIC_CAST; }
};
template<typename S, typename D>
struct DynamicConverter: Converter
{
virtual ~DynamicConverter() {}
virtual Value convert(const Value& src) const
{
return dynamic_cast<D>(variant_cast<S>(src));
}
virtual CastType getCastType() const { return DYNAMIC_CAST; }
};
template<typename S, typename D>
struct ReinterpretConverter: Converter
{
virtual ~ReinterpretConverter() {}
virtual Value convert(const Value& src) const
{
return reinterpret_cast<D>(variant_cast<S>(src));
}
virtual CastType getCastType() const { return REINTERPRET_CAST; }
};
}
#endif