PropertyBag.cpp

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/***************************************************************************
  tag: Peter Soetens  Mon May 10 19:10:30 CEST 2004  PropertyBag.cxx

                        PropertyBag.cxx -  description
                           -------------------
    begin                : Mon May 10 2004
    copyright            : (C) 2004 Peter Soetens
    email                : peter.soetens@mech.kuleuven.ac.be

 ***************************************************************************
 *   This library 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;                 *
 *   version 2 of the License.                                             *
 *                                                                         *
 *   As a special exception, you may use this file as part of a free       *
 *   software library without restriction.  Specifically, if other files   *
 *   instantiate templates or use macros or inline functions from this     *
 *   file, or you compile this file and link it with other files to        *
 *   produce an executable, this file does not by itself cause the         *
 *   resulting executable to be covered by the GNU General Public          *
 *   License.  This exception does not however invalidate any other        *
 *   reasons why the executable file might be covered by the GNU General   *
 *   Public License.                                                       *
 *                                                                         *
 *   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 GNU     *
 *   Lesser General Public License for more details.                       *
 *                                                                         *
 *   You should have received a copy of the GNU General Public             *
 *   License along with this library; if not, write to the Free Software   *
 *   Foundation, Inc., 59 Temple Place,                                    *
 *   Suite 330, Boston, MA  02111-1307  USA                                *
 *                                                                         *
 ***************************************************************************/

#ifdef ORO_PRAGMA_INTERFACE
#pragma implementation
#endif
#include "PropertyBag.hpp"
#include "Property.hpp"
#include "types/PropertyDecomposition.hpp"
#include "types/Types.hpp"
#include "Logger.hpp"
#include <algorithm>
#include "rtt-fwd.hpp"

namespace RTT
{
    using namespace detail;
    using namespace std;

    PropertyBag::PropertyBag( )
        : mproperties(), type("PropertyBag")
    {}

    PropertyBag::PropertyBag( const std::string& _type)
        : mproperties(), type(_type)
    {}

    PropertyBag::PropertyBag( const PropertyBag& orig)
        : mproperties(), type( orig.getType() )
    {
        for( const_iterator i = orig.mproperties.begin(); i != orig.mproperties.end(); ++i) {
            if ( orig.ownsProperty( *i ) ) {
                PropertyBase* copy = (*i)->clone();
                this->ownProperty( copy );
            } else {
                this->add( *i );
            }
        }
    }

    PropertyBag::~PropertyBag()
    {
        this->clear();
    }

    void PropertyBag::add(PropertyBase *p)
    {
        this->addProperty(*p);
    }

    void PropertyBag::remove(PropertyBase *p)
    {
        this->removeProperty(p);
    }

    bool PropertyBag::ownProperty(PropertyBase* p)
    {
        if (p == 0)
            return false;
        if ( ! p->ready() )
            return false;
        removeProperty(p);
        mproperties.push_back(p);
        mowned_props.push_back(p);
        return true;
    }

    bool PropertyBag::ownsProperty(PropertyBase* p) const
    {
        if (p == 0)
            return false;
        const_iterator i = std::find(mowned_props.begin(), mowned_props.end(), p);
        if ( i != mowned_props.end() )
            return true;
        return false;
    }

    bool PropertyBag::addProperty(PropertyBase& p)
    {
        if (&p == 0)
            return false;
        if ( ! p.ready() )
            return false;
        mproperties.push_back(&p);
        return true;
    }

    bool PropertyBag::removeProperty(PropertyBase *p)
    {
        if (p == 0)
            return false;
        iterator i = std::find(mproperties.begin(), mproperties.end(), p);
        if ( i != mproperties.end() ) {
            mproperties.erase(i);
            i = std::find(mowned_props.begin(), mowned_props.end(), p);
            if ( i != mowned_props.end() ) {
                delete *i;
                mowned_props.erase(i); // invalidates i
            }
            return true;
        }
        return false;
    }

    void PropertyBag::clear()
    {
        mproperties.clear();
        for ( iterator i = mowned_props.begin();
              i != mowned_props.end();
              i++ )
            {
                delete *i;
            }
        mowned_props.clear();
    }

    void PropertyBag::list(std::vector<std::string> &names) const
    {
        for ( const_iterator i = mproperties.begin();
              i != mproperties.end();
              i++ )
            {
                names.push_back( (*i)->getName() );
            }
    }

    std::vector<std::string> PropertyBag::list() const
    {
        std::vector<std::string> names;
        for ( const_iterator i = mproperties.begin();
              i != mproperties.end();
              i++ )
            {
                names.push_back( (*i)->getName() );
            }
        return names;
    }

    PropertyBag::Properties PropertyBag::getProperties(const std::string& name) const
    {
        Properties names;
        for ( const_iterator i = mproperties.begin();
              i != mproperties.end();
              i++ )
            {
                if ( (*i)->getName() ==  name )
                    names.push_back( (*i) );
            }
        return names;
    }


    void PropertyBag::identify( PropertyIntrospection* pi ) const
    {
        for ( const_iterator i = mproperties.begin();
              i != mproperties.end();
              i++ )
            {
                (*i)->identify(pi);
            }
    }

    void PropertyBag::identify( PropertyBagVisitor* pi ) const
    {
        for ( const_iterator i = mproperties.begin();
              i != mproperties.end();
              i++ )
            {
                (*i)->identify(pi);
            }
    }

    struct FindProp : public std::binary_function<const base::PropertyBase*,const std::string, bool>
    {
        bool operator()(const base::PropertyBase* b1, const std::string& b2) const { return b1->getName() == b2; }
    };
    PropertyBase* PropertyBag::find(const std::string& name) const
    {
        const_iterator i( std::find_if(mproperties.begin(), mproperties.end(), std::bind2nd(FindProp(), name ) ) );
        if ( i != mproperties.end() )
            return ( *i );
        return 0;
    }

    base::PropertyBase* PropertyBag::getProperty(const std::string& name) const
    {
        const_iterator i( std::find_if(mproperties.begin(), mproperties.end(), std::bind2nd(FindProp(), name ) ) );
        if ( i != mproperties.end() )
            return *i;
        return 0;
    }


    PropertyBag& PropertyBag::operator=(const PropertyBag& orig)
    {
        if(this == &orig)
            return *this;

        this->clear();

        const_iterator i = orig.getProperties().begin();
        while (i != orig.getProperties().end() )
            {
                add( (*i) );
                ++i;
            }
        this->setType( orig.getType() );
        return *this;
    }

    PropertyBag& PropertyBag::operator<<=(const PropertyBag& source)
    {
        //iterate over orig, update or clone PropertyBases
        const_iterator it(source.getProperties().begin());
        while ( it != source.getProperties().end() )
            {
                PropertyBase* mine = find( (*it)->getName() );
                if (mine != 0)
                    remove(mine);
                add( (*it) );
                ++it;
            }
        this->setType( source.getType() );
        return *this;
    }

    template<>
    bool Property<PropertyBag>::update( const Property<PropertyBag>& orig)
    {
        if ( !ready() )
            return false;
        if ( _description.empty() )
            _description = orig.getDescription();
        return updateProperties( this->_value->set(), orig.rvalue() );
    }

    template<>
    bool Property<PropertyBag>::refresh( const Property<PropertyBag>& orig)
    {
        if ( !ready() )
            return false;
        return refreshProperties( this->_value->set(), orig.rvalue() );
    }

    template<>
    bool Property<PropertyBag>::copy( const Property<PropertyBag>& orig)
    {
        if ( !ready() )
            return false;
        _name = orig.getName();
        _description = orig.getDescription();
        return copyProperties( this->_value->set(), orig.rvalue() );
    }

    std::ostream& operator<<(std::ostream& os, const PropertyBag& bag) {
        int size = bag.size();
        os << "[[";
        for(int i=0; i != size; ++i) {
            os << bag.getItem(i)->getName() << "='"<< bag.getItem(i) <<"'"<<endl;
        }
        os << "]]";

        return os;
    }

    std::istream& operator>>(std::istream& is, PropertyBag& bag) { return is; }


    PropertyBase* findProperty(const PropertyBag& bag, const std::string& nameSequence, const std::string& separator)
    {
        PropertyBase* result;
        Property<PropertyBag>*  result_bag;
        std::string token;
        std::string::size_type start = 0;
        if ( separator.length() != 0 && nameSequence.find(separator) == 0 ) // detect 'root' attribute
            start = separator.length();
        std::string::size_type len = nameSequence.find(separator, start);
        if (len != std::string::npos) {
            token = nameSequence.substr(start,len-start);
            start = len + separator.length();      // reset start to next token.
            if ( start >= nameSequence.length() )
                start = std::string::npos;
        }
        else {
            token = nameSequence.substr(start);
            start = std::string::npos; // do not look further.
        }
        result = bag.find(token);
        if (result != 0 ) // get the base with this name
        {
            result_bag = dynamic_cast<Property<PropertyBag>*>(result);
            if ( result_bag != 0 && start != std::string::npos ) {
                return findProperty( result_bag->rvalue(), nameSequence.substr( start ), separator );// a bag so search recursively
            }
            else
                return result; // not a bag, so it is a result.
        }
        return 0; // failure
    }

    void listPropertiesHelper(const PropertyBag& source, const std::string& separator, const string& prefix, vector<string>& result)
    {
        PropertyBag::const_iterator it( source.getProperties().begin() );
        while ( it != source.getProperties().end() ) {
            Property<PropertyBag>* sub = dynamic_cast<Property<PropertyBag>*>(*it);
            string itemname = prefix.empty() ? (*it)->getName() : prefix + separator + (*it)->getName();
            result.push_back( itemname );
            if ( sub && sub->ready() ) {
                listPropertiesHelper( sub->value(), separator, itemname, result );
            }
            ++it;
        }
    }

    void listDescriptionsHelper(const PropertyBag& source, const std::string& separator, vector<string>& result)
    {
        PropertyBag::const_iterator it( source.getProperties().begin() );
        while ( it != source.getProperties().end() ) {
            Property<PropertyBag>* sub = dynamic_cast<Property<PropertyBag>*>(*it);
            result.push_back( (*it)->getDescription() );
            if ( sub && sub->ready() ) {
                listDescriptionsHelper( sub->value(), separator, result );
            }
            ++it;
        }
    }
    vector<string> listProperties(const PropertyBag& source, const std::string& separator)
    {
        vector<string> result;
        listPropertiesHelper( source, separator, "", result);
        return result;
    }

    vector<string> listPropertyDescriptions(const PropertyBag& source, const std::string& separator)
    {
        vector<string> result;
        listDescriptionsHelper( source, separator, result);
        return result;
    }

    bool storeProperty(PropertyBag& bag, const std::string& path, base::PropertyBase* item, const std::string& separator )
    {
        Logger::In in("storeProperty");
        if ( path.empty() || path == separator )
            return bag.ownProperty( item );
        // find top-level parent
        string pname, rest;
        if ( path.find(separator) != string::npos ) {
            pname = path.substr( 0, path.find(separator));
            rest  = path.substr( path.find(separator) + separator.length() );
        } else {
            pname = path;
        }

        if ( pname.empty() && !rest.empty() )
            return storeProperty( bag, rest, item, separator); // recurse

        // pname is parent
        PropertyBase* parent = bag.find(pname);
        if (!parent) {
            bag.ownProperty( new Property<PropertyBag>(pname,"") );
            parent = bag.find(pname);
        }
        Property<PropertyBag>* parentbag = dynamic_cast<Property<PropertyBag>* >(parent);
        if ( !parentbag ) {
            log(Error) << "Path component '" << pname << "' in path '"<<path<<"' does not point to a PropertyBag."<<endlog();
            return false;
        }
        // recurse using new parentbag and rest.
        return storeProperty( parentbag->value(), rest, item, separator);
    }

    bool removeProperty(PropertyBag& bag, const std::string& path, const std::string& separator )
    {
        // empty path
        if ( path.empty() || path == separator )
            return false;
        // single item path
        if ( path.find( separator ) == string::npos)
            return bag.removeProperty( bag.find(path) );
        // multi item path
        string prefix = path.substr( 0, path.rfind(separator));
        string pname  = path.substr( path.rfind(separator) + separator.length() );
        // '.item' form:
        if ( prefix.empty() )
            return bag.removeProperty( bag.find(pname) );
        // 'bag.item' form:
        Property<PropertyBag> parent = findProperty( bag, prefix);
        if ( !parent.ready() )
            return false;
        return parent.value().removeProperty( parent.value().find( pname ) );
    }

    bool updateOrRefreshProperty( PropertyBase* source, PropertyBase* target, bool update)
    {
#ifndef NDEBUG
        if (update)
            log(Debug) << "updateProperties: updating Property "
            << source->getType() << " "<< source->getName()
            << "." << endlog();
        else
            log(Debug) << "refreshProperties: refreshing Property "
            << source->getType() << " "<< source->getName()
            << "." << endlog();
#endif
        // no need to make new one, just update existing one
        if ( (update && target->update( source ) == false ) || (!update && target->refresh( source ) == false ) ) {
            // try conversion
            DataSourceBase::shared_ptr converted = target->getTypeInfo()->convert( source->getDataSource() );
            if ( !converted || converted == source->getDataSource() ) {
                // no conversion, try composition:
                converted = target->getDataSource();
                if (target->getTypeInfo()->composeType( source->getDataSource(), converted ) ) {
                    // case where there is a type composition -> target was updated by composeType
                    log(Debug) << "Composed Property "
                            << target->getType() << " "<< source->getName() << " to type " <<target->getType()
                            << " from type "  << source->getType() << endlog();
                    return true;
                } else {
                    //if ( !target->getTypeInfo()->composeType( source->getDataSource(), target->getDataSource() ) )
                    log(Error) << (update ? "updateProperties: " : "refreshProperties: ") << " Could not update, nor convert Property "
                            << target->getType() << " "<< target->getName()
                            << ": type mismatch, can not update with "
                            << source->getType() << " "<< source->getName() << endlog();
                    return false;
                }
            } else {
                // conversion: update with converted value:
                // case where there is a type conversion -> do the update of the target
                // since 'converted' might be a non-Assignable DataSource, we need a work-around:
                PropertyBase* dummy = target->getTypeInfo()->buildProperty("","");
                dummy->getDataSource()->update( converted.get() );
                assert(dummy->getTypeInfo() == converted->getTypeInfo() );
                // we need to use the PropertyBase API and not the DataSource API !
                if (update)
                    target->update(dummy);
                else
                    target->refresh(dummy);
                log(Debug) << "Converted Property "
                        << target->getType() << " "<< source->getName() << " to type " <<dummy->getType()
                        << " from type "  << source->getType() << endlog();
            }
        }
        return true;
    }

    bool refreshProperties(const PropertyBag& target, const PropertyBag& source, bool allprops)
    {
        Logger::In in("refreshProperties");

        // if the target is of different type than source, it is replaced by source.
        if ( Types()->type(target.getType()) != Types()->getTypeInfo<PropertyBag>() && Types()->type( target.getType() ) != Types()->type( source.getType() ) ) {
            log(Error) << "Can not populate typed PropertyBag '"<< target.getType() <<"' from '"<<source.getType()<<"' (source and target type differed)."<<endlog();
            return false;
        }

        //iterate over source, update PropertyBases
        PropertyBag::const_iterator it( target.getProperties().begin() );
        bool failure = false;
        while ( it != target.getProperties().end() )
        {
            PropertyBase* srcprop;
            if ( (*it)->getName() == "" ) //&& target.getType() == "Sequence" )
                srcprop = source.getItem( it - target.getProperties().begin() );
            else
                srcprop = source.find( (*it)->getName() );
            PropertyBase* tgtprop = *it;
            if (srcprop != 0)
            {
                if (updateOrRefreshProperty( srcprop, tgtprop, false) == false)
                    return false;
                // ok.
            } else if (allprops) {
                log(Error) << "Could not find Property "
                           << tgtprop->getType() << " "<< tgtprop->getName()
                           << " in source."<< endlog();
                failure = true;
            }
            ++it;
        }
        return !failure;
    }

    bool refreshProperty(const PropertyBag& target, const PropertyBase& source)
    {
        PropertyBase* target_prop;
        // dynamic_cast ?
        if ( 0 != (target_prop = target.find( source.getName() ) ) )
            {
                return target_prop->refresh( &source );
            }
        return false;
    }

    bool copyProperties(PropertyBag& target, const PropertyBag& source)
    {
        // Make a full deep copy.
        //iterate over source, clone all PropertyBases
        PropertyBag::const_iterator it( source.getProperties().begin() );
        while ( it != source.getProperties().end() )
        {
            // step 1 : clone a new instance (non deep copy)
            PropertyBase* temp = (*it)->create();
            // step 2 : deep copy clone with original.
            temp->copy( *it );
            // step 3 : add result to target bag.
            target.add( temp );
            ++it;
        }
        return true;
    }


    bool updateProperties(PropertyBag& target, const PropertyBag& source)
    {
        // check type consistency...
        if ( target.getType() == "" || target.getType() == "type_less" )
            target.setType("PropertyBag"); // RTT 1.2.0

        // if the target is of different type than source, it is replaced by source.
        if ( Types()->type( target.getType() ) != Types()->getTypeInfo<PropertyBag>() && Types()->type(target.getType()) != Types()->type(source.getType()) ) {
            log(Error) << "Can not populate typed PropertyBag '"<< target.getType() <<"' from '"<<source.getType()<<"' (source and target type differed)."<<endlog();
            return false;
        }

        target.setType( source.getType() );

        // Make an updated if present, create if not present
        //iterate over source, update or clone PropertyBases

        PropertyBag::Names allnames = source.list();
        PropertyBag::Names::const_iterator endnames = std::unique(allnames.begin(), allnames.end());
        PropertyBag::Names::const_iterator it( allnames.begin() );
        while ( it != endnames )
        {
            PropertyBag::Properties sources = source.getProperties(*it);
            PropertyBag::Properties mines = target.getProperties(*it);
            PropertyBag::iterator mit = mines.begin();
            for( PropertyBag::const_iterator sit = sources.begin(); sit != sources.end(); ++sit ) {
                if ( mit != mines.end() ) {
                    assert( (*sit)->getName() == (*mit)->getName());
                    if ( updateOrRefreshProperty( *sit, *mit, true) == false)
                        return false;
                    // ok.
                    ++mit;
                }
                else
                    {
#ifndef NDEBUG
                        Logger::log() << Logger::Debug;
                        Logger::log() << "updateProperties: creating Property "
                                      << (*sit)->getType() << " "<< (*sit)->getName()
                                      << "." << Logger::endl;
#endif
                        // step 1: test for composing a typed property bag:
                        PropertyBase* temp = 0;
#if 0
                        Property<PropertyBag>* tester = dynamic_cast<Property<PropertyBag>* >(*sit);
                        if (tester && Types()->type( tester->value().getType() ) != Types()->getTypeInfo<PropertyBag>()) {
                            if (TypeInfo* ti = types::Types()->type(tester->value().getType())) {
                                temp = ti->buildProperty( tester->getName(), tester->getDescription() );
                                assert(temp);
                                bool res = temp->getTypeInfo()->composeType( tester->getDataSource(), temp->getDataSource() );
                                if (!res ) return false;
                            }
                        }
#endif
                        if (!temp) {
                            // fallback : clone a new instance (non deep copy)
                            temp = (*sit)->create();
                            // deep copy clone with original, will never fail.
                            temp->update( (*sit) );
                        }
                        // step 3 : add result to target bag.
                        target.add( temp );
                    }
            }
            ++it;
        }
        return true;
    }

    bool updateProperty(PropertyBag& target, const PropertyBag& source, const std::string& name, const std::string& separator)
    {
        Logger::In in("updateProperty");
        // this code has been copied&modified from findProperty().
        PropertyBase* source_walker;
        PropertyBase* target_walker;
        std::string token;
        std::string::size_type start = 0;
        if ( separator.length() != 0 && name.find(separator) == 0 ) // detect 'root' attribute
            start = separator.length();
        std::string::size_type len = name.find(separator, start);
        if (len != std::string::npos) {
            token = name.substr(start,len-start);
            start = len + separator.length();      // reset start to next token.
            if ( start >= name.length() )
                start = std::string::npos;
        }
        else {
            token = name.substr(start);
            start = std::string::npos; // do not look further.
        }
        source_walker = source.find(token);
        target_walker = target.find(token);
        if (source_walker != 0 )
        {
            if ( target_walker == 0 ) {
                // if not present in target, create it !
                target_walker = source_walker->create();
                target.ownProperty( target_walker );
            }
            Property<PropertyBag>*  source_walker_bag;
            Property<PropertyBag>*  target_walker_bag;
            source_walker_bag = dynamic_cast<Property<PropertyBag>*>(source_walker);
            target_walker_bag = dynamic_cast<Property<PropertyBag>*>(target_walker);
            if ( source_walker_bag != 0 && start != std::string::npos ) {
                if ( target_walker_bag == 0 ) {
                    log(Error) << "Property '"<<target_walker->getName()<<"' is not a PropertyBag !"<<endlog();
                    return false;
                }
                return updateProperty( target_walker_bag->value(), source_walker_bag->rvalue(), name.substr( start ), separator );// a bag so search recursively
            }
            else {
                // found it, update !
                if (updateOrRefreshProperty( source_walker, target_walker, true) == false)
                    return false;
                log(Debug) << "Found Property '"<<target_walker->getName() <<"': update done." << endlog();
                return true;
            }
        } else {
            // error wrong path, not present in source !
            log(Error) << "Property '"<< token <<"' is not present in the source PropertyBag !"<<endlog();
            return false;
        }
        // not reached.
        return false; // failure
    }

    bool refreshProperty(PropertyBag& target, const PropertyBag& source, const std::string& name, const std::string& separator)
    {
        Logger::In in("refreshProperty");
        // this code has been copied&modified from findProperty().
        PropertyBase* source_walker;
        PropertyBase* target_walker;
        std::string token;
        std::string::size_type start = 0;
        if ( separator.length() != 0 && name.find(separator) == 0 ) // detect 'root' attribute
            start = separator.length();
        std::string::size_type len = name.find(separator, start);
        if (len != std::string::npos) {
            token = name.substr(start,len-start);
            start = len + separator.length();      // reset start to next token.
            if ( start >= name.length() )
                start = std::string::npos;
        }
        else {
            token = name.substr(start);
            start = std::string::npos; // do not look further.
        }
        source_walker = source.find(token);
        target_walker = target.find(token);
        if (source_walker != 0 )
        {
            if ( target_walker == 0 ) {
                log(Error) << "Property '"<<source_walker->getName()<<"' was not found in target !"<<endlog();
                return false;
            }
            Property<PropertyBag>*  source_walker_bag;
            Property<PropertyBag>*  target_walker_bag;
            source_walker_bag = dynamic_cast<Property<PropertyBag>*>(source_walker);
            target_walker_bag = dynamic_cast<Property<PropertyBag>*>(target_walker);
            if ( source_walker_bag != 0 && start != std::string::npos ) {
                if ( target_walker_bag == 0 ) {
                    log(Error) << "Property '"<<target_walker->getName()<<"' is not a PropertyBag !"<<endlog();
                    return false;
                }
                return refreshProperty( target_walker_bag->value(), source_walker_bag->rvalue(), name.substr( start ), separator );// a bag so search recursively
            }
            else {
                if (updateOrRefreshProperty( source_walker, target_walker, false) == false)
                    return false;
                log(Debug) << "Found Property '"<<target_walker->getName() <<"': refresh done." << endlog();
                return true;
            }
        } else {
            // error wrong path, not present in source !
            log(Error) << "Property '"<< token <<"' is not present in the source PropertyBag !"<<endlog();
            return false;
        }
        // not reached.
        return false; // failure
    }

    void deleteProperties(PropertyBag& target)
    {
        //non-recursive delete.
        PropertyBag::const_iterator it( target.getProperties().begin() );
        while ( it != target.getProperties().end() )
        {
            // This loop is solely for deleting not owned properties.
            if (!target.ownsProperty( *it ))
                delete (*it);
            ++it;
        }
        target.clear();
    }

    void deletePropertyBag(PropertyBag& target)
    {
        //iterate over target, delete PropertyBases
        PropertyBag::const_iterator it( target.getProperties().begin() );
        while ( it != target.getProperties().end() )
        {
            // This loop is solely for deleting not owned properties and recursing
            Property<PropertyBag>* result = dynamic_cast< Property<PropertyBag>* >( *it );
            if ( result != 0 )
                deletePropertyBag( result->value() );
            if (!target.ownsProperty( *it ))
                delete (*it);
            ++it;
        }
        // deletes owned properties.
        target.clear();
    }

    void flattenPropertyBag(PropertyBag& target, const std::string& separator)
    {
        //iterate over target, recursively flatten bags.
        Property<PropertyBag>* result;
        PropertyBag::const_iterator it( target.getProperties().begin() );
        while ( it != target.getProperties().end() )
        {
            result = dynamic_cast< Property<PropertyBag>* >( *it );
            if ( result != 0 )
            {
                flattenPropertyBag( result->value(), separator );// a bag so flatten recursively
                // copy all elements from result to target.
                PropertyBag::const_iterator flat_it( result->value().getProperties().begin() ) ;
                if ( flat_it != result->value().getProperties().end() )
                {
                    while (flat_it != result->value().getProperties().end() )
                    {
                        (*flat_it)->setName( result->getName() + separator + (*flat_it)->getName() );
                        target.add( (*flat_it) );
                        result->value().remove( *flat_it );
                        flat_it =  result->value().getProperties().begin();
                    }
                    it = target.getProperties().begin(); // reset iterator
                    continue;                            // do not increase it
                }
                // the bag is empty now, but it must stay in target.
            }
            ++it;
        }
    }

}