X-Git-Url: http://g0dil.de/git?a=blobdiff_plain;f=senf%2FPackets%2FListBParser.ih;fp=senf%2FPackets%2FListBParser.ih;h=fe61177aeef3954143709ccb083a1316f4e78701;hb=601d1f509f5bb24df167a4dd5a20da67a0af9af8;hp=0000000000000000000000000000000000000000;hpb=164fe477094d42463722584e527a02379ab5d985;p=senf.git diff --git a/senf/Packets/ListBParser.ih b/senf/Packets/ListBParser.ih new file mode 100644 index 0000000..fe61177 --- /dev/null +++ b/senf/Packets/ListBParser.ih @@ -0,0 +1,163 @@ +// $Id$ +// +// Copyright (C) 2007 +// Fraunhofer Institute for Open Communication Systems (FOKUS) +// Competence Center NETwork research (NET), St. Augustin, GERMANY +// Stefan Bund +// +// 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. + +/** \file + \brief ListBParser internal header */ + +#ifndef IH_SENF_Packets_ListBParser_ +#define IH_SENF_Packets_ListBParser_ 1 + +// Custom includes +#include "ListParser.ih" + +///////////////////////////////ih.p//////////////////////////////////////// + +namespace senf { +namespace detail { + + /** \brief Internal: ListPolicy defing the ListBParser parser + \internal + \see \ref ListBParser + */ + template + struct ListBParser_Policy + : public AuxPolicy + { + // This policy needs to work around a serious problem with this type of list: When we change + // the size of any (direct or indirect) sub-element of the list, this will change will + // render the list completely invalid and un-parseable since the 'byte' field will now be + // invalid. + // + // The solution we apply is to store the *size* (i.e. the number of elements) of the list + // when creating the container wrapper. We also maintain this value across insert/erase + // statements. Additionally we also safe the complete size of the data container (the vector + // holding the bytes). Since we only allow packet changes through this container while it + // exists, any change in the container size must be a change within this list and therefore + // mandates an update of the 'bytes' field. + // + // The list container wrapper will call 'update' policy member before every access to the + // container and also in the destructor. This gives us a chance to fix the bytes header + // before the invalid header is seen by anyone (This is so, since we only allow access to + // the list through the container wrapper ...). Since we know the number of list elements, + // we can always find the correct 'bytes' value by traversing the list for that number of + // elements. + // + // By caching the container size, all this can be made reasonably efficient and usable: The + // updates are done automatically by only if needed. It would of course be more efficient to + // just apply the size change directly to the bytes header (no need to traverse the + // list). However, the implementation of this approach would be much more complex and even + // more invasive and would probably suffer from the same restrictions to the user. + + struct container_policy; + + typedef PacketParserBase::data_iterator data_iterator; + typedef PacketParserBase::state_type state_type; + typedef PacketParserBase::size_type size_type; + + typedef ElementParser element_type; + typedef ListParser< ListBParser_Policy > parser_type; + typedef ListParser_Container< container_policy > container_type; + + static const size_type init_bytes = AuxPolicy::aux_bytes; + + ListBParser_Policy(); + template ListBParser_Policy(Arg const & arg); + + size_type bytes (data_iterator i, state_type s) const; + size_type size (data_iterator i, state_type s) const; + void init (data_iterator i, state_type s) const; + + /** \brief Internal: ListBParser container/wrapper policy */ + struct container_policy + : public AuxPolicy + { + typedef PacketParserBase::data_iterator data_iterator; + typedef PacketParserBase::state_type state_type; + typedef PacketParserBase::size_type size_type; + + typedef ListBParser_Policy parser_policy; + typedef typename parser_policy::element_type element_type; + typedef typename parser_policy::parser_type parser_type; + typedef typename parser_policy::container_type container_type; + + static const size_type init_bytes = parser_policy::init_bytes; + + container_policy(parser_policy const & p); + + size_type bytes (data_iterator i, state_type s) const; + size_type size (data_iterator i, state_type s) const; + void init (data_iterator i, state_type s); + + void erase (container_type & c, data_iterator p); + void insert (container_type & c, data_iterator p); + void update (container_type const & c) const; + + /** \brief Internal: ListBParser specific iterator data */ + struct iterator_data {}; + + data_iterator setBegin (container_type const & c, iterator_data & d) const; + data_iterator setEnd (container_type const & c, iterator_data & d) const; + void setFromPosition (container_type const & c, iterator_data & d, + data_iterator p) const; + + data_iterator next (container_type const & c, iterator_data & d) const; + data_iterator raw (container_type const & c, iterator_data const & d) const; + + size_type n_; + mutable size_type container_size_; + }; + }; + +#ifndef DOXYGEN + + template + struct ListParserPolicy + { + typedef ListBParser_Policy type; + }; + + template + struct ListParserPolicy > + { + typedef ListBParser_Policy< ElementParser, + TransformAuxParserPolicy > type; + }; + +#endif + +}} + +///////////////////////////////ih.e//////////////////////////////////////// +#endif + + +// Local Variables: +// mode: c++ +// fill-column: 100 +// comment-column: 40 +// c-file-style: "senf" +// indent-tabs-mode: nil +// ispell-local-dictionary: "american" +// compile-command: "scons -u test" +// End: