Dogcows Code - chaz/yoink/blob - src/stlplus/persistence/persistent_xref.tpp

   1 ////////////////////////////////////////////////////////////////////////////////
   2
   3 //   Author:    Andy Rushton
   4 //   Copyright: (c) Southampton University 1999-2004
   5 //              (c) Andy Rushton           2004-2009
   6 //   License:   BSD License, see ../docs/license.html
   7
   8 //   format: magic_key [ data ]
   9
  10 ////////////////////////////////////////////////////////////////////////////////
  11 #include "persistent_int.hpp"
  12
  13 namespace stlplus
  14 {
  15
  16   ////////////////////////////////////////////////////////////////////////////////
  17
  18   template<typename T>
  19   void dump_xref(dump_context& context, const T* const data)
  20     throw(persistent_dump_failed)
  21   {
  22     // register the address and get the magic key for it
  23     std::pair<bool,unsigned> mapping = context.pointer_map(data);
  24     // if this is the first view of this pointer, simply throw an exception
  25     if (!mapping.first) throw persistent_dump_failed("tried to dump a cross-reference not seen before");
  26     // otherwise, just dump the magic key
  27     dump_unsigned(context,mapping.second);
  28   }
  29
  30   ////////////////////////////////////////////////////////////////////////////////>
  31
  32   template<typename T>
  33   void restore_xref(restore_context& context, T*& data)
  34     throw(persistent_restore_failed)
  35   {
  36     // Note: I do not try to delete the old data because this is a cross-reference
  37     // get the magic key
  38     unsigned magic = 0;
  39     restore_unsigned(context,magic);
  40     // now lookup the magic key to see if this pointer has already been restored
  41     // null pointers are always flagged as already restored
  42     std::pair<bool,void*> address = context.pointer_map(magic);
  43     // if this is the first view of this pointer, simply throw an exception
  44     if (!address.first) throw persistent_restore_failed("tried to restore a cross-reference not seen before");
  45     // seen before, so simply assign the old address
  46     data = (T*)address.second;
  47   }
  48
  49   ////////////////////////////////////////////////////////////////////////////////
  50
  51 } // end namespace stlplus