Dogcows Code - chaz/yoink/blob - src/stlplus/persistence/persistent_pointer.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, typename D>
  19   void dump_pointer(dump_context& context, const T* const data, D dump_fn)
  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     dump_unsigned(context,mapping.second);
  25     // if the address is null, then that is all that we need to do
  26     // however, if it is non-null and this is the first sight of the address, dump the contents
  27     // note that the address is mapped before it is dumped so that self-referential structures dump correctly
  28     if (data && !mapping.first)
  29       dump_fn(context,*data);
  30   }
  31
  32   ////////////////////////////////////////////////////////////////////////////////
  33
  34   template<typename T, typename R>
  35   void restore_pointer(restore_context& context, T*& data, R restore_fn)
  36     throw(persistent_restore_failed)
  37   {
  38     if (data)
  39     {
  40       delete data;
  41       data = 0;
  42     }
  43     // get the magic key
  44     unsigned magic = 0;
  45     restore_unsigned(context,magic);
  46     // now lookup the magic key to see if this pointer has already been restored
  47     // null pointers are always flagged as already restored
  48     std::pair<bool,void*> address = context.pointer_map(magic);
  49     if (address.first)
  50     {
  51       // seen before, so simply assign the old address
  52       data = (T*)address.second;
  53     }
  54     else
  55     {
  56       // this pointer has never been seen before and is non-null
  57       data = new T();
  58       // add this pointer to the set of already seen objects
  59       // do this before restoring the object so that self-referential structures restore correctly
  60       context.pointer_add(magic,data);
  61       // now restore it
  62       restore_fn(context,*data);
  63     }
  64   }
  65
  66   ////////////////////////////////////////////////////////////////////////////////
  67
  68 } // end namespace stlplus