Dogcows Code - chaz/yoink/blob - src/stlplus/persistence/persistent_contexts.hpp

   1 #ifndef STLPLUS_PERSISTENT_CONTEXTS
   2 #define STLPLUS_PERSISTENT_CONTEXTS
   3 ////////////////////////////////////////////////////////////////////////////////
   4
   5 //   Author:    Andy Rushton
   6 //   Copyright: (c) Southampton University 1999-2004
   7 //              (c) Andy Rushton           2004-2009
   8 //   License:   BSD License, see ../docs/license.html
   9
  10 //   Core context classes used to control the persistent dump/restore operations
  11
  12 ////////////////////////////////////////////////////////////////////////////////
  13
  14 #include "persistence_fixes.hpp"
  15 #include "persistent.hpp"
  16 #include <iostream>
  17 #include <map>
  18 #include <typeinfo>
  19
  20 ////////////////////////////////////////////////////////////////////////////////
  21
  22 namespace stlplus
  23 {
  24
  25   ////////////////////////////////////////////////////////////////////////////////
  26   // Internals
  27
  28   class dump_context_body;
  29   class restore_context_body;
  30
  31   ////////////////////////////////////////////////////////////////////////////////
  32   // The format version number currently supported
  33   ////////////////////////////////////////////////////////////////////////////////
  34
  35   extern unsigned char PersistentVersion;
  36
  37   ////////////////////////////////////////////////////////////////////////////////
  38   // dump_context controls the formatting of a persistent dump
  39   ////////////////////////////////////////////////////////////////////////////////
  40
  41   class dump_context
  42   {
  43     friend class persistent;
  44   public:
  45     //////////////////////////////////////////////////////////////////////////////
  46
  47     // device must be in binary mode
  48     dump_context(std::ostream& device, unsigned char version = PersistentVersion) throw(persistent_dump_failed);
  49     ~dump_context(void);
  50
  51     // low level output used to dump a byte
  52     void put(unsigned char data) throw(persistent_dump_failed);
  53
  54     // access the device, for example to check the error status
  55     const std::ostream& device(void) const;
  56
  57     // recover the version number of the dumped output
  58     unsigned char version(void) const;
  59
  60     // test whether the current platform uses little-endian or big-endian addressing of bytes
  61     // this is used in dump/restore of integers and is exported so that other routines can use it
  62     bool little_endian(void) const;
  63
  64     // Assist functions for Pointers
  65     // the return pair value is a flag saying whether this is a new pointer and the magic key to dump to file
  66     std::pair<bool,unsigned> pointer_map(const void* const pointer);
  67
  68     // Assist functions for Polymorphous classes (i.e. subclasses) using callback approach
  69     typedef void (*dump_callback)(dump_context&,const void*);
  70     unsigned register_callback(const std::type_info& info, dump_callback);
  71     bool is_callback(const std::type_info& info) const;
  72     typedef std::pair<unsigned,dump_callback> callback_data;
  73     callback_data lookup_callback(const std::type_info&) const throw(persistent_illegal_type);
  74
  75     // Assist functions for Polymorphous classes (i.e. subclasses) using interface approach
  76     unsigned register_interface(const std::type_info& info);
  77     bool is_interface(const std::type_info& info) const;
  78     unsigned lookup_interface(const std::type_info&) const throw(persistent_illegal_type);
  79
  80     // Register all Polymorphous classes using either approach by calling an installer callback
  81     typedef void (*installer)(dump_context&);
  82     void register_all(installer);
  83
  84   private:
  85     friend class dump_context_body;
  86     dump_context_body* m_body;
  87
  88     // disallow copying by making assignment and copy constructor private
  89     dump_context(const dump_context&);
  90     dump_context& operator=(const dump_context&);
  91   };
  92
  93   ////////////////////////////////////////////////////////////////////////////////
  94   // restore_context controls the reading of the persistent data during a restore
  95
  96   class restore_context
  97   {
  98     friend class persistent;
  99   public:
 100     //////////////////////////////////////////////////////////////////////////////
 101
 102     // device must be in binary mode
 103     restore_context(std::istream& device) throw(persistent_restore_failed);
 104     ~restore_context(void);
 105
 106     // low level input used to restore a byte
 107     int get(void) throw(persistent_restore_failed);
 108
 109     // access the device, for example to check the error status
 110     const std::istream& device(void) const;
 111
 112     // access the version number of the input being restored
 113     unsigned char version(void) const;
 114
 115     // test whether the current platform uses little-endian or big-endian addressing of bytes
 116     // this is used in dump/restore of integers
 117     bool little_endian(void) const;
 118
 119     // Assist functions for Pointers
 120     std::pair<bool,void*> pointer_map(unsigned magic);
 121     void pointer_add(unsigned magic, void* new_pointer);
 122
 123     // Assist functions for Polymorphous classes using the callback approach
 124     typedef void* (*create_callback)(void);
 125     typedef void (*restore_callback)(restore_context&,void*);
 126     unsigned register_callback(create_callback,restore_callback);
 127     bool is_callback(unsigned) const;
 128     typedef std::pair<create_callback, restore_callback> callback_data;
 129     callback_data lookup_callback(unsigned) const throw(persistent_illegal_type);
 130
 131     // Assist functions for Polymorphous classes using the interface approach
 132     unsigned register_interface(persistent*);
 133     bool is_interface(unsigned) const;
 134     persistent* lookup_interface(unsigned) const throw(persistent_illegal_type);
 135
 136     // Register all Polymorphous classes using either approach by calling an installer callback
 137     typedef void (*installer)(restore_context&);
 138     void register_all(installer);
 139
 140   private:
 141     friend class restore_context_body;
 142     restore_context_body* m_body;
 143
 144     typedef std::pair<unsigned,persistent*> interface_data;
 145
 146     // disallow copying by making assignment and copy constructor private
 147     restore_context(const restore_context&);
 148     restore_context& operator=(const restore_context&);
 149   };
 150
 151   ////////////////////////////////////////////////////////////////////////////////
 152
 153 } // end namespace stlplus
 154
 155   ////////////////////////////////////////////////////////////////////////////////
 156 #endif