| Brian Silverman | 8867871 | 2018-08-04 23:56:48 -0700 | [diff] [blame^] | 1 | <!doctype HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
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| 3 | <!-- |
| 4 | (C) Copyright 2002-4 Robert Ramey - http://www.rrsd.com . |
| 5 | Use, modification and distribution is subject to the Boost Software |
| 6 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
| 7 | http://www.boost.org/LICENSE_1_0.txt) |
| 8 | --> |
| 9 | <head> |
| 10 | <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> |
| 11 | <link rel="stylesheet" type="text/css" href="../../../boost.css"> |
| 12 | <link rel="stylesheet" type="text/css" href="style.css"> |
| 13 | <title>Serialization - Code Structure</title> |
| 14 | </head> |
| 15 | <body link="#0000ff" vlink="#800080"> |
| 16 | <table border="0" cellpadding="7" cellspacing="0" width="100%" summary="header"> |
| 17 | <tr> |
| 18 | <td valign="top" width="300"> |
| 19 | <h3><a href="../../../index.htm"><img height="86" width="277" alt="C++ Boost" src="../../../boost.png" border="0"></a></h3> |
| 20 | </td> |
| 21 | <td valign="top"> |
| 22 | <h1 align="center">Serialization</h1> |
| 23 | <h2 align="center">Code Structure</h2> |
| 24 | </td> |
| 25 | </tr> |
| 26 | </table> |
| 27 | <hr> |
| 28 | |
| 29 | <dl class="page-index"> |
| 30 | <dt><a href="#userincludes">Files Included by User Programs</a> |
| 31 | <dl class="page-index"> |
| 32 | <dt><a href="#archiveimplementations">Archive Implementations</a> |
| 33 | <dt><a href="#serializationdeclarations">Serialization Declarations</a> |
| 34 | <dt><a href="#serializationimplementations">Serialization Implementations</a> |
| 35 | </dl> |
| 36 | <dt><a href="#libraryimplementation">Files Which Implement the Library</a> |
| 37 | <dl class="page-index"> |
| 38 | <dt><a href="#archivedevelopment">Archive Development</a> |
| 39 | <dt><a href="#archiveinternals">Archive Internals</a> |
| 40 | <dt><a href="#codemodules">Archive Library Code Modules</a> |
| 41 | <dt><a href="#dataflowiterators">Dataflow Iterators</a> |
| 42 | </dl> |
| 43 | </dl> |
| 44 | |
| 45 | This library includes a large number of files. They are organized and classified |
| 46 | according to the purposes listed in the above index. |
| 47 | <p> |
| 48 | <code style="white-space: normal">namespace</code> of classes and templates is synchronized |
| 49 | with the directory in which the file is found. For example, the class declaration |
| 50 | <pre><code> |
| 51 | boost::archive::text_oarchive |
| 52 | </code></pre> |
| 53 | is included with the following declaration |
| 54 | <pre><code> |
| 55 | #include <boost/archive/text_oarchive.hpp> |
| 56 | </code></pre> |
| 57 | |
| 58 | <a name="userincludes"> |
| 59 | <h3>Files Included by User Programs</h3> |
| 60 | Using this library entails including headers listed in this section. |
| 61 | It should not be necessary to explictly include any other header files. |
| 62 | |
| 63 | <a name="archiveimplementations"> |
| 64 | <h4>Archive Implementations</h4> |
| 65 | These header files contain declarations used to save and restore data to each type |
| 66 | of archive. Include the archives according to the facilities the code module requires. |
| 67 | |
| 68 | <dl> |
| 69 | |
| 70 | <dt><a target="archive_exception" href="../../../boost/archive/archive_exception.hpp"> |
| 71 | boost/archive/archive_exception.hpp |
| 72 | </a> |
| 73 | <dd>Exceptions which might be invoked by the library.</dd> |
| 74 | |
| 75 | <dt><a target="binary_iarchive" href="../../../boost/archive/binary_iarchive.hpp"> |
| 76 | boost/archive/binary_iarchive.hpp |
| 77 | </a> |
| 78 | <dd>native binary input archive used for loading.</dd> |
| 79 | |
| 80 | <dt><a target="binary_oarchive" href="../../../boost/archive/binary_oarchive.hpp"> |
| 81 | boost/archive/binary_oarchive.hpp |
| 82 | </a> |
| 83 | <dd>native binary output archive used for saving.</dd> |
| 84 | |
| 85 | <dt><a target="text_iarchive" href="../../../boost/archive/text_iarchive.hpp"> |
| 86 | boost/archive/text_iarchive.hpp |
| 87 | </a> |
| 88 | <dd>text input archive used for loading.</dd> |
| 89 | |
| 90 | <dt><a target="text_oarchive" href="../../../boost/archive/text_oarchive.hpp"> |
| 91 | boost/archive/text_oarchive.hpp |
| 92 | </a> |
| 93 | <dd>text output archive used for saving.</dd> |
| 94 | |
| 95 | <dt><a target="text_wiarchive" href="../../../boost/archive/text_wiarchive.hpp"> |
| 96 | boost/archive/text_wiarchive.hpp |
| 97 | </a> |
| 98 | <dd>wide character text input archive used for loading.</dd> |
| 99 | |
| 100 | <dt><a target="text_woarchive" href="../../../boost/archive/text_woarchive.hpp"> |
| 101 | boost/archive/text_woarchive.hpp |
| 102 | </a> |
| 103 | <dd>wide character text input archive used for saving.</dd> |
| 104 | |
| 105 | <dt><a target="xml_iarchive" href="../../../boost/archive/xml_iarchive.hpp"> |
| 106 | boost/archive/xml_iarchive.hpp |
| 107 | </a> |
| 108 | <dd>xml input archive used for loading.</dd> |
| 109 | |
| 110 | <dt><a target="text_oarchive" href="../../../boost/archive/xml_oarchive.hpp"> |
| 111 | boost/archive/xml_oarchive.hpp |
| 112 | </a> |
| 113 | <dd>xml output archive used for saving.</dd> |
| 114 | |
| 115 | <dt><a target="text_wiarchive" href="../../../boost/archive/xml_wiarchive.hpp"> |
| 116 | boost/archive/xml_wiarchive.hpp |
| 117 | </a> |
| 118 | <dd>wide character xml input archive used for loading.</dd> |
| 119 | |
| 120 | <dt><a target="text_woarchive" href="../../../boost/archive/xml_woarchive.hpp"> |
| 121 | boost/archive/xml_woarchive.hpp |
| 122 | </a> |
| 123 | <dd>wide character xml output archive used for saving.</dd> |
| 124 | |
| 125 | </dl> |
| 126 | |
| 127 | <a name="serializationdeclarations"> |
| 128 | <h4>Serialization Declarations</h4> |
| 129 | To specify how a type is serialized, one codes templates for serialization functions. |
| 130 | In the simplest cases, this does not require the inclusion of any header files for this purpose. |
| 131 | In most cases one or more of the following header files will have to be included in order |
| 132 | to complete or refine the description of the serializaition implementation for a given class. |
| 133 | |
| 134 | <dl> |
| 135 | |
| 136 | <dt><a target="base_object" href="../../../boost/serialization/base_object.hpp"> |
| 137 | boost/serialization/base_object.hpp |
| 138 | </a> |
| 139 | <dd>For serialization of base classes.</dd> |
| 140 | |
| 141 | <dt><a target="nvp" href="../../../boost/serialization/nvp.hpp"> |
| 142 | boost/serialization/nvp.hpp |
| 143 | </a> |
| 144 | <dd>To associate a name tag with a serializable object. This is necessary to |
| 145 | properly render an xml archive which includes the object name.</dd> |
| 146 | |
| 147 | <dt><a target="split_free" href="../../../boost/serialization/split_free.hpp"> |
| 148 | boost/serialization/split_free.hpp |
| 149 | </a> |
| 150 | <dd>To divide implementation of <em>non-intrusive</em> serialization into separate |
| 151 | save and load functions.</dd> |
| 152 | |
| 153 | <dt><a target="split_member" href="../../../boost/serialization/split_member.hpp"> |
| 154 | boost/serialization/split_member.hpp |
| 155 | </a> |
| 156 | <dd>To divide implementation of <em>intrusive</em> serialization into separate |
| 157 | save and load functions.</dd> |
| 158 | |
| 159 | <dt><a target="export" href="../../../boost/serialization/export.hpp"> |
| 160 | boost/serialization/export.hpp |
| 161 | </a> |
| 162 | <dd>For serialization of pointers to derived classes via key export.</dd> |
| 163 | |
| 164 | <dt><a target="assume_abstract" href="../../../boost/serialization/assume_abstract.hpp"> |
| 165 | boost/serialization/assume_abstract.hpp |
| 166 | </a> |
| 167 | <dd>This is just a thin wrapper which permits one to explicitly specify that a |
| 168 | particular type is an abstract base class. It is necessary to use this |
| 169 | for compilers which don't support the boost type traits implementation of |
| 170 | is_abstact. |
| 171 | </dd> |
| 172 | |
| 173 | </dl> |
| 174 | |
| 175 | This group will be required less frequently. The are used to override aspects of |
| 176 | the default implementation of the serialization process for specified types. |
| 177 | |
| 178 | <dl> |
| 179 | |
| 180 | <dt><a target="version" href="../../../boost/serialization/version.hpp"> |
| 181 | boost/serialization/version.hpp |
| 182 | </a> |
| 183 | <dd>To override the default version index (0) assigned to a class.</dd> |
| 184 | |
| 185 | <dt><a target="level" href="../../../boost/serialization/level.hpp"> |
| 186 | boost/serialization/level.hpp |
| 187 | </a> |
| 188 | <dd>To override the default implementaton level trait for a type.</dd> |
| 189 | |
| 190 | <dt><a target="tracking" href="../../../boost/serialization/tracking.hpp"> |
| 191 | boost/serialization/tracking.hpp |
| 192 | </a> |
| 193 | <dd>To override the default tracking trait for a type.</dd> |
| 194 | |
| 195 | <dt><a target="type_info_implementation" href="../../../boost/serialization/type_info_implementation.hpp"> |
| 196 | boost/serialization/type_info_implementation.hpp |
| 197 | </a> |
| 198 | <dd>By default, the library uses RTTI, to identify types at runtime. In some cases, E.G. |
| 199 | such as a platform which doesn't implement RTTI, this header can be included to permit |
| 200 | the override of the default runtime type identification system.</dd> |
| 201 | |
| 202 | </dl> |
| 203 | |
| 204 | <a name="serializationimplementations"> |
| 205 | <h4>Serialization Implementations</h4> |
| 206 | This group of headers includes templates which implement serialization for Standard |
| 207 | Library or Boost Library templates. Any program which uses these templates can |
| 208 | invoke serialization of objects of these types just by including the corresponding header. |
| 209 | <p> |
| 210 | By convention these header files are named: |
| 211 | |
| 212 | boost/serialization/xxx.hpp |
| 213 | |
| 214 | where xxx is the name of the header file which contains the type to be serialized. |
| 215 | For example, the declaration |
| 216 | <pre><code> |
| 217 | #include <boost/serialization/list.hpp> |
| 218 | </code></pre> |
| 219 | |
| 220 | includes the code to implement serialization of the STL |
| 221 | <code style="white-space: normal">std::list</code> type. While |
| 222 | |
| 223 | <pre><code> |
| 224 | #include <boost/serialization/shared_ptr.hpp> |
| 225 | </code></pre> |
| 226 | |
| 227 | includes code to implement serialization of the BOOST <code style="white-space: normal">boost::shared_ptr</code> type. |
| 228 | |
| 229 | Note that including the serialization header for a type automatically includes the |
| 230 | appropriate header of the type to be serialized. |
| 231 | |
| 232 | As of this writing, the library includes templates of all STL library templates as well |
| 233 | as templates for <code style="white-space: normal">boost::optional</code>, |
| 234 | <code style="white-space: normal">boost::shared_ptr</code>, and |
| 235 | <code style="white-space: normal">boost::scoped_ptr</code>. |
| 236 | Presumably, this list will expand with the passage of time. |
| 237 | |
| 238 | <a name="libraryimplementation"> |
| 239 | <h3>Files Which Implement the Library</h3> |
| 240 | |
| 241 | <a name="archivedevelopment"> |
| 242 | <h4>Archive Development</h4> |
| 243 | These header files contain declarations for basic types used to create |
| 244 | concrete archive types that are made available to users above. Users wishing |
| 245 | to make their own type of archive may want to examine these headers to |
| 246 | see how the archives included with the libary have been constructed. |
| 247 | |
| 248 | <dl> |
| 249 | |
| 250 | <dt><a target="basic_archive" href="../../../boost/archive/basic_archive.hpp"> |
| 251 | boost/archive/basic_archive.hpp |
| 252 | </a> |
| 253 | </dt> |
| 254 | <dd> |
| 255 | This file includes declarations for certain types that have to be accounted |
| 256 | for in all archive implementations. The serialization system relies on |
| 257 | certain special types such as <code style="white-space: normal">class_id_type</code> and others to |
| 258 | record information in archives that is required to reconstruct the original |
| 259 | data structure. These are handled exactly as any other serializable type. |
| 260 | That is, they can be handled as simple primitives such as they are in simple |
| 261 | text files, or with special code as they are in xml archives. |
| 262 | </dd> |
| 263 | |
| 264 | <dt><a target="basic_text_oprimitive" href="../../../boost/archive/basic_text_oprimitive.hpp"> |
| 265 | boost/archive/basic_text_oprimitive.hpp |
| 266 | </a> |
| 267 | <dt><a target="basic_text_iprimitive" href="../../../boost/archive/basic_text_iprimitive.hpp"> |
| 268 | boost/archive/basic_text_iprimitive.hpp |
| 269 | </a> |
| 270 | </dt> |
| 271 | <dd> |
| 272 | Implementation of serialization of primitive types in terms of character |
| 273 | or wide character text streams. This is used in the implementation of text and |
| 274 | xml archives. Presumably this would be useful for implementations of other variations |
| 275 | of text archives such as user friendly text or windows ini files. |
| 276 | </dd> |
| 277 | |
| 278 | <dt><a target="basic_binary_oprimitive" href="../../../boost/archive/basic_binary_oprimitive.hpp"> |
| 279 | boost/archive/basic_binary_oprimitive.hpp |
| 280 | </a> |
| 281 | <dt><a target="basic_binary_iprimitive" href="../../../boost/archive/basic_binary_iprimitive.hpp"> |
| 282 | boost/archive/basic_binary_iprimitive.hpp |
| 283 | </a> |
| 284 | </dt> |
| 285 | <dd> |
| 286 | Implementation of serialization of primitive types in terms of character |
| 287 | or wide character binary streams. |
| 288 | </dd> |
| 289 | |
| 290 | <dt><a target="basic_binary_oarchive" href="../../../boost/archive/basic_binary_oarchive.hpp"> |
| 291 | boost/archive/basic_binary_oarchive.hpp |
| 292 | </a> |
| 293 | <dt><a target="basic_binary_iarchive" href="../../../boost/archive/basic_binary_iarchive.hpp"> |
| 294 | boost/archive/basic_binary_iarchive.hpp |
| 295 | </a> |
| 296 | <dd> |
| 297 | Implementation of serialization of all types in terms of character |
| 298 | or wide character binary streams. This is factored out separately from the |
| 299 | implementation of binary primitives above. This may facilitate the creation of |
| 300 | other types of binary archives in the future. It also preserves analogy and symmetry with |
| 301 | the rest of the library which aids in understanding. |
| 302 | </dd> |
| 303 | <dt><a target="basic_text_oarchive" href="../../../boost/archive/basic_text_oarchive.hpp"> |
| 304 | boost/archive/basic_text_oarchive.hpp |
| 305 | </a> |
| 306 | <dt><a target="basic_te't_iarchive" href="../../../boost/archive/basic_text_iarchive.hpp"> |
| 307 | boost/archive/basic_text_iarchive.hpp |
| 308 | </a> |
| 309 | </dt> |
| 310 | <dt><a target="basic_xml_oarchive" href="../../../boost/archive/basic_xml_oarchive.hpp"> |
| 311 | boost/archive/basic_xml_oarchive.hpp |
| 312 | </a> |
| 313 | <dt><a target="basic_xml_iarchive" href="../../../boost/archive/basic_xml_iarchive.hpp"> |
| 314 | boost/archive/basic_xml_iarchive.hpp |
| 315 | </a> |
| 316 | </dt> |
| 317 | <dd> |
| 318 | Implementation of serialization of all types in terms of character |
| 319 | or wide character text streams. These classes specify archive type specific |
| 320 | behavior on a type by type basis. For example, <code style="white-space: normal">basic_xml_oarchive.hpp</code> |
| 321 | includes code to guarantee that any object not attached to a name will |
| 322 | trap during compile time. On the other hand, <code style="white-space: normal">basic_text_oarchive.hpp</code> |
| 323 | contains code to strip out and ingore any names attached to objects. |
| 324 | <p> |
| 325 | <dt><a target="common_iarchive" href="../../../boost/archive/detail/common_iarchive.hpp"> |
| 326 | boost/archive/detail/common_iarchive.hpp |
| 327 | </a> |
| 328 | <dt><a target="common_oarchive" href="../../../boost/archive/detail/common_oarchive.hpp"> |
| 329 | boost/archive/detail/common_oarchive.hpp |
| 330 | </a> |
| 331 | <dd> |
| 332 | All archive implementations are derived from these header files. They provide |
| 333 | the interface to the internal implementation details of the library. |
| 334 | </dd> |
| 335 | |
| 336 | </dl> |
| 337 | |
| 338 | <a name="archiveinternals"> |
| 339 | <h4>Archive Internals</h4> |
| 340 | |
| 341 | The interface (see <a target="detail" href="archives.html">Archive Concepts</a>) |
| 342 | and implementation are factored out into separate classes to minimize code duplication. |
| 343 | |
| 344 | These files are found in the directory |
| 345 | <a target="boost_archive_detail" href="../../../boost/archive/detail">boost/archive/detail</a>. |
| 346 | These are included as necessary by the archive class implemenations listed above. |
| 347 | This has the unfortunate side effect of making the implementation less transparent. |
| 348 | Users should never find it necessary to change these files. |
| 349 | <p> |
| 350 | The following discussion is based on the |
| 351 | <a target="class_diagram" href="class_diagram.html">class diagram</a>. |
| 352 | <p> |
| 353 | <dt><a target="interface_iarchive" href="../../../boost/archive/detail/interface_iarchive.hpp"> |
| 354 | boost/archive/detail/interface_iarchive.hpp</a> |
| 355 | <dt><a target="interface_iarchive" href="../../../boost/archive/detail/interface_iarchive.hpp"> |
| 356 | boost/archive/detail/interface_iarchive.hpp</a> |
| 357 | <dd> |
| 358 | Here are the declarations and definitions for the |
| 359 | <a href="archives.html">archive_concept</a>. This class redirects calls to the |
| 360 | archive interface to a function named <code>save_override</code> in the most derived |
| 361 | archive class. |
| 362 | </dd> |
| 363 | <code>save_override</code> is declared and implemented in each class in |
| 364 | the archive hierarchy. |
| 365 | |
| 366 | <pre><code> |
| 367 | template<class T> |
| 368 | void save_override(T & t, BOOST_PFTO int){ |
| 369 | // All for otherwise unhandled types are forwarded to the base class. |
| 370 | // This emulates behavior for function overloading. |
| 371 | this->base::save_override(t, 0); |
| 372 | } |
| 373 | void save_override(const some_type & t, int){ |
| 374 | // any special handling for some type |
| 375 | // this will usually entail forwarding some other operation |
| 376 | // in the most derived class. |
| 377 | this->This()->... |
| 378 | // or in one of its parents basic_text_oprimitive |
| 379 | this->This()->save(static_cast<int>(t)); |
| 380 | } |
| 381 | ... // other special type handling |
| 382 | </code></pre> |
| 383 | |
| 384 | Note the usage of |
| 385 | <a target="detail" href="implementation.html#functiontemplateordering">Partial Function Template Ordering</a> |
| 386 | to permit the correct save implementation to be selected. |
| 387 | </dd> |
| 388 | |
| 389 | <a name="codemodules"> |
| 390 | <h4>Archive Library Code Modules</h4> |
| 391 | Parts of the library are implemented as library code. All of this code is to be found in |
| 392 | <a target="src" href="../../../libs/serialization/src">libs/serialization/src</a>. |
| 393 | in the form of *.cpp. The directory |
| 394 | <a target="src" href="../../../boost/archive/impl">boost/archive/impl</a> |
| 395 | contains *.ipp files which implement templates. These templates are instantiated |
| 396 | only by archive implementation so are generally not included in user code modules. |
| 397 | <p> |
| 398 | The trade offs related to library implementation via pre-compiled code and templated |
| 399 | headers are well known. This library uses both. It uses templated headers |
| 400 | to generate code to serialize user and primitive types and it uses pre-compiled |
| 401 | library code for that part of the code which only depends upon the archive type. |
| 402 | Building of the library generates and compiles code for all archives implemented. |
| 403 | |
| 404 | <ul> |
| 405 | <li>Serialization of user and primitive types runs at top speed. This is a noticeable |
| 406 | difference with a previous version of the library which did not use templates for archives. |
| 407 | <li>Library implementation code that never changes need only be compiled once |
| 408 | rather than each time a user's program is recompiled. This can save much |
| 409 | development time. |
| 410 | <li>Headers which solely related to implementation need only be included |
| 411 | in the library code modules. This prevents a user program from accidently |
| 412 | depending on an implementation feature of the serialization library. |
| 413 | <li>In building the library I came to the conclusions that there can arise |
| 414 | situations regarding static code/data instantiation that could not be |
| 415 | satisfactorily addressed without a code module. Unfortunately, I've forgotten |
| 416 | the circumstances which led me to this conclusion. |
| 417 | </ul> |
| 418 | An example of this is the usage of the spirit library in the library. |
| 419 | It takes a long time to compile and includes lots of other files. Having this |
| 420 | only in the library is much more convenient that having to include it in every |
| 421 | program which uses xml serialization. |
| 422 | |
| 423 | <a name="dataflowiterators"> |
| 424 | <h4>Dataflow Iterators</h4> |
| 425 | In the course of developing this library, it became convenient to make a set |
| 426 | of composable iterator adaptors for handling archive text. Applications include |
| 427 | escaping and unescaping xml text and implementing to/from base64 conversion among |
| 428 | others. |
| 429 | <p> |
| 430 | This is a ripe topic in itself. It's touched upon by the |
| 431 | <a href="../../../libs/iterator/doc/index.html">boost iterator</a> libraries, |
| 432 | <a href="http://www.zib.de/weiser/vtl/index.html">View Template Library</a>, and others. |
| 433 | <p> |
| 434 | The code for these iterators is really independent of this library. But since it |
| 435 | hasn't been and probably won't be reviewed outside of this context. I've left it in a directory |
| 436 | local to the serialization library: |
| 437 | <a target="archiveiterators" href="../../../boost/archive/iterators">boost/archive/iterators</a>. |
| 438 | These iterators are described in |
| 439 | <a href="dataflow.html">Dataflow Iterators</a>. |
| 440 | <hr> |
| 441 | <p><i>© Copyright <a href="http://www.rrsd.com">Robert Ramey</a> 2002-2004. |
| 442 | Distributed under the Boost Software License, Version 1.0. (See |
| 443 | accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| 444 | </i></p> |
| 445 | </body> |
| 446 | </html> |