ceph/src/boost/libs/wave/doc/compiletime_config.html

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  12     <td width="21"> <h1></h1></td>
  13     <td width="885"> <font face="Verdana, Arial, Helvetica, sans-serif"><b><font size="6">Compile
  14       Time Configuration</font></b></font></td>
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  27 <p><b><a name="compiletime_config"></a>Library compile time configuration</b></p>
  28 <P dir="ltr">The C++ preprocessor iterator library may be configured at compile
  29   time by specifying different preprocessor constants to include different additional
  30   features. The possible preprocessor constants are described in the following
  31   table. </P>
  32 <table width="100%" border="0" align="center">
  33   <tr>
  34     <td colspan="2" class="table_title"><b>Summary of possible preprocessor constants
  35       for<br>
  36       library configuration</b></td>
  37   </tr>
  38   <tr>
  39     <td width="46%" class="table_cells"><code>BOOST_WAVE_SUPPORT_WARNING_DIRECTIVE</code></td>
  40     <td width="54%" class="table_cells"> <p>Support the <span class="preprocessor">#warning</span> directive</p></td>
  41   </tr>
  42   <tr>
  43     <td width="46%" class="table_cells"><code>BOOST_WAVE_SUPPORT_MS_EXTENSIONS</code></td>
  44     <td width="54%" class="table_cells"> <p>Support several MS specific language
  45         extensions (i.e. <tt>__int8</tt> et.al.)</p></td>
  46   </tr>
  47   <tr>
  48     <td class="table_cells"><code>BOOST_WAVE_PREPROCESS_ERROR_MESSAGE_BODY</code></td>
  49     <td class="table_cells"><p>Enable the preprocessing of the message bodies
  50         of <span class="preprocessor">#error</span> and <span class="preprocessor">#warning</span>
  51         directives.</p></td>
  52   </tr>
  53   <tr>
  54     <td class="table_cells"><code>BOOST_WAVE_EMIT_PRAGMA_DIRECTIVES</code></td>
  55     <td class="table_cells"><p>If defined, then the <span class="preprocessor">#pragma</span>
  56         directives are returned as a token sequence to the caller, if not defined,
  57         the whole <span class="preprocessor">#pragma</span> directive is skipped. </p></td>
  58   </tr>
  59   <tr>
  60     <td class="table_cells"><code>BOOST_WAVE_PREPROCESS_PRAGMA_BODY</code></td>
  61     <td class="table_cells"><p>Enable the preprocessing of the bodies of all <span class="preprocessor">
  62         #pragma</span> directives.<br>
  63         Note though, that the body of an <tt>operator&nbsp;_Pragma()</tt> is always preprocessed as this is required by the C99 Standard <a href="references.html#iso_c">[2]</a>.
  64       </p></td>
  65   </tr>
  66   <tr>
  67     <td class="table_cells"><code>BOOST_WAVE_ENABLE_COMMANDLINE_MACROS</code></td>
  68     <td class="table_cells"><p>Enable the functionality required to define macros
  69         with the command line syntax (-DMACRO(x)=definition)</p></td>
  70   </tr>
  71   <tr>
  72     <td class="table_cells"><code>BOOST_WAVE_STRINGTYPE</code></td>
  73     <td class="table_cells"><p>The tokens generated by the <tt>Wave</tt> library
  74         contain the token data and the file position, where this token was found
  75         in the input stream. <br>
  76         This constant may be used to redefine the data type, which is used to
  77         hold the token data and the corresponding file name. If this isn't defined
  78         it defaults to std::string. (The here defined data type should be compatible
  79         to the std::string type)</p></td>
  80   </tr>
  81   <tr>
  82     <td class="table_cells"><code>BOOST_WAVE_SUPPORT_VARIADICS_PLACEMARKERS</code></td>
  83     <td class="table_cells"><p>If defined, then the preprocessor library supports
  84         variadics and placemarkers. Note, to support C99 mode, this constant must
  85         be defined too.</p></td>
  86   </tr>
  87 <tr>
  88     <td class="table_cells"><code>BOOST_WAVE_SUPPORT_CPP0X</code></td>
  89     <td class="table_cells"><p>If defined, then the preprocessor library supports
  90         C++0x keywords and C++0x specific features, such as variadics, placemarkers, extended character and string literals. This implies the definitions of the <code>BOOST_WAVE_SUPPORT_VARIADICS_PLACEMARKERS</code> constant.</p></td>
  91   </tr>  <tr>
  92     <td class="table_cells"><code>BOOST_WAVE_MAX_INCLUDE_LEVEL_DEPTH</code></td>
  93     <td class="table_cells"><p>If defined, it will determine the initial maximal
  94         possible include file nesting depth supported. It defaults to 1024.</p></td>
  95   </tr>
  96   <tr>
  97     <td class="table_cells"><code>BOOST_WAVE_SUPPORT_PRAGMA_ONCE</code></td>
  98     <td class="table_cells"><p>If defined, then the <code>#pragma once</code> directive is supported by <tt>Wave</tt>. This specifies that the file, in which the pragma resides, will be included
  99       (opened) only once by the compiler in a build. </p></td>
 100   </tr>
 101   <tr>
 102     <td class="table_cells"><code>BOOST_WAVE_SUPPORT_PRAGMA_MESSAGE</code></td>
 103     <td class="table_cells"><p>If defined, then the <code class="preprocessor">#pragma message(&quot;&quot;)</code> directive is supported by <tt>Wave</tt>. This pragma simply generates a remark cotaining the message text. The body of the #pragma message is preprocessed whenever the <code><code>BOOST_</code>WAVE_PREPROCESS_PRAGMA_BODY</code> constant is defined as well . </p></td>
 104   </tr>
 105   <tr>
 106     <td class="table_cells"><code>BOOST_WAVE_SUPPORT_INCLUDE_NEXT</code></td>
 107     <td class="table_cells"><p>If defined, then the <code>#include_next</code> directive is supported by <tt>Wave</tt>. This is syntactically equivalent to the <code class="preprocessor">#include</code> directives, but may be used to inherit a header file (i.e. to include a file, which is named as the current file containing the <code>#include_next</code>).</p></td>
 108   </tr>
 109   <tr>
 110     <td class="table_cells"><code>BOOST_WAVE_USE_STRICT_LEXER</code></td>
 111     <td class="table_cells"><p>If this is defined to something != 0, then the C/C++ lexers recognize the
 112       strict C99/C++ basic source character set. If it is not defined or defined
 113     to zero, the lexers recognize the <span class="string">'$'</span> character as part of identifiers.</p></td>
 114   </tr>
 115   <tr>
 116     <td class="table_cells"><code>BOOST_WAVE_PRAGMA_KEYWORD</code></td>
 117     <td class="table_cells"><p>If this is defined to a string literal it will be used as the pragma keyword recogniyed by the library as specific Wave pragma's. This constant defaults to <span class="literal">&quot;wave&quot;</span>, i.e. the library recognizes all      <span class="preprocessor">#pragma wave option [(argument)]</span>  directives and dispatches the handling to the interpret_pragma() preprocessing hook function (see: <a href="class_reference_ctxpolicy.html">Preprocessing Hooks</a>). The arguments part of the  pragma is optional.<br>
 118       </p>    </td>
 119   </tr>
 120   <tr>
 121     <td class="table_cells"><code>BOOST_WAVE_USE_DEPRECIATED_PREPROCESSING_HOOKS</code></td>
 122     <td class="table_cells"><p>If defined to something not equal to zero (<span class="literal">'0'</span>) Wave will be compiled to use the depreciated preprocessing hooks. The interface of the preprocessing hooks has been changed after the Boost V1.34.x releases. This constant allows to compile applications using the older interface. </p></td>
 123   </tr>
 124   <tr>
 125     <td class="table_cells"><code>BOOST_WAVE_SUPPORT_LONGLONG_INTEGER_LITERALS</code></td>
 126     <td class="table_cells"><p>The C++ standard requires the preprocessor to use one of the following
 127       types for integer literals: <code>long</code> or <code>unsigned long</code> depending on a optional
 128       suffix (<span class="literal">'u'</span>, <span class="literal">'l'</span>, <span class="literal">'ul'</span>, or <span class="literal">'lu'</span>). Sometimes it is required to preprocess integer literals larger than that
 129         (i.e. <code>long long</code> or <code>unsigned long long</code>). Defining this pp constant enables the recognition of long long integers
 130 even if these do not have the <span class="literal">'ll'</span> suffix.</p>
 131       <p>This preprocessor constant is effective only, if your target platform supports
 132         long long integers (<code>BOOST_HAS_LONG_LONG</code> is defined). Please note, that this setting doesn't relate to the Wave support option
 133         <code>support_option_long_long</code>, which enables the recognition of <span class="literal">'ll'</span> suffixes
 134         only.
 135     </p>
 136       </td>
 137   </tr>
 138     <tr>
 139         <td class="table_cells">
 140             <code>BOOST_WAVE_SUPPORT_THREADING</code></td>
 141         <td class="table_cells">
 142             <p>This preprocessor constant allows to configer whether the Wave library will be built
 143                 with threading support enabled or not. This value (if defined) should be set to
 144                 zero ('0') if threading needs to be disabled and to a numerical value not equal
 145                 to zero, if threading should be enabled explicitely.
 146             </p>
 147             <p>
 148                 If this constant is not defined, the Wave library will be built using the threading
 149                 as picked up from the Boost build environment (see <code>BOOST_HAS_THREADS</code> in the Boost
 150                     configuration dosumentation).</p>
 151         </td>
 152     </tr>
 153 </table>
 154 <P dir="ltr"><b><a name="using_custom_lexer"></a>Using a different token type or lexer type in conjunction with Wave </b></P>
 155 <P dir="ltr">It is possible to use the <tt>Wave</tt> library while using your own token and/or lexer types. This may be achieved by providing your lexer type as the second template parameter while instantiating the <tt>boost::wave::context&lt;&gt;</tt> object. The token type used by the library is derived from the <tt>token_type</tt> typedef to be provided by the lexer type. If you want to provide your own token type only, you may use the <tt>boost::wave::lex_iterator&lt;&gt;</tt> type contained with the library. This type needs to be parametrized with the token type to use. </P>
 156 <P dir="ltr">The <tt>Wave</tt> library contains several samples illustrating these possibilities. The <tt>cpp_tokens</tt> sample shows the usage of a custom lexer and a custom token types. The lexer type used is functionally fully compatible to the <tt>re2c</tt> <a href="references.html#re2c">[3]</a> based lexer used by default. It is implemented based on the <tt>SLex</tt> <a href="references.html#slex">[5]</a> lexer example written by Dan Nuffer. The token type used therein is functionally equivalent to the default token type except for an additional <tt>operator&lt;&lt;</tt> used for dumping the information carried by the token.</P>
 157 <P dir="ltr"><b><a name="compilation_models"></a>Separation and inclusion compilation
 158   models</b></P>
 159 <P dir="ltr">The <tt>Wave</tt> C++ preprocessor iterator library is build almost
 160   completely as a header only library (except for the re2c based lexer). If you're
 161   trying to include all required files at once you will mention, that the resulting
 162   compilation times are very large (up to an hour - depending on your system configuration).
 163   This straightforward method we'll call the inclusion compilation model. If you
 164   do not pay attention to compilation times, that's the way to go, no special
 165   handling is needed.</P>
 166 <P dir="ltr">If you're interested in decreasing compilation times, the following
 167   method is to be used. This we will call it the separation compilation model.
 168   The trick is to separate the different objects such, that they are compilable
 169   separately. The function, which instantiates the templated object in question
 170   is factored out such, that its definition is visible to only one translation
 171   unit. To simplify this further this creation function is packaged into a small
 172   generator template structure.</P>
 173 <P dir="ltr">There are two levels of separation implemented: the separation of
 174   the compilation of the C++ lexer and the separation of the compilation of the
 175   different Spirit grammars used. To use these separations you will have to define
 176   two preprocessor constants while compiling the whole application and you will
 177   have to explicitely instantiate some helper templates. The following tables
 178   shows these constants in detail.</P>
 179 <table width="90%" border="0" align="center">
 180   <tr>
 181     <td colspan="2" class="table_title"><b>Summary of possible compilation constants
 182       required <br>
 183       to enable the separation compilation model</b></td>
 184   </tr>
 185   <tr class="table_title">
 186     <td width="25%"><b>Separate</b></td>
 187     <td width="75%"><p><code><font face="Verdana, Arial, Helvetica, sans-serif">Preprocessor
 188         constant</font></code></p></td>
 189   </tr>
 190   <tr>
 191     <td width="25%" class="table_cells"><code>C++ lexer</code></td>
 192     <td width="75%" class="table_cells"> <p><code><code>BOOST_</code>WAVE_SEPARATE_LEXER_INSTANTIATION</code></p></td>
 193   </tr>
 194   <tr>
 195     <td width="25%" class="table_cells"><code>Spirit grammars</code></td>
 196     <td width="75%" class="table_cells"> <p><code><code>BOOST_</code>WAVE_SEPARATE_GRAMMAR_INSTANTIATION</code></p></td>
 197   </tr>
 198 </table>
 199 <P dir="ltr">The following table shows the explicit template instantiations required,
 200   if you want to use the separation compilation model. The <tt>TokenT</tt> placeholder
 201   type has to be replaced with your token type to use and the <code><tt>LexIteratorT</tt></code> placeholder type has to be replaced with your lex iterator type you've used while instantiation of the <tt>boost::wave::context&lt;&gt;</tt> object. You will achieve the best
 202   results, if you place these into separate compilation units each. The <tt>IteratorT</tt>
 203   placeholder should be replaced by the iterator type, which was used to instantiate
 204   the <tt>boost::wave::context&lt;&gt;</tt> object.</P>
 205 <table width="90%" border="0" align="center">
 206   <tr>
 207     <td colspan="2" class="table_title"><b>Summary of required explicit template
 208       instantiations <br>
 209       required when using the separation compilation model</b></td>
 210   </tr>
 211   <tr class="table_title">
 212     <td width="25%"><b>Separate</b></td>
 213     <td width="75%"><p><code><font face="Verdana, Arial, Helvetica, sans-serif">Templates
 214         to explicitly instantiate</font></code></p></td>
 215   </tr>
 216   <tr>
 217     <td width="25%" class="table_cells"><code>C++ lexer</code></td>
 218     <td width="75%" class="table_cells"> <code><span class="keyword">template</span>
 219       cpplexer::re2clex::new_lexer_gen&lt;<tt>IteratorT</tt>&gt;;</code></td>
 220   </tr>
 221   <tr>
 222     <td width="25%" class="table_cells"><code>Spirit grammars</code></td>
 223     <td width="75%" class="table_cells"> <p><code><span class="keyword">template</span> wave::grammars::expression_grammar_gen&lt<tt>TokenT</tt>&gt;;<br>
 224         <span class="keyword"> template</span> wave::grammars::intlit_grammar_gen&lt;<tt>TokenT</tt>&gt;;<br>
 225         <span class="keyword"> template</span> wave::grammars::chlit_grammar_gen&lt;<tt>TokenT</tt>&gt;;<br>
 226         <span class="keyword"> template</span> wave::grammars::cpp_grammar_gen&lt;<tt>LexIteratorT</tt>&gt;;<br>
 227         <span class="keyword"> template</span> wave::grammars::predefined_macros_grammar_gen&lt;<tt>LexIteratorT</tt>&gt;;<br>
 228     <span class="keyword"> template</span> wave::grammars::defined_grammar_gen&lt;<tt>LexIteratorT</tt>&gt;;</code></p></td>
 229   </tr>
 230 </table>
 231 <p>To see an example of this you can look at the <tt>Wave</tt> driver program
 232   included as an acompanion sample to the C++ preprocessor iterator library. The
 233   corresponding files are named obviously <span class="string">&quot;instantiate_...something.cpp&quot;</span>,
 234   where the <span class="string">'...somthing'</span> is a hint, which grammars
 235   are explicitely instantiated inside. By using the separation model the compilation
 236   times required to build the <tt>Wave</tt> example are dropped by up to 90%.</p>
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 245 <hr size="1">
 246 <p class="copyright">Copyright &copy; 2003-2011 Hartmut Kaiser<br>
 247   <br>
 248 <font size="2">Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) </font> </p>
 249 <span class="updated"></span>
 250 <p class="copyright"><span class="updated">Last updated:
 251   <!-- #BeginDate format:fcAm1m -->Sunday, January 9, 2011  16:16<!-- #EndDate -->
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