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Wave: a Standard conformant C++ preprocessor library

, 10 Jan 2004
Describes a free and fully Standard conformant C++ preprocessor library
wave_preprocessor_demo.zip
wave.exe
wave_preprocessor_demo1.zip
wave.exe
wave_preprocessor_src.zip
wave
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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  <tr> 
    <td width="21"> <h1></h1></td>
    <td width="885"> <font face="Verdana, Arial, Helvetica, sans-serif"><b><font size="6">Quick 
      Start </font></b></font></td>
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<p>The actual preprocessing itself is a highly configurable process, so obviously 
  you have to define a couple of parameters to&nbsp;control this process, such 
  as:</p>
<BLOCKQUOTE dir="ltr" style="MARGIN-RIGHT: 0px"> 
  <P><STRONG><IMG id="IMG1" height="13" src="theme/bullet.gif" width="13"></STRONG>&nbsp;include 
    search pathes, which define, where to search for files to be included with 
    <tt>#include&nbsp;&lt;...&gt;</tt> and <tt>#include&nbsp;"..."</tt> directives<br>
    <STRONG><img src="theme/bullet.gif" width="13" height="13">&nbsp;</STRONG>which 
    macros to predefine and which of the predefined macros to undefine<br>
    <STRONG><img src="theme/bullet.gif" width="13" height="13">&nbsp;</STRONG>several 
    other options as for instance to control, whether to enable several extensions 
    to the C++ Standard (as for instance variadics and placemarkers) or not.</P>
</BLOCKQUOTE>
<p>You can access all these processing parameters through the <tt>wave::context</tt> 
  object. So you have to instantiate one object of this type to use the <tt>Wave</tt> 
  library. For more information about the context template class please refer 
  to the class reference <a href="class_reference_context.html">here</a>. To instantiate 
  the <tt>wave::context</tt> object you have to supply at least two template parameters: 
  the iterator type of the underlying input stream to use and the type of the 
  token to be returned from the preprocessing engine.</p>
<P dir="ltr">The main preprocessing iterators are not to be instantiated directly, 
  but should be generated through this context object too. </P>
<pre><span class="comment">    // The following preprocesses a given input file.
    // Open the file and read it into a string variable</span>
    <span class="keyword">std::ifstream</span> instream(<span class="string">&quot;input.cpp&quot;</span>);<br>    <span class="keyword">std::string </span>input<span class="keyword">(
        std::istreambuf_iterator&lt;char&gt;</span>(instream.rdbuf());
        <span class="keyword">std::istreambuf_iterator&lt;char&gt;</span>());

    <span class="comment">// The template wave::cpplexer::lex_token&lt;&gt; is the token 
    // type to be used by the Wave library.
    // This token type is one of the central types throughout 
    // the library, because it is a template parameter to many 
    // of the public classes and templates and it is returned 
    // from the iterators itself.</span>
    <span class="keyword">typedef</span> wave::context&lt;<span class=keyword>std::string::iterator</span>, 
                wave::cpplexer::lex_token&lt;&gt; &gt;
            context_t;

    <span class="comment">// The C++ preprocessor iterators shouldn't be constructed 
    // directly. These are to be generated through a 
    // wave::context&lt;&gt; object. Additionally this wave::context&lt;&gt; 
    // object is to be used to initialize and define different 
    // parameters of the actual preprocessing.
</span>    context_t ctx(input.begin(), input.end(), <span class="string">&quot;input.cpp&quot;</span>);
    context_t::iterator_t first = ctx.begin();
    context_t::iterator_t last = ctx.end();

<span class="comment">    // The preprocessing of the input stream is done on the fly 
    // behind the scenes during the iteration over the 
    // context_t::iterator_t based stream. </span>
       <span class="keyword">while</span> (first != last) {
           <span class="keyword">std::cout</span> &lt;&lt; (*first).get_value();
           ++first;
       }

</pre>
<P dir="ltr">The constructor of the <tt>wave::context&lt;&gt;</tt> object can 
  take a pair of arbitrary iterator types (at least <tt>input_iterator</tt> type 
  iterators) to the input stream, from where should be read the data to be preprocessed. 
  The third parameter supplies a filename, which is used subsequently inside the 
  preprocessed tokens returned from the preprocessing to indicate the token position 
  inside the underlying input stream. Note though, that this filename is used 
  only as long no <tt>#include</tt> or <tt>#line</tt> directives are encountered, 
  which in turn will alter the current filename.</P>
<P dir="ltr">The iteration over the preprocessed tokens is relativly straight 
  forward. Just get the starting and the ending iterators from the context object 
  (maybe after initializing some include search paths) and you are done! The dereferencing 
  of the iterator will return the preprocessed tokens, which are generated on 
  the fly from the input stream. To get further information about the token type, 
  you may want to look <a href="class_reference_tokentype.html">here</a>.</P>
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<p class="copyright">Copyright &copy; 2003-2004 Hartmut Kaiser<br>
  <br>
  <font size="2">Use, modification and distribution is subject to 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>
<span class="updated">Last updated: 
  <!-- #BeginDate format:fcAm1m -->Monday, January 5, 2004  14:57<!-- #EndDate -->
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About the Author

Hartmut Kaiser

United States United States
Actively involved in Boost and the development of the Spirit parser construction framework.

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