122 lines
7.1 KiB
HTML
122 lines
7.1 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>Quick Start</title>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<link href="theme/style.css" rel="stylesheet" type="text/css">
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</head>
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<body text="#000000" background="theme/bkd.gif">
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<table width="100%" border="0" cellspacing="2" background="theme/bkd2.gif">
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<tr>
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<td width="21"> <h1></h1></td>
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<td width="885"> <font face="Verdana, Arial, Helvetica, sans-serif"><b><font size="6">Quick
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Start </font></b></font></td>
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<td width="96"><a href="http://www.boost.org"><img src="theme/wave.gif" width="93" height="68" align="right" border="0"></a></td>
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</tr>
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</table>
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<br>
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<table border="0">
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<tr>
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<td width="10"></td>
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<td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td>
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<td width="30"><a href="introduction.html"><img src="theme/l_arr.gif" width="20" height="19" border="0"></a></td>
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<td width="30"><a href="class_reference_context.html"><img src="theme/r_arr.gif" border="0"></a></td>
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</tr>
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</table>
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<p>Preprocessing with <tt>Wave</tt> is highly configurable. You must
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define a few options to control it. Here are a few of the
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options you can define:</p>
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<BLOCKQUOTE dir="ltr" style="MARGIN-RIGHT: 0px">
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<P><STRONG><IMG id="IMG1" height="13" src="theme/bullet.gif" width="13"></STRONG> include
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search paths defining where to search for files to be included with
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<tt>#include <...></tt> and <tt>#include "..."</tt> directives<br>
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<STRONG><img src="theme/bullet.gif" width="13" height="13"> </STRONG>which
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macros to predefine and which of the predefined macros to undefine<br>
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<STRONG><img src="theme/bullet.gif" width="13" height="13"> </STRONG>whether to enable any of several extensions to the C++
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Standard (such as for variadics and placemarkers)
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</P>
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</BLOCKQUOTE>
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<p>You can access all these processing parameters through the <tt>boost::wave::context</tt>
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object. So you must instantiate one object instance of this type to use the <tt>Wave</tt>
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library. (For more information about the context template class, please refer
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to the class reference <a href="class_reference_context.html">here</a>.) To instantiate
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the <tt>boost::wave::context</tt> object you have to supply at least two template parameters:
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the iterator type of the underlying input stream to use and the type of the lexer iterator to be used as the token source for the preprocessing engine.</p>
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<P dir="ltr">Do not instantiate the main preprocessing iterators yourself.
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Get them from the <tt>boost::wave::context</tt> object instead.
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The following code snippet is taken from the <tt>quick_start</tt> sample, which shows a minimal usage scenario for <tt>Wave</tt>. </P>
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<pre><span class="comment"> // The following preprocesses a given input file.
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// Open the file and read it into a string variable</span>
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<span class="keyword">std::ifstream</span> instream(<span class="string">"input.cpp"</span>);
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<span class="keyword">std::string </span>input<span class="keyword">(
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std::istreambuf_iterator<char></span>(instream.rdbuf()),
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<span class="keyword">std::istreambuf_iterator<char></span>());
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<span class="comment">// The template boost::wave::cpplexer::lex_token<> is the
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// token type to be used by the Wave library.
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// This token type is one of the central types throughout
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// the library, because it is a template parameter to some
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// of the public classes and templates and it is returned
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// from the iterators.
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// The template boost::wave::cpplexer::lex_iterator<> is
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// the lexer iterator to use as the token source for the
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// preprocessing engine. In this case this is parametrized
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// with the token type.</span>
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<span class="keyword">typedef</span> <span class="identifier">boost::wave::cpplexer::lex_iterator</span><span class="special"><</span>
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<span class="identifier">boost::wave::cpplexer::lex_token</span><span class="special"><> ></span>
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<span class="identifier">lex_iterator_type</span><span class="special">;</span>
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<span class="keyword">typedef</span> <span class="identifier">boost::wave::context</span><span class="special"><</span>
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std::string::iterator<span class="special">,</span> lex_iterator_type<span class="special">></span>
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<span class="identifier">context_type</span><span class="special">;</span>
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context_type ctx(input.begin(), input.end(), <span class="string">"input.cpp"</span>);
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<span class="comment">
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// At this point you may want to set the parameters of the
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// preprocessing as include paths and/or predefined macros.
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</span> ctx.add_include_path(<span class="literal">"..."</span>);
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ctx.add_macro_definition(...);
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<span class="comment">
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// Get the preprocessor iterators and use them to generate
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// the token sequence.
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</span> context_type::iterator_type first = ctx.begin();
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context_type::iterator_type last = ctx.end();
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<span class="comment"> // The input stream is preprocessed for you during iteration<br> // over [first, last)<br></span> <span class="keyword">while</span> (first != last) {
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<span class="keyword">std::cout</span> << (*first).get_value();
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++first;
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}
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</pre>
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<P dir="ltr">The constructor of the <tt>boost::wave::context</tt> object can
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take a pair of arbitrary iterator types (at least <tt>input_iterator</tt> type
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iterators) to the input stream, which must supply the data to be processed.
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The third parameter supplies a filename, which is reported in the preprocessor output to
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indicate the current context.
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Note though, that this filename is used
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only as long as no <tt>#include</tt> or <tt>#line</tt> directives are encountered,
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which in turn will alter the current reported filename.</P>
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<P dir="ltr">The iteration over the preprocessed tokens is relatively straightforward. Just get the starting and the ending iterators from the context object
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(maybe after initializing some include search paths) and you are done! Dereferencing
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the iterator will return the preprocessed tokens generated on
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the fly from the input stream. (To get further information about the token type,
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you may want to look <a href="class_reference_tokentype.html">here</a>.)</P>
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<table border="0">
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<tr>
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<td width="10"></td>
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<td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td>
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<td width="30"><a href="introduction.html"><img src="theme/l_arr.gif" width="20" height="19" border="0"></a></td>
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<td width="30"><a href="class_reference_context.html"><img src="theme/r_arr.gif" border="0"></a></td>
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</tr>
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</table>
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<hr size="1">
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<p class="copyright">Copyright © 2003-2011 Hartmut Kaiser<br>
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<br>
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<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>
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<span class="updated"></span>
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<p class="copyright"><span class="updated">Last updated:
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<!-- #BeginDate format:fcAm1m -->Tuesday, July 29, 2008 20:34<!-- #EndDate -->
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</span></p>
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</body>
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</html>
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