ceph/src/boost/libs/spirit/classic/doc/regular_expression_parser.html

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  13     <td width="85%" height="49"> <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Regular Expression Parser</b></font></td>
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  26 <p><a name="regular_expression_parser"></a>Regular expressions are a form of pattern-matching
  27   that are often used in text processing. Many users will be familiar with the
  28   usage of regular expressions. Initially there were the Unix utilities grep,
  29   sed and awk, and the programming language perl, each of which make extensive
  30   use of regular expressions. Today the usage of such regular expressions is integrated
  31   in many more available systems.</p>
  32 <p>During parser construction it is often useful to have the power of regular
  33   expressions available. The Regular Expression Parser was introduced, to make
  34   the use of regular expressions accessible for Spirit parser construction.</p>
  35 <p>The Regular Expression Parser <tt>rxstrlit</tt> has a single template type
  36   parameter: an iterator type. Internally, <tt>rxstrlit</tt> holds the Boost Regex
  37   object containing the provided regular expression. The <tt>rxstrlit</tt> attempts
  38   to match the current input stream with this regular expression. The template
  39   type parameter defaults to <tt>char const<span class="operators">*</span></tt>.
  40   <tt>rxstrlit</tt> has two constructors. The first accepts a null-terminated
  41   character pointer. This constructor may be used to build <tt>rxstrlit's</tt>
  42   from quoted regular expression literals. The second constructor takes in a first/last
  43   iterator pair. The function generator version is <tt>regex_p</tt>. </p>
  44 <p>Here are some examples:</p>
  45 <pre><code><span class=comment>    </span><span class=identifier>rxstrlit</span><span class=special>&lt;&gt;(</span><span class=string>"Hello[[:space:]]+[W|w]orld"</span><span class=special>)
  46     </span><span class=identifier>regex_p</span><span class=special>(</span><span class=string>"Hello[[:space:]]+[W|w]orld"</span><span class=special>)
  47
  48     </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=identifier>msg</span><span class=special>(</span><span class=string>"Hello[[:space:]]+[W|w]orld"</span><span class=special>);
  49     rx</span><span class=identifier>strlit</span><span class=special>&lt;&gt;(</span><span class=identifier>msg</span><span class=special>.</span><span class=identifier>begin</span><span class=special>(), </span><span class=identifier>msg</span><span class=special>.</span><span class=identifier>end</span><span class=special>());</span></code></pre>
  50 <p>The generated parser object acts at the character level, thus an eventually
  51   given skip parser is not used during the attempt to match the regular expression
  52   (see <a href="faq.html#scanner_business">The Scanner Business</a>).</p>
  53 <p>The Regular Expression Parser is implemented by the help of the <a href="http://www.boost.org/libs/regex/index.html">Boost
  54   Regex++ library</a>, so you have to have some limitations in mind. </p>
  55 <blockquote>
  56   <p><img src="theme/bullet.gif" width="12" height="12"> Boost libraries have
  57     to be installed on your computer and the Boost root directory has to be added
  58     to your compiler <tt>#include&lt;...&gt;</tt> search path. You can download
  59     the actual version at the <a href="http://www.boost.org/">Boost web site</a>.</p>
  60   <p><img src="theme/bullet.gif" width="12" height="12"> The Boost Regex library
  61     requires the usage of bi-directional iterators. So you have to ensure this
  62     during the usage of the Spirit parser, which contains a Regular Expression
  63     Parser.</p>
  64   <p><img src="theme/bullet.gif" width="12" height="12"> The Boost Regex library
  65     is not a header only library, as Spirit is, though it provides the possibility
  66     to include all of the sources, if you are using it in one compilation unit
  67     only. Define the preprocessor constant <tt>BOOST_SPIRIT_NO_REGEX_LIB</tt> before
  68     including the spirit Regular Expression Parser header, if you want to include
  69     all the Boost Regex sources into this compilation unit. If you are using the
  70     Regular Expression Parser in more than one compilation unit, you should not
  71     define this constant and must link your application against the regex library
  72     as described in the related documentation.</p>
  73 </blockquote>
  74 <p> <img src="theme/lens.gif" width="15" height="16"> See <a href="../example/fundamental/regular_expression.cpp">regular_expression.cpp</a> for a compilable example. This is part of the Spirit distribution.</p>
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  85 <p class="copyright">Copyright &copy; 2001-2002 Hartmut Kaiser<br>
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  87   <font size="2">Use, modification and distribution is subject to the Boost Software
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