123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293 |
- <html>
- <head>
- <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
- <title>Number List Redux - list syntax</title>
- <link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css">
- <meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
- <link rel="home" href="../../index.html" title="Spirit X3 3.0.4">
- <link rel="up" href="../tutorials.html" title="Tutorials">
- <link rel="prev" href="number_list___stuffing_numbers_into_a_std__vector.html" title="Number List - stuffing numbers into a std::vector">
- <link rel="next" href="number_list_attribute___one_more__with_style.html" title="Number List Attribute - one more, with style">
- </head>
- <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
- <table cellpadding="2" width="100%"><tr>
- <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td>
- <td align="center"><a href="../../../../../../../index.html">Home</a></td>
- <td align="center"><a href="../../../../../../../libs/libraries.htm">Libraries</a></td>
- <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
- <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
- <td align="center"><a href="../../../../../../../more/index.htm">More</a></td>
- </tr></table>
- <hr>
- <div class="spirit-nav">
- <a accesskey="p" href="number_list___stuffing_numbers_into_a_std__vector.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../tutorials.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="number_list_attribute___one_more__with_style.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a>
- </div>
- <div class="section">
- <div class="titlepage"><div><div><h3 class="title">
- <a name="spirit_x3.tutorials.number_list_redux___list_syntax"></a><a class="link" href="number_list_redux___list_syntax.html" title="Number List Redux - list syntax">Number
- List Redux - list syntax</a>
- </h3></div></div></div>
- <p>
- So far, we've been using the syntax:
- </p>
- <pre class="programlisting"><span class="identifier">double_</span> <span class="special">>></span> <span class="special">*(</span><span class="char">','</span> <span class="special">>></span> <span class="identifier">double_</span><span class="special">)</span>
- </pre>
- <p>
- to parse a comma-delimited list of numbers. Such lists are common in parsing
- and Spirit provides a simpler shortcut for them. The expression above can
- be simplified to:
- </p>
- <pre class="programlisting"><span class="identifier">double_</span> <span class="special">%</span> <span class="char">','</span>
- </pre>
- <p>
- read as: a list of doubles separated by <code class="computeroutput"><span class="char">','</span></code>.
- </p>
- <p>
- This sample, again a variation of our previous example, demonstrates just
- that:
- </p>
- <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">></span>
- <span class="keyword">bool</span> <span class="identifier">parse_numbers</span><span class="special">(</span><span class="identifier">Iterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">Iterator</span> <span class="identifier">last</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">double</span><span class="special">>&</span> <span class="identifier">v</span><span class="special">)</span>
- <span class="special">{</span>
- <span class="keyword">using</span> <span class="identifier">x3</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span>
- <span class="keyword">using</span> <span class="identifier">x3</span><span class="special">::</span><span class="identifier">phrase_parse</span><span class="special">;</span>
- <span class="keyword">using</span> <span class="identifier">x3</span><span class="special">::</span><span class="identifier">_attr</span><span class="special">;</span>
- <span class="keyword">using</span> <span class="identifier">ascii</span><span class="special">::</span><span class="identifier">space</span><span class="special">;</span>
- <span class="keyword">auto</span> <span class="identifier">push_back</span> <span class="special">=</span> <span class="special">[&](</span><span class="keyword">auto</span><span class="special">&</span> <span class="identifier">ctx</span><span class="special">){</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">_attr</span><span class="special">(</span><span class="identifier">ctx</span><span class="special">));</span> <span class="special">};</span>
- <span class="keyword">bool</span> <span class="identifier">r</span> <span class="special">=</span> <span class="identifier">phrase_parse</span><span class="special">(</span><span class="identifier">first</span><span class="special">,</span> <span class="identifier">last</span><span class="special">,</span>
- <span class="comment">// Begin grammar</span>
- <span class="special">(</span>
- <span class="identifier">double_</span><span class="special">[</span><span class="identifier">push_back</span><span class="special">]</span> <span class="special">%</span> <span class="char">','</span>
- <span class="special">)</span>
- <span class="special">,</span>
- <span class="comment">// End grammar</span>
- <span class="identifier">space</span><span class="special">);</span>
- <span class="keyword">if</span> <span class="special">(</span><span class="identifier">first</span> <span class="special">!=</span> <span class="identifier">last</span><span class="special">)</span> <span class="comment">// fail if we did not get a full match</span>
- <span class="keyword">return</span> <span class="keyword">false</span><span class="special">;</span>
- <span class="keyword">return</span> <span class="identifier">r</span><span class="special">;</span>
- <span class="special">}</span>
- </pre>
- <p>
- The full cpp file for this example can be found here: <a href="../../../../../example/x3/num_list/num_list3.cpp" target="_top">num_list3.cpp</a>
- </p>
- </div>
- <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
- <td align="left"></td>
- <td align="right"><div class="copyright-footer">Copyright © 2001-2018 Joel de Guzman,
- Hartmut Kaiser<p>
- Distributed under the Boost Software License, Version 1.0. (See accompanying
- file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
- </p>
- </div></td>
- </tr></table>
- <hr>
- <div class="spirit-nav">
- <a accesskey="p" href="number_list___stuffing_numbers_into_a_std__vector.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../tutorials.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="number_list_attribute___one_more__with_style.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a>
- </div>
- </body>
- </html>
|