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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="spirit.qi.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> |
| </h4></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> |
| <p> |
| |
| </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">qi</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">phrase_parse</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">_1</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">using</span> <span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">push_back</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">phoenix</span><span class="special">::</span><span class="identifier">ref</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="identifier">ref</span><span class="special">(</span><span class="identifier">v</span><span class="special">),</span> <span class="identifier">_1</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> |
| </p> |
| <p> |
| The full cpp file for this example can be found here: <a href="../../../../../example/qi/num_list3.cpp" target="_top">../../example/qi/num_list3.cpp</a> |
| </p> |
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