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POBoost Spirit Qi: Omit element in Kleene Star parser
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  1. POBoost Spirit Qi: Omit element in Kleene Star parser
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    copied!<p>I want to parse special constructs and throw the rest away. But I don't want to use a skipper.</p> <p>I want to get a vector of these constructs, so I use a Kleene Star parser as main rule. But, everytime something gets thrown away, a default constructed element is inserted into the vector.</p> <p>Here is a made up example. It just looks for the string <code>Test</code> and throws the rest away, at least this is the plan. But every time the rule <code>garbage</code> succeeds it adds a default constructed item to the vector in the rule <code>all</code>, giving an output of 7 insteat of 1. How can I tell Spirit to just add to the vector if the rule <code>item</code> succeeds?</p> <pre><code>#define BOOST_SPIRIT_USE_PHOENIX_V3 #include &lt;boost/config/warning_disable.hpp&gt; #include &lt;boost/spirit/include/qi.hpp&gt; #include &lt;boost/fusion/adapted/struct.hpp&gt; #include &lt;boost/spirit/include/phoenix.hpp&gt; #include &lt;iostream&gt; #include &lt;string&gt; #include &lt;vector&gt; namespace qi = boost::spirit::qi; struct container { std::string name; bool dummy; }; BOOST_FUSION_ADAPT_STRUCT(::container, (std::string, name) (bool, dummy)) int main() { typedef std::string::const_iterator iterator; qi::rule&lt;iterator, std::vector&lt;container&gt;()&gt; all; qi::rule&lt;iterator, container()&gt; item; qi::rule&lt;iterator, std::string()&gt; string_rule; qi::rule&lt;iterator&gt; garbage; all = *(garbage | item); garbage = qi::char_ - qi::lit("Test"); string_rule = qi::string("Test"); item = string_rule &gt;&gt; qi::attr(true); std::vector&lt;container&gt; ast; std::string input = "blaTestbla"; iterator first = input.begin(); iterator last = input.end(); bool result = qi::parse(first, last, all, ast); if (result) { result = first == last; } if (result) { std::cout &lt;&lt; "Parsed " &lt;&lt; ast.size() &lt;&lt; " element(s)" &lt;&lt; std::endl; } else { std::cout &lt;&lt; "failure" &lt;&lt; std::endl; } } </code></pre>
 

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