l>(</span><span class=identifier>ch</span><span class=special>); 
        }
    };</span></code></pre>
<a name="match_policy"></a>
<h2>match_policy</h2>
<p> Here are the default policies that govern recognition and matching:</p>
<pre>
    <code><span class=keyword>struct </span><span class=identifier>match_policy
    </span><span class=special>{
        </span><span class=keyword>template </span><span class=special>&lt;</span><span class=keyword>typename </span><span class=identifier>T</span><span class=spe