title: antlr4 + python: debug token match
body: <p>I'm using antlr4 + python target to match a phrase like this，</p>
  
  <pre><code>select 1 from dual where id=.0union select 1
  </code></pre>
  
  <p>The tokens are:</p>
  
  <pre><code>['select', '1', 'from', 'dual', 'where', 'id', '=', '.0union', 'select', '1']
  </code></pre>
  
  <p>My problem is, the <code>.0</code> and <code>union</code> token has been merged into one single token, aka <code>.0union</code>, and antlr reports an error like this,</p>
  
  <pre><code>line 1:32 mismatched input '=' expecting {&lt;EOF&gt;, '&amp;&amp;', &lt;INVALID&gt;, ';', &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;, &lt;INVALID&gt;}
  </code></pre>
  
  <p>Any ideas on debugging it? </p>
  
  <p>Is there any way to debug the token match process?</p>