title: Own DSL with XText. Problem with unlimited brackets ("(", ")")
body: <p>I am developing my own DSL in XText.</p>
  
  <p>I want do something like this:</p>
  
  <pre><code>1 AND (2 OR (3 OR 4))
  </code></pre>
  
  <p>Here my current .xtext file:</p>
  
  <pre><code>grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals
  
  generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"
  
  Model:
      (greetings+=CONDITION_LEVEL)
  ;
  
  terminal NUMBER :
      ('1'..'9') ('0'..'9')*
  ;
  
  AND:
      ' AND '
  ;
  
  OR:
      ' OR '
  ;
  
  OPERATOR : 
      AND | OR
  ;
  
  CONDITION_LEVEL:
      ('('* NUMBER (=&gt;')')* OPERATOR)+ NUMBER ')'*
  ;
  </code></pre>
  
  <p>The problem I am having is that the dsl should have the possibility to make unlimited bracket, but show an error when the programmer don't closes all opened bracket.</p>
  
  <p>example:</p>
  
  <pre><code>1 AND (2 OR (3 OR 4)
  </code></pre>
  
  <p>one bracket is missing --> should make error.</p>
  
  <p>I don't know how I can realize this in XText. Can anybody help?</p>
  
  <p>thx for helping.</p>