function nameClause(previousExpr, detection ) {
     
      var name = detection[NAME_INDEX],
            
          matchesName = ( !name || name == '*' ) 
                           ?  always
                           :  function(ascent){return headKey(ascent) == name};
     

      return lazyIntersection(matchesName, previousExpr);
   }
Create an evaluator function for a named path node, expressed in the
JSONPath like:
   foo
   ["bar"]
   [2]