[antlr-interest] Rewrite rule ambiguity(newbie)

[ali azimi]

Hi,
   
  Thank you very much in advance.
   
  I have a rule which causes some errors (e.g. outOfMemory errors). The rule is:
   
   r :  'block'  q?  b COMMA
      ( c  |  e )*  (   f  |  g ) ?
      'endblock' ( q ?  b ) ? COMMA
      ;
   
  Could you please give your opinion as to whether the following two options are correct?
   
   
  OptionA:
   
  r :  'block'  q?  b COMMA
   
  (L1^  c*  f? |L2^  c* g? |L3^ e* f? |L4^ e* g?) 
   
   'endblock' q ?  b  ? COMMA
    ;
   
   
   
  OptionB:
   
  r  :  r1 | r2
      ;
   
  r1 : 'block'  q1=q?  b1=b COMMA  c*  (  f?  'endblock'  (q2=q? b2=b)? COMMA                    
   
  ->   ^( 'block'    $q1?    $b1   c*    f?      'endblock'      (BLOCK   $q2?   $b2)? )
                                              
                                                                 |  g? 'endblock' ( q3=q?  b3=b)? COMMA 
   
  ->   ^(  'block'  $q1?     $b1    c*    g?     'endblock'      (BLOCK   $q3?   $b3)? )
                                                                 );
   
   
  r2  :  'block' q1=q?  b1=b  COMMA e* ( f?   'endblock'  (q4=q? b4=b)? COMMA   
       
  ->   ^(  'block'   $q1?    $b1    e*   f?     'endblock'       (BLOCK   $q4?    $b4)? )
                                              
                                                                  | g?  'endblock'  (q5=q? b5=b)? COMMA
   
  ->   ^(   'block'   $q11?   $b11     e*  g?     'endblock'        (BLOCK   $q5?    $b5)?)
   
                                                              );
   
  Very much appreciated.
  Best regards,
   
  Al
                              
       
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