grammar catalog;

catalog
  :  item* 
  ;

item   :  'item' name require*
  ;

name   :  STRING;

require   :  'requires' resource;

resource
  :  (acid | electricity)
  ;


electricity  :   'electricity' NUMBER;

acid   :  'acid' acidType grade;

acidType 
  :  ('hcl' | 'hno3');
  
grade   :  NUMBER;


/*------------------------------------------------------------------
 * LEXER RULES
 *------------------------------------------------------------------*/

NUMBER  : (DIGIT)+ ;
  
WHITESPACE : ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+   { channel = 99; } ;
  
fragment DIGIT  : '0'..'9' ;

STRING   :  (LETTER)+;
LETTER   : 'a'..'z';