In order to define a new way of formatting la new language, you must defined first the formatting rules as follow:
pre "\n" : "{", "}",";;" post "\n" : ";", "}", "=" surround " " : EQUALS, PLUS childIndent "\t" : (LPAREN, RPAREN), ("{", "}") selfIndent "\t" : (LPAREN, RPAREN), ("{", "}")
The following description will: a+b={c+d};; expected outputs: (surround PLUS is the first match) a + b = (* \n car post EQUALS*) { (self indent here) c + d (child indent here and surround PLUS) } (child indent is finished because RPAREN is the end tag ;; (\n because pre ;;*)