ANTLR4 grammar for rule-based DSL

RuleDSL.g4

grammar RuleDSL;

rules: (basic_rule)+ EOF;

basic_rule: 'rule' SPACE rule_name SPACE '{' EOL conditions '}' EOL;

name: ID;
list_index: '[' IND ']';
name_expr: name list_index*;
rule_name: name_expr ('.' name_expr)*;

conditions: when_condition_expr+ otherwise_condition_expr?;

condition: .*?;
result:  ~EOL* ;
when_condition_expr: result WHEN condition;

otherwise_condition_expr: result IN_OTHER_CASES;

WHEN: 'when';
IN_OTHER_CASES: 'in' 'other' 'cases';

ID: CHAR+;
IND: DIGIT+;
fragment DIGIT: '0'..'9';
fragment CHAR: 'a'..'z' | 'A'..'Z';

SYMBOL: '?' | '!' | '&' | '.' | ',' | '(' | ')' | '[' | ']' | '\\' | '/' | '%' 
      | '*' | '-' | '+' | '=' | '<' | '>' | '_' | '|' | '"' | '\'' | '~';


// Whitespace and comments

SPACE: [ \t]+;
EOL: ('\n' | '\r\n')+;
WS: [\t\u000C]+ -> skip;
COMMENT: '/*' .*? '*/' -> skip;