Learning ANTLR

Grunge.g4

grammar Grunge;

root : statement*;

// language rules
literal     : LITERAL
            | '{' LITERAL ( ',' LITERAL )* '}'
            ;
variable    : VAR ;
constant    : CONSTANT ;
expression  : literal
            | variable
            | constant
            | expression '==' expression 
            | '(' expression ')'
            ;
assignment  : VAR '=' expression ';' ;
conditional : IF '(' expression ')'
              ( '{' statement* '}' | statement )
              ( ELSE ( '{' statement* '}' | statement ) )?
            ;
call        : VAR '(' ( expression ( ',' expression )* )? ')' ';' ;
closure     : VAR '{' statement* '}' ;
statement   : assignment
            | conditional
            | call
            | closure
            ;

// keywords
IF   : 'if' ;
ELSE : 'else' ;

// tokens
CONSTANT : UPPER_ALPHA ( UPPER_ALPHA | DIGIT | UNDERSCORE )* ;
VAR      : LOWER_ALPHA ( ALPHA | DIGIT | UNDERSCORE )* ;
ARRAY    : '{' LITERAL ( ',' LITERAL )* '}' ;
LITERAL  : STRING | INT | CHAR ;

// skip tokens
COMMENT            : ( MULTILINE_COMMENT | SINGLELINE_COMMENT ) -> skip ;
MULTILINE_COMMENT  : '/*' .*? '*/' ;
SINGLELINE_COMMENT : ( '#' | '//' ) ~[\r\n]* NEWLINE ;
WHITESPACE         : ( ' ' | '	' )+ -> skip ;
NEWLINE            : [\r\n]+ -> skip ;

// building blocks
fragment STRING      : QUOTE ( ESC_QUOTE | ~["] )* QUOTE ;
fragment CHAR        : TICK ( ESC_TICK | SYMBOL | ALPHA | DIGIT ) TICK ;
fragment INT         : DIGIT+ ;
fragment LOWER_ALPHA : [a-z] ;
fragment UPPER_ALPHA : [A-Z] ;
fragment ALPHA       : [a-zA-Z] ;
fragment DIGIT       : [0-9] ;
fragment SYMBOL      : [`~!@#$%^&*()-_=+{}\[\]\\|;:'",.<>/?] ;
fragment UNDERSCORE  : '_' ;
fragment QUOTE       : '"' ;
fragment ESC_QUOTE   : '\\\"' ;
fragment ESC_TICK    : '\\\'' ;
fragment TICK        : ['] ;

sample.txt

# Test comment
myClosure {
	myVar = "My Literal";
	myVar2=
		"Another$_1234=   \\ \"  Literal";
	myVar_3  =123;
	// My comment
	myVar456_='$' // Intrusive comment
				;
}

myClosure_2 {
	myVar  = "Assignment";
	
	if (myVar == "My Literal") {
		myVar = "Another Literal" /** really stupidly inline
* comment
up in here


*/

;
		myFunc("Param1", /* inline comment */ var2, var1 == var2);
		myVar = (var1 == var2); 
		myFunc("Param2", myVar, {1, 2, 3});
	}
}