program         -> statement* EOF ;

statement       -> if_stmt
                | print_stmt
                | while_stmt
                | for_stmt
                | declaration
                | block
                | expr_stmt
                | break
                | return_stmt ;

if_stmt         -> "if" "(" expression ")" statement ( "else" statement )? ;
print_stmt      -> "print" expression ";" ;
while_stmt      -> "while" "(" expression ")" statement ;
for_stmt        -> "for" "(" (declaration | expr_stmt | ";") ";" expression? ";" expression ";" ")" statement ;
declaration     -> var_decl | fun_decl ;
block           -> "{" statement* "}" ;
expr_Stmt       -> expression ";" ;
break           -> "break" ";" ;
return          -> "return" expression? ";" ;

var_decl        -> "var" IDENTIFIER ( "=" expression )? ";"
fun_decl        -> "fun" IDENTIFIER "(" parameters ")" block ;

expression		-> assignment

assignment      -> IDENTIFIER "=" assignment | logic_or ;
logic_or        -> logic_and ( "or" logic_and )* ;
logic_and       -> equality ( "and" equality )* ;
equality		-> comparison ( ( "==" | "!=" ) comparison )* ;
comparison		-> term ( ">" | ">=" | "<" | "<=" term )* ;
term			-> factor ( ( "+" | "-" ) factor )*
factor			-> unary ( ( "*" | "/" ) unary )* ;
unary			-> ( "!" | "-" ) unary | call ;

call            -> primary ( "(" arguments? ")" )* ;
arguments       -> expression ( "," expression )* ;

primary			-> "(" expression ")" | IDENTIFIER | fun_expr | NUMBER | STRING | "true" | "false" | "nil" ;

fun_expr        -> "fun" "(" parameters ")" block ;

parameters      -> ( IDENTIFIER ( "," IDENTIFIER )* )? ;