grammar

program : PROGRAM ID ';' variable_declaration function_declaration block 

empty : 

variable_declaration : type ids ';' variable_declaration
	| empty 

ids : id other_ids 

other_ids : ',' ids 
	| empty 

id : ID 
	| ID '[' expression ']' 

expression : level1 
	| level1 EXPONENTIATION level1  

level1 : level2 
	| '+' level2
	| '-' level2

level2 : level3 
	| level3 OR level3 
	| level3 AND level3 

level3 : level4
	| level4 '<' level4
	| level4 '>' level4
	| level4 LESS_EQUAL_THAN level4
	| level4 GREATER_EQUAL_THAN level4
	| level4 EQUALS level4 

level4 : level5
	| level5 '+' level5
	| level5 '-' level5 

level5 : level6
	| NOT level6
	| level6 '*' level6
	| level6 '/' level6
	| level6 MOD level6 

level6 : '(' expression ')'
	| const
	| increment
	| decrement 

increment : INCREMENT id 

decrement : DECREMENT id 

function_declaration : function function_declaration
	| empty

'''function : FUN return_type ID '(' parameters ')' '{' variable_declaration statutes '}' ';' 

return_type : type 
	| VOID 

type : INT 
	| DEC 
	| CHAR 
	| STR 
	| BOOL 

statutes : statute ';' statutes
	| empty

'''statute   : call
	| assignment
	| condition
	| cycle 
	| special 
	| return
	| increment
	| decrement 

call : ID '(' expressions ')' 

expressions : expression
	| expression ',' expressions 

assignment : id '=' expression 

condition : IF '(' expression ')' block elses 

cycle : WHILE '(' expression ')' block 

special : SPECIAL_ID '(' expressions ')' 

return : RETURN expression
	| RETURN 

elses : empty
	| ELSE block
	| ELSEIF '(' expression ')' block elses 

parameters : type ID other_parameters
	| empty 

other_parameters : ',' type ID other_parameters
	| empty 

const : id 
	| call
	| special
	| INT_VAL
	| DEC_VAL
	| CHAR_VAL
	| STR_VAL
	| BOOL_VAL 

block : '{' statutes '}'