~/2020/worng

Rules

expression → literal
| unary
| binary
| grouping ;

literal    → NUMBER | STRING | "true" | "false" | "nil" ;
grouping   → "(" expression ")" ;
unary      → ( "-" | "!" ) expression ;
binary     → expression operator expression ;
operator   → "==" | "!=" | "<" | "<=" | ">" | ">="
| "+"  | "-"  | "*" | "/" ;


---------------------------------

program     → declaration* EOF ;

declaration → class_declaration
 | function_declaration
 | var_declaration
 | statement ;

class_declaration → "class" IDENTIFIER ( "<" IDENTIFIER )?
 "{" function* "}" ;

function_declaration  → "fun" function ;
function → IDENTIFIER "(" parameters? ")" block ;
parameters → IDENTIFIER ( "," IDENTIFIER )* ;

statement  → expression_statement
| for_statement
| if_statement
| print_statement
| return_statement
| while_statement
| block_statement ;

return_statement → "return" expression? ";" ;

for_statement   → "for" "(" ( var_declaration | expression_statement | ";" )
					 expression? ";"
					 expression? ")" statement ;


if_statement    → "if" "(" expression ")" statement ( "else" statement )? ;

expression      → assignment ;
print_statement → "print" expression ";" ;
block           → "{" declaration* "}" ;


assignment → ( call "." )? IDENTIFIER "=" assignment
| logic_or ;

logic_or   → logic_and ( "or" logic_and )* ;
logic_and  → equality ( "and" equality )* ;

equality       → comparison ( ( "!=" | "==" ) comparison )* ;
comparison     → addition ( ( ">" | ">=" | "<" | "<=" ) addition )* ;
addition       → multiplication ( ( "-" | "+" ) multiplication )* ;
multiplication → unary ( ( "/" | "*" ) unary )* ;


unary → ( "!" | "-" ) unary | call ;
call → primary ( "(" arguments? ")" | "." IDENTIFIER )* ;

arguments → expression ( "," expression )* ;    // eg (arg1, arg2) or more args.

primary → "true" | "false" | "nil" | "this"
| NUMBER | STRING | IDENTIFIER | "(" expression ")"
| "super" "." IDENTIFIER ;