questebnf-old.ebnf

program := {<expr>} ;
expr := <block> | <unary-op> | <binary-op> | <ecall>

unary-op := UNARY_OP <expr> ;
binary-op := <expr> BINARY_OP <expr> ;

fn-call := <primary> '(' <fn-call-args> ')' ;
attr-access := <primary> '.' <primary>;
array-access := <primarY> '[' <fn-call-args> ']' ;

literal := STRING_LITERAL | 

array-literal := '[' {<expression> ','} [<expression>] '}' ;
block := '{' {<expression> NEWLINE} [<expression>] '}' ;

number-literal := ['+' | '-'] (<integer-literal> | <float-literal>) ;
(* NOTE: {...}'_' is the same as )
integer-literal
 := '0' 'x' {'_'} HEX_DIGIT {'_' | HEX_DIGIT}
  | '0' 'b' {'_'} ('0' | '1') {'_' | '0' | '1'}
  | '0' 'o' {'_'} OCTAL_DIGIT {'_' | OCTAL_DIGIT}
  | ['0' 'd'] {'_'} DIGIT {'_' | DIGIT} ;
float-literal
 := DIGIT {'_' | DIGIT}
 	('.' {'_'} DIGIT {'_' DIGIT}
 		| ('e' | 'E') ['+' | '-'] {'_'} DIGIT {'_' DIGIT}) ;


string-literal := <string-single> | <string-double> | <string-raw> ;
string-single := "'" ( BACKSLASH <string-single-escape> | (? any non-"'" char ?) ) "'" ;
string-single-escape := "'" | '"' | BACKSLASH ;
string-double := '"' ( BACKSLASH <string-double-escape> | (? any non-'"' char ?) ) '"' ;
string-double-escape
 := <string-single-escape>
  | 'x' HEX_DIGIT HEX_DIGIT
  | 'u' HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT
  | 'n' | 'r' | 't' | 'f' | '0' ;
string-raw := 'r' {'#'} '"' (? any character, but not greedily ?) '"' (? same amount of `#`s as the start ?) ;

BACKSLASH := '\\' ;
HEX_DIGIT
 := 'a' | 'b' | 'c' | 'd' | 'e' | 'f'
  | 'A' | 'B' | 'C' | 'D' | 'E' | 'F'
  | DIGIT ;

OCTAL_DIGIT := '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' ;
DIGIT := '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;
NEWLINE := ';' | '\n' ;