# grammar grammar

## terminals

ANY =| . ;

SPACE       =| ' ';
TAB         =| '\t';
RETURN      =| '\r';
NEWLINE     =| '\n';
SEMICOLON   =| ';';
EQUAL       =| '=';
PIPE        =| '|';
EXCLAMATION =| '!';
QUESTION    =| '?';
PLUS        =| '+';
STAR        =| '*';
APOSTROPHE  =| '\'';
BACKSLASH   =| '\\';
DOT         =| '.';

## rules

start =| _ rule* ;

_ =
| SPACE
| TAB
| RETURN
| NEWLINE
| comment
;

comment =| SEMICOLON (!NEWLINE ANY)* NEWLINE ; # XXX

rule =| id EQUAL option* SEMICOLON ;

id =| alpha alphanum* ;

alpha =
|'_'
|'a'|'b'|'c'|'d'|'e'|'f'|'g'|'h'|'i'|'j'|'k'|'l'|'m'
|'n'|'o'|'p'|'q'|'r'|'s'|'t'|'u'|'v'|'w'|'x'|'y'|'z'
|'A'|'B'|'C'|'D'|'E'|'F'|'G'|'H'|'I'|'J'|'K'|'L'|'M'
|'N'|'O'|'P'|'Q'|'R'|'S'|'T'|'U'|'V'|'W'|'X'|'Y'|'Z'
;

alphanum =
| alpha
| numeric
;

numeric =
|'0'|'1'|'2'|'3'|'4'
|'5'|'6'|'7'|'8'|'9'
;

option =| PIPE expr* ;

expr =
| id
| EXCLAMATION id
| id QUESTION
| id PLUS
| id STAR
| term
;

term =
# TODO review specifics of the exclamation usage
# basically, charset filters
| APOSTROPHE !BACKSLASH !APOSTROPHE ANY APOSTROPHE
| APOSTROPHE  BACKSLASH             ANY APOSTROPHE
| DOT
| byte
;

byte =| '0' 'x' hex hex ;

hex =
| numeric
|'a'|'b'|'c'|'d'|'e'|'f'
|'A'|'B'|'C'|'D'|'E'|'F'
;