| Grammar <- Spacing Definition+ EndOfFile |
| Definition <- Identifier LEFTARROW Expression |
| Expression <- Sequence (SLASH Sequence)* |
| Sequence <- Prefix* |
| Prefix <- (AND / NOT)? Suffix |
| Suffix <- Primary (QUESTION / STAR / PLUS)? |
| Primary <- Identifier !LEFTARROW |
| / DOLLAR OPEN Expression CLOSE |
| / OPEN Expression CLOSE |
| / Literal |
| / Class |
| / DOT |
| Identifier <- $(IdentStart IdentCont*) Spacing |
| IdentStart <- [a-zA-Z_] |
| IdentCont <- IdentStart |
| / [0-9] |
| Literal <- ['] (!['] Char)* ['] Spacing |
| / ["] (!["] Char)* ["] Spacing |
| Class <- '[' (!']' Range)* ']' Spacing |
| Range <- Char '-' Char |
| / Char |
| Char <- '\\' [nrt'"\[\]\\] |
| / '\\' [0-2] [0-7] [0-7] |
| / '\\' [0-7] [0-7]? |
| / !'\\' . |
| LEFTARROW <- '<-' Spacing |
| SLASH <- '/' Spacing |
| AND <- '&' Spacing |
| NOT <- '!' Spacing |
| QUESTION <- '?' Spacing |
| STAR <- '*' Spacing |
| PLUS <- '+' Spacing |
| OPEN <- '(' Spacing |
| CLOSE <- ')' Spacing |
| DOT <- '.' Spacing |
| DOLLAR <- '$' Spacing |
| Spacing <- $((Space / Comment)*) |
| Comment <- '#' (!EndOfLine .)* EndOfLine |
| Space <- ' ' |
| / '\t' |
| / EndOfLine |
| EndOfLine <- '\r\n' |
| / '\n' |
| / '\r' |
| EndOfFile <- !. |
