scala - How to match exactly 'n' given characters with FastParse -


the fastparse parser-combinator scala library gives .rep(n) 'repeat' method allow create new parser attempts parse givenparser n or more times. what's canonical way if want exactly n matches?

in case, want parse 40-character git commit id - if longer 40 characters, that's not commit id, , shouldn't match.

the closest example i've found in docs far is:

val unicodeescape = p( "u" ~ hexdigit ~ hexdigit ~ hexdigit ~ hexdigit )

...which matches 4 characters simple repetition (verbose 40-character commit id).

these parser-combinators, not regex, answer \p{xdigit}{40}.

since issue closed commit, rep supports max keyword argument. supports keyword argument. 

hexdigit.rep(exactly = 40)

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