sqids-decode ( sqids id -- numbers )
Sqids: encode numbers into short, unique, URL-safe IDs

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Vocabulary
sqids

Inputs

sqids	a sqids encoder
id	a string

Outputs

numbers

a sequence

Word description
Decodes an ID back into the original sequence of non-negative integers, using the same alphabet as the encoder. Returns an empty sequence if the ID is empty or contains a character not in the encoder's alphabet. Decoding does not enforce the blocklist or minimum length, and multiple IDs can decode to the same numbers. Re-encode the result and compare it with the original ID to check whether it is canonical for the current configuration.

Definition

USING: accessors combinators.short-circuit kernel make sequences
sqids.private ;

IN: sqids

:: sqids-decode ( sqids id -- numbers )
    sqids alphabet>> :> alphabet id
    { [ empty? not ] [ [ alphabet member? ] all? ] } 1&& [
        id first alphabet index
        :> offset alphabet offset cut swap append
        reverse :> rotated
        [ id rest rotated decode-numbers ] { } make
    ] [ { } ] if ;