LispIsh Documentation - Gerrit0/CTFd_unique_challenges GitHub Wiki

LispIsh is a minimal lisp like language used for sandboxed evaluation of advanced challenge requirements.

(and
    (<=
        (user-score)
        1)
    (/=
        (user-name)
        "gerrit"))

Since LispIsh is built on top of Python, 0 is falsy and any other number is truthy. Unlike Python, function names are case-insensitive. (AND 1 2) is equivalent to (and 1 2). However, string comparison is case sensitive. (= "a" "A") is false.

The advanced requirements editor allows administrators to insert a function call that will be evaluated to determine if the user can access the given challenge.

The following builtin functions exist:

Function	Arguments	Description
=	2+	Checks if all arguments are equal, (= 1 2) is false while (= 1 1) is true.
/=	2+	Checks if all arguments are distinct, (/= 1 2) is true, while (/= 1 2 2) is false.
and	0+	False if any arguments are falsy, otherwise true.
or	0+	True if at least one argument is truthy, otherwise false.
not	1	Inverts the truthiness of the argument. (not 1) is false, (not 0) is true.
+	0+	Sums the arguments, if no arguments are provided produces 0. (add 1 2 3) is 6.
-	1+	Starts with the first argument, and subtracts each argument after it from the initial value. (sub 4 1 2) is 1. If only one argument is provided, returns the negation of it. (- 1) is equivalent to (- 0 1).
max	1+	Returns the maximum of the arguments, (max 1 2) is 2.
min	1+	Returns the minimum of the arguments, (min 1 2) is 1.
>	2+	Checks if each argument provided is greater than the argument following it. (> 1 2) is false because 1 > 2 is false. (> 3 2 1) is true because 3 > 2 and 2 > 1.
>=	2+	Checks if each argument provided is greater than or equal to the argument following it. (>= 1 1) is true, while (>= 1 2) is false.
<	2+	Checks if each argument provided is less than the argument following it. (< 1 2) is true, while (< 2 1) is false.
<=	2+	Checks if each argument provided is less than or equal to the argument following it. (<= 0 1 1) is true, while (<= 2 1) is false.

In addition to the default language functions, the advanced requirements page provides some helper functions for querying challenge info.

Function	Arguments	Description
completed	0+	For each argument, if it is an integer, look up the challenge with that ID. If the argument is a string, look up the challenge having that name. If any of the challenges have not been completed, returns false. Otherwise, returns true.
cohort	0+	True if the current user is in all of the specified cohorts, behaves the same as completed for cohorts instead of challenges.
before	1	Returns true if the current time is before the given time. Time may be specified as an integer, which will be treated as the epoch time, or as a string with format YYYY-MM-DD or YYYY-MM-DD HH:MM.
after	1	Logical inverse of before.
user-email	0	Returns the current user's email.
user-name	0	Returns the current user's name. Note: Names are not necessarily unique.
user-id	0	Returns the current user's ID.
user-score	0	Returns the current user's overall score from completing challenges and receiving awards.