Fix function parsing with ambiguous lists in parameters. #6579
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sovdeeth
reviewed
Apr 17, 2024
src/test/skript/tests/regressions/4988-function uuid multiple parameters.sk
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APickledWalrus
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Apr 22, 2024
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Summary
Upon failing to parse a function (with too few arguments) Skript will re-attempt it explicitly as an ExpressionList of arguments.
This fixes
func(uuid of player, "hello")being wrongly-interpreted asfunc(uuid of (player, "hello"))and failing to parse.Note: the Git diff is a nightmare because the methods in SkriptParser are nine million lines long, I can't do anything about that, sorry 😦
The problem
Functions struggle with ambiguous parameters: is
func(uuid of {_a}, {_b})asking for a function with two parameters (uuid of {_a}and{_b}) or is it asking for a function with a single parameter (uuid of {_a} and {_b})?Most rational people would say the first, but Skript does not think so! Lists are checked after singular expression parsing (for arguably good reason), so
uuid of {_a} and {_b}will be matched first.This means that your function
func(uuid: string, something: string)will fail.This on its own is fine. Everything here is intended, however we have a secret enemy: string converters!
Since 2.6 we are in an era where a string can be anything it wants. This means that while
uuid of "hello"ought to fail (because how can a text have a UUID?) the text can be implicitly converted to a World, which can have a UUID.This means that even nonsensical stuff like
uuid of {_a}, "have a nice day!"is technically admissible at parse time.Converters bring us lots of nice things, but they've also exacerbated this issue with function parsing, because it's even harder for us to identify a mistake.
My Lovely(ish) Solution
My fix is as follows:
If the function fails -- specifically because it has too few parameters -- the arguments string is reparsed as only a list of expressions, and then it's tested again. If it still fails, oh well.
This isn't perfect: obviously it's a second needless check for things that are actually just wrong, but that's not the end of the world.
It also can't fix parsing ambiguity mid-way through the arguments:"hello", uuid of {_a}, "there"is still gonna be parsed the wrong way because that's how Skript parses stuff, and we probably shouldn't change that.Walrus said it's fine 🙂
Target Minecraft Versions: any
Requirements: none
Related Issues: closes #4988