Modify the CSP Evaluator to handle negated expressions #4441
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This commit adds support to use straightforward negated expressions in Alpine directives in the CSP build. While we (probably) do not want to rewrite a full CSP-save expression evaluator to handle expressions of arbitrary complexity, directives with negation are such a common use case that it makes sense to support them. Consider, for example, * `x-show="!loading"` * `:disabled="!valid"` In the CSP, we would have to write custom getters for each boolean attribute whose negation we might want to use, adding needless verbosity. On the other hand, being a unary operator, hand-rolling negation is easy enough. To test that it all works, we add relevant cypress tests to the csp spec to verify that we can negate both a plain attribute as well as the result of a function call.
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The part for "negation of a function call" I think is problematic. As this would now introduce unique behavior to the CSP build that doesn't work in Alpine standard, or in javascript. 🤔 It introduces a bit of unnecessary magic I think... |
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Thanks for the feedback. Just so I understand correctly, current Alpine.js wouldn't be able to handle an expression like |
It would. but Here, your case seems to be running the function, and then negativing it's result. Based on that second test. That is different results than the normal evaluator. |
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I think you can apply the negation to evaluatedExpression before passing it into runIfTypeOfFunction to preserve the same behaviour as the non-CSP built |
That's what I did initially, and then I started overthinking it, assuming that I needed to support the function-calling thing. |
To keep feature parity with the Alpine standard build, we remove function evaluation of negated function calls (`x-show=!foo`) where foo is a function. Also adjust the test so it checks for proper trimming and modify the trimming of the expression to be evaluated to allow for whitespace between the negation operatior and the expression: `x-show="! foo`.
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Thanks for your comments, everyone. I made the changes as recommended and pushed a new commit. |
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Yeah, I could see the motivation for it, and it could make sense in a strict "built from nothing" situation. But in this case, divergent behaviors would be an issue. |
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@ekwoka I've taken out the extra function evaluation magic; wondering if anyone wants to take a second look. |
This commit adds support to use straightforward negated expressions in Alpine directives in the CSP build.
While we (probably) do not want to rewrite a full CSP-save expression evaluator to handle expressions of arbitrary complexity, directives with negation are such a common use case that it makes sense to support them.
Consider, for example,
x-show="!loading":disabled="!valid"In the CSP, we would have to write custom getters for each boolean attribute whose negation we might want to use, adding needless verbosity.
On the other hand, being a unary operator, hand-rolling negation is easy enough.
To test that it all works, we add relevant cypress tests to the csp spec to verify that we can negate both a plain attribute as well as the result of a function call.