custom language: resolving psi elements (for ParameterInfoHandler) while there are syntax errors
While implementing a custom language plugin, I stumbled upon a problem with displaying a function call hints using ParameterInfoHandler. Basically:
* it works correctly for empty function call, like method(|) and for typed parameter, like method(a;b|) (with pipe being a caret position)
* it breaks when typing parameter separator, method(a;|)
because in the second case, the call doesn't meet the grammar requirements (trailing separator is not allowed) and ParameterInfoHandler::findElementForParameterInfo and findElementForUpdatingParameterInfo provide only ) psi element parented to PsiErrorElement. Which means I can't resolve the function call expression.
I can see that this works correctly in kotlin (e.g. method(|,foo) displays the popup, despite invalid syntax).
Is there a way to resolve this function call and find the declaration in this case? Alternatively, does the grammar need to allow such cases (and report errors via an annotator instead)?
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Hi,
I think that you should play with your grammar to make a tree less broken in this case.
For example, this is a Java method call with redundant comma:
The error element is inside and it seems to not break the situation.
If you use GrammarKit, consider playing with pins (see https://github.com/JetBrains/Grammar-Kit/blob/master/TUTORIAL.md).
If it doesn't help, an annotator is an alternative solution.
Wow, pins were definitely the thing that was missing. Adding one immediately fixed the issue (
PsiErrorElementbecame a sibling of other call parameters/separators).Thanks a lot for the quick answer! So far I mostly avoided playing with pins/recoverWhile, but I probably need to look at it more.