Preserve the extras map after modifying nodes

[natanfudge]

In Modify nodes, the documentation states

Note, since extraMap support relies on object identities and this creates entirely new objects in the immutable tree, the extra map becomes invalid on this step. This is not solved in the library yet, but could be done fairly easily.

Since my use case relies on mutating the tree and keeping the comments, I need this functionality. How can this be done?

[cretz]

I haven't really looked at this project in a while, but IIRC, that extras is an identity map which means you can't look things up by a JVM object's identity if you're working on a new one. You need some other way to map the extras. You can maintain your own IDs or whatever. You can extend the converter and store the comments however you want, see the existing extras map code at

kastree/ast-psi/src/main/kotlin/kastree/ast/psi/Converter.kt

Line 707 in 1608de6

open class WithExtras : Converter(), ExtrasMap {

. Feel free to make a custom converter storing the extras however you want (there's even a mutable var called tag on every Node where you can put stuff).

[natanfudge]

Thank you, I will try that.