Is it possible to extend the grammar

[evil-shrike]

Hi

I want to parse queries in my own SQL flavor (extension to Google Ads Query Language):

SELECT
  ad_group_ad.policy_summary.policy_topic_entries:topic~0 as topic_id
FROM ad_group_ad

mostly it's basic SQL-compatible but columns can have ~ symbols (it's kinda operator to extract resource id from resource name).
Currently the parsing fails at ~ symbols.
Is it possible to extend the grammar somehow?
I guess parser is a generated code (pegjs? btw why didn't you move to peggyjs), so I doubt, but want to confirm.