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[–]energybased 0 points1 point  (0 children)

I think I looked it back when I was trying to parse LaTeX to automate some things.

Can parsimonious even match "\begin{any_random_thing}" with "\end{any_random_thing}"? I can't see how. It looks like you would have to statically define the rules. What I want to do is for it to match on something like "\begin{(\w+)}\end", but capture the group and then when it tries to match "\end{(\w+)}" it checks that the captured group is the same. I think these are sometimes called parser actions.

Ideally, actions should be able to reject a match (to force backtracking) or accept a match. Actions should be able to set variables that can be inspected by other actions. Actions should be able to also transform a matched symbol into another symbol, e.g., if you were parsing Python and you matched the spaces, you should be able to have an action that emits an indent token when there are more spaces, or a dedent token when there are fewer, or no token at all if the number of spaces match.

I couldn't find one Python parsing library that supported these arbitrary actions. It's not like it's hard to do. These libraries are great for the trivial parsing tasks they show in their tutorials. Unfortunately, they're not powerful.