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Comment by irdc | Hacker News Reader

I’d be interested to see a re-usable implementation of joe's[0] syntax highlighting.[1] The format is powerful enough to allow for the proper highlighting of Python f-strings.[2]

0. https://joe-editor.sf.net/

1. https://github.com/cmur2/joe-syntax/blob/joe-4.4/misc/HowItW...

2. https://gist.github.com/irdc/6188f11b1e699d615ce2520f03f1d0d...

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I've actually made several lexers and parsers based on the joe DFA style of parsing. The state and transition syntax was something that I always understood much more easily than the standard tools.

The downside is your rulesets tend to get more verbose and are a little bit harder to structure than they might ideally be in other languages more suited towards the purpose, but I actually think that's an advantage, as it's much easier to reason about every production rule when looking at the code.

Interestingly, python f-strings changed their syntax at version 3.12, so highlighting should depend on the version.

It’s just that nesting them arbitrarily is now allowed, right? That shouldn’t matter much for a mere syntax highlighter then. And one could even argue that code that relies on this too much is not really for human consumption.

Also, you can now use the same quote character that encloses an f-string within the {} expressions. That could make them harder to tokenize, because it makes it harder to recognise the end of the string.

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