Hi Jan,

2015-04-02 16:36 GMT+02:00 Jan Kurš <kurs@iam.unibe.ch>:

Hi All,

I have pushed a new version for indentation sensitivity into the PetitParser. If I am not mistaken, with the new changes, you can parse languages such as Python, F#, Haskell, YAML or Markdown. There are proof of concept implementations in the PetitParser repository. YAML and Markdwon are almost complete, for Python only the indentation-sensitive rules.

There is a small introduction to the indentation parsing with PetitParser (http://scg.unibe.ch/research/indentParsing), let me know, if you are missing something or if you want to know something more. There are also many examples of the indentation sensitive grammars in the repository.

This is interesting. Thanks for the description and the link.

One note in the end: isn't it that in fact what you are eating with the indentation stack is more than whitespace (i.e. bullet points)? See last paragraph, because your approach benefit is that you can use more than whitespace as indent, anything arbitrary would do, if I have understood correctly.

If you wonder about performance, the indentation sensitive grammar is approximately five times slower, because the position and an extra indentation stack is remembered instead of the simple position. If you don't use indentation, there is no slowdown. I am working on improvements, any ideas are welcome :)

Totally out of the blue: your typical indentation parsing expression is a regex type of thing. What about compiling it as a SmaCC scanner? Such a PP parser would be equivalent to a Lexing automaton, and good compilers exist for such automatons.

Thierry

If you don't like new changes, you can still stable version (ConfigurationOfPetitParser loadStable) or version 1.11.

Regards,
Jan

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