Support :rept expressions in PEG

[stouset]

:rept wasn't supported in the PEG, even though it exists for ABNF.

When implementing a PEG parser based on ABNF with an a*b-style rule, you currently get

RuntimeError: attempt to parse unknown rule type: rept

[gkellogg]

You may need to parse the ABNF, and then run the to_peg method to generate a grammar that can be parsed.

You can see how it's done in the ABNF example.

If it's still not working for you, please give me the example you're using and I'll work it up. If the README needs updates to clarify this, please consider a PR.

[gkellogg]

(Sorry, thinking this was an issue, not a PR). I'll look at this more closely and consider. There are working examples that use rept, so the to_peg process may handle this, but direct support would be better.

[stouset]

PEG didn't have the support to handle rept(input, m, prod) in the AST, from what I could tell. A simple ABNF parsed by

EBNF.parse(File.read(abnf_path), format: :abnf).make_peg.ast

has rept rules in it, but actually trying to run a parser with them fails.

[gkellogg]

As you know, things get very meta quickly when you're working on this stuff :) This can make it challenging to keep things straight. I believe the Rule#parse method did have direct support for this, but it must have been dropped accidentally along the way.

Ideally, one of the examples in the ABNF example directory would also exercise this functionality (I'm surprised it doesn't).

Also, as this is a substantive change, if you haven't already done so, and as called for in the README, please consider making a public domain dedication, as part of this PR. This will cover any future contributions, as well.

[stouset]

This is free and unencumbered software released into the public domain.

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[gkellogg]

Thanks, but that was the body of the unlicensed the dedication is the following

I dedicate any and all copyright interest in this software to the
public domain. I make this dedication for the benefit of the public at
large and to the detriment of my heirs and successors. I intend this
dedication to be an overt act of relinquishment in perpetuity of all
present and future rights to this software under copyright law.

[stouset]

Whoops, I should have scrolled down farther.

I dedicate any and all copyright interest in this software to the
public domain. I make this dedication for the benefit of the public at
large and to the detriment of my heirs and successors. I intend this
dedication to be an overt act of relinquishment in perpetuity of all
present and future rights to this software under copyright law.