C style comments

[chrysn]

Back in the day, we resolved #8 towards having only end-of-line comments (and nothing /* foo / bar */ style) because "PEG can't express that there have to be as many asterisks before the end slash as there were after the first one".

Now that raw strings are back and need this mechanism, I ask that we reconsider the comment situation.

The end-of-line solution worked but is far from satisfactory, especially when creating annotations automatically: rather than deciding the flow by width and structure alone, suddenly extending the list [1 / AES-CCM /, 2 / 3DES-YOLO /] can force a style change just because the next item is 3 # ChaCha20/Poly1305.

The proposal from back then is IMO still sound: A slash comment that has any number of asterisks after the slash needs to end with at least the same number of asterisks. This is compatible with existing use that was just no asterisks, and works with C-style comments (/* foo */).

[cabo]

I don't have a strong opinion on this.
If adopted, this is going to be one of the few places where we aren't fully backwards compatible with EDN that is out now; I don't have a corpus to check this against but would expect that people using *+ at the start of an in-line comment will have the right comment terminator already just for esthetical reasons.

Will implement this now in edn-abnf.

[cabo]

Will implement this now in edn-abnf.

Done:

cabo/edn-abnf#8

Install as

gem install edn-abnf -v 0.6.1pre

Try it:

$ edn-abnf -e '/*/ 0 /*/5/** foo /1/ */ 3 /* / ***** / ***/2/8/'
5, 2