alt Hacker NewsI have the experience of writing parsers (lexers) in Ragel, using Go, Java C++, and C. I must say, once you have some boilerplate generator in place, raw C is as good as the Rust code the author describes. Maybe even better because simplicity. For example, this is the most of code necessary to have a JSON parser: https://github.com/gritzko/librdx/blob/master/JSON.lex
In fact, that eBNF only produces the lexer. The parser part is not that impressive either, 120 LoC and quite repetitive https://github.com/gritzko/librdx/blob/master/JSON.c
So, I believe, a parser infrastructure evolves till it only needs eBNF to make a parser. That is the saturation point.
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I love love love ragel.
Won't the code here:
https://github.com/gritzko/librdx/blob/master/JSON.lex
accept "[" as valid json?
delimiter = OpenObject | CloseObject | OpenArray | CloseArray | Comma | Colon;
primitive = Number | String | Literal;
JSON = ws* ( primitive? ( ws* delimiter ws* primitive? )* ) ws*;
Root = JSON;
I usually begin with the RFCs:
https://datatracker.ietf.org/doc/html/rfc4627#autoid-3
I'm not sure one can implement JSON with ragel... I believe ragel can only handle regular languages and JSON is context free.
C/Ragel bug was the cause of Cloudbleed, and the reason why Cloudflare switched to Rust.
That repetitivness can be seen as a downside, not a virtue. And I feel that Rust's ADTs make working with the resulting syntax tree much easier.
Though I agree that a little code generation and/or macro magic can make C significantly more workable.