adds a basic CLI

[jwarner112]

I wanted to be able to invoke this on the CLI to extract some data from a folder of JSON files. JQ doesn't implement RFC-9535 yet, so this is the next best thing but had no CLI. I've added a basic one -- define the query, pipe JSON to it via stdin, et voila. Example:

$ echo '{"lorem":{"ipsum":{"dolor":[{"sit":true,"amet":{"hello":"world"}},{"sit":false,"amet":{"foo":"bar"}}]}}}' | go run ./cmd/jsonpath/... "\$.lorem.ipsum.dolor[?(@.sit == true)].amet" | jq .
[
  {
    "hello": "world"
  }
]

[jwarner112]

this has some very rough edges, for instance if the JSONpath is nonsense in some way it panics. it also doesn't respond with exit codes. so consider this a starting point.

[theory]

I like the idea of a jq-like tool that uses RFC 9535 jsonpath expressions. This seems like a nice start to play around with, though I personally lean toward designing something more like a well thought-out app with proper error handling, options, docs, etc. Maybe call it something like jpq :-)

Is this something you'd like to keep working on?

[jwarner112]

Given the time and space, I'd love to work on it AND make it something more polished than this. I don't think it's nearly release-ready. But at present I wrote it purely to unblock myself on a work task and I'm not sure when I'd personally be able to come back to it. I don't mind if this doesn't get merged in, my fork unblocks me for now and I wouldn't want to introduce such a kluge upstream unless there were immediate plans to fix it up. 👍

[jwarner112]

Having written the above, it occurs to me a big blocker for me is deciding exactly how someone else's CLI should behave. If you had a think and decided on how you'd like it to work, me or any other contributor are more likely to be able implement it?

[theory]

I don't have strong feelings about it in advance, no, other than I like short names where possible. My first thought is to mimic how jq works, but it also has pretty unusual syntax that I can never remember. I think starting out with something simple that selects and shows values from STDIN, a file, or option — and perhaps has a pretty-printing (and color?) option — would be nice. I'll be happy to collaborate on the design.