jq needs a library!

[nicowilliams]

A C library for jq would. be. awesome. Ditto Python, node/JS, ..., but a C library should be easier given that jq is already written in C.

This is really like XSLT/XPath for JSON, and simplified a great deal. I can do things with jq in a few characters that require multiple lines of Python/whatever, so I'm starting to resort to popen(). A library would be easier to use :)

[nicowilliams]

This is a bit of a dup of #12 :(

[nicowilliams]

This might not be so difficult... Looking at main.c the internals look very much like a decent API. The one issue is that there's some global state that needs to be moved into a context handle in order to make the API thread-safe and re-entrant. These are the global variables used to hold state outside of main.c:

cbuiltins
function_list
data_stk
fork_stk
frame_stk
pathbuf
pathsize

[nicowilliams]

See pull request #109.

[stedolan]

Thank you! I'd definitely intended to get around to doing this at some point, glad that someone else has beaten me to it :)

That looks like the right list of global variables, except cbuiltins can stay global (it's readonly and should be marked const). I haven't gotten around to reading through your pull rq yet, but at first glance it looks good.

[icholy]

@stedolan with the current autotools setup, is it still possible to build as a library?

[nicowilliams]

with the current autotools setup, is it still possible to build as a library?

No, there's no trace of it left. I've been meaning to find time to
implement the library API we've talked about.

[icholy]

@nicowilliams that would be very much appreciated. I'm looking to write bindings for Go.

[progrium]

+1 +1 +1 Especially @icholy on the Go bindings.

[netsgnut]

@dtolnay, should this be reopened or a new issue to be created instead? Thanks!

[dtolnay]

A library exists already. For example jq.py is built on it. The documentation is lacking but see C API: libjq for what is exported and public.

[netsgnut]

Oops my bad, didn't realize we now have a binding library now. Thanks for the pointer.

[nicowilliams]

Until we have good docs I wouldn't say that the API is stable, though we're unlikely to make backwards-incompatible changes, really.

[nicowilliams]

Also, if someone sends a PR with docs for the API...