feat(jq): add support for all options, and fix --from-file

[rrthomas]

The options are not all listed by --help, so look in the man page to find a
nearly complete list (I hope!). Neither the man page nor --help mentions --help
or --version; I have not looked elsewhere to see if there might be yet more.

The treatment of -f|--from-file was incorrect: that option’s argument is the
filter, so the argument should be counted towards the total number of arguments
so far. Hence, remove --from-file from the list of options whose argument is
counted as an option.

[scop]

Thanks! Options commit pushed as be4e155

For the other parts, we could brush up a crystal ball and try to figure out if the jq being used does output a "complete enough" listing of its options with --help. If it doesn't, then use our hardcoded list here as a fallback -- either amending what we got, or replacing it altogether. Brittle/ugly, sure. Would you find that tolerable? If yes, what would you use as the "canary" to trigger use of our list?

[rrthomas]

For the other parts, we could brush up a crystal ball and try to figure out if the jq being used does output a "complete enough" listing of its options with --help. If it doesn't, then use our hardcoded list here as a fallback -- either amending what we got, or replacing it altogether. Brittle/ugly, sure. Would you find that tolerable? If yes, what would you use as the "canary" to trigger use of our list?

How about --help as the canary?

[scop]

Maybe. Or if we predict they might not repeat --help in --help output, maybe --version.

[rrthomas]

@scop your guess is as good as mine! But it would be weird not to include --help in the output after I filed an issue about this problem, and as most programs do…

[scop]

Cool. Would you mind revising this to implement the fallback behavior? --help works as the canary for me too.

[rrthomas]

Sure, I can do that.

[rrthomas]

Apologies for my slowness, I have been very busy, and just now that includes using jq.

I found that there's a serious problem with the completion as it stands. It tries to force the user to use a "mode" argument first, such as --slurp. However, the code as it stands does not count any mode arguments, so the number of arguments never exceeds 1 unless you manually type a file argument, so file arguments are never auto-completed.

I had a look at the manual of jq to determine what these mode arguments are, because in theory adding a list of them as the third argument to _count_args would make the code work.

However, the concept of "mode" does not seem to exist in the manual. Indeed, no such argument is required. (You can run jq quite happily without any command-line option.)

So, I propose simply deleting the args-counting code, specifically this bit:

    local args
    # TODO: DTRT with args taking 2 options
    # -f|--from-file are not counted here because they supply the filter
    _count_args "" "@(--arg|--arg?(json|file)|--slurpfile|--indent|--run-tests|-!(-*)L)"

    # 1st arg is filter
    echo jq args: $args
    ((args == 1)) && return
    # 2... are input files

[rrthomas]

(I can still implement the --help canary when I finally get a moment, of course!)

[scop]

No problem wrt slowness. My time for bash-completion is spotty, too.

But I don't quite follow the suggestion, could you elaborate it with a literal example what doesn't work? I also think that's a separate issue from the original one, and would be better off handled in a separate issue if there is one.

Anyway, as a counterexample, if I delete the code you suggested, jq --slurpfile foo <TAB> no longer completes with (.json) filenames. In my jq manpage, --slurpfile is documented to take two args, first of which is a variable name (which we explicitly don't complete), and the second is a JSON filename.

[rrthomas]

@scop I opened #510, and tried to improve the presentation to make it easier to understand what the problem is.

[rrthomas]

@scop, I"ve updated my PR with the --help canary.

[rrthomas]

Thanks very much for your patience and detailed feedback, @scop; as you can see, I'm not fluent programming in bash!

I hope I've dealt with all your feedback…

[scop]

I took the liberty to do some line wrapping changes, removed duplicated --version, fixed s/--compact-input/--compact-output/, and removed some superfluous quotes (shfmt -s is our friend). Thanks!

[rrthomas]

Thanks for the polish and applying the PR; I've installed shfmt for future use.

[rrthomas]

And good spot with the typo!

[scop]

Re shfmt, I suggest installing pre-commit if you wish to run all pre-commit checks configured for the project. CI also runs them, but is badly broken for other reasons at the moment.

[rrthomas]

Thanks for the tip!