Re: Completion script for the ctags program

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

Jacob Gelbman wrote on Wed, Feb 24, 2021 at 01:20:24 -0600:
> #compdef ctags

apt-file(1) on Debian stable shows a few more names:

arduino-ctags: /usr/bin/arduino-ctags
emacs-bin-common: /usr/bin/ctags.emacs
emacs-bin-common: /usr/bin/etags.emacs
exuberant-ctags: /usr/bin/ctags-exuberant
universal-ctags: /usr/bin/ctags-universal
xemacs21-bin: /usr/bin/etags.xemacs21

I assume at least some of these should be added to the #compdef line.  Would
you do the honours?

>     "--alias-<lang>=[add a pattern detecting a name, can be used as an alt name for lang]:pattern"

As Oliver said, literal angle brackets in the option name to be
completed aren't especially helpful.  In fact, I'll go as far as to say
I don't want users to run into it in released code.  Please change them.

You can use _call_program with --list-languages to generate the right set of
option names dynamically.

> elif [ "$_ctags_type" = "exuberant" ]; then
>   arguments=(
>     "-a[append to tags file]"
>     "-B[use backward searching patterns (?...?)]"
>     "-e[output tag file for use with emacs]"
>     "-f[write tags to specified file. - is stdout]:file:_files"

Is the argument to the -f option allowed to be pasted to it?  If so, s/-f/-f+/.

Also, s/:file:/:output file:/.  That part of the string is a user-facing
message, so the extra detail is helpful.

Also, you can drop the "- is stdout" part.  The descriptions are only
a summary of the functionality; they aren't meant to be a complete copy of
the manual.

>     "-F[use forward searching patterns (/.../)]"
>     "-h[specify list of file extensions to be treated as include files]:"

Write something after the colon.

>     "-I[a list of tokens to be specifically handled is read from either the command line or the specified file]:"

The thing in brackets doesn't describe the action of the option.  Please edit.

>     "-L[a list of input file names is read from the specified file. - is stdin]:file:_files"

Rephrase in the imperative.

>     "-R[equivalent to --recurse]"

This is normally rendered as:

      '(-r --recurse)'{-R,--recurse}'[description]'

>     "--fields=[include selected extension fields (flags afmikKlnsStz)]:flags"

Recommend to move the afmikKlnsStz thing to after the colon, so it'll be
shown at a more appropriate point.  Also, it would be helpful to display
descriptions to the flags using, e.g., «compset» (for the leading plus
sign) followed by «_values -s ''».

>     "--file-scope=[should tags scoped only for a single file be included in output]:bool:(yes no)"
>     "--filter=[behave as a filter, reading file names from stdin and writing tags to stdout]:bool:(yes no)"
>     "--filter-terminator=[specify string to print to stdout following the tags for each file parsed when --filter is enabled]:string"
>     "--format=[force output of specified tag file format]:level"
>     "--help[help text]"

"help text" is just a noun phrase.  Please use complete decsriptions.

Please use exclusions if needed («'(--foo)--bar[baz]'»).

>     "--language-force=[force all files to be interpreted using specified language]:language:->language"
>     "--languages=[restrict files scanned to these comma-separated languages]:language:->languages"

Can't say I'm a fan of having two states that differ by a single letter,
but so be it.

>     "--recurse=[recurse]:bool:(yes no)"

Fix the bracketed description.

> _arguments $arguments

Pass any arguments to _arguments that may be needed (for
instance, -s).

> if [[ "$state" = language* ]]; then
>   local -a languages
>   languages=(`ctags --list-languages | cut -d" " -f1`)

Use _call_program and $service.

>   if [ "$state" = "language" ]; then
>     _wanted languages expl language compadd $languages

Don't pass unsanitized command output to a builtin.  In this case,
«compadd -a languages» would do.

>   elif [ "$state" = "languages" ]; then
>     _values -s , languages $languages

Don't pass unsanitized command output to a builtin.  I don't know the
fix off the top of my head.

Thanks for the patch, and especially for adding exubertant and BSD ctags
support!

Daniel


> 
> 
> 
> 
> > On Feb 23, 2021, at 10:45 PM, Jacob Gelbman <gelbman@xxxxxxxxx> wrote:
> > 
> > Hey, thanks for looking at the script and adding it to the repo, although I think some of got pasted in wrong. There’s a lot to writing completion functions and I’m still not 100% sure how to do it right.
> > 
> >> On Feb 23, 2021, at 3:39 PM, Oliver Kiddle <opk@xxxxxxx> wrote:
> >> 
> >> Jacob Gelbman wrote:
> >>> I wrote a completion script for the ctags program. Someone might be able to use it:
> >> 
> >> Which ctags!?
> > 
> > I have Universal Ctags 5.9.0
> > 
> >> This doesn't match what I have installed on any of my systems. There
> >> are multiple implementations of ctags, with it often being just a link
> >> to etags - for which there is a completion albeit not a well maintained
> >> one. One of the main reasons, a completion doesn't already exist is
> >> that it would ideally need to detect the variant and at least have sane
> >> fallbacks for variants that aren't handled. It could be useful to check
> >> what the existing _etags is handling - that might be the exhuberant or
> >> emacs variant.
> >> 
> > 
> > I located a few other ctags on my computers, I have BSD ctags that comes by default on the mac. Exuberant Ctags 5.8. and there’s etags that comes with emacs. I can probably add an if statement based on the output of ctags —version, and modify the function from that. If it’s etags, I’ll just:
> > 
> > _comps[ctags]=“_etags”; _etags
> > 
> > And exit.
> > 
> >> In general, please follow the conventions outlined in
> >> Etc/completion-style-guide in the zsh source distribution. For example,
> >> completion functions usually use just 2 spaces for indentation.
> >> 
> >>> #compdef ctags
> >>> 
> >>> local state
> >> 
> >> If you use states, you need to also handle the context which means
> >> either passing -C to _arguments and setting up $curcontext or declaring
> >> context local and passing it to later functions like _values.
> > 
> > The -C argument and the context/curcontext variables are confusing me, a lot.
> > 
> >> 
> >>>   "--alias-<lang>=[add a pattern detecting a name, can be used as an alt name for lang]:pattern" \
> >>>   "--input-encoding-<lang>=[specify encoding of the <lang> input files]:encoding" \
> >>>   "--kinddef-<lang>=[define new kind for <lang>]:kind" \
> >>>   "--kinds-<lang>=[enable/disable tag kinds for <lang>]:kind" \
> >> 
> >> These would not complete especially helpfully. I suspect that <lang> there is
> >> supposed to be substituted.
> > 
> > They’d show up in the menu when you press tab, but if I filled in the actual values, the list would be too long.
> > 
> >> 
> >>> if [ "$state" = "language" ]; then
> >>>   compadd `ctags --list-languages | cut -d" " -f1`
> >> 
> >> It would be nicer to use a description by calling for example, _wanted
> >> here.
> > 
> > I can do that.
> > 
> >> 
> >>> elif [ "$state" = "languages" ]; then
> >>>   _values -s , "languages" `ctags --list-languages | cut -d" " -f1`
> >>> fi
> >> 
> >> I'd probably use _sequence here as it is smaller and simpler. But
> >> _values is fine if none of the languages contain characters that need
> >> quoting from it.
> > 
> > This too.
> > 
> >> 
> >> The return status from this function will not be correct in all cases.
> >> This can have effects like approximate completion being activated
> >> despite matches having been added by earlier completers. Where states
> >> are needed, you nearly always need to either save the status from
> >> _arguments, typically via a ret variable or check $compstate[nmatches]
> >> on exit.
> >> 
> >> Oliver
> > 
> 
>