* use arithmetic evaluation in numeric context
* remove unnecessary $ from array index variables
* [[ ]] over [ ], == over =, remove unnecessary quoting
* use ${foo-} rather than ${foo:-} in emptiness check
The result of the expansion is null no matter if the variable is unset
or null in both cases; the former form is arguably easier on the eye.
* remove unnecessary trailing linefeed removal
No longer needed as of f464d6c82e, saves
a subshell.
* use herestring in activehelp extraction
Herestrings read cleaner than process substitutions, and work in posix
mode (but we do and will have some process substitutions so this doesn't
matter much). Both approaches may end up using temporary files.
```shell
$ set -u
$ foo=()
$ echo ${#foo}
bash: foo: unbound variable
echo ${#foo[*]}
0
```
The above shows that an empty array needs the suffix `[*]` when checking its length, or else it is considered unbound.
Not that it'd really matter that much performancewise given the level we
are at for this case, but this change makes the short circuit roughly
twice as fast on my box as it was for the 1000 rounds done in
marckhouzam/cobra-completion-testing.
Perhaps more importantly, this makes the code arguably slightly cleaner.
If the list of candidates has no descriptions, short circuit all the
description processing logic, basically just do a `compgen -W` for the
whole list and be done with it.
We could conceivably do some optimizations like this and more when
generating the completions with `--no-descriptions` in Go code, by
omitting some parts we know won't be needed, or doing some things
differently. But doing it this way in bash, the improvements are
available also to completions generated with descriptions enabled when
they are invoked for completion cases that produce no
descriptions. The result after this for descriptionless entries seems
fast enough so it seems there's no immediate need to look into doing
that.
For legacy bash completions, similarly as commit
4f0facbcee is for bash completions v2.
As a side effect, fixes test suite with shellcheck 0.8.0 installed;
apparently the 0.7.0 that's in GitHub Actions' ubuntu-latest at the
moment does not flag the array quoting related issue that was provoked
from 0.8.0 before this change.
Refactor to remove two loops over the entire list of candidates.
Format descriptions only for completions that are actually going to be
displayed, instead of for all candidates.
Format descriptions inline in completions array, removing need for a
command substitution/subshell and a printf escape per displayed
completion.
Ville Skyttä