This is a rewrite of __fzf_parse_commandline function, that fixes the
following issues, when CTRL-T/ALT-C is used and current command line
token contains:
- Escaped newlines (\n): This never worked correctly, but after 282884a,
the string would split, and the script would enter an infinite loop
while trying to set $dir.
- Escaped bell (\a, \cg), backspace (\b), form feed (\v, \cl), carriage
return (\r), vertical tab (\v, \ck): walker-root would not set
correctly for existing directories containing any of those characters.
- Regular expression special characters (^, +, ? etc): $dir would not be
be stripped from $fzf_query if it contained any of those characters.
The lowest supported fish version is v3.1b. For optimal operation, the
function uses more recent commands when supported by the running
version. Specifically, for versions equal or newer than:
- v3.2.0: Sets variables using PCRE2 capture groups of `string match
--regex` when needing to preserve any trailing newlines and
simultaneously omit the extra newline that is appended by `string
collect -N`.
- v3.5.0: Uses the builtin path command for path normalization, dirname
extraction and existing directories check.
- v4.0.0: Uses the --tokens-expanded option of commandline, for
expansion and dealing with unbalanced quotes and incomplete escape
sequences. It also uses the regex style of string-escape, to prepare
variable contents for regex operations. This is not used in older
versions, because they don't escape newlines.