PATCH: description alignment with _regex_words

[Oliver Kiddle <okiddle@xxxxxxxxxxx>]

Currently _regex_words generates a regex that is roughly:
  ( /word1/ ':tag:desc:(( word1:desc1 ))' $word1_morestuff |
    /word2/ ':tag:desc:(( word2:desc2 ))' $word2_morestuff |
    /word3/ ':tag:desc:(( word3:desc3 ))' $word3_morestuff )

This results in ugly misaligned descriptions and is calling _describe
three times underneath which is not too efficient. With this patch,
you'll instead get:

  ( /word1/ $word1_morestuff |
    /word2/ $word2_morestuff |
    /word3/ $word3_morestuff |
    /'[]'/ ':tag:desc:(( word1:desc1 word2:desc2 word3:desc3 ))' )

I'm fairly sure this will be functionally identical other than fixing
the alignment. The case with -t passed to _regex_words (which uses
_values) is also handled.

It also is unfortunate that _regex_words encourages exact matching
patterns which tends to lead to things like ip completion printing
"parse failed before current word" when a new -c option has been added.
I'd recommend using generous patterns when not branching down separate
parts of the regex tree based on what it matches. That way new
subcommands and options don't break the existing completions.

Oliver

diff --git a/Completion/Base/Utility/_regex_words b/Completion/Base/Utility/_regex_words
index 62c2491bb..90b4a9735 100644
--- a/Completion/Base/Utility/_regex_words
+++ b/Completion/Base/Utility/_regex_words
@@ -1,6 +1,6 @@
 #autoload
 
-local opt OPTARG
+local opt OPTARG matches end
 local term=$'\0'
 
 while getopts "t:" opt; do
@@ -31,19 +31,22 @@ fi
 integer i
 local -a wds
 
+if [[ $term = $'\0' ]]; then
+  matches=":${tag}:${desc}:(( "
+  end="))"
+else
+  matches=":${tag}:${desc}:_values -s ${(q)term} ${(q)desc}"
+fi
+
 for (( i = 1; i <= $#; i++ )); do
   wds=(${(s.:.)argv[i]})
   reply+=(/${wds[1]//\**/"[^$term]#"}"$term"/)
   if [[ $term = $'\0' ]]; then
-    reply+=(":${tag}:${desc}:(( ${wds[1]//\*}:${wds[2]//(#m)[: \(\)]/\\$MATCH} ))")
+    matches+="${wds[1]//\*}${wds[2]:+\\:${wds[2]//(#m)[: \(\)]/\\$MATCH}} "
   else
-    reply+=(":${tag}:${desc}:_values -s ${(q)term} ${(q)desc} \
-${(q)${${wds[1]//\*}//(#m)[:\[\]]/\\$MATCH}}\\[${(q)${wds[2]//(#m)[:\[\]]/\\$MATCH}}\\]")
+    matches+=" ${(q)${${wds[1]//\*}//(#m)[:\[\]]/\\$MATCH}}\\[${(q)${wds[2]//(#m)[:\[\]]/\\$MATCH}}\\]"
   fi
   eval "reply+=($wds[3])"
-  if (( $i == $# )); then
-    reply+=(\))
-  else
-    reply+=(\|)
-  fi
+  reply+=(\|)
 done
+reply+=( /'[]'/ "${matches}${end}" \) )