[PATCH] _git: improve max-verbose, other descriptions

[dana <dana@xxxxxxx>]

this is an improvement to the max-verbose feature pws added to show
descriptions for branch HEADs etc in workers/37062

- include the current tag when checking for the style, so you can
  disable the feature entirely for certain ref types. i feel like this
  works more consistently than checking the number of added matches

- improve performance when the ref names can all be unambiguously
  resolved. this will be the case when they're all local branches or
  'prefixed' remote branches (like origin/master). if they're not, fall
  back to the old way for now

- for the old method, don't leave a trailing : on ref names without
  descriptions (_describe handles them weirdly)

- make the descriptions for both this feature and __git_recent_branches
  match the format of __git_recent_commits (bracketed hash)

with max-verbose enabled only for local branches, completing
`git switch` in my zsh clone went from 300 ms with the old method down
to 70 ms with the new one. in another repo with 140 local branches it
went from 1150 ms to 230 ms

i experimented with improving the fall-back case as well, using show-ref
to bulk-resolve remote names, but it seems tricky to do the right thing
when the same branch name exists on multiple remotes etc. maybe later

there's also a trivial change to the format of alias descriptions, to
make them look nicer when a command contains quotes or new-lines, which
i'll commit separately probably. after release

dana


diff --git a/Completion/Unix/Command/_git b/Completion/Unix/Command/_git
index 702360ef3..f5ed2ed1a 100644
--- a/Completion/Unix/Command/_git
+++ b/Completion/Unix/Command/_git
@@ -36,6 +36,17 @@
 # use the `use-fallback' style like this:
 #
 #     % zstyle ':completion:*:*:git*:*' use-fallback false
+#
+# To show verbose descriptions for certain refs (the messages associated with
+# branch HEADs and other commits), set the `max-verbose` style:
+#
+#     % zstyle ':completion:*:*:git*:*' max-verbose 99
+#
+# The value specifies the number of matches already added for completion after
+# which descriptions should not be provided. You can also disable descriptions
+# for specific ref types by specifying a tag:
+#
+#     % zstyle ':completion:*:*:git*:remote-branch-names-noprefix' max-verbose 0
 
 # TODO: There is still undocumented configurability in here.
 
@@ -6278,14 +6289,38 @@ __git_describe_branch () {
   local __desc=$3
   shift 3
 
-  integer maxverbose
-  if zstyle -s :completion:$curcontext: max-verbose maxverbose &&
-    (( ${compstate[nmatches]} <= maxverbose )); then
-    local __c
-    local -a __commits
-    for __c in ${(P)__commits_in}; do
-      __commits+=("${__c}:${$(_call_program describe git rev-list -1 --oneline $__c)//:/\\:}")
-    done
+  integer __maxverbose
+  if zstyle -s :completion:$curcontext:$__tag max-verbose __maxverbose &&
+    (( ${compstate[nmatches]} <= __maxverbose )); then
+    local __x __y
+    local -a __cin __revs __descs __commits
+
+    # Calling git rev-list for each individual ref can be slow. We can pass them
+    # all at once instead, but it combines all refs that point to the same rev
+    # into one line in the output, making it difficult to match the results back
+    # to the input. To work around this, we first build a list of individual
+    # revisions that each ref refers to. Then we have rev-list include the full
+    # revision in its output, and we loop through and match everything up
+    __cin=( ${(P)__commits_in} )
+    __revs=( ${(f)"$( _call_program revs git rev-parse ${(q)__cin} )"} )
+
+    if (( $#__revs == $#__cin )); then
+      __descs=( ${${(f)"$( _call_program describe-full-hash \
+        git rev-list --no-walk=unsorted --pretty='"format:%H [%h] %s"' ${(q)__cin}
+      )"}:#commit *} )
+      for __x __y in ${__cin:^__revs}; do
+        __commits+=( $__x:${${__descs[(r)$__y *]}#* } )
+      done
+    # If the above didn't work, the ref names were ambiguous, probably 'bare'
+    # remote branch names. Fall back to the slower method. This won't resolve
+    # anything that rev-parse didn't, but it'll return what it could
+    else
+      for __x in $__cin; do
+        __y=$(_call_program describe git rev-list -1 --format='"[%h] %s"' $__x)
+        __y=${__y#*$'\n'} # Strip off commit header
+        __commits+=("${__x}${__y:+:$__y}")
+      done
+    fi
     _describe -t $__tag $__desc __commits "$@"
   else
     local expl
@@ -7154,7 +7189,10 @@ __git_recent_branches() {
   # 4. Obtain log messages for all of them in one shot.
   # TODO: we'd really like --sort=none here...  but git doesn't support such a thing.
   local z=$'\0'
-  descriptions=( "${(0)"$(_call_program all-descriptions "git --no-pager for-each-ref --format='%(refname)%00%(subject)'" refs/heads/${(q)^branches} "--")"//$'\n'/$z}" )
+  descriptions=( "${(0)"$(_call_program all-descriptions \
+    "git --no-pager for-each-ref --format='%(refname)%00[%(objectname:short)] %(subject)'" \
+      refs/heads/${(q)^branches} "--"
+  )"//$'\n'/$z}" )
 
   # 5. Synthesize the data structure _describe wants.
   local -a branches_colon_descriptions


diff --git a/Completion/Unix/Command/_git b/Completion/Unix/Command/_git
index f5ed2ed1a..1ea5dd4b3 100644
--- a/Completion/Unix/Command/_git
+++ b/Completion/Unix/Command/_git
@@ -6598,7 +6598,7 @@ __git_extract_aliases () {
   local -a tmp
   tmp=(${${(0)"$(_call_program aliases "git config -z --get-regexp '^alias.'")"}#alias.})
   if (( ${#tmp} > 0 )); then
-      aliases=(${^tmp/$'\n'/:alias for \'}\')
+      aliases=(${${tmp/$'\n'/:alias for: }//[[:space:]]##/ })
   else
       aliases=()
   fi