[PATCH 02/12] completion: wrap __git_refs() for better option parsing

["SZEDER Gábor" <szeder.dev@gmail.com>]

__git_refs() currently accepts two optional positional parameters: a
remote and a flag for 'git checkout's tracking DWIMery.  To fix a
minor bug, and, more importantly, for faster refs completion, this
series will add three more parameters: a prefix, the current word to
be completed and a suffix, i.e. the options accepted by __gitcomp() &
friends, and will change __git_refs() to list only refs matching that
given current word and to add that given prefix and suffix to the
listed refs.

However, __git_refs() is the helper function that is most likely used
in users' custom completion scriptlets for their own git commands, and
we don't want to break those, so

  - we can't change __git_refs()'s default output format, i.e. we
    can't by default append a trailing space to every listed ref,
    meaning that the suffix parameter containing the default trailing
    space would have to be specified on every invocation, and

  - we can't change the position of existing positional parameters
    either, so there would have to be plenty of set-but-empty
    placeholder positional parameters all over the completion script.

Furthermore, with five positional parameters it would be really hard
to remember which position means what.

To keep callsites simple, add the new wrapper function
__git_complete_refs() around __git_refs(), which:

  - instead of positional parameters accepts real '--opt=val'-style
    options and with minimalistic option parsing translates them to
    __git_refs()'s and __gitcomp_nl()'s positional parameters, and

  - includes the '__gitcomp_nl "$(__git_refs ...)" ...' command
    substitution to make its behavior match its name and the behavior
    of other __git_complete_* functions, and to limit future changes
    in this series to __git_refs() and this new wrapper function.

Call this wrapper function instead of __git_refs() wherever possible
throughout the completion script, i.e. when __git_refs()'s output is
fed to __gitcomp_nl() right away without further processing, which
means all callsites except a single one in the __git_refs2() helper.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
---
 contrib/completion/git-completion.bash | 102 ++++++++++++++++++++-----------
 t/t9902-completion.sh                  | 106 +++++++++++++++++++++++++++++++++
 2 files changed, 173 insertions(+), 35 deletions(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index f20d4600c..7f19e2a4f 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -354,6 +354,8 @@ __git_tags ()
 #    Can be the name of a configured remote, a path, or a URL.
 # 2: In addition to local refs, list unique branches from refs/remotes/ for
 #    'git checkout's tracking DWIMery (optional; ignored, if set but empty).
+#
+# Use __git_complete_refs() instead.
 __git_refs ()
 {
 	local i hash dir track="${2-}"
@@ -446,6 +448,36 @@ __git_refs ()
 	esac
 }
 
+# Completes refs, short and long, local and remote, symbolic and pseudo.
+#
+# Usage: __git_complete_refs [<option>]...
+# --remote=<remote>: The remote to list refs from, can be the name of a
+#                    configured remote, a path, or a URL.
+# --track: List unique remote branches for 'git checkout's tracking DWIMery.
+# --pfx=<prefix>: A prefix to be added to each ref.
+# --cur=<word>: The current ref to be completed.  Defaults to the current
+#               word to be completed.
+# --sfx=<suffix>: A suffix to be appended to each ref instead of the default
+#                 space.
+__git_complete_refs ()
+{
+	local remote track pfx cur_="$cur" sfx=" "
+
+	while test $# != 0; do
+		case "$1" in
+		--remote=*)	remote="${1##--remote=}" ;;
+		--track)	track="yes" ;;
+		--pfx=*)	pfx="${1##--pfx=}" ;;
+		--cur=*)	cur_="${1##--cur=}" ;;
+		--sfx=*)	sfx="${1##--sfx=}" ;;
+		*)		return 1 ;;
+		esac
+		shift
+	done
+
+	__gitcomp_nl "$(__git_refs "$remote" "$track")" "$pfx" "$cur_" "$sfx"
+}
+
 # __git_refs2 requires 1 argument (to pass to __git_refs)
 __git_refs2 ()
 {
@@ -554,15 +586,15 @@ __git_complete_revlist_file ()
 	*...*)
 		pfx="${cur_%...*}..."
 		cur_="${cur_#*...}"
-		__gitcomp_nl "$(__git_refs)" "$pfx" "$cur_"
+		__git_complete_refs --pfx="$pfx" --cur="$cur_"
 		;;
 	*..*)
 		pfx="${cur_%..*}.."
 		cur_="${cur_#*..}"
-		__gitcomp_nl "$(__git_refs)" "$pfx" "$cur_"
+		__git_complete_refs --pfx="$pfx" --cur="$cur_"
 		;;
 	*)
-		__gitcomp_nl "$(__git_refs)"
+		__git_complete_refs
 		;;
 	esac
 }
@@ -649,21 +681,21 @@ __git_complete_remote_or_refspec ()
 		if [ $lhs = 1 ]; then
 			__gitcomp_nl "$(__git_refs2 "$remote")" "$pfx" "$cur_"
 		else
-			__gitcomp_nl "$(__git_refs)" "$pfx" "$cur_"
+			__git_complete_refs --pfx="$pfx" --cur="$cur_"
 		fi
 		;;
 	pull|remote)
 		if [ $lhs = 1 ]; then
-			__gitcomp_nl "$(__git_refs "$remote")" "$pfx" "$cur_"
+			__git_complete_refs --remote="$remote" --pfx="$pfx" --cur="$cur_"
 		else
-			__gitcomp_nl "$(__git_refs)" "$pfx" "$cur_"
+			__git_complete_refs --pfx="$pfx" --cur="$cur_"
 		fi
 		;;
 	push)
 		if [ $lhs = 1 ]; then
-			__gitcomp_nl "$(__git_refs)" "$pfx" "$cur_"
+			__git_complete_refs --pfx="$pfx" --cur="$cur_"
 		else
-			__gitcomp_nl "$(__git_refs "$remote")" "$pfx" "$cur_"
+			__git_complete_refs --remote="$remote" --pfx="$pfx" --cur="$cur_"
 		fi
 		;;
 	esac
@@ -1061,7 +1093,7 @@ _git_bisect ()
 
 	case "$subcommand" in
 	bad|good|reset|skip|start)
-		__gitcomp_nl "$(__git_refs)"
+		__git_complete_refs
 		;;
 	*)
 		;;
@@ -1083,7 +1115,7 @@ _git_branch ()
 
 	case "$cur" in
 	--set-upstream-to=*)
-		__gitcomp_nl "$(__git_refs)" "" "${cur##--set-upstream-to=}"
+		__git_complete_refs --cur="${cur##--set-upstream-to=}"
 		;;
 	--*)
 		__gitcomp "
@@ -1097,7 +1129,7 @@ _git_branch ()
 		if [ $only_local_ref = "y" -a $has_r = "n" ]; then
 			__gitcomp_nl "$(__git_heads)"
 		else
-			__gitcomp_nl "$(__git_refs)"
+			__git_complete_refs
 		fi
 		;;
 	esac
@@ -1140,18 +1172,18 @@ _git_checkout ()
 	*)
 		# check if --track, --no-track, or --no-guess was specified
 		# if so, disable DWIM mode
-		local flags="--track --no-track --no-guess" track=1
+		local flags="--track --no-track --no-guess" track_opt="--track"
 		if [ -n "$(__git_find_on_cmdline "$flags")" ]; then
-			track=''
+			track_opt=''
 		fi
-		__gitcomp_nl "$(__git_refs '' $track)"
+		__git_complete_refs $track_opt
 		;;
 	esac
 }
 
 _git_cherry ()
 {
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_cherry_pick ()
@@ -1166,7 +1198,7 @@ _git_cherry_pick ()
 		__gitcomp "--edit --no-commit --signoff --strategy= --mainline"
 		;;
 	*)
-		__gitcomp_nl "$(__git_refs)"
+		__git_complete_refs
 		;;
 	esac
 }
@@ -1216,7 +1248,7 @@ _git_commit ()
 {
 	case "$prev" in
 	-c|-C)
-		__gitcomp_nl "$(__git_refs)"
+		__git_complete_refs
 		return
 		;;
 	esac
@@ -1229,7 +1261,7 @@ _git_commit ()
 		;;
 	--reuse-message=*|--reedit-message=*|\
 	--fixup=*|--squash=*)
-		__gitcomp_nl "$(__git_refs)" "" "${cur#*=}"
+		__git_complete_refs --cur="${cur#*=}"
 		return
 		;;
 	--untracked-files=*)
@@ -1267,7 +1299,7 @@ _git_describe ()
 			"
 		return
 	esac
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 __git_diff_algorithms="myers minimal patience histogram"
@@ -1453,7 +1485,7 @@ _git_grep ()
 		;;
 	esac
 
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_help ()
@@ -1621,7 +1653,7 @@ _git_merge ()
 			--rerere-autoupdate --no-rerere-autoupdate --abort --continue"
 		return
 	esac
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_mergetool ()
@@ -1646,7 +1678,7 @@ _git_merge_base ()
 		return
 		;;
 	esac
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_mv ()
@@ -1684,7 +1716,7 @@ _git_notes ()
 	,*)
 		case "$prev" in
 		--ref)
-			__gitcomp_nl "$(__git_refs)"
+			__git_complete_refs
 			;;
 		*)
 			__gitcomp "$subcommands --ref"
@@ -1693,7 +1725,7 @@ _git_notes ()
 		;;
 	add,--reuse-message=*|append,--reuse-message=*|\
 	add,--reedit-message=*|append,--reedit-message=*)
-		__gitcomp_nl "$(__git_refs)" "" "${cur#*=}"
+		__git_complete_refs --cur="${cur#*=}"
 		;;
 	add,--*|append,--*)
 		__gitcomp '--file= --message= --reedit-message=
@@ -1712,7 +1744,7 @@ _git_notes ()
 		-m|-F)
 			;;
 		*)
-			__gitcomp_nl "$(__git_refs)"
+			__git_complete_refs
 			;;
 		esac
 		;;
@@ -1750,10 +1782,10 @@ __git_complete_force_with_lease ()
 	--*=)
 		;;
 	*:*)
-		__gitcomp_nl "$(__git_refs)" "" "${cur_#*:}"
+		__git_complete_refs --cur="${cur_#*:}"
 		;;
 	*)
-		__gitcomp_nl "$(__git_refs)" "" "$cur_"
+		__git_complete_refs --cur="$cur_"
 		;;
 	esac
 }
@@ -1829,7 +1861,7 @@ _git_rebase ()
 
 		return
 	esac
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_reflog ()
@@ -1840,7 +1872,7 @@ _git_reflog ()
 	if [ -z "$subcommand" ]; then
 		__gitcomp "$subcommands"
 	else
-		__gitcomp_nl "$(__git_refs)"
+		__git_complete_refs
 	fi
 }
 
@@ -1986,7 +2018,7 @@ _git_config ()
 		return
 		;;
 	branch.*.merge)
-		__gitcomp_nl "$(__git_refs)"
+		__git_complete_refs
 		return
 		;;
 	branch.*.rebase)
@@ -2460,7 +2492,7 @@ _git_remote ()
 
 _git_replace ()
 {
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_reset ()
@@ -2473,7 +2505,7 @@ _git_reset ()
 		return
 		;;
 	esac
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_revert ()
@@ -2489,7 +2521,7 @@ _git_revert ()
 		return
 		;;
 	esac
-	__gitcomp_nl "$(__git_refs)"
+	__git_complete_refs
 }
 
 _git_rm ()
@@ -2597,7 +2629,7 @@ _git_stash ()
 			;;
 		branch,*)
 			if [ $cword -eq 3 ]; then
-				__gitcomp_nl "$(__git_refs)";
+				__git_complete_refs
 			else
 				__gitcomp_nl "$(__git stash list \
 						| sed -n -e 's/:.*//p')"
@@ -2755,7 +2787,7 @@ _git_tag ()
 		fi
 		;;
 	*)
-		__gitcomp_nl "$(__git_refs)"
+		__git_complete_refs
 		;;
 	esac
 
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index d711bef24..50c534072 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -775,6 +775,112 @@ test_expect_success '__git_refs - unique remote branches for git checkout DWIMer
 	test_cmp expected "$actual"
 '
 
+test_expect_success '__git_complete_refs - simple' '
+	sed -e "s/Z$//g" >expected <<-EOF &&
+	HEAD Z
+	master Z
+	matching-branch Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	matching-tag Z
+	EOF
+	(
+		cur= &&
+		__git_complete_refs &&
+		print_comp
+	) &&
+	test_cmp expected out
+'
+
+test_expect_success '__git_complete_refs - matching' '
+	sed -e "s/Z$//g" >expected <<-EOF &&
+	matching-branch Z
+	matching-tag Z
+	EOF
+	(
+		cur=mat &&
+		__git_complete_refs &&
+		print_comp
+	) &&
+	test_cmp expected out
+'
+
+test_expect_success '__git_complete_refs - remote' '
+	sed -e "s/Z$//g" >expected <<-EOF &&
+	HEAD Z
+	branch-in-other Z
+	master-in-other Z
+	EOF
+	(
+		cur=
+		__git_complete_refs --remote=other &&
+		print_comp
+	) &&
+	test_cmp expected out
+'
+
+test_expect_success '__git_complete_refs - track' '
+	sed -e "s/Z$//g" >expected <<-EOF &&
+	HEAD Z
+	master Z
+	matching-branch Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	matching-tag Z
+	branch-in-other Z
+	master-in-other Z
+	EOF
+	(
+		cur=
+		__git_complete_refs --track &&
+		print_comp
+	) &&
+	test_cmp expected out
+'
+
+test_expect_success '__git_complete_refs - current word' '
+	sed -e "s/Z$//g" >expected <<-EOF &&
+	matching-branch Z
+	matching-tag Z
+	EOF
+	(
+		cur="--option=mat" &&
+		__git_complete_refs --cur="${cur#*=}" &&
+		print_comp
+	) &&
+	test_cmp expected out
+'
+
+test_expect_success '__git_complete_refs - prefix' '
+	sed -e "s/Z$//g" >expected <<-EOF &&
+	v1.0..matching-branch Z
+	v1.0..matching-tag Z
+	EOF
+	(
+		cur=v1.0..mat &&
+		__git_complete_refs --pfx=v1.0.. --cur=mat &&
+		print_comp
+	) &&
+	test_cmp expected out
+'
+
+test_expect_success '__git_complete_refs - suffix' '
+	cat >expected <<-EOF &&
+	HEAD.
+	master.
+	matching-branch.
+	other/branch-in-other.
+	other/master-in-other.
+	matching-tag.
+	EOF
+	(
+		cur= &&
+		__git_complete_refs --sfx=. &&
+		print_comp
+	) &&
+	test_cmp expected out
+'
+
 test_expect_success 'teardown after ref completion' '
 	git branch -d matching-branch &&
 	git tag -d matching-tag &&
-- 
2.11.0.555.g967c1bcb3