completion: refactor diff_index wrappers

At the end of the day what we really need is to find out the files that
have been staged, or modified, because those files are the ones that
make sense to pass as arguments to 'git commit'.

We need diff-index to find those out, since 'git ls-files' doesn't do
that.

But we don't need wrappers and wrappers basically identical to the ones
used for 'git ls-files', when we can pretend it receives a --committable
option that would return what we need.

That way, we can remove a bunch of code without any functional changes.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -297,30 +297,25 @@ __git_index_file_list_filter ()
 	__git_index_file_list_filter_bash
 }
 
-# Execute git ls-files, returning paths relative to the directory
-# specified in the first argument, and using the options specified in
-# the second argument.
+# Execute 'git ls-files', unless the --committable option is specified, in
+# which case it runs 'git diff-index' to find out the files that can be
+# committed.  It return paths relative to the directory specified in the first
+# argument, and using the options specified in the second argument.
 __git_ls_files_helper ()
 {
 	(
 		test -n "${CDPATH+set}" && unset CDPATH
-		# NOTE: $2 is not quoted in order to support multiple options
-		cd "$1" && git ls-files --exclude-standard $2
+		cd "$1"
+		if [ "$2" == "--committable" ]; then
+			git diff-index --name-only --relative HEAD
+		else
+			# NOTE: $2 is not quoted in order to support multiple options
+			git ls-files --exclude-standard $2
+		fi
 	) 2>/dev/null
 }
 
 
-# Execute git diff-index, returning paths relative to the directory
-# specified in the first argument, and using the tree object id
-# specified in the second argument.
-__git_diff_index_helper ()
-{
-	(
-		test -n "${CDPATH+set}" && unset CDPATH
-		cd "$1" && git diff-index --name-only --relative "$2"
-	) 2>/dev/null
-}
-
 # __git_index_files accepts 1 or 2 arguments:
 # 1: Options to pass to ls-files (required).
 # 2: A directory path (optional).
@@ -337,22 +332,6 @@ __git_index_files ()
 	fi
 }
 
-# __git_diff_index_files accepts 1 or 2 arguments:
-# 1) The id of a tree object.
-# 2) A directory path (optional).
-#    If provided, only files within the specified directory are listed.
-#    Sub directories are never recursed.  Path must have a trailing
-#    slash.
-__git_diff_index_files ()
-{
-	local dir="$(__gitdir)" root="${2-.}"
-
-	if [ -d "$dir" ]; then
-		__git_diff_index_helper "$root" "$1" | __git_index_file_list_filter |
-			sort | uniq
-	fi
-}
-
 __git_heads ()
 {
 	local dir="$(__gitdir)"
@@ -550,8 +529,10 @@ __git_complete_revlist_file ()
 }
 
 
-# __git_complete_index_file requires 1 argument: the options to pass to
-# ls-file
+# __git_complete_index_file requires 1 argument:
+# 1: the options to pass to ls-file
+#
+# The exception is --committable, which finds the files appropriate commit.
 __git_complete_index_file ()
 {
 	local pfx cur_="$cur"
@@ -570,26 +551,6 @@ __git_complete_index_file ()
 	esac
 }
 
-# __git_complete_diff_index_file requires 1 argument: the id of a tree
-# object
-__git_complete_diff_index_file ()
-{
-	local pfx cur_="$cur"
-
-	case "$cur_" in
-	?*/*)
-		pfx="${cur_%/*}"
-		cur_="${cur_##*/}"
-		pfx="${pfx}/"
-
-		__gitcomp_file "$(__git_diff_index_files "$1" "$pfx")" "$pfx" "$cur_"
-		;;
-	*)
-		__gitcomp_file "$(__git_diff_index_files "$1")" "" "$cur_"
-		;;
-	esac
-}
-
 __git_complete_file ()
 {
 	__git_complete_revlist_file
@@ -1211,7 +1172,7 @@ _git_commit ()
 	esac
 
 	if git rev-parse --verify --quiet HEAD >/dev/null; then
-		__git_complete_diff_index_file "HEAD"
+		__git_complete_index_file "--committable"
 	else
 		# This is the first commit
 		__git_complete_index_file "--cached"