[RFC/PATCH 3/5] ls-files: add and use a new --sparse option

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-ls-files.txt           |  4 ++
 builtin/ls-files.c                       | 10 ++++-
 t/t1091-sparse-checkout-builtin.sh       |  9 ++--
 t/t1092-sparse-checkout-compatibility.sh | 57 ++++++++++++++++--------
 4 files changed, 56 insertions(+), 24 deletions(-)

diff --git a/Documentation/git-ls-files.txt b/Documentation/git-ls-files.txt
index 6d11ab506b..1145e960a4 100644
--- a/Documentation/git-ls-files.txt
+++ b/Documentation/git-ls-files.txt
@@ -71,6 +71,10 @@ OPTIONS
 --unmerged::
 	Show unmerged files in the output (forces --stage)
 
+--sparse::
+	Show sparse directories in the output instead of expanding
+	them (forces --stage)
+
 -k::
 --killed::
 	Show files on the filesystem that need to be removed due
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 4db75351f2..1ebbb63c10 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -26,6 +26,7 @@ static int show_deleted;
 static int show_cached;
 static int show_others;
 static int show_stage;
+static int show_sparse;
 static int show_unmerged;
 static int show_resolve_undo;
 static int show_modified;
@@ -639,6 +640,8 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 			DIR_SHOW_IGNORED),
 		OPT_BOOL('s', "stage", &show_stage,
 			N_("show staged contents' object name in the output")),
+		OPT_BOOL(0, "sparse", &show_sparse,
+			N_("show unexpanded sparse directories in the output")),
 		OPT_BOOL('k', "killed", &show_killed,
 			N_("show files on the filesystem that need to be removed")),
 		OPT_BIT(0, "directory", &dir.flags,
@@ -705,12 +708,17 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 		tag_skip_worktree = "S ";
 		tag_resolve_undo = "U ";
 	}
+	if (show_sparse) {
+		prepare_repo_settings(the_repository);
+		the_repository->settings.command_requires_full_index = 0;
+	}
 	if (show_modified || show_others || show_deleted || (dir.flags & DIR_SHOW_IGNORED) || show_killed)
 		require_work_tree = 1;
-	if (show_unmerged)
+	if (show_unmerged || show_sparse)
 		/*
 		 * There's no point in showing unmerged unless
 		 * you also show the stage information.
+		 * The same goes for the --sparse option.
 		 */
 		show_stage = 1;
 	if (show_tag || show_stage)
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index ff1ad570a2..c823df423c 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -208,12 +208,13 @@ test_expect_success 'sparse-checkout disable' '
 test_expect_success 'sparse-index enabled and disabled' '
 	git -C repo sparse-checkout init --cone --sparse-index &&
 	test_cmp_config -C repo true extensions.sparseIndex &&
-	test-tool -C repo read-cache --table >cache &&
-	grep " tree " cache &&
+	git -C repo ls-files --sparse >cache &&
+	grep "^040000 " cache >lines &&
+	test_line_count = 3 lines &&
 
 	git -C repo sparse-checkout disable &&
-	test-tool -C repo read-cache --table >cache &&
-	! grep " tree " cache &&
+	git -C repo ls-files --sparse >cache &&
+	! grep "^040000 " cache &&
 	git -C repo config --list >config &&
 	! grep extensions.sparseindex config
 '
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index d97bf9b645..48d3920490 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -136,48 +136,67 @@ test_sparse_match () {
 	test_cmp sparse-checkout-err sparse-index-err
 }
 
+test_index_entry_like () {
+	dir=$1
+	shift
+	fmt=$1
+	shift
+	rev=$1
+	shift
+	entry=$1
+	shift
+	file=$1
+	shift
+	hash=$(git -C "$dir" rev-parse "$rev") &&
+	printf "$fmt\n" "$hash" "$entry" >expected &&
+	if grep "$entry" "$file" >line
+	then
+		test_cmp expected line
+	else
+		cat cache &&
+		false
+	fi
+}
+
 test_expect_success 'sparse-index contents' '
 	init_repos &&
 
-	test-tool -C sparse-index read-cache --table >cache &&
+	git -C sparse-index ls-files --sparse >cache &&
 	for dir in folder1 folder2 x
 	do
-		TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
-		grep "040000 tree $TREE	$dir/" cache \
-			|| return 1
+		test_index_entry_like sparse-index "040000 %s 0\t%s" "HEAD:$dir" "$dir/" cache || return 1
 	done &&
 
 	git -C sparse-index sparse-checkout set folder1 &&
 
-	test-tool -C sparse-index read-cache --table >cache &&
+	git -C sparse-index ls-files --sparse >cache &&
 	for dir in deep folder2 x
 	do
-		TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
-		grep "040000 tree $TREE	$dir/" cache \
-			|| return 1
+		test_index_entry_like sparse-index "040000 %s 0\t%s" "HEAD:$dir" "$dir/" cache || return 1
 	done &&
 
 	git -C sparse-index sparse-checkout set deep/deeper1 &&
 
-	test-tool -C sparse-index read-cache --table >cache &&
+	git -C sparse-index ls-files --sparse >cache &&
 	for dir in deep/deeper2 folder1 folder2 x
 	do
-		TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
-		grep "040000 tree $TREE	$dir/" cache \
-			|| return 1
+		test_index_entry_like sparse-index "040000 %s 0\t%s" "HEAD:$dir" "$dir/" cache || return 1
 	done &&
 
+	grep 040000 cache >lines &&
+	test_line_count = 4 lines &&
+
 	# Disabling the sparse-index removes tree entries with full ones
 	git -C sparse-index sparse-checkout init --no-sparse-index &&
 
-	test-tool -C sparse-index read-cache --table >cache &&
-	! grep "040000 tree" cache &&
-	test_sparse_match test-tool read-cache --table
+	git -C sparse-index ls-files --sparse >cache &&
+	! grep "^040000 " cache >lines &&
+	test_sparse_match git ls-tree -r HEAD
 '
 
 test_expect_success 'expanded in-memory index matches full index' '
 	init_repos &&
-	test_sparse_match test-tool read-cache --expand --table
+	test_sparse_match git ls-tree -r HEAD
 '
 
 test_expect_success 'status with options' '
@@ -394,9 +413,9 @@ test_expect_success 'submodule handling' '
 	test_all_match git commit -m "add submodule" &&
 
 	# having a submodule prevents "modules" from collapse
-	test-tool -C sparse-index read-cache --table >cache &&
-	grep "100644 blob .*	modules/a" cache &&
-	grep "160000 commit $(git -C initial-repo rev-parse HEAD)	modules/sub" cache
+	git -C sparse-index ls-files --sparse >cache &&
+	test_index_entry_like sparse-index "100644 %s 0\t%s" "HEAD:modules/a" "modules/a" cache &&
+	test_index_entry_like sparse-index "160000 %s 0\t%s" "HEAD:modules/sub" "modules/sub" cache
 '
 
 test_expect_success 'sparse-index is expanded and converted back' '
-- 
2.31.0.260.g719c683c1d