[RFC PATCH 7/7] ls-tree.c: support `--object-only` option for "git-ls-tree"

From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Dec 17, 2021, 13:30 UTC
Message-ID: <RFC-patch-7.7-5e34df4f8dd-20211217T131635Z-avarab@gmail.com>
In-Reply-To: <RFC-cover-0.7-00000000000-20211217T131635Z-avarab@gmail.com>

From: Teng Long <dyroneteng@gmail.com>

We usually pipe the output from `git ls-trees` to tools like `sed` or `cut` when we only want to extract some fields.

When we want only the pathname component, we can pass `--name-only` option to omit such a pipeline, but there are no options for extracting other fields.

Teach the "--object-only" option to the command to only show the object name. This option cannot be used together with "--name-only" or "--long" (mutually exclusive).

Signed-off-by: Teng Long <dyroneteng@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-ls-tree.txt |  7 ++++-
 builtin/ls-tree.c             |  6 +++++
 t/t3103-ls-tree-misc.sh       |  8 ++++++
 t/t3104-ls-tree-oid.sh        | 51 +++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100755 t/t3104-ls-tree-oid.sh

diff --git a/Documentation/git-ls-tree.txt b/Documentation/git-ls-tree.txt
index db02d6d79a9..729370f2357 100644
--- a/Documentation/git-ls-tree.txt
+++ b/Documentation/git-ls-tree.txt
@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git ls-tree' [-d] [-r] [-t] [-l] [-z]
-	    [--name-only] [--name-status] [--full-name] [--full-tree] [--abbrev[=<n>]]
+	    [--name-only] [--name-status] [--object-only] [--full-name] [--full-tree] [--abbrev[=<n>]]
 	    <tree-ish> [<path>...]
 
 DESCRIPTION
@@ -59,6 +59,11 @@ OPTIONS
 --name-only::
 --name-status::
 	List only filenames (instead of the "long" output), one per line.
+	Cannot be combined with `--object-only`.
+
+--object-only::
+	List only names of the objects, one per line. Cannot be combined
+	with `--name-only` or `--name-status`.
 
 --abbrev[=<n>]::
 	Instead of showing the full 40-byte hexadecimal object
diff --git a/builtin/ls-tree.c b/builtin/ls-tree.c
index efd85cab088..f19b0138362 100644
--- a/builtin/ls-tree.c
+++ b/builtin/ls-tree.c
@@ -20,6 +20,7 @@ static int line_termination = '\n';
 #define LS_SHOW_TREES 4
 #define LS_NAME_ONLY 8
 #define LS_SHOW_SIZE 16
+#define LS_OBJECT_ONLY 32
 static int abbrev;
 static int ls_options;
 static struct pathspec pathspec;
@@ -31,6 +32,7 @@ static const char *ls_tree_prefix;
  */
 static const char *ls_tree_format_d = "%(objectmode) %(objecttype) %(objectname)%x09%(path)";
 static const char *ls_tree_format_l = "%(objectmode) %(objecttype) %(objectname) %(objectsize:padded)%x09%(path)";
+static const char *ls_tree_format_o = "%(objectname)";
 static const char *ls_tree_format_n = "%(path)";
 
 static const  char * const ls_tree_usage[] = {
@@ -271,6 +273,8 @@ int cmd_ls_tree(int argc, const char **argv, const char *prefix)
 			LS_NAME_ONLY),
 		OPT_BIT(0, "name-status", &ls_options, N_("list only filenames"),
 			LS_NAME_ONLY),
+		OPT_BIT(0, "object-only", &ls_options, N_("list only objects"),
+			LS_OBJECT_ONLY),
 		OPT_SET_INT(0, "full-name", &chomp_prefix,
 			    N_("use full path names"), 0),
 		OPT_BOOL(0, "full-tree", &full_tree,
@@ -302,6 +306,8 @@ int cmd_ls_tree(int argc, const char **argv, const char *prefix)
 		implicit_format = ls_tree_format_n;
 	if (ls_options & LS_SHOW_SIZE)
 		implicit_format = ls_tree_format_l;
+	if (ls_options & LS_OBJECT_ONLY)
+		implicit_format = ls_tree_format_o;
 
 	if (format && implicit_format)
 		usage_msg_opt(_("providing --format cannot be combined with other format-altering options"),
diff --git a/t/t3103-ls-tree-misc.sh b/t/t3103-ls-tree-misc.sh
index d18ba1bd84b..a8641706a6e 100755
--- a/t/t3103-ls-tree-misc.sh
+++ b/t/t3103-ls-tree-misc.sh
@@ -23,4 +23,12 @@ test_expect_success 'ls-tree fails with non-zero exit code on broken tree' '
 	test_must_fail git ls-tree -r HEAD
 '
 
+test_expect_success 'usage: incompatible options: --name-status with --long' '
+	test_expect_code 129 git ls-tree --long --name-status
+'
+
+test_expect_success 'usage: incompatible options: --name-only with --long' '
+	test_expect_code 129 git ls-tree --long --name-only
+'
+
 test_done
diff --git a/t/t3104-ls-tree-oid.sh b/t/t3104-ls-tree-oid.sh
new file mode 100755
index 00000000000..81304e7b13a
--- /dev/null
+++ b/t/t3104-ls-tree-oid.sh
@@ -0,0 +1,51 @@
+#!/bin/sh
+
+test_description='git ls-tree objects handling.'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit A &&
+	test_commit B &&
+	mkdir -p C &&
+	test_commit C/D.txt &&
+	find *.txt path* \( -type f -o -type l \) -print |
+	xargs git update-index --add &&
+	tree=$(git write-tree) &&
+	echo $tree
+'
+
+test_expect_success 'usage: --object-only' '
+	git ls-tree --object-only $tree >current &&
+	git ls-tree $tree >result &&
+	cut -f1 result | cut -d " " -f3 >expected &&
+	test_cmp current expected
+'
+
+test_expect_success 'usage: --object-only with -r' '
+	git ls-tree --object-only -r $tree >current &&
+	git ls-tree -r $tree >result &&
+	cut -f1 result | cut -d " " -f3 >expected &&
+	test_cmp current expected
+'
+
+test_expect_success 'usage: --object-only with --abbrev' '
+	git ls-tree --object-only --abbrev=6 $tree >current &&
+	git ls-tree --abbrev=6 $tree >result &&
+	cut -f1 result | cut -d " " -f3 >expected &&
+	test_cmp current expected
+'
+
+test_expect_success 'usage: incompatible options: --name-only with --object-only' '
+	test_expect_code 129 git ls-tree --object-only --name-only
+'
+
+test_expect_success 'usage: incompatible options: --name-status with --object-only' '
+	test_expect_code 129 git ls-tree --object-only --name-status
+'
+
+test_expect_success 'usage: incompatible options: --long with --object-only' '
+	test_expect_code 129 git ls-tree --object-only --long
+'
+
+test_done

-- 
2.34.1.1119.g7a3fc8778ee