ref-filter: add %(rest) atom

%(rest) is a atom used for cat-file batch mode, which can split
the input lines at the first whitespace boundary, all characters
before that whitespace are considered to be the object name;
characters after that first run of whitespace (i.e., the "rest"
of the line) are output in place of the %(rest) atom.

In order to let "cat-file --batch=%(rest)" use the ref-filter
interface, add %(rest) atom for ref-filter.

Introduce the reject_atom() to reject the atom %(rest) for
"git for-each-ref", "git branch", "git tag" and "git verify-tag".

Reviewed-by: Jacob Keller <jacob.keller@gmail.com>
Suggected-by: Jacob Keller <jacob.keller@gmail.com>
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Hariom Verma <hariom18599@gmail.com>
Signed-off-by: ZheNing Hu <adlternative@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ref-filter.c

@@ -157,6 +157,7 @@ enum atom_type {
 	ATOM_IF,
 	ATOM_THEN,
 	ATOM_ELSE,
+	ATOM_REST,
 };
 
 /*
@@ -559,6 +560,15 @@ static int if_atom_parser(struct ref_format *format, struct used_atom *atom,
 	return 0;
 }
 
+static int rest_atom_parser(struct ref_format *format, struct used_atom *atom,
+			    const char *arg, struct strbuf *err)
+{
+	if (arg)
+		return strbuf_addf_ret(err, -1, _("%%(rest) does not take arguments"));
+	format->use_rest = 1;
+	return 0;
+}
+
 static int head_atom_parser(struct ref_format *format, struct used_atom *atom,
 			    const char *arg, struct strbuf *unused_err)
 {
@@ -615,6 +625,7 @@ static struct {
 	[ATOM_IF] = { "if", SOURCE_NONE, FIELD_STR, if_atom_parser },
 	[ATOM_THEN] = { "then", SOURCE_NONE },
 	[ATOM_ELSE] = { "else", SOURCE_NONE },
+	[ATOM_REST] = { "rest", SOURCE_NONE, FIELD_STR, rest_atom_parser },
 	/*
 	 * Please update $__git_ref_fieldlist in git-completion.bash
 	 * when you add new atoms
@@ -992,6 +1003,11 @@ static const char *find_next(const char *cp)
 	return NULL;
 }
 
+static int reject_atom(enum atom_type atom_type)
+{
+	return atom_type == ATOM_REST;
+}
+
 /*
  * Make sure the format string is well formed, and parse out
  * the used atoms.
@@ -1012,6 +1028,8 @@ int verify_ref_format(struct ref_format *format)
 		at = parse_ref_filter_atom(format, sp + 2, ep, &err);
 		if (at < 0)
 			die("%s", err.buf);
+		if (reject_atom(used_atom[at].atom_type))
+			die(_("this command reject atom %%(%.*s)"), (int)(ep - sp - 2), sp + 2);
 
 		if ((format->quote_style == QUOTE_PYTHON ||
 		     format->quote_style == QUOTE_SHELL ||
@@ -1931,6 +1949,12 @@ static int populate_value(struct ref_array_item *ref, struct strbuf *err)
 			v->handler = else_atom_handler;
 			v->s = xstrdup("");
 			continue;
+		} else if (atom_type == ATOM_REST) {
+			if (ref->rest)
+				v->s = xstrdup(ref->rest);
+			else
+				v->s = xstrdup("");
+			continue;
 		} else
 			continue;
 
@@ -2148,6 +2172,7 @@ static struct ref_array_item *new_ref_array_item(const char *refname,
 
 	FLEX_ALLOC_STR(ref, refname, refname);
 	oidcpy(&ref->objectname, oid);
+	ref->rest = NULL;
 
 	return ref;
 }

ref-filter.h

@@ -38,6 +38,7 @@ struct ref_sorting {
 
 struct ref_array_item {
 	struct object_id objectname;
+	const char *rest;
 	int flag;
 	unsigned int kind;
 	const char *symref;
@@ -76,14 +77,16 @@ struct ref_format {
 	 * verify_ref_format() afterwards to finalize.
 	 */
 	const char *format;
+	const char *rest;
 	int quote_style;
+	int use_rest;
 	int use_color;
 
 	/* Internal state to ref-filter */
 	int need_color_reset_at_eol;
 };
 
-#define REF_FORMAT_INIT { NULL, 0, -1 }
+#define REF_FORMAT_INIT { .use_color = -1 }
 
 /*  Macros for checking --merged and --no-merged options */
 #define _OPT_MERGED_NO_MERGED(option, filter, h) \

t/t3203-branch-output.sh

@@ -340,6 +340,10 @@ test_expect_success 'git branch --format option' '
 	test_cmp expect actual
 '
 
+test_expect_success 'git branch with --format=%(rest) must fail' '
+	test_must_fail git branch --format="%(rest)" >actual
+'
+
 test_expect_success 'worktree colors correct' '
 	cat >expect <<-EOF &&
 	* <GREEN>(HEAD detached from fromtag)<RESET>

t/t6300-for-each-ref.sh

@@ -1211,6 +1211,10 @@ test_expect_success 'basic atom: head contents:trailers' '
 	test_cmp expect actual.clean
 '
 
+test_expect_success 'basic atom: rest must fail' '
+	test_must_fail git for-each-ref --format="%(rest)" refs/heads/main
+'
+
 test_expect_success 'trailer parsing not fooled by --- line' '
 	git commit --allow-empty -F - <<-\EOF &&
 	this is the subject

t/t7004-tag.sh

@@ -1998,6 +1998,10 @@ test_expect_success '--format should list tags as per format given' '
 	test_cmp expect actual
 '
 
+test_expect_success 'git tag -l with --format="%(rest)" must fail' '
+	test_must_fail git tag -l --format="%(rest)" "v1*"
+'
+
 test_expect_success "set up color tests" '
 	echo "<RED>v1.0<RESET>" >expect.color &&
 	echo "v1.0" >expect.bare &&

t/t7030-verify-tag.sh

@@ -194,6 +194,10 @@ test_expect_success GPG 'verifying tag with --format' '
 	test_cmp expect actual
 '
 
+test_expect_success GPG 'verifying tag with --format="%(rest)" must fail' '
+	test_must_fail git verify-tag --format="%(rest)" "fourth-signed"
+'
+
 test_expect_success GPG 'verifying a forged tag with --format should fail silently' '
 	test_must_fail git verify-tag --format="tagname : %(tag)" $(cat forged1.tag) >actual-forged &&
 	test_must_be_empty actual-forged