[PATCH 10/19] [GSOC] ref-filter: introduce reject_atom()

["ZheNing Hu via GitGitGadget" <gitgitgadget@gmail.com>]

From: ZheNing Hu <adlternative@gmail.com>

Add `cat_file_mode` member in struct `ref_format` and introduce
the function `reject_atom()`, when `cat-file --batch` use ref-filter
logic later, it can help us reject atoms in verify_ref_format()
which cat-file cannot use, e.g. `%(refname)`, `%(push)`,
`%(upstream)`... or the atom `%(rest)` which for-each-ref family
cannot use.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Christian Couder <christian.couder@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>
---
 ref-filter.c | 25 ++++++++++++++++++++++---
 ref-filter.h |  1 +
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/ref-filter.c b/ref-filter.c
index 80b09fce1d5..27199ba40f5 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1000,6 +1000,26 @@ static const char *find_next(const char *cp)
 	return NULL;
 }
 
+static int reject_atom(int cat_file_mode, enum atom_type atom_type)
+{
+	if (!cat_file_mode)
+		return atom_type == ATOM_REST;
+
+	/* cat_file_mode */
+	switch (atom_type) {
+	case ATOM_FLAG:
+	case ATOM_HEAD:
+	case ATOM_PUSH:
+	case ATOM_REFNAME:
+	case ATOM_SYMREF:
+	case ATOM_UPSTREAM:
+	case ATOM_WORKTREEPATH:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
 /*
  * Make sure the format string is well formed, and parse out
  * the used atoms.
@@ -1020,9 +1040,8 @@ 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 (used_atom[at].atom_type == ATOM_REST)
-			die("this command reject atom %%(%.*s)", (int)(ep - sp - 2), sp + 2);
+		if (reject_atom(format->cat_file_mode, 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 ||
diff --git a/ref-filter.h b/ref-filter.h
index 44e6dc05ac2..053980a6a42 100644
--- a/ref-filter.h
+++ b/ref-filter.h
@@ -78,6 +78,7 @@ struct ref_format {
 	 */
 	const char *format;
 	const char *rest;
+	int cat_file_mode;
 	int quote_style;
 	int use_rest;
 	int use_color;
-- 
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