[PATCH v3 3/5] name-rev: factor code for sharing with a new command

[kristofferhaugsbakk@fastmail.com]

From: Kristoffer Haugsbakk <code@khaugsbakk.name>

We are about to introduce a new command git-format-rev(1) to this
file. Let’s factor some code so that we can share it with the new
command.

We want to be able to format commits found in freeform text, and
git-name-rev(1) already has a function for that but for symbolic
names. Let’s use a tagged union for the command-specific payload.

No functional changes.

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
---
 builtin/name-rev.c | 54 +++++++++++++++++++++++++++++++++++-----------
 1 file changed, 41 insertions(+), 13 deletions(-)

diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index 6357eaa76d0..dc4136f4de3 100644
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -272,6 +272,24 @@ struct name_ref_data {
 	struct string_list exclude_filters;
 };
 
+enum command_type {
+	NAME_REV = 1,
+};
+
+struct command {
+	enum command_type type;
+	union {
+		int name_only;
+	} u;
+};
+
+static void init_name_rev_command(struct command *cmd,
+				  int name_only)
+{
+	cmd->type = NAME_REV;
+	cmd->u.name_only = name_only;
+}
+
 static struct tip_table {
 	struct tip_table_entry {
 		struct object_id oid;
@@ -507,7 +525,7 @@ static char const * const name_rev_usage[] = {
 	NULL
 };
 
-static void name_rev_line(char *p, struct name_ref_data *data)
+static void name_rev_line(char *p, struct command *cmd)
 {
 	struct strbuf buf = STRBUF_INIT;
 	int counter = 0;
@@ -516,6 +534,7 @@ static void name_rev_line(char *p, struct name_ref_data *data)
 
 	for (p_start = p; *p; p++) {
 #define ishex(x) (isdigit((x)) || ((x) >= 'a' && (x) <= 'f'))
+	start:
 		if (!ishex(*p)) {
 			counter = 0;
 		} else if (++counter == hexsz &&
@@ -524,25 +543,32 @@ static void name_rev_line(char *p, struct name_ref_data *data)
 			const char *name = NULL;
 			char c = *(p + 1);
 			int p_len = p - p_start + 1;
+			struct object *o = NULL;
+			int oid_ret = 1;
 
 			counter = 0;
 
 			*(p + 1) = 0;
-			if (!repo_get_oid(the_repository, p - (hexsz - 1), &oid)) {
-				struct object *o =
-					lookup_object(the_repository, &oid);
+			oid_ret = repo_get_oid(the_repository, p - (hexsz - 1), &oid);
+
+			switch (cmd->type) {
+			case NAME_REV:
+				if (!oid_ret)
+					o = lookup_object(the_repository, &oid);
 				if (o)
 					name = get_rev_name(o, &buf);
+				*(p + 1) = c;
+				if (!name)
+					goto start;
+				if (cmd->u.name_only)
+					printf("%.*s%s", p_len - hexsz, p_start, name);
+				else
+					printf("%.*s (%s)", p_len, p_start, name);
+				break;
+			default:
+				BUG("uncovered case: %d", cmd->type);
 			}
-			*(p + 1) = c;
-
-			if (!name)
-				continue;
 
-			if (data->name_only)
-				printf("%.*s%s", p_len - hexsz, p_start, name);
-			else
-				printf("%.*s (%s)", p_len, p_start, name);
 			p_start = p + 1;
 		}
 	}
@@ -567,6 +593,7 @@ int cmd_name_rev(int argc,
 #endif
 	int all = 0, annotate_stdin = 0, allow_undefined = 1, always = 0, peel_tag = 0;
 	struct name_ref_data data = { 0, 0, STRING_LIST_INIT_NODUP, STRING_LIST_INIT_NODUP };
+	struct command cmd;
 	struct option opts[] = {
 		OPT_BOOL(0, "name-only", &data.name_only, N_("print only ref-based names (no object names)")),
 		OPT_BOOL(0, "tags", &data.tags_only, N_("only use tags to name the commits")),
@@ -596,6 +623,7 @@ int cmd_name_rev(int argc,
 	init_commit_rev_name(&rev_names);
 	repo_config(the_repository, git_default_config, NULL);
 	argc = parse_options(argc, argv, prefix, opts, name_rev_usage, 0);
+	init_name_rev_command(&cmd, data.name_only);
 
 #ifndef WITH_BREAKING_CHANGES
 	if (transform_stdin) {
@@ -663,7 +691,7 @@ int cmd_name_rev(int argc,
 
 		while (strbuf_getline(&sb, stdin) != EOF) {
 			strbuf_addch(&sb, '\n');
-			name_rev_line(sb.buf, &data);
+			name_rev_line(sb.buf, &cmd);
 		}
 		strbuf_release(&sb);
 	} else if (all) {
-- 
2.54.0.13.g9c7419e39f8