[PATCH 04/16] list-files: add tag to each entry, filter duplicate tags

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

All entry strings start with two-letter tag and a space. If all
entries have the same tags, tags are not displayed.

The outcome before and after this patch is the same. But it will be
useful in future when there are more than one type of entry.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/list-files.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/builtin/list-files.c b/builtin/list-files.c
index c444a53..18af65c 100644
--- a/builtin/list-files.c
+++ b/builtin/list-files.c
@@ -18,12 +18,16 @@ struct option ls_options[] = {
 	OPT_END()
 };
 
-static void add_one(struct string_list *result, const char *name)
+static void add_one(struct string_list *result, const char *name,
+		    const char *tag)
 {
 	struct strbuf sb = STRBUF_INIT;
 	struct string_list_item *item;
 
 	quote_path_relative(name, prefix_length ? prefix : NULL, &sb);
+	strbuf_insert(&sb, 0, "   ", 3);
+	sb.buf[0] = tag[0];
+	sb.buf[1] = tag[1];
 	item = string_list_append(result, strbuf_detach(&sb, NULL));
 	item->util = (char *)name;
 }
@@ -42,7 +46,38 @@ static void populate_cached_entries(struct string_list *result,
 				    S_ISGITLINK(ce->ce_mode)))
 			continue;
 
-		add_one(result, ce->name);
+		add_one(result, ce->name, "  ");
+	}
+}
+
+static void cleanup_tags(struct string_list *result)
+{
+	int i, same_1 = 1, same_2 = 1, pos, len;
+
+	for (i = 1; i < result->nr && (same_1 || same_2); i++) {
+		const char *s0 = result->items[i - 1].string;
+		const char *s1 = result->items[i].string;
+
+		same_1 = same_1 && s0[0] == s1[0];
+		same_2 = same_2 && s0[1] == s1[1];
+	}
+
+	if (same_1 && same_2) {
+		pos = 0;
+		len = 3;
+	} else if (same_1) {
+		pos = 0;
+		len = 1;
+	} else if (same_2) {
+		pos = 1;
+		len = 1;
+	} else
+		return;
+
+	for (i = 0; i < result->nr; i++) {
+		char *s = result->items[i].string;
+		int length = strlen(s);
+		memmove(s + pos, s + pos + len, length - len + 1);
 	}
 }
 
@@ -93,6 +128,7 @@ int cmd_list_files(int argc, const char **argv, const char *cmd_prefix)
 		      &pathspec, NULL, NULL);
 
 	populate_cached_entries(&result, &the_index);
+	cleanup_tags(&result);
 	display(&result);
 	string_list_clear(&result, 0);
 	return 0;
-- 
2.3.0.rc1.137.g477eb31