builtin/repo: fix table alignment for UTF-8 characters

The output table from "git repo structure" is misaligned when displaying
UTF-8 characters (e.g., non-ASCII glyphs). E.g.:

    | 仓库结构   | 值  |
    | -------------- | ---- |
    | * 引用       |      |
    |   * 计数     |   67 |

The previous implementation used simple width formatting with printf()
which didn't properly handle multi-byte UTF-8 characters, causing
misaligned table columns when displaying repository structure
information.

This change modifies the stats_table_print_structure function to use
strbuf_utf8_align() instead of basic printf width specifiers. This
ensures proper column alignment regardless of the character encoding of
the content being displayed.

Also add test cases for strbuf_utf8_align(), a function newly introduced
in "builtin/repo.c".

Signed-off-by: Jiang Xin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: jiangxin

builtin/repo.c

@@ -292,14 +292,20 @@ static void stats_table_print_structure(const struct stats_table *table)
 	int name_col_width = utf8_strwidth(name_col_title);
 	int value_col_width = utf8_strwidth(value_col_title);
 	struct string_list_item *item;
+	struct strbuf buf = STRBUF_INIT;
 
 	if (table->name_col_width > name_col_width)
 		name_col_width = table->name_col_width;
 	if (table->value_col_width > value_col_width)
 		value_col_width = table->value_col_width;
 
-	printf("| %-*s | %-*s |\n", name_col_width, name_col_title,
-	       value_col_width, value_col_title);
+	strbuf_addstr(&buf, "| ");
+	strbuf_utf8_align(&buf, ALIGN_LEFT, name_col_width, name_col_title);
+	strbuf_addstr(&buf, " | ");
+	strbuf_utf8_align(&buf, ALIGN_LEFT, value_col_width, value_col_title);
+	strbuf_addstr(&buf, " |");
+	printf("%s\n", buf.buf);
+
 	printf("| ");
 	for (int i = 0; i < name_col_width; i++)
 		putchar('-');
@@ -317,9 +323,16 @@ static void stats_table_print_structure(const struct stats_table *table)
 			value = entry->value;
 		}
 
-		printf("| %-*s | %*s |\n", name_col_width, item->string,
-		       value_col_width, value);
+		strbuf_reset(&buf);
+		strbuf_addstr(&buf, "| ");
+		strbuf_utf8_align(&buf, ALIGN_LEFT, name_col_width, item->string);
+		strbuf_addstr(&buf, " | ");
+		strbuf_utf8_align(&buf, ALIGN_RIGHT, value_col_width, value);
+		strbuf_addstr(&buf, " |");
+		printf("%s\n", buf.buf);
 	}
+
+	strbuf_release(&buf);
 }
 
 static void stats_table_clear(struct stats_table *table)

t/unit-tests/u-utf8-width.c

@@ -95,3 +95,40 @@ void test_utf8_width__strnwidth_cjk_with_ansi(void)
 	/* "Hello"(5) + "世界"(4) + "!"(1) = 10 */
 	cl_assert_equal_i(10, width);
 }
+
+/*
+ * Test the strbuf_utf8_align function with CJK characters
+ */
+void test_utf8_width__strbuf_utf8_align(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	/* Test left alignment with CJK */
+	strbuf_utf8_align(&buf, ALIGN_LEFT, 10, "你好");
+	/* Since "你好" is 4 display columns, we need 6 more spaces to reach 10 */
+	cl_assert_equal_s("你好      ", buf.buf);
+	strbuf_reset(&buf);
+
+	/* Test right alignment with CJK */
+	strbuf_utf8_align(&buf, ALIGN_RIGHT, 8, "世界");
+	/* "世界" is 4 display columns, so we need 4 leading spaces */
+	cl_assert_equal_s("    世界", buf.buf);
+	strbuf_reset(&buf);
+
+	/* Test center alignment with CJK */
+	strbuf_utf8_align(&buf, ALIGN_MIDDLE, 10, "中");
+	/* "中" is 2 display columns, so (10-2)/2 = 4 spaces on left, 4 on right */
+	cl_assert_equal_s("    中    ", buf.buf);
+	strbuf_reset(&buf);
+
+	strbuf_utf8_align(&buf, ALIGN_MIDDLE, 5, "中");
+	/* "中" is 2 display columns, so (5-2)/2 = 1 spaces on left, 2 on right */
+	cl_assert_equal_s(" 中  ", buf.buf);
+	strbuf_reset(&buf);
+
+	/* Test alignment that is smaller than string width */
+	strbuf_utf8_align(&buf, ALIGN_LEFT, 2, "你好");
+	/* Since "你好" is 4 display columns, it should not be truncated */
+	cl_assert_equal_s("你好", buf.buf);
+	strbuf_release(&buf);
+}