diff --stat: use less columns for change counts

Number of columns required for change counts is now computed based on
the maximum number of changed lines instead of being fixed. This means
that usually a few more columns will be available for the filenames
and the graph.

The graph width logic is also modified to include enough space for
"Bin XXX -> YYY bytes".

If changes to binary files are mixed with changes to text files,
change counts are padded to take at least three columns. And the other
way around, if change counts require more than three columns, then
"Bin"s are padded to align with the change count. This way, the +-
part starts in the same column as "XXX -> YYY" part for binary files.
This makes the graph easier to parse visually thanks to the empty
column. This mimics the layout of diff --stat before this change.

Tests and the tutorial are updated to reflect the new --stat output.
This means either the removal of extra padding and/or the addition of
up to three extra characters to truncated filenames. One test is added
to check the graph alignment when a binary file change and text file
change of more than 999 lines are committed together.

Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 38 insertions, 10 deletions

diff --git a/diff.c b/diff.c
index 22288b0..c316e0c 100644
--- a/diff.c
+++ b/diff.c
@@ -1443,8 +1443,8 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 {
 	int i, len, add, del, adds = 0, dels = 0;
 	uintmax_t max_change = 0, max_len = 0;
-	int total_files = data->nr;
-	int width, name_width, graph_width, number_width = 4, count;
+	int total_files = data->nr, count;
+	int width, name_width, graph_width, number_width = 0, bin_width = 0;
 	const char *reset, *add_c, *del_c;
 	const char *line_prefix = "";
 	int extra_shown = 0;
@@ -1480,8 +1480,21 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		if (max_len < len)
 			max_len = len;
 
-		if (file->is_binary || file->is_unmerged)
+		if (file->is_unmerged) {
+			/* "Unmerged" is 8 characters */
+			bin_width = bin_width < 8 ? 8 : bin_width;
 			continue;
+		}
+		if (file->is_binary) {
+			/* "Bin XXX -> YYY bytes" */
+			int w = 14 + decimal_width(file->added)
+				+ decimal_width(file->deleted);
+			bin_width = bin_width < w ? w : bin_width;
+			/* Display change counts aligned with "Bin" */
+			number_width = 3;
+			continue;
+		}
+
 		if (max_change < change)
 			max_change = change;
 	}
@@ -1506,12 +1519,22 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 	 * stat_name_width fixes the maximum width of the filename,
 	 * and is also used to divide available columns if there
 	 * aren't enough.
+	 *
+	 * Binary files are displayed with "Bin XXX -> YYY bytes"
+	 * instead of the change count and graph. This part is treated
+	 * similarly to the graph part, except that it is not
+	 * "scaled". If total width is too small to accomodate the
+	 * guaranteed minimum width of the filename part and the
+	 * separators and this message, this message will "overflow"
+	 * making the line longer than the maximum width.
 	 */
 
 	if (options->stat_width == -1)
 		width = term_columns();
 	else
 		width = options->stat_width ? options->stat_width : 80;
+	number_width = decimal_width(max_change) > number_width ?
+		decimal_width(max_change) : number_width;
 
 	if (options->stat_graph_width == -1)
 		options->stat_graph_width = diff_stat_graph_width;
@@ -1525,10 +1548,14 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 
 	/*
 	 * First assign sizes that are wanted, ignoring available width.
+	 * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
+	 * starting from "XXX" should fit in graph_width.
 	 */
-	graph_width = (options->stat_graph_width &&
-		       options->stat_graph_width < max_change) ?
-		options->stat_graph_width : max_change;
+	graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
+	if (options->stat_graph_width &&
+	    options->stat_graph_width < graph_width)
+		graph_width = options->stat_graph_width;
+
 	name_width = (options->stat_name_width > 0 &&
 		      options->stat_name_width < max_len) ?
 		options->stat_name_width : max_len;
@@ -1583,7 +1610,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		if (data->files[i]->is_binary) {
 			fprintf(options->file, "%s", line_prefix);
 			show_name(options->file, prefix, name, len);
-			fprintf(options->file, "  Bin ");
+			fprintf(options->file, " %*s ", number_width, "Bin");
 			fprintf(options->file, "%s%"PRIuMAX"%s",
 				del_c, deleted, reset);
 			fprintf(options->file, " -> ");
@@ -1596,7 +1623,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		else if (data->files[i]->is_unmerged) {
 			fprintf(options->file, "%s", line_prefix);
 			show_name(options->file, prefix, name, len);
-			fprintf(options->file, "  Unmerged\n");
+			fprintf(options->file, " Unmerged\n");
 			continue;
 		}
 
@@ -1625,8 +1652,9 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		}
 		fprintf(options->file, "%s", line_prefix);
 		show_name(options->file, prefix, name, len);
-		fprintf(options->file, "%5"PRIuMAX"%s", added + deleted,
-				added + deleted ? " " : "");
+		fprintf(options->file, " %*"PRIuMAX"%s",
+			number_width, added + deleted,
+			added + deleted ? " " : "");
 		show_graph(options->file, '+', add, add_c, reset);
 		show_graph(options->file, '-', del, del_c, reset);
 		fprintf(options->file, "\n");