diff: add --compact-summary

Certain information is currently shown with --summary, but when used
in combination with --stat it's a bit hard to read since info of the
same file is in two places (--stat and --summary).

On top of that, commits that add or remove files double the number of
display lines, which could be a lot if you add or remove a lot of
files.

--compact-summary embeds most of --summary back in --stat in the
little space between the file name part and the graph line, e.g. with
commit 0433d533f1:

   Documentation/merge-config.txt         |  4 +
   builtin/merge.c                        |  2 +
   ...-pull-verify-signatures.sh (new +x) | 81 ++++++++++++++
   t/t7612-merge-verify-signatures.sh     | 45 ++++++++
   4 files changed, 132 insertions(+)

It helps both condensing information and saving some text
space. What's new in diffstat is:

- A new 0644 file is shown as (new)
- A new 0755 file is shown as (new +x)
- A new symlink is shown as (new +l)
- A deleted file is shown as (gone)
- A mode change adding executable bit is shown as (mode +x)
- A mode change removing it is shown as (mode -x)

Note that --compact-summary does not contain all the information
--summary provides. Rewrite percentage is not shown but it could be
added later, like R50% or C20%.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

8 files changed, 83 insertions, 0 deletions

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 743af97b06..0c7fd5815e 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -128,6 +128,14 @@ have to use `--diff-algorithm=default` option.
 These parameters can also be set individually with `--stat-width=<width>`,
 `--stat-name-width=<name-width>` and `--stat-count=<count>`.
 
+--compact-summary::
+	Output a condensed summary of extended header information such
+	as file creations or deletions ("new" or "gone", optionally "+l"
+	if it's a symlink) and mode changes ("+x" or "-x" for adding
+	or removing executable bit respectively) in diffstat. The
+	information is put betwen the filename part and the graph
+	part. Implies `--stat`.
+
 --numstat::
 	Similar to `--stat`, but shows number of added and
 	deleted lines in decimal notation and pathname without
diff --git a/diff.c b/diff.c
index c0b75de45f..95124c0e7c 100644
--- a/diff.c
+++ b/diff.c
@@ -2129,6 +2129,7 @@ struct diffstat_t {
 		char *from_name;
 		char *name;
 		char *print_name;
+		const char *comments;
 		unsigned is_unmerged:1;
 		unsigned is_binary:1;
 		unsigned is_renamed:1;
@@ -2205,6 +2206,9 @@ static void fill_print_name(struct diffstat_file *file)
 	else
 		quote_c_style(file->name, &pname, NULL, 0);
 
+	if (file->comments)
+		strbuf_addf(&pname, " (%s)", file->comments);
+
 	file->print_name = strbuf_detach(&pname, NULL);
 }
 
@@ -3239,6 +3243,32 @@ static void builtin_diff(const char *name_a,
 	return;
 }
 
+static char *get_compact_summary(const struct diff_filepair *p, int is_renamed)
+{
+	if (!is_renamed) {
+		if (p->status == DIFF_STATUS_ADDED) {
+			if (S_ISLNK(p->two->mode))
+				return "new +l";
+			else if ((p->two->mode & 0777) == 0755)
+				return "new +x";
+			else
+				return "new";
+		} else if (p->status == DIFF_STATUS_DELETED)
+			return "gone";
+	}
+	if (S_ISLNK(p->one->mode) && !S_ISLNK(p->two->mode))
+		return "mode -l";
+	else if (!S_ISLNK(p->one->mode) && S_ISLNK(p->two->mode))
+		return "mode +l";
+	else if ((p->one->mode & 0777) == 0644 &&
+		 (p->two->mode & 0777) == 0755)
+		return "mode +x";
+	else if ((p->one->mode & 0777) == 0755 &&
+		 (p->two->mode & 0777) == 0644)
+		return "mode -x";
+	return NULL;
+}
+
 static void builtin_diffstat(const char *name_a, const char *name_b,
 			     struct diff_filespec *one,
 			     struct diff_filespec *two,
@@ -3258,6 +3288,8 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
 
 	data = diffstat_add(diffstat, name_a, name_b);
 	data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
+	if (o->flags.stat_with_summary)
+		data->comments = get_compact_summary(p, data->is_renamed);
 
 	if (!one || !two) {
 		data->is_unmerged = 1;
@@ -4528,6 +4560,11 @@ int diff_opt_parse(struct diff_options *options,
 	else if (starts_with(arg, "--stat"))
 		/* --stat, --stat-width, --stat-name-width, or --stat-count */
 		return stat_opt(options, av);
+	else if (!strcmp(arg, "--compact-summary")) {
+		 options->flags.stat_with_summary = 1;
+		 options->output_format |= DIFF_FORMAT_DIFFSTAT;
+	} else if (!strcmp(arg, "--no-compact-summary"))
+		 options->flags.stat_with_summary = 0;
 
 	/* renames options */
 	else if (starts_with(arg, "-B") ||
diff --git a/diff.h b/diff.h
index 7cf276f077..28a8fb4346 100644
--- a/diff.h
+++ b/diff.h
@@ -93,6 +93,7 @@ struct diff_flags {
 	unsigned funccontext:1;
 	unsigned pickaxe_ignore_case:1;
 	unsigned default_follow_renames:1;
+	unsigned stat_with_summary:1;
 };
 
 static inline void diff_flags_or(struct diff_flags *a,
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index f10798b2df..3f9a24fd56 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -361,6 +361,11 @@ diff --no-index --raw dir2 dir
 diff --no-index --raw --abbrev=4 dir2 dir
 :noellipses diff --no-index --raw --abbrev=4 dir2 dir
 diff --no-index --raw --no-abbrev dir2 dir
+
+diff-tree --pretty --root --stat --compact-summary initial
+diff-tree --pretty -R --root --stat --compact-summary initial
+diff-tree --stat --compact-summary initial mode
+diff-tree -R --stat --compact-summary initial mode
 EOF
 
 test_expect_success 'log -S requires an argument' '
diff --git a/t/t4013/diff.diff-tree_--pretty_--root_--stat_--compact-summary_initial b/t/t4013/diff.diff-tree_--pretty_--root_--stat_--compact-summary_initial
new file mode 100644
index 0000000000..d6451ff7cc
--- /dev/null
+++ b/t/t4013/diff.diff-tree_--pretty_--root_--stat_--compact-summary_initial
@@ -0,0 +1,12 @@
+$ git diff-tree --pretty --root --stat --compact-summary initial
+commit 444ac553ac7612cc88969031b02b3767fb8a353a
+Author: A U Thor <author@example.com>
+Date:   Mon Jun 26 00:00:00 2006 +0000
+
+    Initial
+
+ dir/sub (new) | 2 ++
+ file0 (new)   | 3 +++
+ file2 (new)   | 3 +++
+ 3 files changed, 8 insertions(+)
+$
diff --git a/t/t4013/diff.diff-tree_--pretty_-R_--root_--stat_--compact-summary_initial b/t/t4013/diff.diff-tree_--pretty_-R_--root_--stat_--compact-summary_initial
new file mode 100644
index 0000000000..1989e55cd0
--- /dev/null
+++ b/t/t4013/diff.diff-tree_--pretty_-R_--root_--stat_--compact-summary_initial
@@ -0,0 +1,12 @@
+$ git diff-tree --pretty -R --root --stat --compact-summary initial
+commit 444ac553ac7612cc88969031b02b3767fb8a353a
+Author: A U Thor <author@example.com>
+Date:   Mon Jun 26 00:00:00 2006 +0000
+
+    Initial
+
+ dir/sub (gone) | 2 --
+ file0 (gone)   | 3 ---
+ file2 (gone)   | 3 ---
+ 3 files changed, 8 deletions(-)
+$
diff --git a/t/t4013/diff.diff-tree_--stat_--compact-summary_initial_mode b/t/t4013/diff.diff-tree_--stat_--compact-summary_initial_mode
new file mode 100644
index 0000000000..9c7c8f63af
--- /dev/null
+++ b/t/t4013/diff.diff-tree_--stat_--compact-summary_initial_mode
@@ -0,0 +1,4 @@
+$ git diff-tree --stat --compact-summary initial mode
+ file0 (mode +x) | 0
+ 1 file changed, 0 insertions(+), 0 deletions(-)
+$
diff --git a/t/t4013/diff.diff-tree_-R_--stat_--compact-summary_initial_mode b/t/t4013/diff.diff-tree_-R_--stat_--compact-summary_initial_mode
new file mode 100644
index 0000000000..e38f3d3bfb
--- /dev/null
+++ b/t/t4013/diff.diff-tree_-R_--stat_--compact-summary_initial_mode
@@ -0,0 +1,4 @@
+$ git diff-tree -R --stat --compact-summary initial mode
+ file0 (mode -x) | 0
+ 1 file changed, 0 insertions(+), 0 deletions(-)
+$