[PATCH 02/18] Add a new builtin: branch-diff

[Johannes Schindelin <johannes.schindelin@gmx.de>]

This builtin does not do a whole lot so far, apart from showing a usage
that is oddly similar to that of `git tbdiff`. And for a good reason:
the next commits will turn `branch-diff` into a full-blown replacement
for `tbdiff`.

At this point, we ignore tbdiff's color options, as they will all be
implemented later and require some patches to the diff machinery.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 .gitignore            |  1 +
 Makefile              |  1 +
 builtin.h             |  1 +
 builtin/branch-diff.c | 40 ++++++++++++++++++++++++++++++++++++++++
 command-list.txt      |  1 +
 git.c                 |  1 +
 6 files changed, 45 insertions(+)
 create mode 100644 builtin/branch-diff.c

diff --git a/.gitignore b/.gitignore
index 833ef3b0b78..1346a64492f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,6 +20,7 @@
 /git-bisect--helper
 /git-blame
 /git-branch
+/git-branch-diff
 /git-bundle
 /git-cat-file
 /git-check-attr
diff --git a/Makefile b/Makefile
index 96f2e76a904..9b1984776d8 100644
--- a/Makefile
+++ b/Makefile
@@ -953,6 +953,7 @@ BUILTIN_OBJS += builtin/archive.o
 BUILTIN_OBJS += builtin/bisect--helper.o
 BUILTIN_OBJS += builtin/blame.o
 BUILTIN_OBJS += builtin/branch.o
+BUILTIN_OBJS += builtin/branch-diff.o
 BUILTIN_OBJS += builtin/bundle.o
 BUILTIN_OBJS += builtin/cat-file.o
 BUILTIN_OBJS += builtin/check-attr.o
diff --git a/builtin.h b/builtin.h
index 42378f3aa47..e1c4d2a529a 100644
--- a/builtin.h
+++ b/builtin.h
@@ -135,6 +135,7 @@ extern int cmd_archive(int argc, const char **argv, const char *prefix);
 extern int cmd_bisect__helper(int argc, const char **argv, const char *prefix);
 extern int cmd_blame(int argc, const char **argv, const char *prefix);
 extern int cmd_branch(int argc, const char **argv, const char *prefix);
+extern int cmd_branch_diff(int argc, const char **argv, const char *prefix);
 extern int cmd_bundle(int argc, const char **argv, const char *prefix);
 extern int cmd_cat_file(int argc, const char **argv, const char *prefix);
 extern int cmd_checkout(int argc, const char **argv, const char *prefix);
diff --git a/builtin/branch-diff.c b/builtin/branch-diff.c
new file mode 100644
index 00000000000..97266cd326d
--- /dev/null
+++ b/builtin/branch-diff.c
@@ -0,0 +1,40 @@
+#include "cache.h"
+#include "parse-options.h"
+
+static const char * const builtin_branch_diff_usage[] = {
+	N_("git rebase--helper [<options>] ( A..B C..D | A...B | base A B )"),
+	NULL
+};
+
+#define COLOR_DUAL_MODE 2
+
+static int parse_creation_weight(const struct option *opt, const char *arg,
+				 int unset)
+{
+	double *d = opt->value;
+	if (unset)
+		*d = 0.6;
+	else
+		*d = atof(arg);
+	return 0;
+}
+
+int cmd_branch_diff(int argc, const char **argv, const char *prefix)
+{
+	int no_patches = 0;
+	double creation_weight = 0.6;
+	struct option options[] = {
+		OPT_BOOL(0, "no-patches", &no_patches,
+			 N_("short format (no diffs)")),
+		{ OPTION_CALLBACK,
+			0, "creation-weight", &creation_weight, N_("factor"),
+			N_("Fudge factor by which creation is weighted [0.6]"),
+			0, parse_creation_weight },
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, NULL, options,
+			builtin_branch_diff_usage, 0);
+
+	return 0;
+}
diff --git a/command-list.txt b/command-list.txt
index a1fad28fd82..c89ac8f417f 100644
--- a/command-list.txt
+++ b/command-list.txt
@@ -19,6 +19,7 @@ git-archive                             mainporcelain
 git-bisect                              mainporcelain           info
 git-blame                               ancillaryinterrogators
 git-branch                              mainporcelain           history
+git-branch-diff                         mainporcelain           info
 git-bundle                              mainporcelain
 git-cat-file                            plumbinginterrogators
 git-check-attr                          purehelpers
diff --git a/git.c b/git.c
index f598fae7b7a..d2794fb6f5d 100644
--- a/git.c
+++ b/git.c
@@ -377,6 +377,7 @@ static struct cmd_struct commands[] = {
 	{ "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 	{ "blame", cmd_blame, RUN_SETUP },
 	{ "branch", cmd_branch, RUN_SETUP | DELAY_PAGER_CONFIG },
+	{ "branch-diff", cmd_branch_diff, RUN_SETUP | USE_PAGER },
 	{ "bundle", cmd_bundle, RUN_SETUP_GENTLY | NO_PARSEOPT },
 	{ "cat-file", cmd_cat_file, RUN_SETUP },
 	{ "check-attr", cmd_check_attr, RUN_SETUP },
-- 
2.17.0.395.g6a618d6010f.dirty