1 files changed, 146 insertions, 0 deletions
diff --git a/diff-merges.c b/diff-merges.c
new file mode 100644
index 0000000000..146bb50316
--- /dev/null
+++ b/diff-merges.c
@@ -0,0 +1,146 @@
+#include "diff-merges.h"
+
+#include "revision.h"
+
+static void suppress(struct rev_info *revs)
+{
+	revs->separate_merges = 0;
+	revs->first_parent_merges = 0;
+	revs->combine_merges = 0;
+	revs->dense_combined_merges = 0;
+	revs->combined_all_paths = 0;
+	revs->combined_imply_patch = 0;
+	revs->merges_need_diff = 0;
+}
+
+static void set_separate(struct rev_info *revs)
+{
+	suppress(revs);
+	revs->separate_merges = 1;
+}
+
+static void set_first_parent(struct rev_info *revs)
+{
+	set_separate(revs);
+	revs->first_parent_merges = 1;
+}
+
+static void set_m(struct rev_info *revs)
+{
+	/*
+	 * To "diff-index", "-m" means "match missing", and to the "log"
+	 * family of commands, it means "show full diff for merges". Set
+	 * both fields appropriately.
+	 */
+	set_separate(revs);
+	revs->match_missing = 1;
+}
+
+static void set_combined(struct rev_info *revs)
+{
+	suppress(revs);
+	revs->combine_merges = 1;
+	revs->dense_combined_merges = 0;
+}
+
+static void set_dense_combined(struct rev_info *revs)
+{
+	suppress(revs);
+	revs->combine_merges = 1;
+	revs->dense_combined_merges = 1;
+}
+
+static void set_diff_merges(struct rev_info *revs, const char *optarg)
+{
+	if (!strcmp(optarg, "off") || !strcmp(optarg, "none")) {
+		suppress(revs);
+		/* Return early to leave revs->merges_need_diff unset */
+		return;
+	}
+
+	if (!strcmp(optarg, "1") || !strcmp(optarg, "first-parent"))
+		set_first_parent(revs);
+	else if (!strcmp(optarg, "m") || !strcmp(optarg, "separate"))
+		set_separate(revs);
+	else if (!strcmp(optarg, "c") || !strcmp(optarg, "combined"))
+		set_combined(revs);
+	else if (!strcmp(optarg, "cc") || !strcmp(optarg, "dense-combined"))
+		set_dense_combined(revs);
+	else
+		die(_("unknown value for --diff-merges: %s"), optarg);
+
+	/* The flag is cleared by set_xxx() functions, so don't move this up */
+	revs->merges_need_diff = 1;
+}
+
+/*
+ * Public functions. They are in the order they are called.
+ */
+
+int diff_merges_parse_opts(struct rev_info *revs, const char **argv)
+{
+	int argcount = 1;
+	const char *optarg;
+	const char *arg = argv[0];
+
+	if (!strcmp(arg, "-m")) {
+		set_m(revs);
+	} else if (!strcmp(arg, "-c")) {
+		set_combined(revs);
+		revs->combined_imply_patch = 1;
+	} else if (!strcmp(arg, "--cc")) {
+		set_dense_combined(revs);
+		revs->combined_imply_patch = 1;
+	} else if (!strcmp(arg, "--no-diff-merges")) {
+		suppress(revs);
+	} else if (!strcmp(arg, "--combined-all-paths")) {
+		revs->combined_all_paths = 1;
+	} else if ((argcount = parse_long_opt("diff-merges", argv, &optarg))) {
+		set_diff_merges(revs, optarg);
+	} else
+		return 0;
+
+	revs->explicit_diff_merges = 1;
+	return argcount;
+}
+
+void diff_merges_suppress(struct rev_info *revs)
+{
+	suppress(revs);
+}
+
+void diff_merges_default_to_first_parent(struct rev_info *revs)
+{
+	if (!revs->explicit_diff_merges)
+		revs->separate_merges = 1;
+	if (revs->separate_merges)
+		revs->first_parent_merges = 1;
+}
+
+void diff_merges_default_to_dense_combined(struct rev_info *revs)
+{
+	if (!revs->explicit_diff_merges)
+		set_dense_combined(revs);
+}
+
+void diff_merges_set_dense_combined_if_unset(struct rev_info *revs)
+{
+	if (!revs->combine_merges)
+		set_dense_combined(revs);
+}
+
+void diff_merges_setup_revs(struct rev_info *revs)
+{
+	if (revs->combine_merges == 0)
+		revs->dense_combined_merges = 0;
+	if (revs->separate_merges == 0)
+		revs->first_parent_merges = 0;
+	if (revs->combined_all_paths && !revs->combine_merges)
+		die("--combined-all-paths makes no sense without -c or --cc");
+	if (revs->combined_imply_patch)
+		revs->diff = 1;
+	if (revs->combined_imply_patch || revs->merges_need_diff) {
+		if (!revs->diffopt.output_format)
+			revs->diffopt.output_format = DIFF_FORMAT_PATCH;
+	}
+}