[PATCH 2/9] diff-merges: refactor set_diff_merges()

[Sergey Organov <sorganov@xxxxxxxxx>]

Split set_diff_merges() into separate parsing and execution functions,
the former to be reused later in the series for parsing of
configuration values.

Signed-off-by: Sergey Organov <sorganov@xxxxxxxxx>
---
 diff-merges.c | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/diff-merges.c b/diff-merges.c
index 0887a07cfc67..93ede09fb36f 100644
--- a/diff-merges.c
+++ b/diff-merges.c
@@ -3,6 +3,9 @@
 #include "revision.h"
 
 typedef void (*diff_merges_setup_func_t)(struct rev_info *);
+static void set_separate(struct rev_info *revs);
+
+static diff_merges_setup_func_t set_to_default = set_separate;
 
 static void suppress(struct rev_info *revs)
 {
@@ -21,8 +24,6 @@ static void set_separate(struct rev_info *revs)
 	revs->separate_merges = 1;
 }
 
-static diff_merges_setup_func_t set_to_default = set_separate;
-
 static void set_first_parent(struct rev_info *revs)
 {
 	set_separate(revs);
@@ -54,29 +55,35 @@ static void set_dense_combined(struct rev_info *revs)
 	revs->dense_combined_merges = 1;
 }
 
-static void set_diff_merges(struct rev_info *revs, const char *optarg)
+static diff_merges_setup_func_t func_by_opt(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, "off") || !strcmp(optarg, "none"))
+		return suppress;
 	if (!strcmp(optarg, "1") || !strcmp(optarg, "first-parent"))
-		set_first_parent(revs);
+		return set_first_parent;
 	else if (!strcmp(optarg, "m") || !strcmp(optarg, "separate"))
-		set_separate(revs);
+		return set_separate;
 	else if (!strcmp(optarg, "c") || !strcmp(optarg, "combined"))
-		set_combined(revs);
+		return set_combined;
 	else if (!strcmp(optarg, "cc") || !strcmp(optarg, "dense-combined"))
-		set_dense_combined(revs);
+		return set_dense_combined;
 	else if (!strcmp(optarg, "def"))
-		set_to_default(revs);
-	else
+		return set_to_default;
+	return NULL;
+}
+
+static void set_diff_merges(struct rev_info *revs, const char *optarg)
+{
+	diff_merges_setup_func_t func = func_by_opt(optarg);
+
+	if (!func)
 		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;
+	func(revs);
+
+	/* NOTE: the merges_need_diff flag is cleared by func() call */
+	if (func != suppress)
+		revs->merges_need_diff = 1;
 }
 
 /*
-- 
2.25.1