versioncmp: factor out helper for suffix matching

As the number of identical steps to be done for both tagnames grows,
extract them into a helper function, with the additional benefit that
the conditionals near the end of swap_prereleases() will use more
meaningful variable names.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/versioncmp.c b/versioncmp.c
index ae0a919..4cb400f 100644 (file)
--- a/versioncmp.c
+++ b/versioncmp.c
@@ -24,6 +24,31 @@
 static const struct string_list *prereleases;
 static int initialized;
 
+struct suffix_match {
+       int conf_pos;
+       int start;
+       int len;
+};
+
+static void find_better_matching_suffix(const char *tagname, const char *suffix,
+                                       int suffix_len, int start, int conf_pos,
+                                       struct suffix_match *match)
+{
+       /*
+        * A better match either starts earlier or starts at the same offset
+        * but is longer.
+        */
+       int end = match->len < suffix_len ? match->start : match->start-1;
+       int i;
+       for (i = start; i <= end; i++)
+               if (starts_with(tagname + i, suffix)) {
+                       match->conf_pos = conf_pos;
+                       match->start = i;
+                       match->len = suffix_len;
+                       break;
+               }
+}
+
 /*
  * off is the offset of the first different character in the two strings
  * s1 and s2. If either s1 or s2 contains a prerelease suffix containing
@@ -47,46 +72,35 @@ static int swap_prereleases(const char *s1,
                            int off,
                            int *diff)
 {
-       int i, i1 = -1, i2 = -1;
-       int start_at1 = off, start_at2 = off, match_len1 = -1, match_len2 = -1;
+       int i;
+       struct suffix_match match1 = { -1, off, -1 };
+       struct suffix_match match2 = { -1, off, -1 };
 
        for (i = 0; i < prereleases->nr; i++) {
                const char *suffix = prereleases->items[i].string;
-               int j, start, end, suffix_len = strlen(suffix);
+               int start, suffix_len = strlen(suffix);
                if (suffix_len < off)
                        start = off - suffix_len;
                else
                        start = 0;
-               end = match_len1 < suffix_len ? start_at1 : start_at1-1;
-               for (j = start; j <= end; j++)
-                       if (starts_with(s1 + j, suffix)) {
-                               i1 = i;
-                               start_at1 = j;
-                               match_len1 = suffix_len;
-                               break;
-                       }
-               end = match_len2 < suffix_len ? start_at2 : start_at2-1;
-               for (j = start; j <= end; j++)
-                       if (starts_with(s2 + j, suffix)) {
-                               i2 = i;
-                               start_at2 = j;
-                               match_len2 = suffix_len;
-                               break;
-                       }
+               find_better_matching_suffix(s1, suffix, suffix_len, start,
+                                           i, &match1);
+               find_better_matching_suffix(s2, suffix, suffix_len, start,
+                                           i, &match2);
        }
-       if (i1 == -1 && i2 == -1)
+       if (match1.conf_pos == -1 && match2.conf_pos == -1)
                return 0;
-       if (i1 == i2)
+       if (match1.conf_pos == match2.conf_pos)
                /* Found the same suffix in both, e.g. "-rc" in "v1.0-rcX"
                 * and "v1.0-rcY": the caller should decide based on "X"
                 * and "Y". */
                return 0;
 
-       if (i1 >= 0 && i2 >= 0)
-               *diff = i1 - i2;
-       else if (i1 >= 0)
+       if (match1.conf_pos >= 0 && match2.conf_pos >= 0)
+               *diff = match1.conf_pos - match2.conf_pos;
+       else if (match1.conf_pos >= 0)
                *diff = -1;
-       else /* if (i2 >= 0) */
+       else /* if (match2.conf_pos >= 0) */
                *diff = 1;
        return 1;
 }