diff: round down similarity index

Rounding down the printed (dis)similarity index allows us to use
"100%" as a special value that indicates complete rewrites and
fully equal file contents, respectively.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/diff-format.txt b/Documentation/diff-format.txt
index 18d49d2c3baa81983b19a938598eb091fb7809ef..001503205b24d5c20ec10792c4ab6c4c7221bcb7 100644 (file)
--- a/Documentation/diff-format.txt
+++ b/Documentation/diff-format.txt
@@ -126,6 +126,13 @@ the file that rename/copy produces, respectively.
     If there is need for such substitution then the whole
     pathname is put in double quotes.
 
+The similarity index is the percentage of unchanged lines, and
+the dissimilarity index is the percentage of changed lines.  It
+is a rounded down integer, followed by a percent sign.  The
+similarity index value of 100% is thus reserved for two equal
+files, while 100% dissimilarity means that no line from the old
+file made it into the new one.
+
 
 combined diff format
 --------------------

diff --git a/diff.c b/diff.c
index 9938969fa50e8af2a4eabe96ae122111ae42fe75..e0edb98846753f39cab9e377c9ac4af2d7fdbf35 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -1813,6 +1813,11 @@ static void diff_fill_sha1_info(struct diff_filespec *one)
                hashclr(one->sha1);
 }
 
+static int similarity_index(struct diff_filepair *p)
+{
+       return p->score * 100 / MAX_SCORE;
+}
+
 static void run_diff(struct diff_filepair *p, struct diff_options *o)
 {
        const char *pgm = external_diff();
@@ -1847,23 +1852,20 @@ static void run_diff(struct diff_filepair *p, struct diff_options *o)
                                "similarity index %d%%\n"
                                "copy from %s\n"
                                "copy to %s\n",
-                               (int)(0.5 + p->score * 100.0/MAX_SCORE),
-                               name_munged, other_munged);
+                               similarity_index(p), name_munged, other_munged);
                break;
        case DIFF_STATUS_RENAMED:
                len += snprintf(msg + len, sizeof(msg) - len,
                                "similarity index %d%%\n"
                                "rename from %s\n"
                                "rename to %s\n",
-                               (int)(0.5 + p->score * 100.0/MAX_SCORE),
-                               name_munged, other_munged);
+                               similarity_index(p), name_munged, other_munged);
                break;
        case DIFF_STATUS_MODIFIED:
                if (p->score) {
                        len += snprintf(msg + len, sizeof(msg) - len,
                                        "dissimilarity index %d%%\n",
-                                       (int)(0.5 + p->score *
-                                             100.0/MAX_SCORE));
+                                       similarity_index(p));
                        complete_rewrite = 1;
                        break;
                }
@@ -2387,8 +2389,7 @@ static void diff_flush_raw(struct diff_filepair *p,
        }
 
        if (p->score)
-               sprintf(status, "%c%03d", p->status,
-                       (int)(0.5 + p->score * 100.0/MAX_SCORE));
+               sprintf(status, "%c%03d", p->status, similarity_index(p));
        else {
                status[0] = p->status;
                status[1] = 0;
@@ -2670,8 +2671,7 @@ static void show_rename_copy(const char *renamecopy, struct diff_filepair *p)
 {
        char *names = pprint_rename(p->one->path, p->two->path);
 
-       printf(" %s %s (%d%%)\n", renamecopy, names,
-              (int)(0.5 + p->score * 100.0/MAX_SCORE));
+       printf(" %s %s (%d%%)\n", renamecopy, names, similarity_index(p));
        free(names);
        show_mode_change(p, 0);
 }
@@ -2695,7 +2695,7 @@ static void diff_summary(struct diff_filepair *p)
                if (p->score) {
                        char *name = quote_one(p->two->path);
                        printf(" rewrite %s (%d%%)\n", name,
-                               (int)(0.5 + p->score * 100.0/MAX_SCORE));
+                              similarity_index(p));
                        free(name);
                        show_mode_change(p, 0);
                } else  show_mode_change(p, 1);