[PATCH] diff: optimise parse_dirstat_params() to only compare strings when necessary

[Dragos Foianu]

parse_dirstat_params() goes through a chain of if statements using
strcmp to parse parameters. When the parameter is a digit, the
value must go through all comparisons before the function realises
it is a digit. Optimise this logic by only going through the chain
of string compares when the parameter is not a digit.

Signed-off-by: Dragos Foianu <dragos.foi...@gmail.com>
---
 diff.c | 37 +++++++++++++++++++------------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/diff.c b/diff.c
index e343191..733764e 100644
--- a/diff.c
+++ b/diff.c
@@ -84,20 +84,25 @@ static int parse_dirstat_params(struct diff_options 
*options, const char *params
                string_list_split_in_place(&params, params_copy, ',', -1);
        for (i = 0; i < params.nr; i++) {
                const char *p = params.items[i].string;
-               if (!strcmp(p, "changes")) {
-                       DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
-                       DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
-               } else if (!strcmp(p, "lines")) {
-                       DIFF_OPT_SET(options, DIRSTAT_BY_LINE);
-                       DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
-               } else if (!strcmp(p, "files")) {
-                       DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
-                       DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
-               } else if (!strcmp(p, "noncumulative")) {
-                       DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
-               } else if (!strcmp(p, "cumulative")) {
-                       DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
-               } else if (isdigit(*p)) {
+               if (!isdigit(*p)) {
+                       if (!strcmp(p, "changes")) {
+                               DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
+                               DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
+                       } else if (!strcmp(p, "lines")) {
+                               DIFF_OPT_SET(options, DIRSTAT_BY_LINE);
+                               DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
+                       } else if (!strcmp(p, "files")) {
+                               DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
+                               DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
+                       } else if (!strcmp(p, "noncumulative")) {
+                               DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
+                       } else if (!strcmp(p, "cumulative")) {
+                               DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
+                       } else {
+                               strbuf_addf(errmsg, _("  Unknown dirstat 
parameter '%s'\n"), p);
+                               ret++;
+                       }
+               } else  {
                        char *end;
                        int permille = strtoul(p, &end, 10) * 10;
                        if (*end == '.' && isdigit(*++end)) {
@@ -114,11 +119,7 @@ static int parse_dirstat_params(struct diff_options 
*options, const char *params
                                            p);
                                ret++;
                        }
-               } else {
-                       strbuf_addf(errmsg, _("  Unknown dirstat parameter 
'%s'\n"), p);
-                       ret++;
                }
-
        }
        string_list_clear(&params, 0);
        free(params_copy);
-- 
1.8.3.2

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