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

[Dragos Foianu <dragos.foianu@gmail.com>]

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.foianu@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