grep: Put calls to fixmatch() and regmatch() into patmatch()

Both match_one_pattern() and look_ahead() use fixmatch() and regmatch()
in the same way. They really want to match a pattern againt a string,
but now they need to know if the pattern is fixed or regexp.

This change cleans this up by introducing patmatch() (from "pattern
match") and also simplifies inserting other ways of matching a string.

Signed-off-by: Michał Kiedrowicz <michal.kiedrowicz@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

grep.c

@@ -412,6 +412,19 @@ static int regmatch(const regex_t *preg, char *line, char *eol,
 	return regexec(preg, line, 1, match, eflags);
 }
 
+static int patmatch(struct grep_pat *p, char *line, char *eol,
+		    regmatch_t *match, int eflags)
+{
+	int hit;
+
+	if (p->fixed)
+		hit = !fixmatch(p, line, eol, match);
+	else
+		hit = !regmatch(&p->regexp, line, eol, match, eflags);
+
+	return hit;
+}
+
 static int strip_timestamp(char *bol, char **eol_p)
 {
 	char *eol = *eol_p;
@@ -461,10 +474,7 @@ static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 	}
 
  again:
-	if (p->fixed)
-		hit = !fixmatch(p, bol, eol, pmatch);
-	else
-		hit = !regmatch(&p->regexp, bol, eol, pmatch, eflags);
+	hit = patmatch(p, bol, eol, pmatch, eflags);
 
 	if (hit && p->word_regexp) {
 		if ((pmatch[0].rm_so < 0) ||
@@ -791,10 +801,7 @@ static int look_ahead(struct grep_opt *opt,
 		int hit;
 		regmatch_t m;
 
-		if (p->fixed)
-			hit = !fixmatch(p, bol, bol + *left_p, &m);
-		else
-			hit = !regmatch(&p->regexp, bol, bol + *left_p, &m, 0);
+		hit = patmatch(p, bol, bol + *left_p, &m, 0);
 		if (!hit || m.rm_so < 0 || m.rm_eo < 0)
 			continue;
 		if (earliest < 0 || m.rm_so < earliest)