parse-options.c: introduce OPT_DATE

There are quite a few places that will need to call approxidate(),
when they'll adopt the parse-options system, so this patch adds the
function parse_opt_approxidate_cb(), used by OPT_DATE.

Signed-off-by: Michele Ballabio <barra_cuda@katamail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options.c

@@ -409,3 +409,10 @@ int parse_opt_abbrev_cb(const struct option *opt, const char *arg, int unset)
 	*(int *)(opt->value) = v;
 	return 0;
 }
+
+int parse_opt_approxidate_cb(const struct option *opt, const char *arg,
+			     int unset)
+{
+	*(unsigned long *)(opt->value) = approxidate(arg);
+	return 0;
+}

parse-options.h

@@ -94,6 +94,9 @@ struct option {
 #define OPT_SET_PTR(s, l, v, h, p)  { OPTION_SET_PTR, (s), (l), (v), NULL, (h), 0, NULL, (p) }
 #define OPT_INTEGER(s, l, v, h)     { OPTION_INTEGER, (s), (l), (v), NULL, (h) }
 #define OPT_STRING(s, l, v, a, h)   { OPTION_STRING,  (s), (l), (v), (a), (h) }
+#define OPT_DATE(s, l, v, h) \
+	{ OPTION_CALLBACK, (s), (l), (v), "time",(h), 0, \
+	  parse_opt_approxidate_cb }
 #define OPT_CALLBACK(s, l, v, a, h, f) \
 	{ OPTION_CALLBACK, (s), (l), (v), (a), (h), 0, (f) }
 
@@ -110,6 +113,7 @@ extern NORETURN void usage_with_options(const char * const *usagestr,
 
 /*----- some often used options -----*/
 extern int parse_opt_abbrev_cb(const struct option *, const char *, int);
+extern int parse_opt_approxidate_cb(const struct option *, const char *, int);
 
 #define OPT__VERBOSE(var)  OPT_BOOLEAN('v', "verbose", (var), "be verbose")
 #define OPT__QUIET(var)    OPT_BOOLEAN('q', "quiet",   (var), "be quiet")