parseopt: add OPT_NUMBER_CALLBACK

Add a way to recognize numerical options.  The number is passed to
a callback function as a string.

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

Documentation/technical/api-parse-options.txt

@@ -170,6 +170,14 @@ There are some macros to easily define options:
 `OPT_ARGUMENT(long, description)`::
 	Introduce a long-option argument that will be kept in `argv[]`.
 
+`OPT_NUMBER_CALLBACK(&var, description, func_ptr)`::
+	Recognize numerical options like -123 and feed the integer as
+	if it was an argument to the function given by `func_ptr`.
+	The result will be put into `var`.  There can be only one such
+	option definition.  It cannot be negated and it takes no
+	arguments.  Short options that happen to be digits take
+	precedence over it.
+
 
 The last element of the array must be `OPT_END()`.
 

parse-options.c

@@ -129,11 +129,33 @@ static int get_value(struct parse_opt_ctx_t *p,
 
 static int parse_short_opt(struct parse_opt_ctx_t *p, const struct option *options)
 {
+	const struct option *numopt = NULL;
+
 	for (; options->type != OPTION_END; options++) {
 		if (options->short_name == *p->opt) {
 			p->opt = p->opt[1] ? p->opt + 1 : NULL;
 			return get_value(p, options, OPT_SHORT);
 		}
+
+		/*
+		 * Handle the numerical option later, explicit one-digit
+		 * options take precedence over it.
+		 */
+		if (options->type == OPTION_NUMBER)
+			numopt = options;
+	}
+	if (numopt && isdigit(*p->opt)) {
+		size_t len = 1;
+		char *arg;
+		int rc;
+
+		while (isdigit(p->opt[len]))
+			len++;
+		arg = xmemdupz(p->opt, len);
+		p->opt = p->opt[len] ? p->opt + len : NULL;
+		rc = (*numopt->callback)(numopt, arg, 0) ? (-1) : 0;
+		free(arg);
+		return rc;
 	}
 	return -2;
 }
@@ -411,6 +433,8 @@ int usage_with_options_internal(const char * const *usagestr,
 			pos += fprintf(stderr, ", ");
 		if (opts->long_name)
 			pos += fprintf(stderr, "--%s", opts->long_name);
+		if (opts->type == OPTION_NUMBER)
+			pos += fprintf(stderr, "-NUM");
 
 		switch (opts->type) {
 		case OPTION_ARGUMENT:
@@ -447,7 +471,7 @@ int usage_with_options_internal(const char * const *usagestr,
 					pos += fprintf(stderr, " ...");
 			}
 			break;
-		default: /* OPTION_{BIT,BOOLEAN,SET_INT,SET_PTR} */
+		default: /* OPTION_{BIT,BOOLEAN,NUMBER,SET_INT,SET_PTR} */
 			break;
 		}
 

parse-options.h

@@ -6,6 +6,7 @@ enum parse_opt_type {
 	OPTION_END,
 	OPTION_ARGUMENT,
 	OPTION_GROUP,
+	OPTION_NUMBER,
 	/* options with no arguments */
 	OPTION_BIT,
 	OPTION_NEGBIT,
@@ -105,6 +106,9 @@ struct option {
 	  parse_opt_approxidate_cb }
 #define OPT_CALLBACK(s, l, v, a, h, f) \
 	{ OPTION_CALLBACK, (s), (l), (v), (a), (h), 0, (f) }
+#define OPT_NUMBER_CALLBACK(v, h, f) \
+	{ OPTION_NUMBER, 0, NULL, (v), NULL, (h), \
+	  PARSE_OPT_NOARG | PARSE_OPT_NONEG, (f) }
 
 /* parse_options() will filter out the processed options and leave the
  * non-option arguments in argv[].

t/t0040-parse-options.sh

@@ -30,6 +30,7 @@ String options
 
 Magic arguments
     --quux                means --quux
+    -NUM                  set integer to NUM
 
 Standard options
     --abbrev[=<n>]        use <n> digits to display SHA-1s
@@ -275,4 +276,21 @@ test_expect_success 'OPT_NEGBIT() works' '
 	test_cmp expect output
 '
 
+cat > expect <<EOF
+boolean: 0
+integer: 12345
+timestamp: 0
+string: (not set)
+abbrev: 7
+verbose: 0
+quiet: no
+dry run: no
+EOF
+
+test_expect_success 'OPT_NUMBER_CALLBACK() works' '
+	test-parse-options -12345 > output 2> output.err &&
+	test ! -s output.err &&
+	test_cmp expect output
+'
+
 test_done

test-parse-options.c

@@ -19,6 +19,12 @@ int length_callback(const struct option *opt, const char *arg, int unset)
 	return 0;
 }
 
+int number_callback(const struct option *opt, const char *arg, int unset)
+{
+	*(int *)opt->value = strtol(arg, NULL, 10);
+	return 0;
+}
+
 int main(int argc, const char **argv)
 {
 	const char *usage[] = {
@@ -46,6 +52,8 @@ int main(int argc, const char **argv)
 			"set string to default", (unsigned long)"default"),
 		OPT_GROUP("Magic arguments"),
 		OPT_ARGUMENT("quux", "means --quux"),
+		OPT_NUMBER_CALLBACK(&integer, "set integer to NUM",
+			number_callback),
 		OPT_GROUP("Standard options"),
 		OPT__ABBREV(&abbrev),
 		OPT__VERBOSE(&verbose),