[PATCH 2/3] parseopt: introduce OPT_RECURSE to specify shared options

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

The diff options should not need to be defined in every user of the
diffcore.  This provides the framework:

	extern struct option *diff_options;

	struct option options[] = {
		OPT_RECURSE(diff_options),
		...
		OPT_END(),
	};

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 parse-options.c          |   68 +++++++++++++++++++++++++++++++++++-----------
 parse-options.h          |    2 +
 t/t0040-parse-options.sh |   26 +++++++++++++++++
 test-parse-options.c     |   10 +++++++
 4 files changed, 90 insertions(+), 16 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 15b32f7..ed8e951 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -4,6 +4,8 @@
 #define OPT_SHORT 1
 #define OPT_UNSET 2
 
+#define OPT_NOT_FOUND -2
+
 struct optparse_t {
 	const char **argv;
 	int argc;
@@ -111,8 +113,14 @@ static int parse_short_opt(struct optparse_t *p, const struct option *options)
 			p->opt = p->opt[1] ? p->opt + 1 : NULL;
 			return get_value(p, options, OPT_SHORT);
 		}
+		if (options->type == OPTION_RECURSE) {
+			const struct option *sub = options->value;
+			int result = parse_short_opt(p, sub);
+			if (result != OPT_NOT_FOUND)
+				return result;
+		}
 	}
-	return error("unknown switch `%c'", *p->opt);
+	return OPT_NOT_FOUND;
 }
 
 static int parse_long_opt(struct optparse_t *p, const char *arg,
@@ -129,6 +137,13 @@ static int parse_long_opt(struct optparse_t *p, const char *arg,
 		const char *rest;
 		int flags = 0;
 
+		if (options->type == OPTION_RECURSE) {
+			const struct option *sub = options->value;
+			int result = parse_long_opt(p, arg, sub);
+			if (result != OPT_NOT_FOUND)
+				return result;
+		}
+
 		if (!options->long_name)
 			continue;
 
@@ -187,14 +202,14 @@ is_abbreviated:
 			abbrev_option->long_name);
 	if (abbrev_option)
 		return get_value(p, abbrev_option, abbrev_flags);
-	return error("unknown option `%s'", arg);
+	return OPT_NOT_FOUND;
 }
 
 int parse_options(int argc, const char **argv, const struct option *options,
                   const char * const usagestr[], int flags)
 {
 	struct optparse_t args = { argv + 1, argc - 1, NULL };
-	int j = 0;
+	int j = 0, result;
 
 	for (; args.argc; args.argc--, args.argv++) {
 		const char *arg = args.argv[0];
@@ -209,8 +224,13 @@ int parse_options(int argc, const char **argv, const struct option *options,
 			do {
 				if (*args.opt == 'h')
 					usage_with_options(usagestr, options);
-				if (parse_short_opt(&args, options) < 0)
+				result = parse_short_opt(&args, options);
+				if (result < 0) {
+					if (result == OPT_NOT_FOUND)
+						error("unknown switch `%c'",
+								arg[1]);
 					usage_with_options(usagestr, options);
+				}
 			} while (args.opt);
 			continue;
 		}
@@ -225,8 +245,12 @@ int parse_options(int argc, const char **argv, const struct option *options,
 
 		if (!strcmp(arg + 2, "help"))
 			usage_with_options(usagestr, options);
-		if (parse_long_opt(&args, arg + 2, options))
+		result = parse_long_opt(&args, arg + 2, options);
+		if (result) {
+			if (result == OPT_NOT_FOUND)
+				error("unknown option `%s'", arg + 2);
 			usage_with_options(usagestr, options);
+		}
 	}
 
 	memmove(argv + j, args.argv, args.argc * sizeof(*argv));
@@ -237,22 +261,18 @@ int parse_options(int argc, const char **argv, const struct option *options,
 #define USAGE_OPTS_WIDTH 24
 #define USAGE_GAP         2
 
-void usage_with_options(const char * const *usagestr,
-                        const struct option *opts)
+static void usage_show_options(const struct option *opts)
 {
-	fprintf(stderr, "usage: %s\n", *usagestr++);
-	while (*usagestr && **usagestr)
-		fprintf(stderr, "   or: %s\n", *usagestr++);
-	while (*usagestr)
-		fprintf(stderr, "    %s\n", *usagestr++);
-
-	if (opts->type != OPTION_GROUP)
-		fputc('\n', stderr);
-
 	for (; opts->type != OPTION_END; opts++) {
 		size_t pos;
 		int pad;
 
+		if (opts->type == OPTION_RECURSE) {
+			const struct option *sub = opts->value;
+			usage_show_options(sub);
+			continue;
+		}
+
 		if (opts->type == OPTION_GROUP) {
 			fputc('\n', stderr);
 			if (*opts->help)
@@ -304,6 +324,22 @@ void usage_with_options(const char * const *usagestr,
 		}
 		fprintf(stderr, "%*s%s\n", pad + USAGE_GAP, "", opts->help);
 	}
+}
+
+void usage_with_options(const char * const *usagestr,
+                        const struct option *opts)
+{
+	fprintf(stderr, "usage: %s\n", *usagestr++);
+	while (*usagestr && **usagestr)
+		fprintf(stderr, "   or: %s\n", *usagestr++);
+	while (*usagestr)
+		fprintf(stderr, "    %s\n", *usagestr++);
+
+	if (opts->type != OPTION_GROUP)
+		fputc('\n', stderr);
+
+	usage_show_options(opts);
+
 	fputc('\n', stderr);
 
 	exit(129);
diff --git a/parse-options.h b/parse-options.h
index 3a470e5..9ec1e35 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -8,6 +8,7 @@ enum parse_opt_type {
 	OPTION_STRING,
 	OPTION_INTEGER,
 	OPTION_CALLBACK,
+	OPTION_RECURSE,
 };
 
 enum parse_opt_flags {
@@ -44,6 +45,7 @@ struct option {
 #define OPT_STRING(s, l, v, a, h)   { OPTION_STRING,  (s), (l), (v), (a), (h) }
 #define OPT_CALLBACK(s, l, v, a, h, f) \
 	{ OPTION_CALLBACK, (s), (l), (v), (a), (h), 0, (f) }
+#define OPT_RECURSE(options)        { OPTION_RECURSE, 0, NULL, options }
 
 /* parse_options() will filter out the processed options and leave the
  * non-option argments in argv[].
diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index 462fdf2..9c3efaa 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh
@@ -13,6 +13,8 @@ usage: test-parse-options <options>
     -b, --boolean         get a boolean
     -i, --integer <n>     get a integer
     -j <n>                get a integer, too
+    -n, --narf            what are we doing tonight?
+    -z, --zort <n>        try to take over the world
 
 string options
     -s, --string <string>
@@ -29,6 +31,8 @@ test_expect_success 'test help' '
 '
 
 cat > expect << EOF
+narf: 0
+zort: 1
 boolean: 2
 integer: 1729
 string: 123
@@ -40,6 +44,8 @@ test_expect_success 'short options' '
 	test ! -s output.err
 '
 cat > expect << EOF
+narf: 0
+zort: 1
 boolean: 2
 integer: 1729
 string: 321
@@ -53,6 +59,8 @@ test_expect_success 'long options' '
 '
 
 cat > expect << EOF
+narf: 0
+zort: 1
 boolean: 1
 integer: 13
 string: 123
@@ -69,6 +77,8 @@ test_expect_success 'intermingled arguments' '
 '
 
 cat > expect << EOF
+narf: 0
+zort: 1
 boolean: 0
 integer: 2
 string: (not set)
@@ -92,6 +102,22 @@ test_expect_failure 'ambiguously abbreviated option' '
 '
 
 cat > expect << EOF
+narf: 1
+zort: 5
+boolean: 0
+integer: 3
+string: (not set)
+EOF
+
+test_expect_success 'recurse works' '
+	test-parse-options --narf -z5 --int=3 > output 2> output.err &&
+	test ! -s output.err &&
+	git diff expect output
+'
+
+cat > expect << EOF
+narf: 0
+zort: 1
 boolean: 0
 integer: 0
 string: 123
diff --git a/test-parse-options.c b/test-parse-options.c
index 4d3e2ec..ee64fb3 100644
--- a/test-parse-options.c
+++ b/test-parse-options.c
@@ -1,6 +1,8 @@
 #include "cache.h"
 #include "parse-options.h"
 
+static int narf = 0;
+static int zort = 1;
 static int boolean = 0;
 static int integer = 0;
 static char *string = NULL;
@@ -11,10 +13,16 @@ int main(int argc, const char **argv)
 		"test-parse-options <options>",
 		NULL
 	};
+	struct option sub[] = {
+		OPT_BOOLEAN('n', "narf", &narf, "what are we doing tonight?"),
+		OPT_INTEGER('z', "zort", &zort, "try to take over the world"),
+		OPT_END(),
+	};
 	struct option options[] = {
 		OPT_BOOLEAN('b', "boolean", &boolean, "get a boolean"),
 		OPT_INTEGER('i', "integer", &integer, "get a integer"),
 		OPT_INTEGER('j', NULL, &integer, "get a integer, too"),
+		OPT_RECURSE(sub),
 		OPT_GROUP("string options"),
 		OPT_STRING('s', "string", &string, "string", "get a string"),
 		OPT_STRING(0, "string2", &string, "str", "get another string"),
@@ -25,6 +33,8 @@ int main(int argc, const char **argv)
 
 	argc = parse_options(argc, argv, options, usage, 0);
 
+	printf("narf: %d\n", narf);
+	printf("zort: %d\n", zort);
 	printf("boolean: %d\n", boolean);
 	printf("integer: %d\n", integer);
 	printf("string: %s\n", string ? string : "(not set)");
-- 
1.5.3.5.1549.g91a3