[PATCH] parse-options: Allow abbreviated options when unambiguous

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

When there is an option "--amend", the option parser now recognizes
"--am" for that option, provided that there is no other option beginning
with "--am".

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---

	On Sun, 14 Oct 2007, Pierre Habouzit wrote:

	> On Sun, Oct 14, 2007 at 09:18:55AM +0000, Eric Wong wrote:
	> > 
	> > One feature I really like is automatically handling of long 
	> > option abbreviations.  gitopt supported this at the expense of 
	> > complexity and the aforementioned intrusivenes.  This allows 
	> > automatic handling of the abbreviation style seen commonly in 
	> > git shell scripts:
	> > 
	> >    --a|--am|--ame|--amen|--amend)  (from git-commit.sh)
	> 
	> Yes, but if you do that, you can't order options in the order 
	> you want (because of first match issues), making the help dumps 
	> hopelessly random.

I think this patch proves that you do not need to order the options...

;-)

 parse-options.c          |   32 ++++++++++++++++++++++++++++++++
 t/t0040-parse-options.sh |   22 ++++++++++++++++++++++
 2 files changed, 54 insertions(+), 0 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 72656a8..afc6c89 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -102,6 +102,13 @@ static int parse_short_opt(struct optparse_t *p, const struct option *options)
 static int parse_long_opt(struct optparse_t *p, const char *arg,
                           const struct option *options)
 {
+	const char *arg_end = strchr(arg, '=');
+	const struct option *abbrev_option = NULL;
+	int abbrev_flags = 0;
+
+	if (!arg_end)
+		arg_end = arg + strlen(arg);
+
 	for (; options->type != OPTION_END; options++) {
 		const char *rest;
 		int flags = 0;
@@ -111,10 +118,33 @@ static int parse_long_opt(struct optparse_t *p, const char *arg,
 
 		rest = skip_prefix(arg, options->long_name);
 		if (!rest) {
+			/* abbreviated? */
+			if (!strncmp(options->long_name, arg, arg_end - arg)) {
+is_abbreviated:
+				if (abbrev_option)
+					die ("Ambiguous option: %s "
+						"(could be --%s%s or --%s%s)",
+						arg,
+						(flags & OPT_UNSET) ?
+							"no-" : "",
+						options->long_name,
+						(abbrev_flags & OPT_UNSET) ?
+							"no-" : "",
+						abbrev_option->long_name);
+				if (!(flags & OPT_UNSET) && *arg_end)
+					p->opt = arg_end + 1;
+				abbrev_option = options;
+				abbrev_flags = flags;
+				continue;
+			}
+			/* negated? */
 			if (strncmp(arg, "no-", 3))
 				continue;
 			flags |= OPT_UNSET;
 			rest = skip_prefix(arg + 3, options->long_name);
+			/* abbreviated and negated? */
+			if (!rest && !prefixcmp(options->long_name, arg + 3))
+				goto is_abbreviated;
 			if (!rest)
 				continue;
 		}
@@ -125,6 +155,8 @@ static int parse_long_opt(struct optparse_t *p, const char *arg,
 		}
 		return get_value(p, options, flags);
 	}
+	if (abbrev_option)
+		return get_value(p, abbrev_option, abbrev_flags);
 	return error("unknown option `%s'", arg);
 }
 
diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index 09b3230..e4dd86f 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh
@@ -66,4 +66,26 @@ test_expect_success 'intermingled arguments' '
 	git diff expect output
 '
 
+cat > expect << EOF
+boolean: 0
+integer: 2
+string: (not set)
+EOF
+
+test_expect_success 'unambiguously abbreviated option' '
+	test-parse-options --int 2 --boolean --no-bo > output 2> output.err &&
+	test ! -s output.err &&
+	git diff expect output
+'
+
+test_expect_success 'unambiguously abbreviated option with "="' '
+	test-parse-options --int=2 > output 2> output.err &&
+	test ! -s output.err &&
+	git diff expect output
+'
+
+test_expect_failure 'ambiguously abbreviated option' '
+	test-parse-options --strin 123
+'
+
 test_done
-- 
1.5.3.4.1174.gcd0d6-dirty