1 files changed, 102 insertions, 0 deletions
diff --git a/examples/rev-parse.c b/examples/rev-parse.c
new file mode 100644
index 0000000..3f68d79
--- /dev/null
+++ b/examples/rev-parse.c
@@ -0,0 +1,102 @@
+/*
+ * libgit2 "rev-parse" example - shows how to parse revspecs
+ *
+ * Written by the libgit2 contributors
+ *
+ * To the extent possible under law, the author(s) have dedicated all copyright
+ * and related and neighboring rights to this software to the public domain
+ * worldwide. This software is distributed without any warranty.
+ *
+ * You should have received a copy of the CC0 Public Domain Dedication along
+ * with this software. If not, see
+ * <http://creativecommons.org/publicdomain/zero/1.0/>.
+ */
+
+#include "common.h"
+
+/** Forward declarations for helpers. */
+struct parse_state {
+	const char *repodir;
+	const char *spec;
+	int not;
+};
+static void parse_opts(struct parse_state *ps, int argc, char *argv[]);
+static int parse_revision(git_repository *repo, struct parse_state *ps);
+
+int lg2_rev_parse(git_repository *repo, int argc, char *argv[])
+{
+	struct parse_state ps = {0};
+
+	parse_opts(&ps, argc, argv);
+
+	check_lg2(parse_revision(repo, &ps), "Parsing", NULL);
+
+	return 0;
+}
+
+static void usage(const char *message, const char *arg)
+{
+	if (message && arg)
+		fprintf(stderr, "%s: %s\n", message, arg);
+	else if (message)
+		fprintf(stderr, "%s\n", message);
+	fprintf(stderr, "usage: rev-parse [ --option ] <args>...\n");
+	exit(1);
+}
+
+static void parse_opts(struct parse_state *ps, int argc, char *argv[])
+{
+	struct args_info args = ARGS_INFO_INIT;
+
+	for (args.pos=1; args.pos < argc; ++args.pos) {
+		const char *a = argv[args.pos];
+
+		if (a[0] != '-') {
+			if (ps->spec)
+				usage("Too many specs", a);
+			ps->spec = a;
+		} else if (!strcmp(a, "--not"))
+			ps->not = !ps->not;
+		else if (!match_str_arg(&ps->repodir, &args, "--git-dir"))
+			usage("Cannot handle argument", a);
+	}
+}
+
+static int parse_revision(git_repository *repo, struct parse_state *ps)
+{
+	git_revspec rs;
+	char str[GIT_OID_SHA1_HEXSIZE + 1];
+
+	check_lg2(git_revparse(&rs, repo, ps->spec), "Could not parse", ps->spec);
+
+	if ((rs.flags & GIT_REVSPEC_SINGLE) != 0) {
+		git_oid_tostr(str, sizeof(str), git_object_id(rs.from));
+		printf("%s\n", str);
+		git_object_free(rs.from);
+	}
+	else if ((rs.flags & GIT_REVSPEC_RANGE) != 0) {
+		git_oid_tostr(str, sizeof(str), git_object_id(rs.to));
+		printf("%s\n", str);
+		git_object_free(rs.to);
+
+		if ((rs.flags & GIT_REVSPEC_MERGE_BASE) != 0) {
+			git_oid base;
+			check_lg2(git_merge_base(&base, repo,
+						git_object_id(rs.from), git_object_id(rs.to)),
+					"Could not find merge base", ps->spec);
+
+			git_oid_tostr(str, sizeof(str), &base);
+			printf("%s\n", str);
+		}
+
+		git_oid_tostr(str, sizeof(str), git_object_id(rs.from));
+		printf("^%s\n", str);
+		git_object_free(rs.from);
+	}
+	else {
+		fatal("Invalid results from git_revparse", ps->spec);
+	}
+
+	return 0;
+}
+