revparse: Parse range-like syntax

Signed-off-by: Greg Price <price@mit.edu>

include/git2/revparse.h

@@ -32,6 +32,19 @@ GIT_BEGIN_DECL
  */
 GIT_EXTERN(int) git_revparse_single(git_object **out, git_repository *repo, const char *spec);
 
+/**
+ * Parse a string with the form of a revision range, as accepted by
+ * `git rev-list`, `git diff`, and others.
+ *
+ * @param left (output) the left-hand commit
+ * @param right (output) the right-hand commit
+ * @param threedots (output) 0 if the endpoints are separated by two dots, 1 if by three
+ * @param repo the repository to find the commits in
+ * @param rangelike the rangelike string to be parsed
+ * @return 0 on success, or any error `git_revparse_single` can return
+ */
+GIT_EXTERN(int) git_revparse_rangelike(git_object **left, git_object **right, int *threedots, git_repository *repo, const char *rangelike);
+
 /** @} */
 GIT_END_DECL
 #endif

src/revparse.c

@@ -866,3 +866,28 @@ cleanup:
 	git_buf_free(&buf);
 	return error;
 }
+
+int git_revparse_rangelike(git_object **left, git_object **right, int *threedots, git_repository *repo, const char *rangelike)
+{
+	int error = 0;
+	const char *p, *q;
+	char *revspec;
+
+	p = strstr(rangelike, "..");
+	if (!p) {
+		giterr_set(GITERR_INVALID, "Malformed range (or rangelike syntax): %s", rangelike);
+		return GIT_EINVALIDSPEC;
+	} else if (p[2] == '.') {
+		*threedots = 1;
+		q = p + 3;
+	} else {
+		*threedots = 0;
+		q = p + 2;
+	}
+
+	revspec = git__substrdup(rangelike, p - rangelike);
+	error = (git_revparse_single(left, repo, revspec)
+	      || git_revparse_single(right, repo, q));
+	git__free(revspec);
+	return error;
+}

tests-clar/refs/revparse.c

@@ -32,6 +32,33 @@ static void test_object(const char *spec, const char *expected_oid)
 	test_object_inrepo(spec, expected_oid, g_repo);
 }
 
+static void test_rangelike(const char *rangelike,
+						   const char *expected_left,
+						   const char *expected_right,
+						   int expected_threedots)
+{
+	char objstr[64] = {0};
+	git_object *left, *right;
+	int threedots;
+	int error;
+
+	error = git_revparse_rangelike(&left, &right, &threedots, g_repo, rangelike);
+
+	if (expected_left != NULL) {
+		cl_assert_equal_i(0, error);
+		cl_assert_equal_i(threedots, expected_threedots);
+		git_oid_fmt(objstr, git_object_id(left));
+		cl_assert_equal_s(objstr, expected_left);
+		git_oid_fmt(objstr, git_object_id(right));
+		cl_assert_equal_s(objstr, expected_right);
+	} else
+		cl_assert(error != 0);
+
+	git_object_free(left);
+	git_object_free(right);
+}
+
+
 void test_refs_revparse__initialize(void)
 {
 	cl_git_pass(git_repository_open(&g_repo, cl_fixture("testrepo.git")));
@@ -595,3 +622,19 @@ void test_refs_revparse__try_to_retrieve_branch_before_abbrev_sha(void)
 	git_object_free(target);
 	cl_git_sandbox_cleanup();
 }
+
+
+void test_refs_revparse__range(void)
+{
+	test_rangelike("be3563a^1..be3563a",
+	               "9fd738e8f7967c078dceed8190330fc8648ee56a",
+	               "be3563ae3f795b2b4353bcce3a527ad0a4f7f644",
+	               0);
+
+	test_rangelike("be3563a^1...be3563a",
+	               "9fd738e8f7967c078dceed8190330fc8648ee56a",
+	               "be3563ae3f795b2b4353bcce3a527ad0a4f7f644",
+	               1);
+
+	test_rangelike("be3563a^1.be3563a", NULL, NULL, 0);
+}