utils: Improve option/result types

And add the beginnings of unit tests.

.gitignore

@@ -122,3 +122,4 @@ mu-*-coverage
 mu*tar.xz
 compile_commands.json
 /lib/utils/test-sexp
+/lib/utils/test-option

lib/utils/Makefile.am

@@ -116,6 +116,14 @@ test_command_parser_SOURCES=					\
 test_command_parser_LDADD=					\
 	libmu-utils.la
 
+TEST_PROGS+=							\
+	test-option
+test_option_SOURCES=						\
+	test-option.cc
+test_option_LDADD=						\
+	libmu-utils.la
+
+
 TESTS=$(TEST_PROGS)
 
 include $(top_srcdir)/aminclude_static.am

lib/utils/mu-option.hh

@@ -19,8 +19,11 @@
 
 namespace Mu {
 
-/// Either a value of type T, or nothing.
+/// Either a value of type T, or None
 template <typename T> using Option=tl::optional<T>;
 
+template <typename T> Option<T> Some(T&& t) { return t; }
+constexpr auto Nothing = tl::nullopt; // 'None' is take already
+
 }
 #endif /*MU_OPTION__*/

lib/utils/mu-result.hh

@@ -29,10 +29,19 @@
 namespace Mu {
 /**
  * A Result is _either_ some value of type T, _or_ an error.
- *
  */
 template <typename T> using Result = tl::expected<T, Error>;
 
+template <typename T> typename Result<T>::expected_type
+Ok(T&& t) {
+        return Result<T>::expected(std::move(t));
+}
+
+template <typename T> typename Result<T>::unexpected_type
+Err(Error&& err) {
+        return Result<T>::unexpected(std::move(err));
+}
+
 } // namespace Mu
 
 

lib/utils/test-option.cc

@@ -0,0 +1,59 @@
+/*
+** Copyright (C) 2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**
+**  This library is free software; you can redistribute it and/or
+**  modify it under the terms of the GNU Lesser General Public License
+**  as published by the Free Software Foundation; either version 2.1
+**  of the License, or (at your option) any later version.
+**
+**  This library is distributed in the hope that it will be useful,
+**  but WITHOUT ANY WARRANTY; without even the implied warranty of
+**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+**  Lesser General Public License for more details.
+**
+**  You should have received a copy of the GNU Lesser General Public
+**  License along with this library; if not, write to the Free
+**  Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+**  02110-1301, USA.
+*/
+
+#include "mu-utils.hh"
+#include "mu-option.hh"
+
+using namespace Mu;
+
+static Option<int>
+get_opt_int (bool b)
+{
+        if (b)
+                return Some(123);
+        else
+                return Nothing;
+}
+
+static void
+test_option()
+{
+        {
+                const auto oi{get_opt_int(true)};
+                g_assert_true(!!oi);
+                g_assert_cmpint(oi.value(),==,123);
+        }
+
+        {
+                const auto oi{get_opt_int(false)};
+                g_assert_false(!!oi);
+                g_assert_false(oi.has_value());
+                g_assert_cmpint(oi.value_or(456),==,456);
+        }
+}
+
+int
+main (int argc, char *argv[])
+{
+	g_test_init (&argc, &argv, NULL);
+
+	g_test_add_func ("/option/option",  test_option);
+
+	return g_test_run ();
+}