utils: add Result / Option types

Add some Rust-style Result/Option types, based on TartanLlama's
expected, optional classes.

There's std::optional of course, but we can't depend on C++17 yet.

lib/utils/Makefile.am

@@ -45,17 +45,24 @@ AM_LDFLAGS=							\
 noinst_LTLIBRARIES=						\
 	libmu-utils.la
 
+
+third_party=							\
+	optional.hpp						\
+	expected.hpp
+
 libmu_utils_la_SOURCES=						\
 	mu-async-queue.hh					\
+	mu-command-parser.cc					\
+	mu-command-parser.hh					\
 	mu-date.c						\
 	mu-date.h						\
 	mu-error.hh						\
 	mu-logger.cc						\
 	mu-logger.hh						\
-	mu-command-parser.cc					\
-	mu-command-parser.hh					\
+	mu-option.hh						\
 	mu-readline.cc						\
 	mu-readline.hh						\
+	mu-result.hh						\
 	mu-sexp.cc						\
 	mu-sexp.hh						\
 	mu-str.c						\
@@ -63,7 +70,8 @@ libmu_utils_la_SOURCES=						\
 	mu-util.c						\
 	mu-util.h						\
 	mu-utils.cc						\
-	mu-utils.hh
+	mu-utils.hh						\
+	${third_party}
 
 libmu_utils_la_LIBADD=						\
 	$(GLIB_LIBS)						\

lib/utils/mu-error.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2019 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2019-2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -129,8 +129,6 @@ private:
         std::string  what_;
 };
 
-
 } // namespace Mu
 
-
 #endif /* MU_ERROR_HH__ */

lib/utils/mu-option.hh

@@ -0,0 +1,26 @@
+/*
+ * Created on 2020-11-08 by Dirk-Jan C. Binnema <dbinnema@logitech.com>
+ *
+ * Copyright (c) 2020 Logitech, Inc.  All Rights Reserved
+ * This program is a trade secret of LOGITECH, and it is not to be reproduced,
+ * published, disclosed to others, copied, adapted, distributed or displayed
+ * without the prior authorization of LOGITECH.
+ *
+ * Licensee agrees to attach or embed this notice on all copies of the program,
+ * including partial copies or modified versions thereof.
+ *
+ */
+
+#ifndef MU_OPTION__
+#define MU_OPTION__
+
+#include "optional.hpp"
+
+
+namespace Mu {
+
+/// Either a value of type T, or nothing.
+template <typename T> using Option=tl::optional<T>;
+
+}
+#endif /*MU_OPTION__*/

lib/utils/mu-result.hh

@@ -0,0 +1,39 @@
+/*
+** Copyright (C) 2019-2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**
+** This program is free software; you can redistribute it and/or modify it
+** under the terms of the GNU General Public License as published by the
+** Free Software Foundation; either version 3, or (at your option) any
+** later version.
+**
+** This program 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 General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software Foundation,
+** Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+**
+*/
+
+
+#ifndef MU_RESULT_HH__
+#define MU_RESULT_HH__
+
+
+#include "expected.hpp"
+#include "utils/mu-error.hh"
+
+
+namespace Mu {
+/**
+ * A Result is _either_ some value of type T, _or_ an error.
+ *
+ */
+template <typename T> using Result = tl::expected<T, Error>;
+
+} // namespace Mu
+
+
+#endif /* MU_ERROR_HH__ */