playlist/Queue: add one-shot to single mode

src/SingleMode.hxx

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2003-2017 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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 2 of the License, 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 MPD_SINGLE_MODE_HXX
+#define MPD_SINGLE_MODE_HXX
+
+#include "Compiler.h"
+
+#include <stdint.h>
+
+enum class SingleMode : uint8_t {
+	OFF,
+	ON,
+	ONE_SHOT,
+};
+
+/**
+ * Return the string representation of a #SingleMode.
+ */
+gcc_pure
+const char *
+SingleToString(SingleMode mode) noexcept;
+
+/**
+ * Parse a string to a #SingleMode.  Throws std::invalid_argument on error.
+ */
+SingleMode
+SingleFromString(const char *s);
+
+#endif