db/upnp: move generic code to lib/upnp/

src/lib/upnp/Action.hxx

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2003-2014 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_UPNP_ACTION_HXX
+#define MPD_UPNP_ACTION_HXX
+
+#include "Compiler.h"
+
+#include <upnp/upnptools.h>
+
+static inline constexpr unsigned
+CountNameValuePairs()
+{
+	return 0;
+}
+
+template<typename... Args>
+static inline constexpr unsigned
+CountNameValuePairs(gcc_unused const char *name, gcc_unused const char *value,
+		    Args... args)
+{
+	return 1 + CountNameValuePairs(args...);
+}
+
+/**
+ * A wrapper for UpnpMakeAction() that counts the number of name/value
+ * pairs and adds the nullptr sentinel.
+ */
+template<typename... Args>
+static inline IXML_Document *
+MakeActionHelper(const char *action_name, const char *service_type,
+		 Args... args)
+{
+	const unsigned n = CountNameValuePairs(args...);
+	return UpnpMakeAction(action_name, service_type, n,
+			      args...,
+			      nullptr, nullptr);
+}
+
+#endif