Add PluginIssue class (#4901)

include/PluginIssue.h

@@ -0,0 +1,66 @@
+/*
+ * PluginIssue.h - PluginIssue class
+ *
+ * Copyright (c) 2019 Johannes Lorenz <j.git$$$lorenz-ho.me, $$$=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * 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 (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef PLUGINISSUE_H
+#define PLUGINISSUE_H
+
+#include <QDebug>
+#include <string>
+
+//! Types of issues that can cause LMMS to not load a plugin
+//! LMMS Plugins should use this to indicate errors
+enum PluginIssueType
+{
+	unknownPortFlow,
+	unknownPortType,
+	tooManyInputChannels,
+	tooManyOutputChannels,
+	noOutputChannel,
+	portHasNoDef,
+	portHasNoMin,
+	portHasNoMax,
+	featureNotSupported, //!< plugin requires functionality LMMS can't offer
+	badPortType, //!< port type not supported
+	noIssue
+};
+
+//! Issue type bundled with informational string
+class PluginIssue
+{
+	static const char* msgFor(const PluginIssueType& it);
+
+	PluginIssueType m_issueType;
+	std::string m_info;
+
+public:
+	PluginIssue(PluginIssueType it, std::string msg = std::string())
+		: m_issueType(it), m_info(msg)
+	{
+	}
+	friend QDebug operator<<(QDebug stream, const PluginIssue& iss);
+};
+
+QDebug operator<<(QDebug stream, const PluginIssue& iss);
+
+#endif // PLUGINISSUE_H