Make Model class visitable

include/AutomatableModel.h

@@ -33,6 +33,7 @@
 #include "MidiTime.h"
 #include "ValueBuffer.h"
 #include "MemoryManager.h"
+#include "ModelVisitor.h"
 
 // simple way to map a property of a view to a model
 #define mapPropertyFromModelPtr(type,getfunc,setfunc,modelname)	\
@@ -68,6 +69,7 @@ class LMMS_EXPORT AutomatableModel : public Model, public JournallingObject
 	Q_OBJECT
 	MM_OPERATORS
 public:
+
 	typedef QVector<AutomatableModel *> AutoModelVector;
 
 	enum ScaleType
@@ -80,6 +82,32 @@ public:
 
 	virtual ~AutomatableModel();
 
+	// Implement those by using the MODEL_IS_VISITABLE macro
+	virtual void accept(ModelVisitor& v) = 0;
+	virtual void accept(ConstModelVisitor& v) const = 0;
+	// use this to make subclasses visitable
+#define MODEL_IS_VISITABLE \
+	void accept(ModelVisitor& v) override { v.visit(*this); } \
+	void accept(ConstModelVisitor& v) const override { v.visit(*this); }
+
+public:
+	//! Return this class casted to Target, or nullptr if impossible
+	template<class Target>
+	Target* dcast(bool doThrow = false)
+	{
+		DCastVisitor<Target> vis; accept(vis);
+		if(doThrow && !vis.result) Q_ASSERT(false);
+		return vis.result;
+	}
+
+	//! Return this class casted to const Target, or nullptr if impossible
+	template<class Target>
+	const Target* dcast(bool doThrow = false) const
+	{
+		ConstDCastVisitor<Target> vis; accept(vis);
+		if(doThrow && !vis.result) Q_ASSERT(false);
+		return vis.result;
+	}
 
 	bool isAutomated() const;
 	bool isAutomatedOrControlled() const
@@ -283,6 +311,20 @@ protected:
 
 
 private:
+	template<class Target>
+	struct DCastVisitor : public ModelVisitor
+	{
+		Target* result = nullptr;
+		void visit(Target& tar) { result = &tar; }
+	};
+
+	template<class Target>
+	struct ConstDCastVisitor : public ConstModelVisitor
+	{
+		const Target* result = nullptr;
+		void visit(const Target& tar) { result = &tar; }
+	};
+
 	static bool mustQuoteName(const QString &name);
 
 	virtual void saveSettings( QDomDocument& doc, QDomElement& element )
@@ -382,6 +424,7 @@ public:
 class LMMS_EXPORT FloatModel : public TypedAutomatableModel<float>
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	FloatModel( float val = 0, float min = 0, float max = 0, float step = 0,
 				Model * parent = NULL,
@@ -399,6 +442,7 @@ public:
 class LMMS_EXPORT IntModel : public TypedAutomatableModel<int>
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	IntModel( int val = 0, int min = 0, int max = 0,
 				Model* parent = NULL,
@@ -414,6 +458,7 @@ public:
 class LMMS_EXPORT BoolModel : public TypedAutomatableModel<bool>
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	BoolModel( const bool val = false,
 				Model* parent = NULL,

include/ComboBoxModel.h

@@ -36,6 +36,7 @@
 class LMMS_EXPORT ComboBoxModel : public IntModel
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	ComboBoxModel( Model* parent = NULL,
 					const QString& displayName = QString(),

include/ModelVisitor.h

@@ -0,0 +1,53 @@
+/*
+ * ModelVisitor.h - visitors for automatable models
+ *
+ * Copyright (c) 2019-2019 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 MODELVISITOR_H
+#define MODELVISITOR_H
+
+class BoolModel;
+class IntModel;
+class FloatModel;
+class ComboBoxModel;
+
+class ModelVisitor
+{
+public:
+	virtual void visit(BoolModel& ) {}
+	virtual void visit(IntModel& ) {}
+	virtual void visit(FloatModel& ) {}
+	virtual void visit(ComboBoxModel& ) {}
+	virtual ~ModelVisitor();
+};
+
+class ConstModelVisitor
+{
+public:
+	virtual void visit(const BoolModel& ) {}
+	virtual void visit(const IntModel& ) {}
+	virtual void visit(const FloatModel& ) {}
+	virtual void visit(const ComboBoxModel& ) {}
+	virtual ~ConstModelVisitor();
+};
+
+#endif // MODELVISITOR_H

src/core/CMakeLists.txt

@@ -40,6 +40,7 @@ set(LMMS_SRCS
 	core/MixerWorkerThread.cpp
 	core/MixHelpers.cpp
 	core/Model.cpp
+	core/ModelVisitor.cpp
 	core/Note.cpp
 	core/NotePlayHandle.cpp
 	core/Oscillator.cpp

src/core/ModelVisitor.cpp

@@ -0,0 +1,28 @@
+/*
+ * ModelVisitor.cpp - visitors for automatable models
+ *
+ * Copyright (c) 2019-2019 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.
+ *
+ */
+
+#include "ModelVisitor.h"
+
+ModelVisitor::~ModelVisitor() {}
+ConstModelVisitor::~ConstModelVisitor() {}