Add C++ ScriptConstructor to replace QML filter/computed-column drag-and-drop constructors

CommonData/scriptconstructormodel.h

@@ -0,0 +1,127 @@
+#ifndef SCRIPTCONSTRUCTORMODEL_H
+#define SCRIPTCONSTRUCTORMODEL_H
+
+#include <QObject>
+#include <QUndoCommand>
+#include <json/json.h>
+#include <vector>
+#include "scriptnode.h"
+#include "scriptconstructorregistry.h"
+
+class QUndoStack;
+
+/// Describes a place where a ScriptNode can be (or is requested to be) inserted.
+struct DropTarget
+{
+	enum class Kind { None, Root, OperatorLeft, OperatorRight, FunctionArg, RowFunctionArg };
+
+	Kind			kind		= Kind::None;
+	ScriptNode	*	parent		= nullptr;	///< Node owning the slot (nullptr for Root)
+	int				index		= -1;		///< Formula index for Root, argument index for Function/RowFunction
+	stringvec		dropKeys;				///< Keys accepted at this spot
+	bool			optional	= false;	///< Empty spot does not fail completeness checks
+	bool			dropsNested	= false;	///< Content dropped here renders nested (e.g. operators get parentheses)
+
+	bool isValid() const { return kind != Kind::None; }
+	bool isRoot() const { return kind == Kind::Root; }
+	bool accepts(ScriptNode * node) const;
+
+	static DropTarget none() { return {}; }
+	static DropTarget root(int formulaIndex = -1) { DropTarget t; t.kind = Kind::Root; t.index = formulaIndex; return t; }
+};
+
+///
+/// Owns the tree of ScriptNodes that make up a drag-and-drop filter / computed column formula.
+/// All mutations go through this class so that undo and change-notification have a single source.
+/// It is UI-agnostic: the QQuickItem view layer renders the tree and forwards user gestures here.
+class ScriptConstructorModel : public QObject
+{
+	Q_OBJECT
+
+public:
+	explicit ScriptConstructorModel(QObject * parent = nullptr);
+	~ScriptConstructorModel() override;
+
+	// (Re)build the whole tree from stored JSON. Does not push undo.
+	void			fromJson(const std::string & json);
+	void			fromJson(const Json::Value & json);
+
+	std::string		toString() const;					///< {"formulas":[...]}
+	Json::Value		toJson() const;
+	std::string		toR() const;						///< R code for all formulas
+
+	bool			checkCompleteness() const;			///< true when every required slot is filled
+	bool			allBoolean() const;					///< true when every root formula returns boolean
+	int				formulaCount() const { return static_cast<int>(_formulas.size()); }
+	ScriptNode	*	formulaAt(int index) const;
+	const std::vector<ScriptNode*> & formulas() const { return _formulas; }
+
+	ScriptConstructorMode mode() const { return _mode; }
+	void			setMode(ScriptConstructorMode mode) { _mode = mode; }
+
+	void			setColumnTypeProvider(const ScriptColumnTypeProvider * provider) { _typeProvider = provider; }
+	const ScriptColumnTypeProvider * columnTypeProvider() const { return _typeProvider; }
+
+	void			setUndoStack(QUndoStack * stack) { _undoStack = stack; }
+
+	// --- editing operations (each pushes an undo command when an undo stack is set) ---
+	void			insertNode(ScriptNode * node, DropTarget target);	///< takes ownership of node
+	void			removeNode(ScriptNode * node);						///< deletes the node subtree
+	void			moveNode(ScriptNode * node, DropTarget target);
+	void			setColumnTypeUser(ScriptNodeColumn * node, int columnType);
+	void			setLiteralNumber(ScriptNodeLiteral * node, double value);
+	void			setLiteralBool(ScriptNodeLiteral * node, bool value);
+	void			setLiteralString(ScriptNodeLiteral * node, const std::string & value);
+	void			clear();
+
+	/// Resolves where a freshly created node should go when the user did not drop it anywhere specific.
+	DropTarget		findReasonableInsertionSpot(ScriptNode * node) const;
+
+	/// Returns the column types (1=scale, 2=ordinal, 3=nominal) that the containing drop slot
+	/// accepts. At the root (no parent) all three are returned.
+	std::vector<int> allowedColumnTypes(ScriptNode * node) const;
+
+	/// Returns the drop keys accepted at a given target (used by the view for hover feedback).
+	static bool		keysOverlap(const stringvec & a, const stringvec & b);
+
+signals:
+	void			changed();		///< tree contents changed (any edit)
+	void			reset();		///< whole tree rebuilt (fromJson/clear/undo); view must rebuild items
+
+private:
+	void			deleteAllFormulas();
+	void			detachFromParent(ScriptNode * node);
+	void			placeAt(ScriptNode * node, const DropTarget & target);
+	void			resolveColumnTypeDrop(ScriptNodeColumn * col, const stringvec & slotKeys);
+	ScriptNode	*	rootFormulaOf(ScriptNode * node) const;
+	int				rootIndexOf(ScriptNode * node) const;
+	bool			isAncestor(ScriptNode * ancestor, ScriptNode * descendant) const;
+	bool			tryGobbleLeft(ScriptNode * node);
+
+	void			beginEdit();
+	void			endEdit(const QString & description);
+
+	std::vector<ScriptNode*>			_formulas;
+	ScriptConstructorMode				_mode			= ScriptConstructorMode::Filter;
+	const ScriptColumnTypeProvider	*	_typeProvider	= nullptr;
+	QUndoStack						*	_undoStack		= nullptr;
+	std::string							_editBeforeJson;
+};
+
+/// Undo command that snapshots the constructor JSON before and after an edit.
+class ScriptConstructorEditCommand : public QUndoCommand
+{
+public:
+	ScriptConstructorEditCommand(ScriptConstructorModel * model, const std::string & beforeJson, const std::string & afterJson, const QString & description);
+
+	void undo() override;
+	void redo() override;
+
+private:
+	ScriptConstructorModel	* _model;
+	std::string				_beforeJson,
+							_afterJson;
+	bool					_firstRedo = true;
+};
+
+#endif // SCRIPTCONSTRUCTORMODEL_H