}
+\f
+////////////////////////////////////////////////////////////////////////
+// Conditions.
+////////////////////////////////////////////////////////////////////////
+
+
+/**
+ * An encoded condition.
+ *
+ * This class encodes a single condition of some sort, possibly
+ * connected with properties.
+ *
+ * This class should migrate to somewhere more general.
+ */
+class FGCondition
+{
+public:
+ FGCondition ();
+ virtual ~FGCondition ();
+ virtual bool test () const = 0;
+};
+
+
+/**
+ * Condition for a single property.
+ *
+ * This condition is true only if the property returns a boolean
+ * true value.
+ */
+class FGPropertyCondition : public FGCondition
+{
+public:
+ FGPropertyCondition (const string &propname);
+ virtual ~FGPropertyCondition ();
+ virtual bool test () const { return _node->getBoolValue(); }
+private:
+ const SGPropertyNode * _node;
+};
+
+
+/**
+ * Condition for a 'not' operator.
+ *
+ * This condition is true only if the child condition is false.
+ */
+class FGNotCondition : public FGCondition
+{
+public:
+ // transfer pointer ownership
+ FGNotCondition (FGCondition * condition);
+ virtual ~FGNotCondition ();
+ virtual bool test () const;
+private:
+ FGCondition * _condition;
+};
+
+
+/**
+ * Condition for an 'and' group.
+ *
+ * This condition is true only if all of the conditions
+ * in the group are true.
+ */
+class FGAndCondition : public FGCondition
+{
+public:
+ FGAndCondition ();
+ virtual ~FGAndCondition ();
+ virtual bool test () const;
+ // transfer pointer ownership
+ virtual void addCondition (FGCondition * condition);
+private:
+ vector<FGCondition *> _conditions;
+};
+
+
+/**
+ * Condition for an 'or' group.
+ *
+ * This condition is true if at least one of the conditions in the
+ * group is true.
+ */
+class FGOrCondition : public FGCondition
+{
+public:
+ FGOrCondition ();
+ virtual ~FGOrCondition ();
+ virtual bool test () const;
+ // transfer pointer ownership
+ virtual void addCondition (FGCondition * condition);
+private:
+ vector<FGCondition *> _conditions;
+};
+
+
+/**
+ * Abstract base class for property comparison conditions.
+ */
+class FGComparisonCondition : public FGCondition
+{
+public:
+ enum Type {
+ LESS_THAN,
+ GREATER_THAN,
+ EQUALS
+ };
+ FGComparisonCondition (Type type, bool reverse = false);
+ virtual ~FGComparisonCondition ();
+ virtual bool test () const;
+ virtual void setLeftProperty (const string &propname);
+ virtual void setRightProperty (const string &propname);
+ // will make a local copy
+ virtual void setRightValue (const SGPropertyNode * value);
+private:
+ Type _type;
+ bool _reverse;
+ const SGPropertyNode * _left_property;
+ const SGPropertyNode * _right_property;
+ const SGPropertyNode * _right_value;
+};
+
+
+/**
+ * Base class for a conditional components.
+ *
+ * This class manages the conditions and tests; the component should
+ * invoke the test() method whenever it needs to decide whether to
+ * active itself, draw itself, and so on.
+ */
+class FGConditional
+{
+public:
+ FGConditional ();
+ virtual ~FGConditional ();
+ // transfer pointer ownership
+ virtual void setCondition (FGCondition * condition);
+ virtual const FGCondition * getCondition () const { return _condition; }
+ virtual bool test () const;
+private:
+ FGCondition * _condition;
+};
+
+
+/**
+ * Global function to make a condition out of properties.
+ *
+ * The top-level is always an implicit 'and' group, whatever the
+ * node's name (it should usually be "condition").
+ *
+ * @param node The top-level condition node (usually named "condition").
+ * @return A pointer to a newly-allocated condition; it is the
+ * responsibility of the caller to delete the condition when
+ * it is no longer needed.
+ */
+FGCondition * fgReadCondition (const SGPropertyNode * node);
+
+
#endif // __FG_PROPS_HXX
projects / flightgear.git / blobdiff