The LINQ3 translator at times need to know if an AstExpression can be rendered as a path of the form "$x.y.z" or "$$var.x.y.z".

This question is most easily answered by defining a new virtual method

• the default implementation of CanBeRenderedAsPath returns false
• AstVarExpression overrides CanBeRenderedAsPath and returns true
• AstGetFieldExpression overrides CanBeRenderedAsPath and returns true if the Input CanBeRenderedAsPath and the field name is safe to use in a path