Add an IExpression parser base class
Current status.
We have an IExpressionVisitor interface that defines visit methods to parse DSML IExpressions in conjunction with the accept methods of IExpressions. Due to the absence of a base class that does NOT perform evaluations but simply visits each part of the expression, defining new visitors (parsers) is cumbersome.
Propsoed solution.
Define a base class that implements each visit method and delegates to sub-expressions. That way single, specific visit methods can be overridden.
(from redmine: issue id 3593, created on 2018-12-13, closed on 2018-12-19)