Developing a DSL Graphical Notation - Eclipse Modeling Project: A Domain-Specific Language Toolkit - page 86

Our tooling model does not require changes because we don't want to allow
for the explicit creation of subtopic nodes; we want to have them visualized
when subtopic links are made. Our mapping model needs a new top-level node
mapping, as shown here along with our original Topic mapping. With two node
mappings for a single domain model element, we need to define a constraint for
each so that the generated code can distinguish between them, as seen in Table
4-8. This is especially important when diagrams are created from existing mod-
els, to remove ambiguity and to allow for the proper notation to be assigned. In
the case of our mindmap, Topic elements with no parent are considered
“root” Topic s and use the rounded rectangle figure. Those that have a parent,
which is the eOpposite of the subtopics reference, will be rendered with our
new underline figure.

Table 4-8 Updated Mindmap Node Mappings

Element Property Value

Mapping

Top Node Reference Containment Feature Map.elements : MapElement

Node Mapping Element Topic → MapElement

Diagram Node Node Topic (TopicFigure)

Tool Creation Tool Topic

Constraint Body self.parent = null

Language ocl

Feature Label Mapping Diagram Label Diagram Label TopicName

Features MapElement.name : EString

Top Node Reference Containment Feature Map.elements : MapElement

Node Mapping Element Topic → MapElement

Diagram Node Node SubTopic (SubTopicFigure)

Constraint Body self.parent <> null

Language ocl

Feature Label Mapping Diagram Label Diagram Label SubtopicName

Features MapElement.name : EString

Regenerating our diagram and testing reveals some problems. Although it's
possible to create subtopic links, the target figure is not immediately updated. If