MPS 2019.1 Help

SModel language Modification operations

Modification operations

Feature changes

The most commonly used change operation in SModel is the act of changing a feature. In order to set a value of a property, or assign a child or reference node of 0..1 or 1 cardinality, you can use straight assignment (with =) or the set operation. In order to add a child to 0..n or 1..n children collection, you can either use the.add operation from the collection language or call add next-sibling/add prev-sibling operations on a node<> passing another node as a parameter.

For example,

  • = "NewClassName";

  • "NewClassName");

  • myNode.condition = trueConstant;

  • node<InstanceMethodDeclaration> method = classDef.member.add new initialized(InstanceMethodDeclaration);

When setting a target to a reference link, there is no need to access a target node. Having a pointer to the target is enough. This is possible with the set ptr operation, which is applicable to reference link access expressions.

node.instanceMethodDeclaration.set ptr(Object->equals)

Similarly, to check that a node is a specific one, there is the "is" operation available.>equals);

New node creation

There are several ways to create a new node:

  • new operation: new node<Concept>()

  • new instance operation on a model: model.newInstance()

  • new instance operation on a concept: concept.newInstance()

  • add new(Concept) and set new(Concept) operations applied to feature expressions

  • replace with new(Concept) operation

  • new root node(Concept) operation applied to a model. In this case the concept should be rootable

  • new next-sibling<Concept>/new prev-sibling<Concept> operations adding new sibling to an existing node


To preserve the tree shape of the model, a node can only have at most one parent. As soon as you add a node as a child to a parent node, the node is detached automatically from any previous parent node that it may have had. Creating copies of nodes, including their sub-trees, may thus come handy. To create a copy of an existing node, you can use the copy operation. E.g., node<> yourNode = myNode.copy

Replace with

To replace a node in the AST with an instance of another node, you can use the 'replace with' operation. If you want to replace and create at the same time, there is a shortcut operation 'replace with new(Concept)', which takes a concept as a parameter.

Delete and detach operations

If you want to delete a node from the model, you can use the detach operation. You can still add the detached node to the model later.

Last modified: 12 April 2019