A “short list” of embedded systems

CS269: HW/SW Engineering of Embedded Systems, Winter02

Visitors

•Traversals of the AST use the Visitor design pattern:

•

“A solution to the problem of adding operations

to the elements of an object structure without

changing the classes on which it operates”

•

–1 traversal = 1 Visitor class

–AST classes not modified when adding new Visitors

–

•The code of the traversal is divided in visit() methods: Object visitNameNode(NameNode node,

LinkedList args)

•There is one _defaultVisit() method used if visit() method is not defined for a class of nodes

•

•Back-end tool may need several traversals of the AST

® Back-end tool = set of visitors + additional classes