Selector node

The selector node has a number of children which will be tried in order. When the root selector node gets selected, it will immediately transition to Running (after checking the decorators). While in Running, it will select the child node for which all predecessors have failing decorator conditions (or where there is none for the first child). Once any child succeeds, the selector node will transition to Succeeded as well. If any child fails during execution (as long as it isn't a decorator failure), the whole node will fail.

Properties

Property	Description
Child semantics	Children are executed in-order until one child succeeds or all have failed (with a condition failure).
Parameters	name: name of the node children: ordered list of sub-trees
Success criterion	Exactly one child has succeeded, if any other children were tried before, they can only have failed with a condition failure.
Failure criterion	All children have failed in the condition stage, or at least one node has failed execution (beyond condition evaluation).

Python API

The node can be constructed by parameterizing it either on creation or by using the builder pattern. Note that the decorator attached to the children determines which child is chosen to be executed.

pick_connector_1 = BT.Sequence(children=[approach_connector_1, pick_connector_1])
pick_connector_1.set_decorators(BT.Decorators(BT.SubTreeCondition(tree=estimate_connector_1)))
pick_connector_2 = BT.Sequence(children=[approach_connector_2, pick_connector_2])
pick_connector_2.set_decorators(BT.Decorators(BT.SubTreeCondition(tree=estimate_connector_2)))
pick_connector_3 = BT.Sequence(children=[approach_connector_3, pick_connector_3])
pick_connector_3.set_decorators(BT.Decorators(BT.SubTreeCondition(tree=estimate_connector_3)))

selector_node = BT.Selector(children=[pick_connector_1, pick_connector_2, pick_connector_3])