GetUnitByNameVisitor.cs

public class GetUnitByNameVisitor : IVisitor 
{
    //The parameter
    private string _unitName;
    //The return value
    public Unit ReturnedUnit { get; private set; }

    public GetUnitByNameVisitor(string unitName) 
    {
        _unitName = unitName;
    }

    public void VisitProcessUnit(ProcessUnit unit) 
    {
        //Accessing the parameter using the private field.
        if (unit.Name == _unitName) 
        {
            //If this process unit is the one we are looking for
            //return, since there is no need to search in other children
            ReturnedUnit = unit;
            return;
        }

        foreach (var childUnit in unit.ChildUnits) 
        {
            childUnit.AcceptVisitor(this);
            //If the unit has been found in this child, return,
            //since there is no need to search in the other siblings.
            if (ReturnedUnit != null)
                return;
        }
    }

    public void VisitAgentUnit(AgentUnit unit)
    {
        //Accessing the parameter using the private field
        if (unit.Name == _unitName)
            ReturnedUnit = unit;
    }
}