public void Step()
{
if (IsFinished)
{
return;
}
SearchNode <TState, TAction> node;
do
{
if (Frontier.IsEmpty())
{
IsFinished = true;
return;
}
node = Frontier.Pop();
} while (_explored.ContainsKey(node.State));
_explored[node.State] = node;
CurrentState = node.State;
var actions = _problem.GetActions(node.State);
foreach (var action in actions)
{
var childState = _problem.DoAction(node.State, action);
var childCost = node.PathCost + _problem.PathCost(node.State, action);
var child = new SearchNode <TState, TAction>(childState, node, action, childCost);
if (_explored.ContainsKey(childState) || Frontier.ContainsState(childState))
{
continue;
}
if (_problem.IsGoal(childState))
{
CurrentState = childState;
IsFinished = true;
IsSolved = true;
// add goal to explored to allow this.getSolutionTo(goal)
_explored[childState] = child;
}
else
{
Frontier.Push(child);
}
}
}
public void Step_ShouldGoToBetterState()
{
var state3 = new StateMock("3");
var state2 = new StateMock("2");
var state1 = new StateMock("1");
var action1 = new ActionMock("1");
var action3 = new ActionMock("3");
A.CallTo(() => _problem.InitialState).Returns(state2);
A.CallTo(() => _problem.GetActions(state2)).Returns(new[] { action1, action3 });
A.CallTo(() => _problem.DoAction(state2, action1)).Returns(state1);
A.CallTo(() => _problem.DoAction(state2, action3)).Returns(state3);
var search = new AStarSearch <StateMock, ActionMock>(_problem, state => int.Parse(state.Value));
// act
search.Step(); // step 1 sets current state to initial state
search.Step();
// assert
Assert.AreEqual(state1, search.CurrentState);
}