/************************************************************************************************************************/
/// <summary>
/// Checks if it is currently possible to enter the specified `state`. This requires
/// <see cref="IState.CanExitState"/> on the <see cref="CurrentState"/> and
/// <see cref="IState.CanEnterState"/> on the specified `state` to both return true.
/// </summary>
public bool CanSetState(TState state)
{
#if UNITY_ASSERTIONS
if (state == null && !AllowNullStates)
{
throw new ArgumentNullException(nameof(state), NullNotAllowed);
}
#endif
StateChange <TState> .Begin(CurrentState, state, out var previouslyActiveChange);
try
{
if (CurrentState != null && !CurrentState.CanExitState)
{
return(false);
}
if (state != null && !state.CanEnterState)
{
return(false);
}
return(true);
}
finally
{
StateChange <TState> .End(previouslyActiveChange);
}
}
/************************************************************************************************************************/
/// <summary>
/// Calls <see cref="IState.OnExitState"/> on the <see cref="CurrentState"/> then changes to the
/// specified `state` and calls <see cref="IState.OnEnterState"/> on it.
/// <para></para>
/// This method does not check <see cref="IState.CanExitState"/> or
/// <see cref="IState.CanEnterState"/>. To do that, you should use <see cref="TrySetState"/> instead.
/// </summary>
public void ForceSetState(TState state)
{
#if UNITY_ASSERTIONS
if (state == null && !AllowNullStates)
{
throw new ArgumentNullException(nameof(state), NullNotAllowed);
}
#endif
StateChange <TState> .Begin(CurrentState, state, out var previouslyActiveChange);
try
{
#if UNITY_EDITOR
if (state is IOwnedState <TState> owned && owned.OwnerStateMachine != this)
{
throw new InvalidOperationException(
$"Attempted to use a state in a machine that is not its owner." +
$"\n State: {state}" +
$"\n Machine: {this}");
}
#endif
CurrentState?.OnExitState();
CurrentState = state;
state?.OnEnterState();
}
finally
{
StateChange <TState> .End(previouslyActiveChange);
}
}
/************************************************************************************************************************/
/// <summary>
/// Attempts to enter the specified `state` and returns true if successful.
/// <para></para>
/// This method does not check if the `state` is already the <see cref="CurrentState"/>. To do so, use
/// <see cref="TrySetState"/> instead.
/// </summary>
public bool TryResetState(TState state)
{
if (!CanSetState(state))
{
return(false);
}
StateChange <TState> .Begin(CurrentState, state, out var previouslyActiveChange);
try
{
ForceSetState(state);
return(true);
}
finally
{
StateChange <TState> .End(previouslyActiveChange);
}
}
/// <summary>Creates a new <see cref="StateMachine{TState}"/> and immediately enters the `defaultState`.</summary>
/// <remarks>This calls <see cref="IState.OnEnterState"/> but not <see cref="IState.CanEnterState"/>.</remarks>
public StateMachine(TState defaultState)
{
#if UNITY_ASSERTIONS
if (defaultState == null && !AllowNullStates)
{
throw new ArgumentNullException(nameof(defaultState), NullNotAllowed);
}
#endif
StateChange <TState> .Begin(null, defaultState, out var previouslyActiveChange);
try
{
CurrentState = defaultState;
defaultState.OnEnterState();
}
finally
{
StateChange <TState> .End(previouslyActiveChange);
}
}
/************************************************************************************************************************/
/// <summary>[<see cref="IDisposable"/>]
/// Re-assigns the values of this change (which were the previous values from when it was created) to be the
/// currently active change. See the constructor for recommended usage.
/// </summary>
/// <remarks>
/// Usually this will be returning to default values (nulls), but if one state change causes another then the
/// second one ending will return to the first which will then return to the defaults.
/// </remarks>
public void Dispose()
{
_Current = this;
}