fsm:use_fsm
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+ | ====== Using OSInet FSM ====== | ||
+ | Code using the FSM revolves around the f_transitions table. This is an array of states and their associated events and transitions. | ||
+ | |||
+ | Each entry in f_transitions represents a state as an array of events. | ||
+ | |||
+ | Each entry in a f_transition state represents an event as an array of accepted results from the method handling the event, the resulting next action as a fsm_result. | ||
+ | |||
+ | The fsm_state field contains the name of the state as a string, and the fsm_action field contains an event (as a string) to fire after setting the state. If fsm_state is NULL, no state change occurs. If fsm_action is NULL, no event is fired. | ||
+ | |||
+ | Syntactic sugar: The action can also be a simple string, in which case it is the name of the next state and no action is taken. Version 1.1 only understood that syntax. | ||
+ | |||
+ | Implementing the FSM once the table is defined means implementing each event (foo) as an event-handling function called f_foo. The return values of this function must be the ones defined in the f_transitions entry for that state. Returning a non accepted value throws an exception. | ||
+ | |||
+ | ===== Controlling the FSM operation ===== | ||
+ | ==== Directed work with the " | ||
+ | |||
+ | A special built-in event is fsm:: | ||
+ | |||
+ | This event can be turned off by setting the FSM " | ||
+ | |||
+ | Syntactic sugar: the idle() method is a shorthand for apply_events(fsm:: | ||
+ | |||
+ | ==== Filtering events ==== | ||
+ | |||
+ | The OSInet FSM has three event processing modes, controlled by the {get|set}_event_mode methods: | ||
+ | |||
+ | * fsm:: | ||
+ | * Switching from fsm:: | ||
+ | * fsm:: | ||
+ | * fsm:: | ||
+ | * Switching from fsm:: | ||
+ | |||
+ | ==== Disabling post-events actions ==== | ||
+ | |||
+ | Firing of post-event actions is enabled by default, but can be disabled by setting the $allow_actions property to false. | ||
+ | |||
+ | In that case, applications can still decide to fire the event themselves by reading the fsm_action field in the fsm_result returns by fsm:: | ||
+ | |||
+ | ===== Example ===== | ||
+ | |||
+ | For a very basic FSM going just from initial to final randomly, building the table and transitions can look like: | ||
+ | |||
+ | <code php> | ||
+ | class foo extends fsm | ||
+ | { | ||
+ | function __construct() | ||
+ | { | ||
+ | $this-> | ||
+ | ( | ||
+ | ' | ||
+ | ( | ||
+ | ' | ||
+ | ( | ||
+ | TRUE => ' | ||
+ | FALSE => ' | ||
+ | ), | ||
+ | ' | ||
+ | ( | ||
+ | TRUE => new fsm_result(NULL, | ||
+ | ), | ||
+ | ), | ||
+ | ' | ||
+ | ); | ||
+ | } | ||
+ | function f_event() | ||
+ | { | ||
+ | return rand(0, 1) > 0 ; | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | |||
+ | |||
+ | Application code not involved in the FSM operation can use the FSM apply_event method($event_name) to submit an event to the FSM. Only allowed events for the given state the FSM is in are allowed: submitting other events throws an exception. |