Statifier.Interpreter.TransitionResolver (statifier v1.9.0)

Handles SCXML transition resolution and conflict resolution.

This module encapsulates the complex logic for finding enabled transitions and resolving conflicts according to SCXML specifications where child state transitions take priority over ancestor state transitions.

Key Responsibilities

Find enabled transitions for events and eventless (NULL) transitions
Evaluate transition conditions using the predicator framework
Resolve transition conflicts according to SCXML semantics
Handle event pattern matching for transition selection

SCXML Compliance

Implements W3C SCXML transition selection semantics:

Child state transitions override ancestor state transitions
Document order determines priority among equivalent transitions
Eventless transitions (NULL transitions) processed after event transitions
Condition evaluation with state chart context

Summary

Functions

find_enabled_transitions(state_chart, event)

Find enabled transitions for a given event.

find_eventless_transitions(state_chart)

Find eventless transitions (also called NULL transitions in SCXML spec).

resolve_transition_conflicts(transitions, document)

Resolve transition conflicts according to SCXML semantics.

transition_condition_enabled?(map, context)

Check if a transition condition is enabled.

Functions

find_enabled_transitions(state_chart, event)

@spec find_enabled_transitions(Statifier.StateChart.t(), Statifier.Event.t()) ::
  {Statifier.StateChart.t(), [Statifier.Transition.t()]}

Find enabled transitions for a given event.

Returns a tuple with updated state chart (with logging) and transitions that match the event and have enabled conditions, filtered by SCXML conflict resolution rules.

Examples

{state_chart, transitions} = TransitionResolver.find_enabled_transitions(state_chart, event)

find_eventless_transitions(state_chart)

@spec find_eventless_transitions(Statifier.StateChart.t()) ::
  {Statifier.StateChart.t(), [Statifier.Transition.t()]}

Find eventless transitions (also called NULL transitions in SCXML spec).

Returns a tuple with updated state chart (with logging) and transitions without event attributes that have enabled conditions, filtered by SCXML conflict resolution rules.

Examples

{state_chart, transitions} = TransitionResolver.find_eventless_transitions(state_chart)

resolve_transition_conflicts(transitions, document)

@spec resolve_transition_conflicts([Statifier.Transition.t()], Statifier.Document.t()) ::
  [
    Statifier.Transition.t()
  ]

Resolve transition conflicts according to SCXML semantics.

Child state transitions take priority over ancestor state transitions. Returns the optimal transition set with conflicts resolved.

SCXML Specification

Per W3C SCXML specification, when multiple transitions are enabled:

Child state transitions override ancestor state transitions
Document order determines priority among equivalent transitions
Only one transition per source state is selected

Examples

optimal_transitions = TransitionResolver.resolve_transition_conflicts(transitions, document)

transition_condition_enabled?(map, context)

@spec transition_condition_enabled?(
  Statifier.Transition.t(),
  Statifier.StateChart.t()
) :: boolean()

Check if a transition condition is enabled.

Evaluates transition conditions using the predicator framework with state chart context including current event and data model.

Examples

enabled? = TransitionResolver.transition_condition_enabled?(transition, state_chart)