Class StateMachine::Branch
In: lib/state_machine/branch.rb
Parent: Object

Represents a set of requirements that must be met in order for a transition or callback to occur. Branches verify that the event, from state, and to state of the transition match, in addition to if/unless conditionals for an object‘s state.

Methods

Included Modules

Assertions EvalHelpers

Attributes

event_requirement  [R]  The requirement for verifying the event being matched
if_condition  [R]  The condition that must be met on an object
known_states  [R]  A list of all of the states known to this branch. This will pull states from the following options (in the same order):
  • from / except_from
  • to / except_to
state_requirements  [R]  One or more requirements for verifying the states being matched. All requirements contain a mapping of {:from => matcher, :to => matcher}.
unless_condition  [R]  The condition that must not be met on an object

Public Instance methods

Draws a representation of this branch on the given graph. This will draw an edge between every state this branch matches from to either the configured to state or, if none specified, then a loopback to the from state.

For example, if the following from states are configured:

  • idling
  • first_gear
  • backing_up

…and the to state is parked, then the following edges will be created:

  • idling -> parked
  • first_gear -> parked
  • backing_up -> parked

Each edge will be labeled with the name of the event that would cause the transition.

The collection of edges generated on the graph will be returned.

Attempts to match the given object / query against the set of requirements configured for this branch. In addition to matching the event, from state, and to state, this will also check whether the configured :if/:unless conditions pass on the given object.

If a match is found, then the event/state requirements that the query passed successfully will be returned. Otherwise, nil is returned if there was no match.

Query options:

  • :from - One or more states being transitioned from. If none are specified, then this will always match.
  • :to - One or more states being transitioned to. If none are specified, then this will always match.
  • :on - One or more events that fired the transition. If none are specified, then this will always match.
  • :guard - Whether to guard matches with the if/unless conditionals defined for this branch. Default is true.

Examples

  branch = StateMachine::Branch.new(:parked => :idling, :on => :ignite)

  branch.match(object, :on => :ignite)  # => {:to => ..., :from => ..., :on => ...}
  branch.match(object, :on => :park)    # => nil

Determines whether the given object / query matches the requirements configured for this branch. In addition to matching the event, from state, and to state, this will also check whether the configured :if/:unless conditions pass on the given object.

Examples

  branch = StateMachine::Branch.new(:parked => :idling, :on => :ignite)

  # Successful
  branch.matches?(object, :on => :ignite)                                   # => true
  branch.matches?(object, :from => nil)                                     # => true
  branch.matches?(object, :from => :parked)                                 # => true
  branch.matches?(object, :to => :idling)                                   # => true
  branch.matches?(object, :from => :parked, :to => :idling)                 # => true
  branch.matches?(object, :on => :ignite, :from => :parked, :to => :idling) # => true

  # Unsuccessful
  branch.matches?(object, :on => :park)                                     # => false
  branch.matches?(object, :from => :idling)                                 # => false
  branch.matches?(object, :to => :first_gear)                               # => false
  branch.matches?(object, :from => :parked, :to => :first_gear)             # => false
  branch.matches?(object, :on => :park, :from => :parked, :to => :idling)   # => false

Protected Instance methods

Builds a matcher strategy to use for the given options. If neither a whitelist nor a blacklist option is specified, then an AllMatcher is built.

Verifies that the event requirement matches the given query

Verifies that all configured requirements (event and state) match the given query. If a match is found, then a hash containing the event/state requirements that passed will be returned; otherwise, nil.

Verifies that the state requirements match the given query. If a matching requirement is found, then it is returned.

Verifies that the conditionals for this branch evaluate to true for the given object

Verifies that an option in the given query matches the values required for that option

[Validate]