=== State Machine Instance Specifiers

A *state machine instance specifier* specifies an instantiated
<<Definitions_State-Machine-Definitions,state machine>> as part
of a
<<Definitions_Component-Definitions,component definition>>.

==== Syntax

`state machine instance`
<<Lexical-Elements_Identifiers,_identifier_>>
`:`
<<Scoping-of-Names_Qualified-Identifiers,_qual-ident_>>
_[_
`priority` <<Expressions,_expression_>>
_]_
_[_
_queue-full-behavior_
_]_

_queue-full-behavior_ has the same syntax as for
<<Specifiers_Port-Instance-Specifiers_Syntax,port instance specifiers>>.

==== Static Semantics

. The identifier names the state machine instance.

. The qualified identifier must
<<Scoping-of-Names_Resolution-of-Qualified-Identifiers,refer to>>
a
<<Definitions_State-Machine-Definitions,state machine definition>>.

. The optional priority and queue full behavior have the same semantics as in
<<Specifiers_Port-Instance-Specifiers_Semantics, async input port instance
specifiers>>.

==== Dynamic Semantics

. Specifying one or more instances of a state machine _M_ in a component _C_
causes the following code to be generated as part of _C_:

.. Pure virtual functions corresponding to the actions and guards of _M_.

.. For each signal _s_ of _M_, a function for sending _s_ to _M_.
The signal function may or may not have a typed argument, depending
on the definition of _s_.
The signal and the argument, if any, are serialized on the component
queue and dispatched from the queue in the ordinary way for
an F Prime active or queued component.
Upon dispatching a signal, the signal and argument, if any,
are used to call the <<Definitions_State-Machine-Definitions_Dynamic-Semantics,
function for sending _s_ to _M_>>.

==== Examples

[source,fpp]
----
state machine M {
  initial S
  state S
}

passive component C {

  @ m1 is an instance of state machine M
  state machine instance m1: M

  @ m2 is an instance of state machine M
  state machine instance m2: M priority 10 drop

}
----