fsm Namespace Reference

Classes
struct	any_t
	Tag type for fsm::any. More...
struct	event_tag
	Tag carrying an event as a compile-time value. More...
struct	from_spec
	Row source: a concrete state or the fsm::any wildcard. More...
struct	initial_spec
	Initial-child declaration for composite states. More...
struct	internal_t
	Tag type for fsm::internal. More...
class	machine
	The state machine engine interpreting a Traits' constexpr tables. More...
struct	no_timeout_t
	Tag type for fsm::no_timeout. More...
struct	observer
	Runtime-attachable debug observer: plain nullable function pointers. More...
struct	on_spec
	Row trigger event, with poison default for omitted .on. More...
struct	parent_spec
	Parent link — a mandatory column: fsm::root or fsm::child_of(P). More...
struct	result
	Dispatch verdict: what happened, where, and why. More...
struct	root_t
	Tag type for fsm::root. More...
struct	row
	One transition-table row: {from, on, when, then, to}. More...
struct	state_id
	State identifier for a state_spec, with poison default. More...
struct	state_spec
	One state's specification: hierarchy links, actions, deadline. More...
struct	target
	Row target: external transition, internal handling, or refusal. More...
struct	timeout_spec
	Per-state deadline declaration — a mandatory column. More...

Enumerations
enum class	status : uint8_t {   transitioned , handled_internally , refused_by_row , refused_guard ,   unhandled , refused_reentrant , not_started }
	Verdict category returned by machine::dispatch(). More...
enum class	from_kind : uint8_t { unspecified , any , state }
	Kinds for row::from. unspecified is the poison default. More...
enum class	on_kind : uint8_t { unspecified , event }
	Kinds for row::on. unspecified is the poison default. More...
enum class	target_kind : uint8_t { unspecified , to , internal_ , refuse_ }
	Kinds for row::to. unspecified is the poison default. More...
enum class	id_kind : uint8_t { unspecified , state }
	Kinds for state_spec::state. unspecified is the poison default. More...
enum class	parent_kind : uint8_t { unspecified , root , child }
	Kinds for state_spec::parent. unspecified is the poison default. More...
enum class	initial_kind : uint8_t { leaf , start_at }
	Kinds for state_spec::initial. Default is leaf (no children). More...
enum class	timeout_kind : uint8_t { unspecified , none , after_ , after_dyn_ }
	Kinds for state_spec::deadline. unspecified is the poison default. More...

Functions
template<class Traits , class W >
void	write_dot (W &&write)
	Emit a Graphviz digraph of Traits' machine through write.
template<class State , class Event , class Reason >
constexpr bool	accepted (const result< State, Event, Reason > &r)
	True when the event was acted on (transitioned or handled internally).
template<class State >
constexpr detail::to_t< State >	to (State s)
	Make an external-transition target.
template<class Reason >
constexpr detail::refuse_t< Reason >	refuse (Reason r)
	Make a declarative refusal target carrying a reason.
template<class State >
constexpr parent_spec< State >	child_of (State s)
	Declare a state's parent in the hierarchy.
template<class State >
constexpr initial_spec< State >	start_at (State s)
	Declare the child entered when a composite state is targeted.
template<class Event >
constexpr timeout_spec< Event >	after (uint32_t ms, Event e)
	Declare "dispatch @p e after @p ms milliseconds in this state".
template<class Event >
constexpr timeout_spec< Event >	after_dyn (Event e)
	Declare a dynamic deadline: duration read from the context at entry time instead of the table.

Variables
constexpr uint16_t	no_row = 0xFFFF
	Sentinel row index meaning "no table row was involved".
constexpr any_t	any {}
	Wildcard row source: matches any state, after all ancestor levels.
constexpr internal_t	internal {}
	Row target: handle the event (run the action) without exit/entry.
constexpr no_timeout_t	no_timeout {}
	State deadline declaration: this state has no timeout (explicitly).
constexpr root_t	root {}
	Parent declaration: this state is a hierarchy root (no parent).

Enumeration Type Documentation

from_kind

enum class fsm::from_kind : uint8_t

strong

Kinds for row::from. unspecified is the poison default.

Enumerator
unspecified
any
state

id_kind

enum class fsm::id_kind : uint8_t

strong

Kinds for state_spec::state. unspecified is the poison default.

Enumerator
unspecified
state

initial_kind

enum class fsm::initial_kind : uint8_t

strong

Kinds for state_spec::initial. Default is leaf (no children).

Enumerator
leaf
start_at

on_kind

enum class fsm::on_kind : uint8_t

strong

Kinds for row::on. unspecified is the poison default.

Enumerator
unspecified
event

parent_kind

enum class fsm::parent_kind : uint8_t

strong

Kinds for state_spec::parent. unspecified is the poison default.

Enumerator
unspecified
root
child

status

enum class fsm::status : uint8_t

strong

Verdict category returned by machine::dispatch().

Refusal is the default: an event no table row matches yields status::unhandled rather than being silently dropped or deferred.

Enumerator
transitioned	A row matched and an external transition completed.
handled_internally	A row matched with target fsm::internal; no state change.
refused_by_row	An explicit fsm::refuse row matched; result carries its reason.
refused_guard	Row(s) matched (from, event) but every guard declined.
unhandled	No row considered this (state, event) pair at all.
refused_reentrant	dispatch() called from inside a guard/action; not allowed.
not_started	dispatch() before machine::start().

target_kind

enum class fsm::target_kind : uint8_t

strong

Kinds for row::to. unspecified is the poison default.

Enumerator
unspecified
to
internal_
refuse_

timeout_kind

enum class fsm::timeout_kind : uint8_t

strong

Kinds for state_spec::deadline. unspecified is the poison default.

Enumerator
unspecified
none
after_
after_dyn_

Function Documentation

accepted()

template<class State , class Event , class Reason >

constexpr bool fsm::accepted ( const result< State, Event, Reason > &  r )

constexpr

True when the event was acted on (transitioned or handled internally).

after()

template<class Event >

constexpr timeout_spec< Event > fsm::after ( uint32_t  ms, Event  e  )

constexpr

Declare "dispatch @p e after @p ms milliseconds in this state".

The deadline is stamped on state entry, disarmed on exit, and fired by machine::service() through the normal transition table — a timeout is just an event with the plumbing supplied.

after_dyn()

template<class Event >

constexpr timeout_spec< Event > fsm::after_dyn ( Event  e )

constexpr

Declare a dynamic deadline: duration read from the context at entry time instead of the table.

The traits must provide static uint32_t deadline_ms(State, const Context&) (compile error otherwise); it is consulted at every entry — including external self-transition re-entry — under the same reentrancy rules as entry hooks (pure read of the context; dispatch from it is refused). A returned 0 means "due now": the deadline arms at now and fires on the next service() call. Returns above half the Time range are clamped there (and assert in debug builds via FSM_DEADLINE_ASSERT). The fired event runs the normal table with a value-initialized Payload, exactly like fsm::after.

{.state = St::Pulsing, .parent = fsm::child_of(St::Seq),
 .deadline = fsm::after_dyn(Ev::PulseDone)},   // width from the profile
// in traits:
static uint32_t deadline_ms(St s, const Ctx& c) {
    return s == St::Pulsing ? c.profile.pulse_ms : 0;
}

child_of()

template<class State >

constexpr parent_spec< State > fsm::child_of ( State  s )

constexpr

Declare a state's parent in the hierarchy.

refuse()

template<class Reason >

constexpr detail::refuse_t< Reason > fsm::refuse ( Reason  r )

constexpr

Make a declarative refusal target carrying a reason.

Combine with guarded rows above it for the "guard chain with reasoned fallback" pattern: the first passing row wins; the trailing refuse row turns "all guards declined" into a reasoned verdict.

start_at()

template<class State >

constexpr initial_spec< State > fsm::start_at ( State  s )

constexpr

Declare the child entered when a composite state is targeted.

Required on every composite (a state that is some state's parent), forbidden on leaves — both validated at compile time.

to()

template<class State >

constexpr detail::to_t< State > fsm::to ( State  s )

constexpr

Make an external-transition target.

{.from = St::Arming, .on = Ev::Confirm, .to = fsm::to(St::Live)} 

write_dot()

template<class Traits , class W >

void fsm::write_dot

(

W &&

write

)

Emit a Graphviz digraph of Traits' machine through write.

Composite states become clusters, transition rows become edges labelled event [guard] /action, per-state timeouts become dashed self-annotations (after N ms: event), refuse rows point at an octagon refused sink, and fsm::any rows originate from a point node. Edges touching a composite anchor at its initial-descent leaf and clip at the cluster border via ltail/lhead. write is called once per line with a NUL-terminated string (no trailing newline); no allocation.

State/event names are emitted verbatim as Graphviz identifiers: keep them to [A-Za-z0-9_] (the default s<N>/e<N> fallback always is), avoid the reserved node names any and refused and dot keywords (node, edge, graph), and keep them short — each output line shares one fixed 224-byte buffer, and a truncated edge line is invalid dot.

Variable Documentation

any

constexpr any_t fsm::any {}

inlineconstexpr

Wildcard row source: matches any state, after all ancestor levels.

internal

constexpr internal_t fsm::internal {}

inlineconstexpr

Row target: handle the event (run the action) without exit/entry.

no_row

constexpr uint16_t fsm::no_row = 0xFFFF

inlineconstexpr

Sentinel row index meaning "no table row was involved".

no_timeout

constexpr no_timeout_t fsm::no_timeout {}

inlineconstexpr

State deadline declaration: this state has no timeout (explicitly).

root

constexpr root_t fsm::root {}

inlineconstexpr

Parent declaration: this state is a hierarchy root (no parent).