Documentation
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Overview ¶
Package fsm provides generic helpers for map-based finite-state-machine transition tables used by kernel state machines. A transition table maps each state to the states reachable from it. A terminal state has no outgoing edges: it may be either absent from the table (lookup miss → nil slice) or present with an explicit empty slice — both deny all transitions identically (slices.Contains over nil and []S{} is false). kernel/outbox uses the explicit-empty-key form so OUTBOX-STATE-TRANSITION-COMPLETENESS-01 can require every State const to be a key; kernel/saga uses the absent form. Either is valid.
kernel/saga uses these helpers. kernel/command predates this package and still inlines the same lookup/defensive-copy bodies; migrating it is a candidate cleanup (it must be done without dropping command below the 90% kernel coverage gate, since the removed lines are fully covered). Tracked in gh issue #936.
The helpers are intentionally tiny and type-agnostic: per-state-machine concerns — the Status enum, its String/Valid/IsTerminal methods, and the package-specific Transition error message — stay in the owning package. This removes the duplicated lookup/defensive-copy boilerplate without flattening the distinct state machines into one type.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
func AllowedTargets ¶
func AllowedTargets[S comparable](table map[S][]S, from S) []S
AllowedTargets returns a defensive copy of the states reachable from `from`, or nil when there are none (terminal or unknown state). Mutating the result does not affect table.
func CanTransition ¶
func CanTransition[S comparable](table map[S][]S, from, to S) bool
CanTransition reports whether table permits a transition from → to. A state with no outgoing edges (absent from table, or present with an empty slice — e.g. a terminal state) permits no transitions.
Types ¶
This section is empty.
Source Files