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(ns statecharts
(:require [clojure.set :as set]))
(def states
(-> (make-hierarchy)
(derive ::update ::displays)
(derive ::wait ::displays)
(derive ::time ::displays)
(derive ::date ::displays)
(derive ::alarm1 ::displays)
(derive ::alarm2 ::displays)
(derive ::chime ::displays)
(derive ::stopwatch ::displays)
(derive ::update1 ::displays)
(derive ::update2 ::displays)
(derive ::alarm1-off ::alarm1)
(derive ::alarm1-on ::alarm1)
(derive ::alarm2-off ::alarm2)
(derive ::alarm2-on ::alarm2)
(derive ::chime-on ::chime)
(derive ::chime-off ::chime)))
(def transitions
{::wait {::2-sec-in-wait ::update
::hat-c ::time}
::update {::b ::time}
::time {::a ::alarm1
::c ::wait
::d ::date}
::date {::d ::time
::2-min-in-date ::time}
::alarm1 {::a ::alarm2
::c ::update1}
::alarm1-off {::d ::alarm1-on}
::alarm1-on {::d ::alarm1-off}
::alarm2 {::c ::update2
::a ::chime}
::chime {::a ::stopwatch}
::stopwatch {::a ::time}
::update1 {::b ::alarm1}
::update2 {::b ::alarm2}
::alarm2-off {::d ::alarm2-on}
::alarm2-on {::d ::alarm2-off}
::chime-on {::d ::chime-off}
::chime-off {::d ::chime-on}})
(def initial-states
{::displays ::time
::chime ::chime-off
::alarm1 ::alarm1-off
::alarm2 ::alarm2-off})
(defn state-descendants [s] (into #{s} (descendants states s)))
(defn state-ancestors [s] (into #{s} (ancestors states s)))
(defn do-step
[fsm from to]
(let [leaving-set (set/intersection fsm (state-descendants from))
entering-set (state-ancestors to)
entering-set (set/difference entering-set fsm)
entering-set (into entering-set (keep initial-states entering-set))]
{:fsm' (-> fsm
(disj leaving-set)
(conj entering-set))
:leaving-set leaving-set
:entering-set entering-set}))
(let [fsm #{::displays ::alarm2 ::alarm2-on}
txns (mapcat (comp keys transitions) fsm)]
(println "before: " fsm)
(doseq [t txns]
(doseq [from fsm]
(when-let [to (get-in transitions [from t])]
(clojure.pprint/pprint
{:from from
:txn t
:to to
:step (do-step fsm from to)})))))
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