Simple state machine

Author: gmulders

src/main/kotlin/nl/fifthpostulate/statemachine/StateMachine.kt

@@ -0,0 +1,47 @@
+package nl.fifthpostulate.statemachine
+
+import nl.fifthpostulate.FizzBuzz
+
+sealed class State : FizzBuzz {
+    lateinit var next: State
+}
+class FizzState : State() {
+    override fun of(n: Int): String = "Fizz"
+}
+class BuzzState : State() {
+    override fun of(n: Int): String = "Buzz"
+}
+class FizzBuzzState : State() {
+    override fun of(n: Int): String = "FizzBuzz"
+}
+class NumberState : State() {
+    override fun of(n: Int): String = n.toString()
+}
+
+fun buildStates(): State {
+    val l = listOf(
+        FizzBuzzState(), NumberState(), NumberState(), FizzState(), NumberState(),
+        BuzzState(), FizzState(), NumberState(), NumberState(), FizzState(),
+        BuzzState(), NumberState(), FizzState(), NumberState(), NumberState(),
+    )
+
+    var state = l.first()
+    for (s in l.drop(1)) {
+        state.next = s
+        state = s
+    }
+    state.next = l.first()
+
+    return l.first()
+}
+
+class StateMachine : FizzBuzz {
+    private val start = buildStates()
+    override fun of(n: Int): String {
+        var state = start
+        repeat(n) {
+            state = state.next
+        }
+        return state.of(n)
+    }
+}

src/test/kotlin/nl/fifthpostulate/FizzBuzzTest.kt

@@ -5,9 +5,9 @@ import nl.fifthpostulate.radix.Radix
 import nl.fifthpostulate.radix.UnrollWithMap
 import nl.fifthpostulate.radix.UnrollWithWhen
 import nl.fifthpostulate.standard.Standard
+import nl.fifthpostulate.statemachine.StateMachine
 import org.junit.jupiter.api.BeforeEach
 import kotlin.random.Random
-import kotlin.random.nextInt
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
@@ -23,6 +23,7 @@ class FizzBuzzTest {
             UnrollWithWhen(),
             UnrollWithMap(),
             CastingNines(),
+            StateMachine(),
             )
     }