Extracting and testing generation emit and checksumming bits

conway/conway_test.go

@@ -452,3 +452,31 @@ func TestGameStateCellsCanHaveTheirValueSet(t *testing.T) {
 		}
 	}
 }
+
+func TestGameOfLifeEmitsGenerationTicksUntilStasis(t *testing.T) {
+	game, err := newTestGameOfLife()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	genTicks, err := game.Generations()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	nGens := 0
+
+	for gen := range genTicks {
+		if gen.N > 3000 {
+			t.Errorf("%v is too many generations!", gen.N)
+			return
+		}
+		nGens = gen.N
+	}
+
+	if nGens < 3 {
+		t.Errorf("%v is too few generations!", nGens)
+	}
+}

conway/conways-game-of-life/main.go

@@ -19,15 +19,6 @@ var (
 		"Millisecond sleep interval per generation")
 )
 
-func pushChecksum(checksum string, checksums []string) {
-	head := make([]string, 3)
-	copy(head, checksums[:3])
-	checksums[0] = checksum
-	checksums[1] = head[0]
-	checksums[2] = head[1]
-	checksums[3] = head[2]
-}
-
 func main() {
 	flag.Parse()
 
@@ -38,52 +29,32 @@ func main() {
 		os.Exit(2)
 	}
 
-	checksums := make([]string, 4)
-	checksums[0], checksums[1], checksums[2], checksums[3] = "foo", "bar", "baz", "qwx"
-	ck, err := game.Checksum()
+	genTicks, err := game.Generations()
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "NAY NAY: %v\n", err)
+		fmt.Fprintf(os.Stderr, "No generations?: %v\n", err)
 		os.Exit(3)
 	}
-	pushChecksum(ck, checksums)
 
-	ticks := time.Tick(time.Duration(*sleepMs) * time.Millisecond)
-	generations := 0
-	for now := range ticks {
-		fmt.Printf("\nGeneration %v\n%v\n", generations, now)
+	sleepInterval := time.Duration(*sleepMs * 1000 * 1000)
+	for genTick := range genTicks {
+		fmt.Printf("\nGeneration %v\n%v\n", genTick.N, time.Now())
 		fmt.Println(game)
 
 		game.EvaluateGeneration()
 
-		curChecksum, err := game.Checksum()
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "Failed to calculate current game checksum: %v\n", err)
+		if genTick.Error != nil {
+			fmt.Fprintf(os.Stderr, "%s: %s\n", genTick.Message, genTick.Error)
 			os.Exit(4)
 		}
 
-		if checksums[0] == curChecksum || checksums[1] == curChecksum {
-			fmt.Println("Stasis!")
-			os.Exit(0)
+		if len(genTick.Message) > 0 {
+			fmt.Println(genTick.Message)
 		}
 
-		if checksums[2] == curChecksum {
-			fmt.Println("Checksum found 2 periods ago")
-			fmt.Println("Stasis with 2-period oscillator(s)!")
-			os.Exit(0)
-		}
-
-		if checksums[3] == curChecksum {
-			fmt.Println("Checksum found 3 periods ago")
-			fmt.Println("Stasis with 3-period oscillator(s)!")
-			os.Exit(0)
-		}
-
-		pushChecksum(curChecksum, checksums)
-
-		if *mutate && generations%2 == 0 {
+		if *mutate && genTick.N%2 == 0 {
 			game.Mutate()
 		}
 
-		generations++
+		time.Sleep(sleepInterval)
 	}
 }

conway/game_of_life.go

@@ -117,3 +117,86 @@ func (game *GameOfLife) ImportRandomState() error {
 func (game *GameOfLife) String() string {
 	return fmt.Sprintf("%s\n", game.State)
 }
+
+func (game *GameOfLife) emitGenerations(genTicks chan *GenerationTick) {
+	defer close(genTicks)
+	n := 0
+
+	checksums := make([]string, 4)
+	checksums[0], checksums[1], checksums[2], checksums[3] = "foo", "bar", "baz", "qwx"
+	ck, err := game.Checksum()
+	if err != nil {
+		genTicks <- &GenerationTick{
+			N:       n,
+			Error:   err,
+			Message: "NAY NAY",
+		}
+	}
+	pushChecksum(ck, checksums)
+
+	for {
+		game.EvaluateGeneration()
+
+		curChecksum, err := game.Checksum()
+		if err != nil {
+			genTicks <- &GenerationTick{
+				N:       n,
+				Error:   err,
+				Message: "Failed to calculate current game checksum",
+			}
+			break
+		}
+
+		if checksums[0] == curChecksum || checksums[1] == curChecksum {
+			genTicks <- &GenerationTick{
+				N:       n,
+				Error:   nil,
+				Message: "Stasis!",
+			}
+			break
+		}
+
+		if checksums[2] == curChecksum {
+			genTicks <- &GenerationTick{
+				N:       n,
+				Error:   nil,
+				Message: "Stasis with 2-period oscillator(s)!",
+			}
+			break
+		}
+
+		if checksums[3] == curChecksum {
+			genTicks <- &GenerationTick{
+				N:       n,
+				Error:   nil,
+				Message: "Stasis with 3-period oscillator(s)!",
+			}
+			break
+		}
+
+		pushChecksum(curChecksum, checksums)
+
+		genTicks <- &GenerationTick{
+			N:       n,
+			Error:   nil,
+			Message: "",
+		}
+
+		n++
+	}
+}
+
+func (game *GameOfLife) Generations() (<-chan *GenerationTick, error) {
+	genTicks := make(chan *GenerationTick)
+	go game.emitGenerations(genTicks)
+	return (<-chan *GenerationTick)(genTicks), nil
+}
+
+func pushChecksum(checksum string, checksums []string) {
+	head := make([]string, 3)
+	copy(head, checksums[:3])
+	checksums[0] = checksum
+	checksums[1] = head[0]
+	checksums[2] = head[1]
+	checksums[3] = head[2]
+}

conway/generation_tick.go

@@ -0,0 +1,7 @@
+package conway
+
+type GenerationTick struct {
+	N       int
+	Error   error
+	Message string
+}