Cells can have their values set when ranging over them

plus more replacement of y, x loops with cell ranges, adding static
neighbor coords.

conway/conway_test.go

@@ -377,14 +377,78 @@ func TestStateCanMutate(t *testing.T) {
 		return
 	}
 
-	curCksum := state.Checksum()
+	curCksum, err := state.Checksum()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
 	err = state.Mutate()
 	if err != nil {
 		t.Error(err)
 		return
 	}
 
-	if curCksum == state.Checksum() {
+	newCksum, err := state.Checksum()
-		t.Errorf("Checksum did not change! %v", curCksum)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	if curCksum == newCksum {
+		t.Errorf("Checksum did not change! %v", newCksum)
+	}
+}
+
+func TestStateProvidesCellIteratorChannel(t *testing.T) {
+	state, err := newTestGameState()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	cells, err := state.Cells()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	cellCount := 0
+	for _ = range cells {
+		cellCount++
+	}
+
+	if cellCount != 256 {
+		t.Fail()
+	}
+}
+
+func TestGameStateCellsCanHaveTheirValueSet(t *testing.T) {
+	state, err := newTestGameState()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	cells, err := state.Cells()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	for cell := range cells {
+		cell.SetValue(1)
+	}
+
+	cells, err = state.Cells()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	for cell := range cells {
+		if cell.Value != 1 {
+			t.Fail()
+		}
 	}
 }

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

@@ -40,7 +40,12 @@ func main() {
 
 	checksums := make([]string, 4)
 	checksums[0], checksums[1], checksums[2], checksums[3] = "foo", "bar", "baz", "qwx"
-	pushChecksum(game.Checksum(), checksums)
+	ck, err := game.Checksum()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "NAY NAY: %v\n", err)
+		os.Exit(3)
+	}
+	pushChecksum(ck, checksums)
 
 	ticks := time.Tick(time.Duration(*sleepMs) * time.Millisecond)
 	generations := 0
@@ -50,7 +55,11 @@ func main() {
 
 		game.EvaluateGeneration()
 
-		curChecksum := game.Checksum()
+		curChecksum, err := game.Checksum()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Failed to calculate current game checksum: %v\n", err)
+			os.Exit(4)
+		}
 
 		if checksums[0] == curChecksum || checksums[1] == curChecksum {
 			fmt.Println("Stasis!")

conway/game_of_life.go

@@ -15,10 +15,28 @@ const (
 	LIVE_CELL = " "
 )
 
+var (
+	neighbors = []neighbor{
+		neighbor{-1, -1},
+		neighbor{-1, 0},
+		neighbor{-1, 1},
+		neighbor{0, -1},
+		neighbor{0, 1},
+		neighbor{1, -1},
+		neighbor{1, 0},
+		neighbor{1, 1},
+	}
+)
+
 func init() {
 	rand.Seed(time.Now().UTC().UnixNano())
 }
 
+type neighbor struct {
+	X int
+	Y int
+}
+
 type GameOfLife struct {
 	State *GameState
 }
@@ -27,6 +45,7 @@ type GameStateCell struct {
 	Value int
 	X     int
 	Y     int
+	cols  []int
 }
 
 type gameGridRow struct {
@@ -124,31 +143,43 @@ func (state *GameState) Import(other *GameState) (err error) {
 	return nil
 }
 
-func (state *GameState) Cells(cells chan *GameStateCell) error {
+func (state *GameState) Cells() (<-chan *GameStateCell, error) {
 	height := state.Height()
 	width := state.Width()
 
 	if height < 0 || width < 0 {
-		return errors.New("state has invalid dimensions!")
+		return nil, errors.New("state has invalid dimensions!")
 	}
 
-	defer close(cells)
+	cells := make(chan *GameStateCell)
+
+	go func(state *GameState, c chan *GameStateCell) {
+		defer close(c)
+		height := state.Height()
+		width := state.Width()
 
 		for y := 0; y < height; y++ {
+			row, err := state.GetRow(y)
+			if err != nil {
+				panic(err)
+			}
+
 			for x := 0; x < width; x++ {
 				value, err := state.Get(x, y)
 				if err != nil {
 					panic(err)
 				}
-			cells <- &GameStateCell{
+				c <- &GameStateCell{
 					Value: value,
 					X:     x,
 					Y:     y,
+					cols:  row.Cols,
 				}
 			}
 		}
+	}(state, cells)
 
-	return nil
+	return (<-chan *GameStateCell)(cells), nil
 }
 
 func (game *GameOfLife) Mutate() error {
@@ -169,20 +200,21 @@ func (state *GameState) Mutate() error {
 	return nil
 }
 
-func (game *GameOfLife) Checksum() string {
+func (game *GameOfLife) Checksum() (string, error) {
 	return game.State.Checksum()
 }
 
-func (state *GameState) Checksum() string {
+func (state *GameState) Checksum() (string, error) {
 	ck := sha1.New()
-	cells := make(chan *GameStateCell)
+	cells, err := state.Cells()
-
+	if err != nil {
-	go state.Cells(cells)
+		return "", err
+	}
 
 	for cell := range cells {
 		fmt.Fprintf(ck, "%v", cell.Value)
 	}
-	return fmt.Sprintf("%x", ck.Sum(nil))
+	return fmt.Sprintf("%x", ck.Sum(nil)), nil
 }
 
 func NewGameOfLife(height, width int) *GameOfLife {
@@ -197,14 +229,15 @@ func (game *GameOfLife) EvaluateGeneration() error {
 	genScore := NewGenerationScoreCard(height, width)
 	genScore.Calculate(game.State)
 
-	for y := 0; y < height; y++ {
+	cells, err := genScore.Cells()
-		for x := 0; x < width; x++ {
-			score, err := genScore.Get(x, y)
 	if err != nil {
 		return err
 	}
 
-			curState, err := game.State.Get(x, y)
+	for cell := range cells {
+		score := cell.Value
+
+		curState, err := game.State.Get(cell.X, cell.Y)
 		if err != nil {
 			return err
 		}
@@ -212,7 +245,7 @@ func (game *GameOfLife) EvaluateGeneration() error {
 		if curState == 1 {
 
 			if score < 2 {
-					err = game.State.Deaden(x, y)
+				err = game.State.Deaden(cell.X, cell.Y)
 				if err != nil {
 					return err
 				}
@@ -224,7 +257,7 @@ func (game *GameOfLife) EvaluateGeneration() error {
 			}
 
 			if score > 3 {
-					err = game.State.Deaden(x, y)
+				err = game.State.Deaden(cell.X, cell.Y)
 				if err != nil {
 					return err
 				}
@@ -233,7 +266,7 @@ func (game *GameOfLife) EvaluateGeneration() error {
 		} else if curState == 0 {
 
 			if score == 3 {
-					err = game.State.Enliven(x, y)
+				err = game.State.Enliven(cell.X, cell.Y)
 				if err != nil {
 					return err
 				}
@@ -243,7 +276,6 @@ func (game *GameOfLife) EvaluateGeneration() error {
 			}
 		}
 	}
-	}
 
 	return nil
 }
@@ -264,13 +296,13 @@ func (game *GameOfLife) ImportRandomState() error {
 
 	randState := NewGameState(height, width)
 
-	for y := 0; y < height; y++ {
+	cells, err := randState.Cells()
-		for x := 0; x < width; x++ {
-			err := randState.Set(x, y, rand.Intn(2))
 	if err != nil {
 		return err
 	}
-		}
+
+	for cell := range cells {
+		cell.SetValue(rand.Intn(2))
 	}
 
 	return game.ImportState(randState)
@@ -280,6 +312,10 @@ func (game *GameOfLife) String() string {
 	return fmt.Sprintf("%s\n", game.State)
 }
 
+func (cell *GameStateCell) SetValue(value int) {
+	cell.cols[cell.X] = value
+}
+
 func (state *GameState) String() string {
 	var rows []string
 
@@ -319,19 +355,20 @@ func NewGenerationScoreCard(height, width int) *GenerationScoreCard {
 }
 
 func (genScore *GenerationScoreCard) Calculate(state *GameState) error {
-	stateHeight, stateWidth := state.Height(), state.Width()
+	stateWidth := state.Width()
-	for y := 0; y < stateHeight; y++ {
+	stateCells, err := state.Cells()
-		for x := 0; x < stateWidth; x++ {
-			value, err := state.Get(x, y)
 	if err != nil {
 		return err
 	}
 
-			if value == 1 {
+	for stateCell := range stateCells {
-				for yOffset := -1; yOffset < 2; yOffset++ {
+		if stateCell.Value == 0 {
-					for xOffset := -1; xOffset < 2; xOffset++ {
+			continue
-						xTarget := x + xOffset
+		}
-						yTarget := y + yOffset
+
+		for _, neighbor := range neighbors {
+			xTarget := stateCell.X + neighbor.X
+			yTarget := stateCell.Y + neighbor.Y
 
 			if xTarget < 0 || yTarget < 0 {
 				continue
@@ -341,23 +378,17 @@ func (genScore *GenerationScoreCard) Calculate(state *GameState) error {
 				continue
 			}
 
-						if xTarget == x && yTarget == y {
+			curScore, err := genScore.Get(xTarget, yTarget)
+			if err != nil {
 				continue
 			}
 
-						curScore, err := genScore.Get(xTarget, yTarget)
-						if err != nil {
-							continue // assume out of bounds, which is stinky
-						}
 			err = genScore.Set(xTarget, yTarget, curScore+1)
 			if err != nil {
 				return err
 			}
 		}
 	}
-			}
-		}
-	}
 
 	return nil
 }