e.g. add an enemy type

buffer.go

@@ -131,8 +131,11 @@ func isCharHunter(x, y int) bool {
 func isCharGhost(x, y int) bool {
 	return isChar(x, y, chGhost)
 }
+func isCharAssassin(x, y int) bool {
+	return isChar(x, y, chAssassin)
+}
 func isCharEnemy(x, y int) bool {
-	return isCharHunter(x, y) || isCharGhost(x, y)
+	return isCharHunter(x, y) || isCharGhost(x, y) || isCharAssassin(x, y)
 }
 func isCharSpace(x, y int) bool {
 	return isChar(x, y, chSpace)

enemy.go

@@ -34,6 +34,9 @@ type hunter struct {
 type ghost struct {
 	enemy
 }
+type assassin struct {
+	enemy
+}
 
 type strategy interface {
 	eval(p *player, x, y int) float64
@@ -148,6 +151,7 @@ type iEnemyBuilder interface {
 	movable(func(int, int) bool) iEnemyBuilder
 	defaultHunter() iEnemyBuilder
 	defaultGhost() iEnemyBuilder
+	defaultAssassin() iEnemyBuilder
 	build() iEnemy
 }
 type enemyBuilder struct {
@@ -169,6 +173,8 @@ func (eb *enemyBuilder) displayFormat(r rune, s string) iEnemyBuilder {
 		eb.color = termbox.ColorRed
 	case "CYAN":
 		eb.color = termbox.ColorCyan
+	case "DARK_GRAY":
+		eb.color = termbox.ColorDarkGray
 	}
 	return eb
 }
@@ -198,6 +204,12 @@ func (eb *enemyBuilder) defaultGhost() iEnemyBuilder {
 	}
 	return eb.displayFormat(chGhost, "CYAN").speed(2).movable(fn).strategize(&assault{})
 }
+func (eb *enemyBuilder) defaultAssassin() iEnemyBuilder {
+	fn := func(x, y int) bool {
+		return !isCharWall(x, y) && !isCharEnemy(x, y)
+	}
+	return eb.displayFormat(chAssassin, "DARK_GRAY").speed(1).movable(fn).strategize(&assault{})
+}
 
 func newEnemyBuilder() iEnemyBuilder {
 	return &enemyBuilder{}

files/stage/map01.txt

@@ -9,7 +9,7 @@
 +    oooo!ooooooooo!oooo    +
 +      oooooo!!!oooooo      +
 +        ooooooooooo        +
-+ oooo     ooooooo    Hoooo +
++ oooo     ooooooo    Aoooo +
 + oooo       ooo       oooo +
 + oooo        o        oooo +
 +++++++++++++++++++++++++++++

main.go

@@ -25,6 +25,7 @@ const (
 	chPlayer    = 'P'
 	chHunter    = 'H'
 	chGhost     = 'G'
+	chAssassin  = 'A'
 	chApple     = 'o'
 	chSpace     = ' '
 	chPoison    = 'X'

stage.go

@@ -10,23 +10,25 @@ import (
 )
 
 type stage struct {
-	level         int
-	mapPath       string
-	hunterBuilder iEnemyBuilder
-	ghostBuilder  iEnemyBuilder
-	enemies       []iEnemy
-	gameSpeed     time.Duration
-	width         int
-	height        int
+	level           int
+	mapPath         string
+	hunterBuilder   iEnemyBuilder
+	ghostBuilder    iEnemyBuilder
+	assassinBuilder iEnemyBuilder // The only change is here.
+	enemies         []iEnemy
+	gameSpeed       time.Duration
+	width           int
+	height          int
 }
 
 func initStages() []stage {
 	return []stage{
 		{
-			level:         1,
-			mapPath:       "files/stage/map01.txt",
-			hunterBuilder: newEnemyBuilder().defaultHunter(),
-			gameSpeed:     1250 * time.Millisecond,
+			level:           1,
+			mapPath:         "files/stage/map01.txt",
+			hunterBuilder:   newEnemyBuilder().defaultHunter(),
+			assassinBuilder: newEnemyBuilder().defaultAssassin(), // The only change is here.
+			gameSpeed:       1250 * time.Millisecond,
 		},
 		{
 			level:         2,
@@ -121,6 +123,12 @@ func (s *stage) plot(b *buffer, p *player) {
 				char, color := g.getDisplayFormat()
 				termbox.SetCell(x, y, char, color, color)
 				s.enemies = append(s.enemies, g)
+			} else if isCharAssassin(x, y) {
+				a := s.assassinBuilder.build()
+				a.setPosition(x, y)
+				char, color := a.getDisplayFormat()
+				termbox.SetCell(x, y, char, color, color)
+				s.enemies = append(s.enemies, a)
 			}
 		}
 	}