algorithms/a_star.py

@@ -11,6 +11,10 @@ RIGHT = 'RIGHT'
 UP = 'UP'
 DOWN = 'DOWN'
 
+TURN_LEFT = 'TURN_LEFT'
+TURN_RIGHT = 'TURN_RIGHT'
+FORWARD = 'FORWARD'
+
 directions = {
     LEFT: (0, -1),
     RIGHT: (0, 1),
@@ -18,10 +22,6 @@ directions = {
     DOWN: (1, 0)
 }
 
-TURN_LEFT = 'TURN_LEFT'
-TURN_RIGHT = 'TURN_RIGHT'
-FORWARD = 'FORWARD'
-
 
 @dataclass
 class State:
@@ -93,8 +93,42 @@ def remove_forward(possible_actions: List[str]) -> None:
         possible_actions.remove(FORWARD)
 
 
-def result(state: State, action: str, grid: List[List[str]]) -> State:
-    pass
+def result(state: State, action: str) -> State:
+    new_state = State(state.position, state.direction)
+
+    if state.direction == UP:
+        if action == TURN_LEFT:
+            new_state.direction = LEFT
+        elif action == TURN_RIGHT:
+            new_state.direction = RIGHT
+        elif action == FORWARD:
+            new_state.position = next_position(state.position, UP)
+
+    elif state.direction == DOWN:
+        if action == TURN_LEFT:
+            new_state.direction = RIGHT
+        elif action == TURN_RIGHT:
+            new_state.direction = LEFT
+        elif action == FORWARD:
+            new_state.position = next_position(state.position, DOWN)
+
+    elif state.direction == LEFT:
+        if action == TURN_LEFT:
+            new_state.direction = DOWN
+        elif action == TURN_RIGHT:
+            new_state.direction = UP
+        elif action == FORWARD:
+            new_state.position = next_position(state.position, LEFT)
+
+    elif state.direction == RIGHT:
+        if action == TURN_LEFT:
+            new_state.direction = UP
+        elif action == TURN_RIGHT:
+            new_state.direction = DOWN
+        elif action == FORWARD:
+            new_state.position = next_position(state.position, RIGHT)
+
+    return new_state
 
 
 def goal_test(state: State, goal_list: List[Tuple[int, int]]) -> bool: