Convert to base class to faciliate inheritance

aoc2024/src/day15/python/solution.py

@@ -11,24 +11,24 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from typing import Sequence
+from typing import Sequence, override
 
 type WarehouseMap = Sequence[Sequence[str]]
 type Position = tuple[int, int]  # (x,y)
 type Direction = tuple[int, int]  # (x,y)
-_ROBOT = '@'
-_BOX = 'O'
-_WALL = '#'
-_EMPTY = '.'
-_DIR_TO_OPPOSITE = {
-  (0, 1): (0, -1),  # Right to left.
-  (0, -1): (0, 1),  # Left to right.
-  (-1, 0): (1, 0),  # Up to down.
-  (1, 0): (-1, 0),  # Down to up.
-}
-
-
-class Warehouse:
+
+
+class BaseWarehouse:
+  _ROBOT = '@'
+  _WALL = '#'
+  _EMPTY = '.'
+  _DIR_TO_OPPOSITE = {
+    (0, 1): (0, -1),  # Right to left.
+    (0, -1): (0, 1),  # Left to right.
+    (-1, 0): (1, 0),  # Up to down.
+    (1, 0): (-1, 0),  # Down to up.
+  }
+
   def __init__(self, warehouse_map: WarehouseMap, robot_moves: Sequence[Position]):
     self._warehouse_map: list[list[str]] = [list(line) for line in warehouse_map]
     self._width = len(self._warehouse_map[0])
@@ -44,25 +44,23 @@ def simulate(self) -> None:
       self._next_move_index += 1
 
   def sum_all_boxes_gps_coordinates(self) -> int:
-    """Returns the sum of all the boxes' GPS coordinates.
-    A box GPS coordinate is 100 times its distance from the top edge of the
-    warehouse plus its distance from the left edge of the map.
-    """
-    result = 0
-    for y in range(self._height):
-      for x in range(self._width):
-        if self._charAt(pos=(x, y)) == _BOX:
-          result += 100 * y + x
-    return result
+    raise NotImplementedError()
 
   def _find_robot_pos(self) -> Position:
     """Returns the position of the robot."""
     for y in range(self._height):
       for x in range(self._width):
-        if self._warehouse_map[y][x] == _ROBOT:
+        if self._warehouse_map[y][x] == self._ROBOT:
           return x, y
     raise ValueError('Robot not found!')
 
+  def _move_robot(self) -> None:
+    """Attempts to move robot one step. If the robot cannot move, it is a NOP."""
+    raise NotImplementedError()
+
+  def _push(self, pos: Position, dir: Direction) -> None:
+    raise NotImplementedError()
+
   def _charAt(self, pos: Position) -> str:
     """Returns what element is on the warehouse at a given position."""
     return self._warehouse_map[pos[1]][pos[0]]
@@ -71,48 +69,67 @@ def _update(self, pos: Position, value: str) -> None:
     """Updates a warehouse position with a given element."""
     self._warehouse_map[pos[1]][pos[0]] = value
 
+  def _within_bounds(self, pos: Position):
+    """Returns true if a position is within warehouse bounds."""
+    return 0 <= pos[0] < self._width and 0 <= pos[1] < self._height
+
+
+class Warehouse(BaseWarehouse):
+  _BOX = 'O'
+
+  @override
+  def sum_all_boxes_gps_coordinates(self) -> int:
+    """Returns the sum of all the boxes' GPS coordinates.
+    A box GPS coordinate is 100 times its distance from the top edge of the
+    warehouse plus its distance from the left edge of the map.
+    """
+    result = 0
+    for y in range(self._height):
+      for x in range(self._width):
+        if self._charAt(pos=(x, y)) == self._BOX:
+          result += 100 * y + x
+    return result
+
+  @override
   def _move_robot(self) -> None:
     """Attempts to move robot one step. If the robot cannot move, it is a NOP."""
     next_move = self._robot_moves[self._next_move_index]
     next_pos = (self._robot_pos[0] + next_move[0], self._robot_pos[1] + next_move[1])
-    if self._charAt(next_pos) == _EMPTY:
-      self._update(self._robot_pos, _EMPTY)
+    if self._charAt(next_pos) == self._EMPTY:
+      self._update(self._robot_pos, self._EMPTY)
       self._robot_pos = next_pos
-      self._update(self._robot_pos, _ROBOT)
-    elif self._charAt(next_pos) == _BOX:
+      self._update(self._robot_pos, self._ROBOT)
+    elif self._charAt(next_pos) == self._BOX:
       self._push(pos=next_pos, dir=next_move)
-      if self._charAt(next_pos) == _EMPTY:
-        self._update(self._robot_pos, _EMPTY)
+      if self._charAt(next_pos) == self._EMPTY:
+        self._update(self._robot_pos, self._EMPTY)
         self._robot_pos = next_pos
-        self._update(self._robot_pos, _ROBOT)
+        self._update(self._robot_pos, self._ROBOT)
 
-  def _within_bounds(self, pos: Position):
-    """Returns true if a position is within warehouse bounds."""
-    return 0 <= pos[0] < self._width and 0 <= pos[1] < self._height
+  @override
+  def _push(self, pos: Position, dir: Direction) -> None:
+    """Attempts to push boxes from given position towards given direction.
+    If there is no space to move boxes, it is a NOP."""
+    next_empty_pos = self._find_next_empty_pos(pos, dir)
+    if next_empty_pos is not None:
+      next_pos = next_empty_pos
+      while next_pos != pos:
+        self._update(next_pos, self._BOX)
+        opposite_dir = self._DIR_TO_OPPOSITE.get(dir)
+        next_pos = (next_pos[0] + opposite_dir[0], next_pos[1] + opposite_dir[1])
+      self._update(pos, self._EMPTY)
 
   def _find_next_empty_pos(self, pos: Position, dir: Direction) -> Position | None:
     """Returns the next empty space from a position towards a given direction."""
     while self._within_bounds(pos):
-      if self._charAt(pos) == _WALL:
+      if self._charAt(pos) == self._WALL:
         return None  # We hit a wall before an empty space.
-      if self._charAt(pos) == _EMPTY:
+      if self._charAt(pos) == self._EMPTY:
         return pos
       pos = (pos[0] + dir[0], pos[1] + dir[1])
     # Empty space was not found.
     return None
 
-  def _push(self, pos: Position, dir: Direction) -> None:
-    """Attempts to push boxes from given position towards given direction.
-    If there is no space to move boxes, it is a NOP."""
-    next_empty_pos = self._find_next_empty_pos(pos, dir)
-    if next_empty_pos is not None:
-      next_pos = next_empty_pos
-      while next_pos != pos:
-        self._update(next_pos, _BOX)
-        opposite_dir = _DIR_TO_OPPOSITE.get(dir)
-        next_pos = (next_pos[0] + opposite_dir[0], next_pos[1] + opposite_dir[1])
-      self._update(pos, _EMPTY)
-
 
 def _parse(input: Sequence[str]) -> tuple[WarehouseMap, Sequence[Position]]:
   """Parses the input and returns the warehouse map and sequence of robot moves."""