feat: add Builder pattern

lomakinae/docs/data/02/src/builder.py

@@ -0,0 +1,38 @@
+from abc import ABC, abstractmethod
+
+from .maze import Maze
+
+
+class MazeBuilder(ABC):
+    @abstractmethod
+    def build_from_file(self, filename: str) -> Maze:
+        pass
+
+
+class TextFileMazeBuilder(MazeBuilder):
+    def build_from_file(self, filename: str) -> Maze:
+        with open(filename, "r", encoding="utf-8") as f:
+            lines = [line.rstrip("\n") for line in f.readlines()]
+        height = len(lines)
+        width = max(len(line) for line in lines) if height > 0 else 0
+
+        start_count = 0
+        exit_count = 0
+        maze = Maze(width, height)
+
+        for y, line in enumerate(lines):
+            for x, ch in enumerate(line):
+                if ch == "#":
+                    maze.set_cell(x, y, "wall")
+                elif ch == "S":
+                    maze.set_cell(x, y, "start")
+                    start_count += 1
+                elif ch == "E":
+                    maze.set_cell(x, y, "exit")
+                    exit_count += 1
+                else:
+                    maze.set_cell(x, y, "path")
+
+        if start_count != 1 or exit_count != 1:
+            raise ValueError(f"S={start_count}, E={exit_count}")
+        return maze