Extract Location into separate file

PFERD/location.py

@@ -0,0 +1,37 @@
+from pathlib import Path, PurePath
+
+
+class ResolveException(Exception):
+    """An exception while resolving a file."""
+    # TODO take care of this when doing exception handling
+
+
+class Location:
+    """
+    An object that has an inherent path.
+    """
+
+    def __init__(self, path: Path):
+        self._path = path.resolve()
+
+    @property
+    def path(self) -> Path:
+        """
+        This object's location.
+        """
+
+        return self._path
+
+    def resolve(self, target: PurePath) -> Path:
+        """
+        Resolve a file relative to the path of this location.
+
+        Raises a [ResolveException] if the file is outside the given directory.
+        """
+        absolute_path = self.path.joinpath(target).resolve()
+
+        # TODO Make this less inefficient
+        if self.path not in absolute_path.parents:
+            raise ResolveException(f"Path {target} is not inside directory {self.path}")
+
+        return absolute_path