Add support for passing pathlib.Path objects to DockerfileParser(path=)

Add new attribute 'dockerfile' to the DockerfileParser class which exposes the path
to the dockerfile as a PathLib object
Add new property 'dockerfile_path' to the DockerfileParser class which exposes the
'dockerfile' attribute as a string for backwards compatibility

Signed-off-by: Ethan Paul <ethan.paul@portalinstruments.com>

Author: enpaul

dockerfile_parse/parser.py

@@ -9,8 +9,8 @@
 
 import json
 import logging
-import os
 import re
+from pathlib import Path
 from contextlib import contextmanager
 from shlex import quote
 
@@ -100,18 +100,19 @@ def __init__(self, path=None,
         """
 
         self.fileobj = fileobj
+        self.dockerfile = None
 
         if self.fileobj is not None:
             if path is not None:
                 raise ValueError("Parameters path and fileobj cannot be used together.")
             else:
                 self.fileobj.seek(0)
         else:
-            path = path or '.'
-            if path.endswith(DOCKERFILE_FILENAME):
-                self.dockerfile_path = path
+            path = Path(path) or Path.cwd()
+            if path.name.endswith(DOCKERFILE_FILENAME):
+                self.dockerfile = path
             else:
-                self.dockerfile_path = os.path.join(path, DOCKERFILE_FILENAME)
+                self.dockerfile = path / DOCKERFILE_FILENAME
 
         self.cache_content = cache_content
         self.cached_content = ''  # unicode string
@@ -149,9 +150,20 @@ def _open_dockerfile(self, mode):
             yield self.fileobj
             self.fileobj.seek(0)
         else:
-            with open(self.dockerfile_path, mode) as dockerfile:
+            with self.dockerfile.open(mode) as dockerfile:
                 yield dockerfile
 
+    @property
+    def dockerfile_path(self):
+        """
+        :return: Path to the Dockerfile as a string, or None if using fileobj
+        """
+        return str(self.dockerfile) if self.dockerfile else None
+    
+    @dockerfile_path.setter
+    def dockerfile_path(self, value):
+        self.dockerfile = Path(value) if value else None
+
     @property
     def lines(self):
         """