Move helper functions into Link

src/pip/_internal/download.py

@@ -100,7 +100,7 @@ if MYPY_CHECK_RUNNING:
 __all__ = ['get_file_content',
            'path_to_url',
            'unpack_vcs_link',
-           'unpack_file_url', 'is_file_url',
+           'unpack_file_url',
            'unpack_http_url', 'unpack_url',
            'parse_content_disposition', 'sanitize_content_filename']
 
@@ -602,23 +602,6 @@ def _get_used_vcs_backend(link):
     return None
 
 
-def is_file_url(link):
-    # type: (Link) -> bool
-    return link.url.lower().startswith('file:')
-
-
-def is_dir_url(link):
-    # type: (Link) -> bool
-    """Return whether a file:// Link points to a directory.
-
-    ``link`` must not have any other scheme but file://. Call is_file_url()
-    first.
-
-    """
-    link_path = link.file_path
-    return os.path.isdir(link_path)
-
-
 def _progress_indicator(iterable, *args, **kwargs):
     return iterable
 
@@ -849,7 +832,7 @@ def unpack_file_url(
     """
     link_path = link.file_path
     # If it's a url to a local directory
-    if is_dir_url(link):
+    if link.is_existing_dir():
         if os.path.isdir(location):
             rmtree(location)
         _copy_source_tree(link_path, location)
@@ -945,7 +928,7 @@ def unpack_url(
         unpack_vcs_link(link, location)
 
     # file urls
-    elif is_file_url(link):
+    elif link.is_file:
         unpack_file_url(link, location, download_dir, hashes=hashes)
 
     # http urls

src/pip/_internal/models/link.py

@@ -1,3 +1,4 @@
+import os
 import posixpath
 import re
 
@@ -180,6 +181,15 @@ class Link(KeyBasedCompareMixin):
         # type: () -> Optional[str]
         return posixpath.basename(self._url.split('#', 1)[0].split('?', 1)[0])
 
+    @property
+    def is_file(self):
+        # type: () -> bool
+        return self.scheme == 'file'
+
+    def is_existing_dir(self):
+        # type: () -> bool
+        return self.is_file and os.path.isdir(self.file_path)
+
     @property
     def is_wheel(self):
         # type: () -> bool

src/pip/_internal/operations/prepare.py

@@ -13,7 +13,7 @@ from pip._internal.distributions import (
     make_distribution_for_install_requirement,
 )
 from pip._internal.distributions.installed import InstalledDistribution
-from pip._internal.download import is_dir_url, is_file_url, unpack_url
+from pip._internal.download import unpack_url
 from pip._internal.exceptions import (
     DirectoryUrlHashUnsupported,
     HashUnpinned,
@@ -160,7 +160,7 @@ class RequirementPreparer(object):
                 # hash provided.
                 if link.is_vcs:
                     raise VcsHashUnsupported()
-                elif is_file_url(link) and is_dir_url(link):
+                elif link.is_existing_dir():
                     raise DirectoryUrlHashUnsupported()
                 if not req.original_link and not req.is_pinned:
                     # Unpinned packages are asking for trouble when a new